3C Neuro Flashcards

Question

There are 4 types of intracranial haemorrhage, what are they are the location of the bleed (layers)

Answer 1

- Extradural haemorrhage - *bleeding between the skull and dura mater* - Subdural haemorrhage - *bleeding between the dura mater and arachnoid mater* - Intracerebral haemorrhage - *bleeding within brain tissue* - Subarachnoid haemorrhage - *bleeding in the subarachnoid space (space between arachnoid mater and pia mater)*

Answer 2

Extradural haemorrhage —>symptoms get worse over hours as the haematoma increases in size & compresses the intracranial contents - bi-convex shape (’lemon’) - limited by the cranial sutures (they do not cross the sutures, which are the points where the skull bones join together)

Answer 3

Middle meningeal artery in the temporoparietal region (can be associated with a fracture of the temporal bone) - vulnerable as it runs close to the inner surface of the skull, particularly beneath the pterion (a region where the skull is thin and therefore more susceptible to fractures)

Answer 4

Subdural haemorrhage - CT scan —> crescent shape (’banana’) and are not limited by the cranial sutures (they can cross over the sutures)

Answer 5

Due to brain shrinkage (atrophy) --> stretches the bridging veins, making them more vulnerable to rupture, even with minor head injuries

Answer 6

- Acute subdural haematoma --> acute blood appears hyperdense (bright) & are more serious - Chronic subdural haematoma --> chronic blood appears hypodense (dark) & often have a better prognosis

Answer 7

Intracerebral haemorrhage (note: presents similarly to an ischaemic stroke)

Answer 8

- Immediate CT head —> to establish diagnosis - Bloods —> FBC (for platelets) and a coagulation screen . 1. Admission to a specialist stroke centre/neurosurgery - If GCS decreased --> consider intubation, ventialtion, and intensive care - Address any bleeding risk --> *reversal agents for anticoagulation, platelet transfusions* - Correct severe hypertension, but avoid hypotension - Surgical decompression options --> *craniotomy (section of skull removed), Burr holes (small holes drilled into skull to drain blood)*

Answer 9

- Warfarin --> *PCC (prothrombin complex concentrate) for rapid reversal + Vitamin K* - Heparin/LMWH --> *protamine sulfate* - Apixaban, edoxaban, and rivaroxaban --> *andexanet alfa* - Dabigatran --> *idarucizunab*

Answer 10

- Traumatic SAH (ie. head injury) --> most common - Spontaneous SAH (in the absence of trauma) --> saccular ("berry") aneurysms account for 85%

Answer 11

1. Severe sudden-onset occipital headache —> “thunderclap” or “hit with a baseball bat” - typically peaking in intensity within 1 to 5 minutes - there may be a history of a less-severe ‘sentinel’ headache in the weeks prior to presentation - Nausea/vomiting - Meningism —> photophobia, neck stiffness - Neurological symptoms —> visual changes, dysphasia, focal weakness, seizures, reduced GCS - **Dilation of pupil**

Answer 12

brain injury/bleed has compressed the oculomotor nerve (loss of parasympathetic innervation to the pupil, causing it to dilate due to unopposed sympathetic activity)

Answer 13

1. Non-contrast CT head is 1st-line - if CT done <6hrs of symptom onset & is normal —> guidelines suggest NOT doing a lumbar puncture (consider alternative diagnosis) - if CT done >6hrs after symptom onset & is normal —> guidelines suggest TO DO a lumbar puncture 2. Lumbar puncture —> should be performed at least 12hrs following the onset of symptoms 3. CT angiogram —> used after confirming diagnosis to locate the source of the bleeding/look for aneurysms 4. Fundoscopy —> may show a pre-retinal haemorrhage (Terson's syndrome)

Answer 14

to allow for development of xanthochromia (result of RBC breakdown - bilirubin) - have to wait >12 hrs to allow for RBCs to be broken down, releasing their oxygen-carrying molecule haem - haem is further metabolised by enzymes in the CSF to form bilirubin

Answer 15

Terson’s syndrome → where intraocular haemorrhage (bleeding within the eye) occurs due to a sudden increase in intracranial pressure, often associated with subarachnoid haemorrhage or other forms of intracranial bleeding

Answer 16

- 4 tubes are used (glucose/protein/WCC/culture) —> 1st and last samples both check for blood (if traumatic tap then blood in 1st but not last sample) . CSF findings: - Appearance: blood-stained initially, with xanthochromia (yellowish) >12hrs later - WBC: elevated (WBC:RBC ratio of approx. 1:1000) - RBC: elevated (>2000 cells/µL) - Protein: elevated - Glucose: normal - Opening pressure: normal/high

Answer 17

1. Supportive - bed rest & analgesia - **VTE prophylaxis** (wait 24-48hrs after stabilising a spontaneous SAH) - **STOP anticoagulation** —> reversal if needed - important to monitor **sodium** —> due to risk of hyponatraemia - **regular neurological observations** —> important to monitor for signs of **raised ICP** (GCS, pupils, vita signs, monitor for raised ICP - eg. **Cushing's reflex**) 2. **Nimodipine** (calcium channel blocker) —> used to prevent **vasospasm** + secondary ischaemia 3. Surgical intervention —> **endovascular coiling** (by interventional neuroradiologists) (a minority require a craniotomy and clipping by a neurosurgeon)

Answer 18

- Re-bleeding —> happens in around 10% of cases and most common in the first 12 hours - Hydrocephalus —> increased CSF, causing expansion of the ventricles - Cerebral oedema —> causing raised ICP - Vasospasm (also termed delayed cerebral ischaemia), typically 7-14 days after onset - Hyponatraemia —> most typically due to syndrome inappropriate anti-diuretic hormone (SIADH) (can exacerbate cerebral oedema, increase ICP, and worsen outcome) - Seizures —> anti-epileptic drugs

Answer 19

- Raccoon eyes (periorbital ecchymosis) --> bruising around the eyes - Battle sign (postauricular ecchymosis) --> bruising behind the ear

Answer 20

CSF leak due to a tear in the dura mater, commonly from a basilar skull fracture

Answer 21

1. CT head - within 1 hour 2. Treatment of CSF leak → antibx +/- surgery (antibiotics given to prevent meningitis)

Answer 22

- obesity / female / pregnancy - **drugs** - steroids - combined oral contraceptive pill (COCP) - tetracyclines (eg. lymecycline) - retinoids (isotretinoin, tretinoin) / vitamin A - lithium

Answer 23

1. Weight loss —> diet, exercise, medications (eg. semaglutide, topiramate) 2. Carbonic anhydrase inhibitors (eg. acetazolamide) —> reduce CSF production —> lowers ICP 3. Repeated lumbar punctures —> temporary measure (removes CSF) (Note: LP can be used in IIH despite contraindication as there is a much lower risk of herniation compared with a space-occupying lesion causing mass effect)

Answer 24

- Optic nerve sheath decompression and fenestration —> to prevent damage to optic nerve - Lumboperitoneal or ventriculoperitoneal shunt —> to reduce ICP

Answer 25

It is a carbonic anhydrase inhibitor that reduces CSF production, lowering ICP - carbonic anhydrase is an enzyme involved in the production of CSF by the choroid plexus in the brain (choroid plexus = a network of blood vessels in each ventricle of the brain that produces CSF)

Answer 26

- the skull is a rigid, closed container, and its total volume of its contents (brain tissue, CSF, and blood) is fixed - if the volume of one component increases (eg. due to brain swelling or a tumour), the pressure inside the skull will rise unless there’s a compensatory decrease in the volume of the other two components (CSF and blood act as buffers, allowing some degree of volume displacement to compensate for changes in brain tissue volume)

Answer 27

- 7–15 mmHg . - CPP is the net pressure gradient causing cerebral blood flow to the brain —> maintaining a normal CPP (ie. pressure required to deliver blood to the brain) is essential for brain function —> Low CPP can lead to brain ischaemia (lack of blood flow) —> High CPP can contribute to elevated ICP, potentially causing brain damage (CPP = mean arterial pressure (MAP) - ICP)

Answer 28

- idiopathic intracranial hypertension (IIH) - bleeds - infections —> eg. meningitis - brain tumours - hydrocephalus

Answer 29

- Headache —> worse on coughing/straining/bending down/lying down/on waking/constant - Vomiting - Reduced level of consciousness - Papilloedema (usually bilateral) —> due to swelling of the optic disc - Cushing's triad (Cushing's reflex) —> late sign

Answer 30

A late sign of raised ICP: 1. **Hypertension with widened pulse pressure** —> direct response to the brainstem's attempt to increase cerebral perfusion pressure to overcome the ICP (widened pulse pressure —> significant increase in systolic BP and decrease in diastolic BP) 2. **Bradycardia** —> a result of the body's attempt to lower blood pressure and compensate for the increased ICP 3. **Irregular breathing (Cheyne-Stokes breathing)** —> a late sign

Answer 31

- Rising ICP reduces cerebral perfusion → sympathetic stimulation to increase BP - Baroreceptor response activates the parasympathetic NS --> leads to reflex bradycardia - Brainstem compression disrupts respiratory centres → irregular breathing (late sign)

Answer 32

1. Neuroimaging (CT/MRI) 2. Invasive ICP monitoring —> catheter placed into the lateral ventricles of the brain to monitor the pressure + allows CSF drainage and sample collection - Intervention is required if ICP >20 mmHg

Answer 33

Due to risk of brain herniation (tonsillar herniation) - LP removes CSF, which can lower the pressure within the brain - this sudden pressure drop can create a pressure gradient, causing the brain to shift and herniate into the spinal canal → if raised ICP is suspected then a CT head should be done before performing an LP to rule out a space-occupying lesion

Answer 34

- Investigate and treat the underlying cause - Head elevation to 30º - IV mannitol (osmotic diuretic) - Controlled hyperventilation . Removal of CSF: - Intraventricular drain - Repeated lumbar puncture —> for IIH - Ventriculoperitoneal (VP) shunt —> for hydrocephalus

Answer 35

- mannitol generates an osmotic pressure difference across the BBB —> driving the movement of water from the brain tissue into the bloodstream - this leads to brain dehydration and a subsequent reduction in ICP

Answer 36

- **Controlled hyperventilation** —> leads to rapid, temporary lowering of ICP (caution needed as may reduce blood flow to already ischaemic parts of brain) - aim is to reduce pCO2 —> vasoconstriction of the cerebral arteries —> reduced ICP

Answer 37

Herniation of the cerebellar tonsils downward through the foramen magnum → compresses brainstem and cervical spinal cord → can cause respiratory arrest, cardiac arrest, and death.

Answer 38

Their cranial sutures/fontanelles are not yet fused, allowing some expansion

Answer 39

1. Osmotherapy: hypertonic saline or IV mannitol 2. Surgical decompression: craniectomy or removal of mass lesion

Answer 40

Herniation of the medial temporal lobe (uncus) through the tentorial notch → compresses brainstem structures (Note: uncal herniation often causes an oculomotor nerve (CN III) palsy, causing ipsilateral fixed dilated pupil & ptosis)

Answer 41

A condition where the cerebellar tonsils herniate downward through the foramen magnum, potentially compressing the brainstem and spinal cord - usually congenital

Answer 42

- Syringomyelia (fluid-filled cavity in spinal cord) --> due to disruption of CSF flow due to the malformation - Non-communicating hydrocephalus (due to CSF flow obstruction) - Tethered cord syndrome

Answer 43

1. Posterior fossa decompression surgery - to relieve pressure on the cerebellum, spinal cord, and brainstem & restore CSF flow / prevent progression

Answer 44

- Valveless, endothelium-lined channels between the two layers of the dura mater, draining venous blood from the brain - Primary function is to collect venous blood and CSF from the brain and cranial tissues and drain it into the internal jugular vein (where it is returned to the heart)

Answer 45

They drain the ophthalmic veins and lie on either side of the sella turcica - into the superior & inferior petrosal veins and then into the internal jugular vein

Answer 46

It allows bidirectional flow, increasing the risk of retrograde infection or clot propagation (eg. in cavernous sinus thrombosis)

Answer 47

- MRI venography (CT venography is a good alternative) - D-dimer levels may be elevated

Answer 48

Anticoagulation with low molecular weight heparin (LMWH)

Answer 49

'empty delta sign' - caused by the presence of a thrombus (blood clot) within the superior sagittal sinus

Answer 50

Remember that the cavernous sinus thrombosis drains the ophthalmic veins & houses several cranial nerves --> a blood clot can compress & damage these nerves leading to nerve palsies - Periorbital oedema & erythema - Ophthalmoplegia (6th nerve first, then 3rd & 4th) - Trigeminal nerve involvement (cavernous sinus houses ophthalmic & maxillary branches) --> facial sensory loss, eye pain - Central retinal vein thrombosis

Answer 51

Produced by the choroid plexuses (in all 4 ventricles) and is absorbed into the venous system by arachnoid granulations

Answer 52

Obstructive ('non-communicating') hydrocephalus - due to structural pathology blocking the flow of CSF (eg. tumours, haemorrhage, developmental abnormalities - eg. aqueduct stenosis) (note: dilatation of the ventricular system is seen superior to site of obstruction) . Non-obstructive ('communicating') hydrocephalus - due to an imbalance of CSF production and absorption - Increased CSF production (choroid plexus tumour) → very rare - Failure of reabsorption at the arachnoid granulations (eg. meningitis or post-haemorrhagic) → more common

Answer 53

Aqueductal stenosis, leading to insufficient drainage of CSF - the cerebral aqueduct that connects the 3rd & 4th ventricle is stenosed (narrowed) - this blocks the normal flow of CSF out of the 3rd ventricle, causing CSF to build up in the lateral and 3rd ventricles (cerebral aqueduct = a narrow channel in the brain that connects the third and fourth ventricles, allowing CSF to flow between them) . - Arnold-Chiari malformation can also cause hydrocephalus

Answer 54

- Enlarged head circumference - Bulging anterior fontanelle - Failure of upward gaze ("sunsetting eyes") → due to compression of the superior colliculus of the midbrain - other signs: poor feeding, vomiting, hypotonia, sleepiness

Answer 55

1. CT head is 1st-line → fast & shows adequate resolution of the brain and ventricles - MRI brain → maybe used to investigate hydrocephalus in more detail, particularly if there is a suspected underlying lesion 2. Lumbar puncture → both diagnostic and therapeutic since it allows you to sample CSF, measure the opening pressure, but also to drain CSF to reduce the pressure (NOTE: lumbar puncture should NOT be used in obstructive hydrocephalus since the difference of cranial and spinal pressures induced by the drainage of CSF will cause brain herniation)

Answer 56

- Acute, severe hydrocephalus → External ventricular drain (EVD) (typically inserted into the right lateral ventricle and drains into a bag at the bedside) - Long-term CSF diversion → ventriculoperitoneal (VP) shunt (CSF is basically juts diverted into the peritoneal cavity) - In obstructive hydrocephalus → treatment may involve surgically treating the obstructing pathology

Answer 57

- urinary incontinence - dementia & bradyphrenia (slowing of cognitive function) - gait abnormality (may be similar to Parkinson's disease) (around 60% of pts will have all 3 features at the time of diagnosis)

Answer 58

CSF is contained within the meninges (in the subarachnoid space)

Answer 59

- Neisseria meningitidis (meningococcus) —> gram -ve diplococcus - Streptococcus pneumoniae (pneumococcus) - Haemophilus influenzae

Answer 60

- Group B streptococcus —> may colonise the vagina - Listeria monocytogenes

Answer 61

Non-blanching rash . Test used for non-blanching rash —> Tumbler test (glass test) - press a clear glass against rash, if it doesn’t fade (non-blanching) then indicates meningitis rash

Answer 62

- Enteroviruses (e.g., coxsackievirus) - Herpes simplex virus (HSV) - Varicella zoster virus (VZV)

Answer 63

- CSF viral PCR —> to identify underlying organism 1. Supportive treatment 2. IV aciclovir + broad-spectrum antibiotics (antibx given if any suspicion of bacterial meningitis or encephalitis) - viral meningitis is usually self-limiting, with symptoms improving over the course of 7-14 days - complications are rare in immunocompetent patients

Answer 64

- Fever - Neck stiffness - Photophobia - Vomiting - Headache - Altered consciousness - Seizures

Answer 65

1. Kernig’s test - lie pt on back + flex one hip and knee to 90° —> then slowly straighten the knee whilst keeping the hip flexed at 90° —> if meningitis, it will produce spinal pain or resistance to movement 2. Brudzinski’s test - lie pt on back + gently lift their head and neck off the bed —> flexing their chin to their chest —> if meningitis, this will cause the pt to flex their hips and knees involuntarily

Answer 66

Mastoiditis can cause meningitis —> look for tenderness/redness around/behind ear

Answer 67

- The spinal cord ends at the L1-L2 vertebral level —> the needle is usually inserted into the L3-L4 or L4/L5 intervertebral space. —> Samples are sent for bacterial culture, viral PCR, cell count, protein and glucose. (a blood glucose sample is sent at the same time for comparison to the CSF sample)

Answer 68

- raised ICP —> do a CT head instead - hemodynamically unstable - active seizure or post-ictal - GCS ≤8

Answer 69

Bacterial VS Viral meningitis: - Bacteria swimming in the CSF will release proteins and use up glucose. Viruses may release a small amount of protein, but do not use up glucose. - The immune system releases more neutrophils with bacteria and lymphocytes with viruses . **Note:** 4 tubes are used (glucose/protein/WCC/culture) —> 1st and last samples both check for blood (if traumatic tap then blood in 1st but not last sample)

Answer 70

Ideally, blood cultures + LP should be performed before starting antibiotics - include a meningococcal PCR (if meningococcus is suspected) —> tests for meningococcal DNA and gives a faster result than blood culture (meningococcal PCR will still be positive after the bacteria has been treated with antibiotics) . 1. Antibiotics —> IV empirical antibiotics 1st-line (3rd gen cephalosporin) - under 3 months —> Cefotaxime + Amoxicillin (amoxicillin covers Listeria) - above 3 months —> Ceftriaxone - If penicillin allergic —> IV chloramphenicol - If penicillin-resistant strain —> IV vancomycin (eg. recent foreign travel or prolonged antibx exposure) 2. IV dexamethasone —> for cerebral oedema + *reduces hearing loss complications* 3. Supportive —> analgesics/antipyretics/antiemetics +/- fluids +/- oxygen (high flow) (if fever —> IV paracetamol) 4. Close monitoring for complications —> raised ICP, seizures, neuro deficits

Answer 71

single-dose of ciprofloxacin (given as soon as possible after diagnosis)

Answer 72

- Hearing loss —> SNHL due to cochlear damage - IV dexamethasone —> reduces inflammation and brain swelling + reduces inflammation in cochlear

Answer 73

- **Viral infection (most common cause) —> Herpes Simplex Virus (HSV)** - HSV-1 (95% of cases in adults) —> from cold sores - affects children/adults - HSV-2 —> from genital herpes - affects neonates

Answer 74

- VZV (varicella zoster virus) —> associated with chickenpox - CMV (cytomegalovirus) —> associated with immunodeficiency - EBV (Epstein-Barr virus) —> associated with infectious mononucleosis, enterovirus, adenovirus, and influenza virus (note: it is important to ask about vaccinations, as polio, mumps, rubella, and measles viruses can cause encephalitis as well)

Answer 75

- a change in personality/behaviour changes (temporal lobe signs —> eg. aphasia)

Answer 76

Temporal lobes — especially medial temporal and inferior frontal areas (MRI of a patient with HSV encephalitis - there is hyperintensity of the affected white matter and cortex in the medial temporal lobes and insular cortex)

Answer 77

1. MRI —> shows medial temporal and inferior frontal changes - Lumbar puncture (LP) —> send CSF for viral PCR testing (for HSV) - WCC: lymphocytosis - Protein: high - EEG pattern —> lateralised periodic discharges at 2 Hz

Answer 78

Encephalitis can be a manifestation of HIV infection, including both acute HIV infection and opportunistic infections in individuals with HIV

Answer 79

1. IV aciclovir —> should be started in all cases of suspected encephalitis (aciclovir —> treats HSV and VZV) (ganciclovir —> treats CMV) 2. Repeated LP —> usually performed to ensure successful treatment prior to stopping antivirals (Supportive management - seizure management, hydration, ICU care if needed)

Answer 80

1. Urgent replacement of thiamine (vitamin B1) - Thiamine is important in glucose metabolism (especially in the brain) 1. Supportive care - alcohol cessation - hydration & electrolyte correction (esp. hypomagnesemia) - Magnesium is important in thiamine activation - Without sufficient magnesium, thiamine cannot be properly activated and thus cannot perform its essential role in glucose metabolism

Answer 81

1. Temporal lobe features: - Déjà vu - strange smells, tastes, sights, or sound sensations - unusual emotions - hallucinations - memory flashbacks - abnormal behaviours —> eg. doing strange things on autopilot 2. Frontal lobe features; - head/leg movements - post-ictal weakness - Jacksonian march —> clonic movements travelling proximally (the "march" typically reflects the organization of the motor cortex, with seizure activity spreading from the inferior (ventral) to the dorsal aspect of the precentral gyrus)

Answer 82

- present as sudden brief muscle contractions —> like a sudden “jump” or “jolt” - pt usually remains awake during the episode (typically part of juvenile myoclonic epilepsy in children)

Answer 83

Tonic seizures —> sudden-onset of increased muscle tone (entire body stiffens) - often results in a fall backwards if the pt is standing . Atonic seizures (”drop attacks”) —> characterised by brief lapses in muscle tone - typically begin in childhood —> may indicate Lennox-Gastaut syndrome

Answer 84

3-Hz spike and wave discharges - T-type channels (particularly in thalamocortical neurons) are primarily responsible for generating the "3-Hz spike-wave discharges" characteristic of absence seizures → Note: Ethosuximide blocks T-type calcium channels to control these seizures

Answer 85

- Rare type of seizure starting in infancy (at around 6 months of age), characterised by clusters of full-body spasms - Characteristic EEG finding —> Hypsarrhythmia (chaotic, high-amplitude electrical activity in the brain) - Management —> ACTH or prednisolone + Vigabatrin (mixed prognosis —> 1/3 die by age 25yrs, however 1/3 will be seizure free)

Answer 86

- A severe epilepsy with mixed seizure types (eg. atypical absences, falls, jerks) - 90% have a moderate-severe mental handicap - EEG: slow spike-and-wave activity (typically between 1.5 and 2.5 Hz) - Management —> ketogenic diet may help

Answer 87

- typical onset in teens (more common in girls) 1. Infrequent generalized seizures, often in morning 2. Daytime absences 3. Sudden, shock-like myoclonic seizure - Management —> usually good response to sodium valproate (other anti-epilpetic drugs can be used too)

Answer 88

- Febrile convulsions are NOT caused by epilepsy or other pathology - tonic-clonic seizures in children with high fever —> around 3% of children will have at least one febrile convulsion (often occur early in viral infection as the temperature rises rapidly) - DO NOT cause any lasting damage - 1/3 of children will have another febrile convulsion - **Management** —> stay calm and try to video the seizure to show the doctor

Answer 89

- pelvic thrusting - more common in femlaes - crying after seizure - Saline drop on eye —> *if psychogenic then pt will blink* - Lactate + Prolactin —> *raised in ‘real’ seizures (lactic acidosis due to muscles working hard due to spasms)*

Answer 90

- Chronic alcohol consumption enhances GABA-mediated inhibition in the CNS (similar to benzodiazepines) and inhibits NMDA-type glutamate receptors - In the absence of alcohol (withdrawal), the GABA activity decreases but the increased glutamate (as compensation) levels remain about the same and leading Glutamate > GABA state

Answer 91

1. Benzodiazepines (eg. diazepam) 2. IV glucose (50ml of 50% solution) 3. IV Pabrinex (thiamine 250mg)

Answer 92

- Hypoglycaemia —> most common cause of a seizure (give IV dextrose) - Epilepsy - Vasovagal syncope (fainting) - Cardiac syncope (e.g., arrhythmias or structural heart disease) - Pseudoseizures (psychogenic non-epileptic attacks)

Answer 93

- EEG (electroencephalogram) —> shows typical patterns in different forms of epilepsy and supports the diagnosis - MRI brain —> used to diagnose structural pathology (eg. tumours)

Answer 94

- a single seizure (ie. first seizure) —> cannot drive for 6 months following a seizure - established epilepsy —> must be seizure-free for 12 months before being able to drive

Answer 95

- take showers rather than baths (drowning is a major risk in epilepsy) - particular caution with swimming, heights, traffic, and dangerous equipment

Answer 96

Other less commonly used anti-epileptic drugs to be aware of include: - Carbamazepine - Phenytoin - Topiramate

Answer 97

- MOA —> increases activity of GABA, which has a relaxing/calming effect on the brain Side effects: - TERATOGENIC (neural tube defects) —> pts need careful advice about contraception - **P450 enzyme inhibitor** —> slower metabolism of drugs, leading to higher drug concentrations in the bloodstream - liver damage and hepatitis - hair loss - tremor

Answer 98

- MOA —> binds to sodium channels increasing their refractory period Side effects: - **P450 enzyme inducer** —> faster metabolism of drugs, decreasing their effectiveness/leading to a reduced therapeutic effect - agranulocytosis —> ie. severe deficiency in neutrophils (susceptible to infection) (seek medical attention if have sore throat) - aplastic anaemia

Answer 99

(Phenytoin is no longer used 1st-line due to side effects) - MOA —> binds to sodium channels, increasing their refractory period Side effects: - **P450 enzyme inducer** —> faster metabolism of drugs, decreasing their effectiveness/leading to a reduced therapeutic effect - peripheral neuropathy - dizziness and ataxia - Folate and vitamin D deficiency: - Megaloblastic anaemia (folate deficiency) - Osteomalacia (vitamin D deficiency)

Answer 100

Stevens-Johnson syndrome (SJS)

Answer 101

- MOA —> blocks T-type calcium channels Side effects: - GI issues → nausea, vomiting, diarrhoea, anorexia - night terrors & insomnia - rashes

Answer 102

- ABCDE approach 1. Benzodiazepines 1st-line —> IV Lorazepam 4mg (if in hospital) - Buccal Midazolam 10mg or PR diazepam (pre-hospital/community) —> if still fitting 5 mins after dose —> contact anaesthetist + give another dose after 5 mins —> if still fitting —> 2nd-line options are IV phenytoin (or IV levetiracetam, sodium valproate) —> 3rd-line options are IV phenobarbital OR general anaesthesia (intubation + ventilation)

Answer 103

Frontal lobe tumour (the frontal lobe is responsible for personality and higher-level decision making)

Answer 104

- Lung (most common) - Breast - Bowel - Skin (namely melanoma) - Kidney (renal cell carcinoma)

Answer 105

Gliomas are tumours of the glial cells in the brain or spinal cord (glial cells surround and support neurones —> eg. astrocytes, oligodendrocytes, and ependymal cells) . Gliomas are graded from 1 to 4: - 1 —> most benign (possibly curable with surgery) - 4 —> most malignant (eg. glioblastoma multiforme)

Answer 106

- Glioblastoma multiforme = most common and aggressive form of astrocytoma - CT showing a peripherally enhancing lesion within the left frontal lobe (solid tumours with central necrosis and a rim that enhances with contrast)

Answer 107

Benign, slow-growing tumour common in the frontal lobes (histology shows calcifications with 'fried-egg' appearance)

Answer 108

- Commonly seen in the 4th ventricle - may obstruct CSF —> hydrocephalus

Answer 109

Pilocytic astrocytoma (Grade 1) - slow-growing, often cystic (fluid-filled)

Answer 110

Remnants of Rathke’s pouch (Rathke's pouch is a developmental structure that forms during fetal development and gives rise to the anterior pituitary gland)

Answer 111

- Vestibular schwannomas are benign tumours of the Schwann cells that surround the 8th cranial nerve (vestibulocochlear nerve) - they occur at the cerebellopontine angle - Features —> gradual onset of unilateral sensorineural HL, facial nerve palsy, and tinnitus (facial nerve palsy due to compression of the nearby facial nerve)

Answer 112

- arachnoid cap cells of the meninges and are typically located next to the dura - MRI shows the typical well-circumscribed appearance with a dural tail (a dural tail can be where the tumour ‘connects’ to the dura - seen in around 65% of meningiomas)

Answer 113

- MRI brain - showing ring-enhancing lesion in the right frontal lobe with surrounding oedema - A brain abscess shows restricted diffusion on diffusion-weighted imaging (DWI), unlike most tumours (the pus within a brain abscess is viscous and contains a high concentration of inflammatory cells, which limits the movement of water molecules, resulting in restricted diffusion on DWI. )

Answer 114

1. MRI —> 1st-line for possible brain tumour 2. Biopsy —> gives definitive histological diagnosis (usually obtained during surgery to remove the tumours)

Answer 115

1. Surgery —> craniotomy + debridement of abscess cavity (the abscess may reform because the head is closed following abscess drainage) 2. IV antibiotics —> 3rd-generation cephalosporin (eg. ceftriaxone) + metronidazole 3. Intracranial pressure management —> IV dexamethasone

Answer 116

- Oligodendrocytes in the central nervous system - Schwann cells in the peripheral nervous system —> MS affects the CNS (oligodendrocytes)

Answer 117

Cerebral toxoplasmosis (≈50% of cases) - causative organism: Toxoplasma gondii (cats carry it)

Answer 118

- Multiple small ring-enhancing lesions - Management: Pyrimethamine + sulphadiazine for at least 6 weeks

Answer 119

**Optic neuritis** —> involves demyelination of the optic nerve and presents with unilateral reduced vision, developing over hrs to days - central scotoma (enlarged central blind spot) - pain with eye movement - impaired colour vision - RAPD

Answer 120

Relapsing-remitting disease (RRMS) - 85% of pts - acute attacks (eg. lasts 1-2 months), followed by periods of remission - symptoms tend to occur in different areas with each episode —> “disseminated in time and space”

Answer 121

- describes relapsing-remitting patients who have deteriorated and have developed neurological signs and symptoms between relapses - around 65% of pts with RRMS go on to develop secondary progressive disease within 15 years of diagnosis - gait and bladder disorders are generally seen

Answer 122

Lesions occur in different CNS locations and at different times, causing variable symptoms - in early disease, re-myelination can occur and the symptoms can resolve - in later stages of disease —> re-myelination is incomplete and the symptoms gradually become more permanent

Answer 123

1. Amyotrophic lateral sclerosis (ALS) – both UMN and LMN signs (50% of cases) 2. Primary lateral sclerosis – UMN signs only 3. Progressive muscular atrophy – LMN signs only (affects distal muscles before proximal) (carries best prognosis) 4. Progressive bulbar palsy – bulbar muscle involvement; worst prognosis (carries worst prognosis)

Answer 124

- CSF —> lumbar puncture can detect oligoclonal bands - bands of immunoglobulins (IgG) that appear on a gel during CSF analysis (indicates presence of inflammation and immune activation in the CNS)

Answer 125

- **Uhthoff’s phenomenon** —> worsening of vision following rise in body temperature (eg. fever) . **Internuclear ophthalmoplegia** - the nerve fibres of the medial longitudinal fasciculus connect the cranial nerve nuclei (”internuclear”) that control eye movements (the 3rd, 4th, and 6th cranial nerve nuclei) - these fibres are responsible for coordinating the eye movements to ensure the eyes move together —> it causes impaired adduction on the same side as the lesion (ipsilateral eye) and nystagmus in the contralateral abducting eye

Answer 126

- Multiple white matter lesions, often periventricular - Dawson fingers —> often seen on FLAIR images (hyperintense lesions perpendicular to the corpus callosum)

Answer 127

- Lhermitte’s sign —> an electric shock sensation that travels down the spine and into the limbs when flexing the neck - indicates disease in the cervical spinal cord in the dorsal column

Answer 128

Acute relapse: 1. High-dose steroids —> oral or IV methylprednisolone (0.5g daily for 5 days) - given for 5 days to shorten the length of an acute relapse (Note: pts presenting with acute loss of vision —> urgent ophthalmology input) . Disease-modifying drugs - aim to induce long-term remission with no disease activity 1. Natalizumab (given IV) —> 1st-line 2. Ocrelizumab (given IV) —> like natalizumab it is considered a high-efficacy drug

Answer 129

- Fatigue —> trial of amantadine +/- CBT (only treat once other problems (eg. anaemia, depression) have been excluded) - Spasticity —> baclofen and gabapentin are 1st-line (physiotherapy is also important) - Bladder dysfunction (eg. urge incontinence) —> antimuscarinic medications (eg. solifenacin) (ultrasound first to assess bladder emptying —> if significant residual volume then intermittent self-catheterisation) - Oscillopsia (visual fields appear to oscillate) —> gabapentin is 1st-line (reduces nystagmus)

Answer 130

Sensory ataxia —> due to loss of proprioception - +ve Romberg’s test (lesion in the dorsal columns of the spine) . Cerebellar ataxia —> results from problems with the cerebellum coordinating movement - indicates a cerebellar lesion

Answer 131

Amyotrophic lateral sclerosis (ALS): - typically LMN signs in arms and UMN signs in legs (in familial cases the gene lies on chromosome 21 and codes for superoxide dismutase)

Answer 132

Primarily affects the muscles of talking and swallowing (ie. the bulbar muscles) - palsy of the tongue, muscles of chewing/swallowing, and facial muscles due to loss of function of brainstem motor nuclei - carries worst prognosis

Answer 133

- Nerve conduction studies —> will show normal motor conduction and can help exclude a neuropathy - Electromyography —> shows a reduced number of action potentials with increased amplitude - MRI —> usually performed to exclude the differential diagnosis of cervical cord compression and myelopathy (Note: diagnosis of MND is often delayed as have to be absolutely sure that MND is the diagnosis)

Answer 134

- **Riluzole** (used mainly in ALS) —> prolongs life by about 3 months (prevents stimulation of glutamate receptors —> helps to reduce the excessive activation of glutamate receptors, potentially protecting neurons from damage in ALS) - **NIV (BIPAP)** —> used at night (can extend survival by about 7 months) - Nutrition —> **percutaneous gastrostomy tube (PEG)** (used due to risk of aspiration pneumonia and choking)

Answer 135

- 50% of pts die within 3 yrs - Patients with MND tend to die of respiratory failure or pneumonia

Answer 136

Parkinson’s disease is a progressive neurodegenerative condition where there is a reduction in dopamine in the basal ganglia, leading to disorders of movement - caused by degeneration of dopaminergic neurons in the substantial nigra (Basal ganglia is where the dopamine-producing cells are located) - The basal ganglia plays a vital role in initiating, coordinating, and controlling voluntary movements

Answer 137

- Bradykinesia (slowness of movement) - Resting tremor (ie. worse at rest) - Rigidity (resisting passive movement) (extrapyramidal rigidity)

Answer 138

- Motor symptoms are rapid onset and bilateral/symmetrical - rigidity and resting tremor are uncommon - Antipsychotics & metoclopramide (they both block dopamine receptors in the brain - specifically D2 receptors which are crucial for motor control)

Answer 139

- frequency —> 4-6 Hz (ie. it cycles 4-6 times per second) - “pill-rolling” —> ie. in the thumb and index finger - worse at rest + when stressed/tired, improves with voluntary movement (note: performing a task with the other hand (eg. mimicking the act of painting a fence) improves the tremor)

Answer 140

Hypokinesia (”poverty of movement”) —> movements getting slower and smaller - Micrographia (handwriting gets smaller and smaller) - “shuffling gait” (small steps when walking) - “festinating gait” (rapid frequency of steps to compensate for the small steps and avoid falling) - difficulty initiating movement —> eg. going from standing still to walking (”stuck”) - difficulty in turning around when standing and having to take lots of little steps to turn - hypomimia (reduced facial movements and facial expressions)

Answer 141

- “cogwheel rigidity” —> the jerking resistance to passive movement - “lead pipe” —> where there's a constant, smooth resistance to movement throughout the entire range of motion, like bending an arm (characterised by increased tone in all the muscle groups around a joint, making it hard to move)

Answer 142

- peripheral decarboxylase inhibitor (eg. carbidopa, benserazide) stop levodopa from being metabolised in the body before it reaches the brain - Co-careldopa (levodopa and **carbidopa**), with the trade name Sinemet - Co-beneldopa (levodopa and **benserazide**), with the trade name Madopa

Answer 143

- Dyskinesia (main adverse effect) —> abnormal movements associated with excessive motor activity (eg. dystonia, chorea, and athetosis) (the use of decarboxylase inhibitors with levodopa prevents the peripheral metabolism of levodopa to dopamine outside of the brain and hence can reduce side effects)

Answer 144

¹²³I-FP-CIT SPECT scan (dopamine transporter imaging) - single photon emission computed tomography (SPECT) - reduced uptake of the tracer in specific brain regions (particularly the striatum) indicates a loss of dopamine transporters, which is characteristic of Parkinson's disease and other conditions.

Answer 145

- Dopamine receptor agonists (eg. bromocriptine, pergolide, cabergoline) —> typically used to delay the use of levodopa, then used in combination with levodopa to reduce the required dose (mimic the action of dopamine in the basal ganglia) - Amantadine —> manages levodopa-induced dyskinesia - COMT inhibitors (entacapone) —> slow down breakdown of levodopa in the brain (extends the effective duration of the levodopa) (the COMT enzyme metabolises levodopa in both the body and brain) - MAO-B inhibitors (eg. selegiline, rasagiline) —> used to delay the use of levodopa, then used in combination with levodopa to reduce the “end of dose” worsening of symptoms (block the action of MAO-B enzymes, helping to increase the circulating dopamine (monoamine oxidase enzymes break down neurotransmitters such as dopamine, serotonin, and adrenaline))

Answer 146

Impulse control disorders —> pathological gambling, compulsive shopping, hypersexuality, binge eating

Answer 147

- Neuroleptic malignant syndrome (requires ITU care) - give a dopamine agonist patch as rescue medication to prevent acute dystonia

Answer 148

- MSA-P —> predominant Parkinsonian features - MSA-C —> predominant cerebellar features

Answer 149

Progressive supranuclear palsy (PSP) - PSP presents with early falls (pts tend to have a stiff, broad-based gait) - impairment of vertical gaze (down gaze worse than up gaze) - Parkinsonism (bradykinesia prominent)

Answer 150

- Parkinsonism - Autonomic dysfunction → eg. erectile dysfunction (early feature), severe postural hypotension, atonic bladder (underactive or flaccid bladder) - Cerebellar signs → eg. ataxia - Vocal cord dystonia → wheezing/stridor (may need tracheostomy)

Answer 151

- Symmetrical fine tremor (6-12 Hz) —> most notable in the hands (can affect other areas —> eg. head tremor, jaw tremor and vocal tremor) - Postural tremor —> worse if arms outstretched - More prominent with voluntary movement - Worse when tired, stressed or after caffeine - Improved by alcohol and rest (absent during sleep)

Answer 152

- Dementia with Lewy bodies —> cognitive symptoms occur before or within 1 year of motor symptoms (cognitive impairment is also fulcutuating in contrast to Alzheimer's) - Parkinson's disease dementia —> dementia occurs after >1 year of established Parkinsonism (motor symptoms)

Answer 153

Corticobasal degeneration - 'Alien limb' —> where a person's hand or limb acts independently of their conscious will - Cortical sensory loss (fronto-parietal) —> interpretation of touch is affected

Answer 154

Propranolol (non-selective beta-blocker)

Answer 155

- Autosomal dominant - It is a trinucleotide repeat disorder --> involving a genetic mutation in the HTT gene on chromosome 4, which codes for the huntingtin (HTT) protein (a trinucleotide (CAG) repeat expansion in the HTT gene)

Answer 156

Where successive generations have more repeats in the gene, resulting in: - Earlier age of onset - Increased severity of disease

Answer 157

- Positive → more than 39 repeats - Negative → less than 27 repeats - Grey zone → 27-35, 36-39

Answer 158

genetic testing via a specialist genetic centre and involves pre and post-test counselling

Answer 159

- Aspiration pneumonia - Suicide - Complications of frailty (eg. falls, pressure ulcers, infections)

Answer 160

- Genetic counselling —> for relatives and family planning - Physiotherapy —> for mobility and contracture prevention - Speech and language therapy —> for dysphagia and communication - **Tetrabenazine** —> for chorea - Antidepressants (e.g., SSRIs) —> for depression - Advanced directives to document their wishes as the disease progresses & end-of-life care

Answer 161

50% (autosomal dominant) (children need to be 18 before they can decide whether to get tested)

Answer 162

- Cerebellar hemisphere lesions —> cause peripheral ('finger-nose ataxia') (cerebellar hemisphere responsible for coordinating limb movements, particularly of the arms and hands) - Cerebellar vermis lesions —> cause gait ataxia (cerebellar vermis is responsible for cooridnating trunk and leg movements, as well as posture and balance)

Answer 163

- D - Dysdiadochokinesia, Dysmetria (past-pointing), patients may appear 'Drunk' - A - Ataxia (limb, truncal) - N - Nystamus (horizontal = ipsilateral hemisphere) - I - Intention tremour - S - Slurred staccato speech, Scanning dysarthria - H - Hypotonia

Answer 164

Ipsilateral signs

Answer 165

- alcohol - drugs: phenytoin, lead poisoning - stroke - multiple sclerosis - Friedreich's ataxia, ataxic telangiectasia - neoplastic: cerebellar haemangioma - hypothyroidism - paraneoplastic e.g. secondary to lung cancer

Answer 166

- An autosomal recessive trinucleotide repeat disorder (GAA repeat in the FXN gene on chromosome 9) - Frataxin (involved in mitochondrial iron regulation) → deficiency leads to oxidative stress and neuronal degeneration

Answer 167

It does not show anticipation (worsening severity/earlier onset in successive generations)

Answer 168

- Friedrich's ataxia → 10–15 years - Ataxia telangiectasia → early childhood (1-2 years)

Answer 169

Genetic testing for FXN gene GAA repeat expansion

Answer 170

A rare autosomal recessive disorder due to mutation in the ATM gene, which impairs DNA repair and causes progressive cerebellar degeneration and immunodeficiency

Answer 171

- Low number of T cells and immunoglobulins (IgA) → causing immunodeficiency & recurrent chest infections - Ataxia: problems with coordination due to cerebellar impairment - Telangiectasia (particularly in the sclera and damaged areas of skin) - Predisposition to cancers (particularly haematological cancers)

Answer 172

(Symptoms initially occur at night & symptoms are worse at rest) - Uncontrollable urge to move legs (akathisia). - Paraesthesias e.g. 'crawling' or 'throbbing' sensations - Movements during sleep may be noted by the partner - periodic limb movements of sleeps (PLMS)

Answer 173

- simple measures: walking, stretching, massaging affected limbs - treat any iron deficiency (this can be a cause/association) 1. Dopamine agonists are first-line treatment (e.g. Pramipexole, ropinirole) (gabapentin & benzodiazepines can be used too)

Answer 174

- Alcohol - Vitamin B12 deficiency - Diabetes

Answer 175

- Loss of vibration & proprioception (dorsal columns) —> +ve Romberg's test - Distal paraesthesia (hands and feet) - Possible UMN signs (due to corticospinal involvement) —> eg. brisk reflexes despite peripheral signs - Glossitis & macrocytic anaemia

Answer 176

- Impaired myelin synthesis - Vitamin B12 plays a crucial role in the production and maintenance of myelin (a fatty substance that insulates nerve fibres and allows for efficient transmission of nerve signals) —> leading to dysfunction of both peripheral nerves and central tracts (dorsal columns affected first)

Answer 177

- IM hydroxycobalamin —> 1mg every other day for 2 weeks - Maintenance —> 1mg IM every 2-3 months if irreversible cause (eg. pernicious anaemia)

Answer 178

- Chronic hyperglycaemia → oxidative stress, advanced glycation end products - Microvascular ischaemia → nerve injury

Answer 179

- Optimise glycaemic control - Neuropathic pain —> amitriptyline, gabapentin - Foot care —> to prevent ulcers & Charcot’s deformity

Answer 180

Length-dependent (”stocking-glove”) —> symptoms affect the longest nerve fibres in the body first (these are the nerves in the feet and toes, which are furthest from the brain and spinal cord) - early features —> loss of vibration and proprioception (large fibres) - later features —> loss of pain and temperature sensation (small fibres) (large fibres are basically just more vulnerable to damage)

Answer 181

- Classically Campylobacter jejuni - other causes: cytomegalovirus (CMV) and Epstein-Barr virus (EBV)

Answer 182

1. **Molecular mimicry** - B cells create antibodies against the antigens on the triggering pathogen (eg. campylobacter jejuni) - these antibodies also match proteins on the peripheral neurones —> they may taret proteins on the myelin sheath or the nerve axon itself - Cross-reaction of antibodies with gangliosides in the peripheral NS (correlation between anti-ganglioside antibody (eg. anti-GM1) and clinical features has been demonstrated) (anti-GM1 antibodies are found in 25% of pts)

Answer 183

- There may be a history of gastroenteritis —> Campylobacter jejuni - flaccid weakness is classically ascending (ie. legs are affected first) + hyporeflexia - symptoms usually start within 4 weeks of the triggering infection - symptoms peak within 2-4 weeks - recovery period can then last months to years

Answer 184

- **Lumbar puncture (CSF analysis)** —> albuminocytological dissociation (raised CSF protein with a normal WCC & glucose) (found in 65%) - **Nerve conduction studies** —> shows reduced motor nerve conduction velocity due to demyelination

Answer 185

1. IV immunoglobulins (IVIG) —> 1st-line - Plasmapheresis (an alternative to IVIG) 2. Supportive care + **VTE prophylaxis** (PE is a leading cause of death) - If respiratory failure —> intubation, ventilation, & admit to ICU

Answer 186

- Most cases are autosomal dominant (there are also autosomal recessive and X-linked forms)

Answer 187

- Inherited mutations affect myelin (demyelinating types) or axon (axonal types) in peripheral nerves - Leads to progressive motor and sensory neuropathy

Answer 188

- History of frequent ankle sprains - Distal muscle weakness (particularly ankle dorsiflexion) → high-stepping gait due to foot drop - High-arched feet (pes cavus) - Hammer toes - Distal muscle wasting/atrophy —> “inverted champagne bottle legs” or “stork leg deformity” (with relative preservation of proximal muscle bulk) - Hyporeflexia (reduced tendon reflexes)

Answer 189

- women under 40 - men over 60

Answer 190

1. The axons release a neurotransmitter called **acetylcholine** from the presynaptic membrane --> acetylcholine travels across the synapse & attaches to the postsynaptic membrane (of the motor end plate of the muscle cell/fibre), stimulating muscle contraction 2. **Acetylcholine receptor (AChR) antibodies** are found in most pts with myasthenia gravis --> these antibodies bind to postsynaptic acetylcholine receptors, blocking them & **preventing sitmulation by acetylcholine** - if the receptors are blocked, then more acetylcholine is released to try and overcome this --> **fatiguabilty** --> there is less effective stimulation of the muscle with increased activity --> with rest, the receptors are cleared, and the symptoms improve 3. These antibodies also activate the complement system within the NMJ --> leading to cell damage at the postsynaptic membrane, further worsening symptoms (MuSK & LRP4 antibodies can also cause myathenia gravis --> these are important proteins for the creation & organisation of the acetylcholine receptor)

Answer 191

- Muscle fatigability (key feature) —> muscles become progressively weaker during periods of activity and slowly improve after periods of rest (symptoms are typically better in the morning and worse at the end of the day) . Muscles most affected: - Proximal muscle weakness (face, neck, limb girdle) —> difficulty climbing stairs, standing from a seat or raising their hands above their head - Extraocular muscle weakness —> causing diplopia (double vision) - Eyelid weakness —> causing ptosis (drooping of eyelids) (Note: gets worse and better) - Difficulty with swallowing (dysphagia) - Fatigue in the jaw when chewing (Note: pts can present with ocular myasthenia gravis only without peripheral symptoms)

Answer 192

**Thymomas (thymus gland tumours)** —> 10-20% of patients with myasthenia gravis have a thymoma - 30% of patients with a thymoma develop myasthenia gravis

Answer 193

- **beta-blockers** —> interfere with neuromuscular transmission (can further block acetylcholine receptors, exacerbating symptoms) - antibiotics: gentamicin, macrolides, quinolones, tetracyclines - lithium

Answer 194

- Repeated blinking → will exacerbate ptosis - Prolonged upward gazing → will exacerbate diplopia on further testing - Repeated abduction of one arm 20 times → will result in unilateral weakness when comparing both sides

Answer 195

1. **Long-acting acetylcholinesterase inhibitors —> pyridostigmine is 1st-line** - reduces the breakdown of acetylcholine in the NMJ —> temporarily improving symptoms (ie. prolongs the action of acetylcholine) 2. **Thymectomy** —> can improve symptoms (even in patients without a thymoma) 3. **Immunosuppression (eg. prednisolone or azathioprine)** —> usually not started at diagnosis, but the majority of pts eventually require it in addition to long-acting acetylcholinesterase inhibitors (suppresses the production of antibodies) 4. Rituximab (a monoclonal antibody against B cells) is considered where other treatments fail

Answer 196

1. Single fibre electromyography —> high sensitivity (92-100%) 2. CT or MRI thorax/thymus gland —> to look for a thymoma 3. Antibodies to acetylcholine receptors (AChR antibodies) —> +ve in 85-90% of pts (in AChR -ve pts, about 40% are +ve for MuSK antibodies) - MuSK (muscle-specific kinase) antibodies - less than 10% - LRP4 (low-density lipoprotein receptor-related protein 4) antibodies - less than 5%

Answer 197

It is most commonly a paraneoplastic syndrome associated with small-cell lung cancer (SCLC) ((However, it can occur as a primary autoimmune disorder without the presence of SCLC))

Answer 198

Electromyography —> incremental response to repetitive electrical stimulation (diagnostic test that measures the electrical activity of your muscles)

Answer 199

1. Lambert-Eaton myasthenic syndrome is caused by an antibody directed against presynaptic voltage-gated calcium channels in the peripheral NS - these antibodies may be produced in response to small-cell lung cancer (SCLC) cells that express voltage-gated calcium channels —> they target and damage voltage-gated Ca2+ channels in the presynaptic membrane of the NMJ 2. Voltage-gated Ca2+ channels are responsible for assisting in the release of acetylcholine into the synapse of the NMJ - when the voltage-gated Ca2+ channels are destroyed, less acetylcholine is released into the synapse —> resulting in a weaker signal and reduced muscle contraction 3. Why symptoms improve with muscle use → temporarily increased Ca2+ influx into nerve terminals - this increase in Ca2+ leads to enhanced release of the neurotransmitter acetylcholine, improving muscle contraction

Answer 200

- often triggered by another illness (eg. respiratory tract infection) - Respiratory muscle weakness —> can lead to respiratory failure 1. IV immunoglobulins (IVIG) 2. Plasmapheresis 3. +/- NIV (BiPAP) or mechanical ventilation

Answer 201

- Repeated muscle contractions lead to increased muscle strength (in contrast to myasthenia gravis) —> note that following prolonged muscle use muscle strength will eventually decrease - Proximal muscle weakness (eg. difficulty climbing stairs, standing from a seat, raising arms above head) - Autonomic dysfunction (eg. dry mouth, impotence) - Hyporeflexia (reduced or absent tendon reflexes)

Answer 202

- Treatment of underlying cancer (ie. small cell lung cancer) - Immunosuppression (eg. prednisolone or azathioprine) - IV immunoglobulin therapy + plasma exchange (plasmapheresis) may be beneficial - Amifampridine —> very new drug

Answer 203

- works by blocking voltage-gated potassium channels in the presynaptic membrane, which in turn prolongs the depolarisation of the cell membrane and assists calcium channels in carrying out their action - therefore calcium channels can then be open for a longer time and allow greater acetylcholine release to then stimulate muscle at the end plate

Answer 204

Clostridium botulinum (gram +ve anaerobic bacillus)

Answer 205

Descending flaccid paralysis (in contrast to Guillain-Barré) - Bulbar muscles (cranial nerves) are most affected, leading to dysphagia, dysarthria, and ophthalmoplegia

Answer 206

- NF1 (more common) —> caused by a gene mutation on chromosome 17, which encodes neurofibromin (neurofibromin is a tumour suppressor protein) - NF2 (rarer) —> caused by a gene mutation on chromosome 22, which codes for a protein called merlin (merlin is a tumour suppressor protein important in Schwann cells)

Answer 207

- botulism antitoxin and supportive care (ventialtion if needed) (Note: antitoxin is only effective if given early - once toxin has bound its actions cannot be reversed) .

Answer 208

- Café-au-lait spots —> ≥15mm is significant - Axillary or inguinal freckles - ≥2 cutaneous neurofibromas or 1 plexiform neurofibroma (a plexiform neurofibroma is a larger, irregular, complex neurofibroma containing multiple cell types) - Iris hematomas (Lisch nodules) —> yellow-brown spots on the iris

Answer 209

Bilateral vestibular schwannomas —> basically indicates NF2

Answer 210

- Malignant peripheral nerve sheath tumours - Gastrointestinal stromal tumour (GIST)

Answer 211

- Hamartomas (characteristic) —> benign tissue growths (cause problems based on the organ they affect) . Skin (cutaneous) features: - Ash leaf spots —> depigmented areas of skin shaped like an ash leaf (fluorescent under UV light) - Shagreen patches —> thickened, dimpled, pigmented patches of skin - Angiofibromas (adenoma sebaceum) —> small skin-coloured or pigmented papules that occur over the nose and cheeks - Poliosis —> an isolated patch of white hair on the head, eyebrows, eyelashes or beard . Neurological features: - Epilepsy (infantile spasms or partial) - Learning disability/intellectual impairment (developmental delay) - Brain tumours

Answer 212

- TSC1 gene on chromosome 9 --> which codes for hamartin - TSC2 gene on chromosome 16 --> which codes for tuberin —> Hamartin and tuberin interact with each other to control the size and growth of cells - abnormalities in one of these proteins lead to abnormal cell size and growth

Answer 213

- X-linked recessive - Dystrophin gene, located on Xp21 (dystrophin connects the muscle membrane to the actin cytoskeleton, maintaining muscle membrane stability)

Answer 214

- Each son has a 50% chance of being affected - Each daughter has a 50% chance of being a carrier --> remember that X-linked conditions primarily affect males (females have a spare copy of the dystrophin gene)

Answer 215

child needs to use their hands and arms to "walk" up their own body from a squatting or lying position, due to insufficient hip and thigh muscle strength - indicates proximal muscle weakness (Duchenne's muscular dystrophy)

Answer 216

- Duchenne's is the most common muscular dystrophy - Duchenne's is a severe form (due to frameshift mutation resulting in one or both binding sites being lost) - Duchenne's presents around 3-5 yrs of age, Becker's presents later (after 10 yrs) - 30% of pts with Duchenne's have intellectual impairment (this isn't really a feature of Becker's) - Duchenne's has calf pseudohypertrophy Duchenne's is associated with dilated cardiomyopathy - In both conditions, pts will end up in a wheelchair --> earlier in Duchenne's

Answer 217

- Creatinine kinase: raised - Genetic testing has now replaced muscle biopsy as the way to obtain a definitive diagnosis

Answer 218

1. Oral steroids have been shown to slow the progression of muscle weakness by as much as two years 2. Creatine supplementation can give a slight improvement in muscle strength - Genetic trials are ongoing

Answer 219

- may qualify for a driving licence if they have been seizure-free for 12 months - if there have been no seizures for 5 years (with medication if necessary) —> a 'til 70 licence is usually restored

Answer 220

- simple faint —> no restriction - single episode, explained and treated —> 4 weeks off - single episode, unexplained —> 6 months off - two or more episodes —> 12 months off

Answer 221

Abducens nerve (CN VI) --> due to its long intracranial course

Answer 222

- Visual aura (occur in 1/3 pts) —> blurred vision, spreading scintillating scotoma ("jagged crescent"), sparks/lines in vision - Sensory —> tingling or numbness - Language —> dysphasia

Answer 223

- tiredness/lack of sleep - stress - alcohol - dehydration - certain foods —> cheese, chocolate, red wines, citrus fruits - bright lights - menstruation - combined oral contraceptive pill

Answer 224

1. Oral triptan + NSAID OR oral triptan + paracetamol - triptan —> eg. sumatriptan - NSAIDs —> eg. ibuprofen or naproxen (Note: if 1st dose of triptan does not work then DON’T give a 2nd dose for the same attack) 2. If the above not effective —> offer an anti-emetic (eg. metoclopramide or prochlorperazine) (Note: patients often go into a darkened, quiet room during an attack)

Answer 225

- A headache diary can help identify triggers and assess the response to treatment —> avoiding triggers can be helpful 1. Options: - Propranolol (non-selective beta-blocker) - Topiramate —> should be avoided in women of childbearing age (teratogenic) - Amitriptyline (tricyclic antidepressant) 2. If these measures fail —> NICE recommends a course of up to 10 sessions of acupuncture over 5-8 weeks 3. NICE recommend that riboflavin (vitamin B2) 400mg OD may be effective in reducing migraine frequency and intensity for some people

Answer 226

- symptoms tend to occur two days before until three days after the start of menstruation 1. Treat with mini-prophylaxis using triptans (eg. frovatriptan or zolmitriptan) . SIGN recommends that women are treated with: - Mefanamic acid - OR a combination of aspirin + paracetamol + caffeine

Answer 227

Migraine with aura: absolute contraindication to COCP due to ↑ risk of stroke - migraines are associated with slightly increased risk of stroke (particularly when associated with aura) —> the risk of stroke is further increased with the combined oral contraceptive pill (COCP) making them a contraindication

Answer 228

1. Paracetamol 1g —> 1st-line 2. NSAIDs in 1st or 2nd trimester only —> 2nd-line

Answer 229

- Triptans are 5-HT receptor agonists —> they bind to and stimulate serotonin receptors (specifically 5-HT1B and 5-HT1D) - Cause cranial vasoconstriction - Inhibit pain signal transmission - Inhibit the release of inflammatory neuropeptides

Answer 230

- hypertension - coronary artery disease (CAD) - previous stroke, TIA, or MI

Answer 231

alcohol, strong smells, or exercise

Answer 232

1. MRI with gadolinium contrast - Done to rule out secondary causes (e.g. pituitary lesion), even if symptoms are typical

Answer 233

Headache on 15 or more days per month

Answer 234

- High-flow 100% oxygen (via non-rebreather mask) (80% response rate within 15 mins) - Subcutaneous triptan (e.g. sumatriptan) (75% response rate within 15 mins)

Answer 235

- Acute treatment —> aspirin, paracetamol, or an NSAID - Prophylaxis —> NICE recommend up to 10 sessions of acupuncture over 5-8 weeks (Note: low-dose amitriptyline is widely used in the UK as prophylaxis, but NICE do not support this)

Answer 236

Stop analgesia abruptly (may temporarily worsen headache) - Simple analgesia or triptans → stop abruptly - Opioids → gradual withdrawal

Answer 237

anterior ischaemic neuropathy - occlusion of posterior ciliary artery (a branch of the ophthalmic artery) —> ischaemia of the optic nerve head

Answer 238

- O/E —> tender, palpable temporal arery - Bloods —> raised inflammatory markers (ESR) - Fundoscopy —> swolen, pale disc + blurred margins (anterior ischaemic neuropathy) - Temporal artery biopsy —> skip lesions may be present

Answer 239

- Conservative —> analgesia (NSAIDs), physio, cervical collar (acute relief) - Interventional procedures —> cervical epidural injections (reduces inflammation around the affected nerve root)

Answer 240

1. Urgent high-dose glucocorticoids (should be given before the temporal artery biopsy) - if there is no visual loss —> give high-dose prednisolone - if there is evolving visual loss —> IV methylprednisolone is usually given prior to starting high-dose prednisolone (Pts with visualsymptoms need an urgent ophthalmology review --> visual damage is often irreversible) (Note: there should be a dramatic response, if not the diagnosis should be reconsidered)

Answer 241

- Meningism (fever, photophobia, neck stiffness) —> suggests meningitis, encephalitis, or brain abscess - New neurological symptoms —> suggests haemorrhage or tumours - Visual disturbance —> GCA, glaucoma, tumours - Sudden-onset occipital headache reaching maximum intensity within 5 mins (’thunderclap’) —> subarachnoid haemorrhage (SAH) - Hx of trauma —> intracranial haemorrhage - Hx of cancer —> brain metastasis - Pregnancy —> pre-eclampsia . Raised ICP signs - worse with coughing/straining + Valsalva manoeuvre (trying to breathe out with nose and mouth blocked) - worse in morning / lying down/bending over - nausea/vomiting - reduced GCS

Answer 242

Divergent strabismus (squint) —> eye is in a ‘down and out’ position (’abducted and depressed’) - the oculomotor nerve supplies all of the extraocular muscles except the lateral rectus (CN VI) and superior oblique (CN IV). - CN III palsy —> only the lateral rectus and superior oblique are still working, which pull the eye downward and outward . - Ptosis —> oculomotor nerve supplies the levator palpebrae superioris, which is responsible for lifting the upper eyelid

Answer 243

The parasympathetic fibres responsible for pupil constriction are located on the superficial (outer) edge of the nerve - Microvascular ischaemia (eg. diabetes or hypertension) —> the damage is mainly due to the central part of the nerve (not the superficial fibres) —> therefore, causing a pupil-sparing third nerve palsy - Compressive causes (eg. aneurysm, tumour) —> external compression first affects the outer parasympathetic fibres —> leading to a dilated, unreactive pupil early on (pupil is involved) (sometimes called a 'surgical' third nerve palsy)

Answer 244

It suggests a 'surgical' cause, meaning there is something pressing against the oculomotor nerve (eg. space-occupying lesion) —> needs URGENT brain imaging (CT)

Answer 245

- Diabetes mellitus - Hypertension - Ischaemia

Answer 246

Posterior communicating artery aneurysm (PCOM aneurysm)

Answer 247

- The oculomotor nerve travels directly from the brainstem to the eye in a straight line - It travels through the cavernous sinus and close to the posterior communicating artery —> Therefore, cavernous sinus thrombosis or a PCOM aneurysm can cause nerve compression

Answer 248

Uncal herniation through the tentorium cerebelli → compresses CN III → third nerve palsy

Answer 249

- Depression and intorsion (inward rotation) of the eye when it is abducted - ie. the trochlear nerve enables the eye to look down when it is abducted (moved towards the nose) --> important for actions like going downstairs or reading

Answer 250

- vertical diplopia (classically noticed when reading a book or going downstairs) - subjective tilting of objects (torsional diplopia) --> due to unopposed extorsion of the eye - the patient may develop a head tilt, which they may or may not be aware of --> pt will tilt their head away from the side of the lesion to minimise diplopia - when looking straight ahead, the affected eye appears to deviate upwards and is rotated outwards

Answer 251

The left eye, the right trochlear nucleus in the midbrain innervates the superior oblique muscle of the left eye - the trochlear nerve is unique as it is the only cranial nerve that exits the brainstem dorsally and decussates (crosses over) before innervating its target muscle (provides contralateral innervation)

Answer 252

Abducens nerve palsy (6th nerve palsy) - Note that a 6th nerve palsy can be a false localizing sign due to its long, vulnerable path

Answer 253

Multiple sclerosis (MS)

Answer 254

1. Carbamazepine —> start at 100mg BD and titrate up until pain relieved (failure to respond to treatment or atypical features (eg. <50 yrs) —> prompt referral to neurology)

Answer 255

Motor function: - Face: muscles of facial expression - Ear: stapedius in the inner ear - Posterior digastric, stylohyoid and platysma muscles (Note: innervation to upper facial muscles is bilateral, innervation to lower facial muscles is contralateral) . Sensory function: - Taste: taste from the anterior 2/3 of the tongue - external auditory canal and pinna . Parasympathetic supply to the: - Submandibular and sublingual salivary glands (ie. salivary glands except parotid) - Tear: lacrimal gland (stimulating tear production)

Answer 256

Motor and sensory roots emerge from the pons at the cerebellopontine angle

Answer 257

- Internal acoustic meatus (in petrous temporal bone) - Inside the internal acoustic meatus

Answer 258

- Greater petrosal nerve --> carries parasympathetic fibres that synapse in the pterygopalatine ganglion and innervate the lacrimal glands, nasal glands, and palatine mucosal glands - Nerve to stapedius --> innervates stapedius muscle in the middle ear - Chorda tympani --> carries taste information from the anterior two-thirds of the tongue and secretomotor fibres to the submandibular and sublingual salivary glands

Answer 259

via the stylomastoid foramen

Answer 260

Parotid gland

Answer 261

- Each side of the forehead has upper motor neurone innervation by both sides of the brain, but only has lower motor neurone innervation from one side of the brain - In an UMN lesion —> forehead will be spared (due to innervation from both sides of the brain)

Answer 262

- **Hyperacusis** → seen in 1/3 pts (facial nerve innervated stapedius muscle) - **Altered taste sensation** → anterior 2/3 tongue (chorda tympani branch of the facial nerve responsible for taste sensation from ant. 2/3 of tongue)

Answer 263

1. **Prednisolone** - 50mg for 10 days - 60mg for 5 days, followed by a 5-day reducing regime (dropping the dose by 10mg per day) - Pts also require lubricating eye drops to prevent the eye from drying out and being damaged --> exposure keratopathy (the eye can be taped closed at night)

Answer 264

If no improvement after 3 weeks → can sometimes be a sign of underlying ear problems, such as cholesteatoma, mastoiditis, or even a temporal bone malignancy

Answer 265

Caused by the reactivation of the varicella zoster virus (VZV) in the geniculate ganglion of CN VII (facial nerve) . - Auricular pain (often first feature) - Unilateral LMN facial nerve palsy - Vestibular rash in ear canal, pinna, and around the ear (often painful and tender) (the rash can extend to the anterior 2/3 of the tongue and hard palate)

Answer 266

1. Oral aciclovir + prednisolone - Lubricating eye drops --> to prevent exposure keratopathy

Answer 267

- Write out the pathway - verbally explain the pathway

Answer 268

- The LGN is located in the thalamus & is a key relay station where the optic nerve synapses, and the 2nd-order neurons then project to the visual cortex - These 2nd-order neurons form the optic radiations, travel through the internal capsule and terminate in the primary visual cortex (V1)

Answer 269

1. Meyer’s loop → through the temporal lobe - carries upper quadrant visual field info (from inferior retina) —> lesion → contralateral superior quadrantinopia 2. Baum’s loop → through the parietal lobe - carries lower quadrant visual field info (from superior retina) —> lesion → contralateral inferior quadrantinopia

Answer 270

1. Optic nerve —> total right eye blindness (complete monoocular vision loss) 2. Optic chiasm —> bitemporal hemianopia (loss of temporal (outer) visual fields) (nasal retinal fibres cross here) 3. Left temporal retinal fibre —> left nasal hemianopia (loss of left nasal field) 4. Left optic tract —> right homonymous hemianopia (right visual field loss in both eyes) 5. Optic radiations —> homonymous quadrantinopias (PITS) - Parietal lobe (Baum's loop) —> Inferior quadrantinopia (contralateral) - Temporal lobe (Meyer's loop) —> Superior quadrantinopia (contralateral)

Answer 271

A contralateral homonymous hemianopia with macular sparing (central vision spared) eg. Right occipital lesion → left homonymous hemianopia with central vision spared (macula sparing)

Answer 272

Review notes on Horner's syndrome - write out the pathway - verbally explain it

Answer 273

1. **Central lesions (occurring before the nerves exit the spinal cord) —> cause anhidrosis of the arm, trunk, and face** - entire pathway is affected (no signal reaches the pre-ganglionic neuron) —> all downstream sympathetic outflow is lost (ie. face, arm, trunk) 2. **Pre-ganglionic lesions —> cause anhidrosis of the face only** - damage is between T1 nerve root and superior cervical ganglion - arm and trunk fibres have already branched off lower in the sympathetic chain —> so face is affected but not rest of the body 3. **Post-ganglionic lesions —> DO NOT cause anhidrosis** - damage is after the superior cervical ganglion - many facial sweat fibres travel with the external carotid artery, but post-ganglionic Horner’s lesions usually follow the internal carotid artery —> sweat fibres to the face are spared

Answer 274

Pancoast tumour (non-small cell) in the right lung - causing a pre-ganglionic Horner's syndrome --> tumour in apices (top) of lung

Answer 275

Cocaine eye drops —> blocks reuptake of noradrenaline at the NMJ (noradrenaline is a neurotransmitter released by the sympathetic NS) - noradrenaline causes a normal eye to dilate (as noradrenaline stimulates the dilator muscles of the iris) - In Horner’s syndrome, the nerves are not releasing noradrenaline (there is a block to sympathetic innervation) —> so blocking re-uptake makes no difference —> therefore, a drop of cocaine does NOT cause pupil dilation

Answer 276

Apraclonidine (alpha-adrenergic agonist) / low-dose adrenaline (0.1%) —> causes pupillary dilation in Horner’s syndrome due to denervation hypersensitivity - basically a weaker form of norepinephrine —> normally too weak to cause pupil dilation - In Horner’s syndrome there is a block to sympathetic innervation, the pupillary dilator muscle becomes ‘starved’ for stimulation (ie. the α1 receptors on the dilator muscle are more responsive to adrenergic agonists like adrenaline) —> therefore, apraclonidine / low-dose adrenaline (0.1%) causes pupil dilation in Horner’s

Answer 277

- painful stimulus → either supra-orbital pressure or trapezius pinch - ≤ 8 → intubation

Answer 278

1. **DCML pathway → fine touch, vibration, and proprioception** - Fasciculus gracilis (medial): carries input from lower body (below T6) - Fasciculus cuneatus (lateral): carries input from upper body (above T6) —> these tracts travel ipsilaterally up the spinal cord & decussate in the medulla to become the medial lemniscus 2. **Anterolateral system (spinothalamic tracts)** - Lateral spinothalamic tract → pain and temperature - Anterior spinothalamic tract → crude touch and pressure —> these tracts decussate immediately (sometimes 1/2 vertebral lvls above entry) & then travel up the spinal cord to the thalamus 3. **Spinocerebellar tracts → unconscious proprioception for motor coordination (coordination, muscle tone) to the cerebellum** - Posterior (dorsal) spinocerebellar tract: from lower limb & trunk (does not decussate - carries info to ipsilateral cerebellum via inferior cerebellar peduncle) - Anterior (ventral) spinocerebellar tract: more complex input from lower limb (double decussation - ends up at ipsilaterla cerebellum via superior cerebellar peduncle) (Cuneocerebellar & Rostral spinocerebellar tracts = equivalent of posterior/anterior spinocerebellar tracts for the upper limbs) 4. Spino-olivary fibres → also transmits unconscious proprioceptive information to inferior olivary nucleus (a brainstem nucleus located in the medulla oblongata - acts as a relay station between the spinal cord and cerebellum)

Answer 279

1. Pyramidal tracts (voluntary movement) - **Lateral corticospinal tract → voluntary movement of limb (distal) muscles (decussate at the medullary pyramids)** *(ie. if carrying info from left side of cerebral cortex → they will travel on the right side of the spinal cord)* - **Anterior corticospinal tract → voluntary movement of axial (trunk) muscles (do not decussate until they reach the spinal cord level that they innervate)** 2. Extra-pyramidal tracts (involuntary movement/postural control) - **Rubrospinal tract** → facilitates flexor muscles in upper limbs (involved in coordinating gross movements & posture) - **Reticulospinal tract** → important for controlling muscle tone & posture (esp. in the legs) - **Vestibulospinal tract** → maintains balance and posture via extensor muscles - **Tectospinal tract** → coordination of reflexive head and eye movements in response to visual and auditory stimuli

Answer 280

1. 1st-order neurons: - sensory receptors in the skin detect pain, temperature, or crude touch - cell bodies are located in the dorsal root ganglia - axons enter the dorsal horn of the spinal cord, where they synapse with 2nd-order neurons - Afferent fibres (ie. sensory fibres) from different body regions: (Upper limb afferent fibres —> enter at the cervical spinal cord levels (C5-T1)) (Lower limb afferent fibres —> enter at the lumbar spinal cord levels (L1-S2)) 2. 2nd-order neurons: - after synapsing, 2nd-order neurons immediately decussate (cross) to the contralateral side via the anterior white commissure (usually within 1-2 segments of their entry point) 3. 2nd-order neurons then ascend on the contralateral side of the spinal cord in the spinothalamic tracts - **Lateral spinothalamic tract** —> pain and temperature - **Anterior spinothalamic tract** —> crude touch and pressure - Somatotopic organisation: (Fibres from the lower limbs are positioned more laterally) (Fibres from the upper limbs are positioned more medially) 4. 2nd-order neurons synpase in the ventral posterolateral (VPL) nucleus of the thalamus - 3rd-order neurons project to the primary somatosensory cortex (postcentral gyrus) for conscious perception

Answer 281

1. 1st-order neurons - sensory receptors detect fine touch, vibration, or proprioception - these sensory signals travel via **afferent fibres** into the spinal cord & ascend ipsilaterally in the dorsal columns (Fasciculus gracilis —> carries signals from the lower body/below T6) (Fasciculus cuneatus —> carries signals from the upper body/above T6) 2. At the medulla oblongata: 1st-order neurons synapse at two nuclei (Nucleus gracilis - lower body) (Nucleus cuneatus - upper body) 3. 2nd-order neuron axons then decussate (this crossing is called the internal arcuate fibres) - after crossing, the fibres from the medial lemniscus —> the fibres then ascend through the brainstem (medulla → pons → midbrain) towards the thalamus 4. At the thalamus: - In the ventral posterolateral nucleus (VPL) of the thalamus, the second-order neurons synapse onto third-order neurons 5. Finally, the 3rd-order neurons send their axons to the primary somatosensory cortex (postcentral gyrus) in the brain for conscious perception of fine touch, vibration, and proprioception

Answer 282

- DCML and anterolateral (spinothalamic) pathways have 3 neurons involved & decussate (either in spinal cord or in medulla) - Spinocerebellar tracts have 2 neurons involved & do not decussate/double decussate, but essentially carry info to the ipsilateral cerebellum

Answer 283

1. UMN begins in the primary motor cortex (pre-central gyrus of the frontal lobe) 2. The fibres then descend: - through the **internal capsule** (a key passageway in the deep brain). - into the **midbrain** (**cerebral peduncles**). - through the pons. - into the **medulla**, where most fibres cross over (**decussate**) at the **decussation of pyramids** 3. After crossing: - most fibres (75%) form the **lateral corticospinal tract** (controls limb muscles for **fine voluntary movements**) - a smaller number (25%) remain uncrossed as the **anterior corticospinal tract** (controls **trunk muscles** for posture and gross movements) 4. In the spinal cord: - the corticospinal axons synapse with **LMNs** in the **ventral (anterior) horn**. - LMNs then send signals directly to **skeletal muscles** to produce movement.

Answer 284

(this patient has secondary metastases causing spinal cord compression) - Urgent MIR spine within 24hrs of presentation 1. Refer to spinal surgeons 2. Give IV Dexamethasone - *to reduce inflammation and minimise neurological damage* 3. Supportive - *analgesics/antipyretics/antiemetics +/- fluids +/- oxygen (high flow)*

Answer 285

- Lateral corticospinal tracts - Bilateral spastic paresis - Dorsal columns - Bilateral loss of proprioception and vibration sensation - Spinocerebellar tracts - Bilateral limb ataxia (+ve Romberg's sign)

Answer 286

Due to the specific role of B12 in myelin synthesis and maintenance - the dorsal columns, spinocerebellar, & corticospinal tracts are particularly susceptible to damage as they rely heavily on myelin for efficient nerve function

Answer 287

- "Cape-like" loss of pain and temperature sensation over the neck, shoulders, and arms, with preservation of light touch, proprioception, and vibration. - due to compression of the spinothalamic tract fibres decussating in the anterior white commissure of the spine (these are the first to be affected)

Answer 288

- ipsilateral weakness below lesion → due to damage to corticospinal tract - ipsilateral loss of proprioception and vibration sensation → due to damage to dorsal columns (DCML) - contralateral loss of pain and temperature sensation → due to damage to spinothalamic tract

Answer 289

- Motor pathway (corticospinal tract) - Medial lemniscus - Medial longitudinal fasciculus (MLF) - Motor cranial nerve nuclei (III, IV, VI, XII)

Answer 290

- Spinocerebellar pathways - Spinothalamic pathway - Sensory nuclei of the 5th cranial nerve - Sympathetic pathway

Answer 291

- 4 above the pons → I, II, III, IV (I and II → above midbrain) (III and IV → within the midbrain) - 4 in the pons → V, VI, VII, VIII - 4 in the medulla → IX, X, XI, XII —> Cranial nerve nuclei found in the midline divide equally into 12 → III, IV, VI, and XII (all motor nerves) —> Cranial nerves V, VII, IX, and XI → in the lateral aspect of the brainstem

Answer 292

→ usually due to infarction of the posterior inferior cerebellar artery (PICA) (PICA is a major artery that branches off the vertebral artery & supplies blood to the medulla and cerebellum)

Answer 293

- Sympathetic tract → ipsilateral Horner’s syndrome - Lateral spinothalamic tract → contralateral loss of pain and temperature sensation - Spinocerebellar tract → ataxia - Vagus (X) & Glossopharyngeal (IX) nucleus/nerves → difficulty swallowing - The VIII nuclei naturally extends slightly into the medulla so can be affected → causes the vertigo, nausea/vomiting - Trigeminal nerve (spinal aspect) → causes ipsilateral loss of sensation to the face (No limb weakness → the motor tract (corticospinal tract) is in the medial aspect of the medulla) (No loss of touch & vibration below the neck → medial lemniscus tract runs in the medial aspect of the medulla)

Answer 294

Right medial aspect of the medulla - Right motor pyramidal tract → contralateral paralysis/weakness of the left upper/lower limb of body - Hypoglossal nerve (CN XII) → deviation of the tongue to the side of the lesion (ipsilateral) - Right medial lemniscus tract → contralateral decrease in proprioception, vibration, and/or fine touch sensation

Answer 295

Degenerative cervical myelopathy - think DCM in older adults with unexplained gait instability or bilateral hand dysfunction - often presents with neck pain and loss of fine motor control of the hands (eg. gripping things, doing up shirt buttons)

Answer 296

1. MRI cervical spine is 1st-line → identifies canal stenosis, cord compression, signal change (Nerve conduction studies (if diagnostic uncertainty) → to rule out peripheral neuropathy or carpal tunnel)

Answer 297

1. Decompressive surgery → only effective intervention (best outcomes if performed within 6 months of symptom onset) (Do not initiate physiotherapy or spinal manipulation in primary care due to risk of worsening cord compression.)

Answer 298

Frontal —> voluntary motor control, higher executive functions (eg. planning, decision making, and problem-solving), speech production (Broca’s area in dominant hemisphere) - also governs aspects of personality and behaviour

Answer 299

Parietal —> processing sensory information (touch, proprioception, pain, and temperature) - also important for spatial awareness and the ability to understand where objects are in space

Answer 300

Temporal —> hearing, language comprehension (Wernicke’s area in dominant hemisphere) - also memory formation (hippocampus), and emotional processing (amygdala)

Answer 301

Occipital —> visual processing (receives and interprets visual information)

Answer 302

Cerebellum —> coordinates movement, balance, posture, and motor learning (eg. learning to ride a bike) - does not initiate movement, but fine-tunes it

Answer 303

Corpus callosum —> large C-shaped bundle of white matter fibres located deep in brain - connects the left and right cerebral hemispheres —> allowing them to communicate and coordinate activities —> damage/disruption can lead to split-brain syndrome (where each hemisphere acts independently), resulting in issues like difficulty naming objects presented to the left visual field

Answer 304

anterior white commissure = a band of nerve fibres in the spinal cord that crosses the midline, connecting the two sides of the spinal cord (eg. nwueona decussate across the spinal cord they cross the midline via the anterior white commissure

Answer 305

Usually lesions affect the lateral spinothalamic tract (pain and temp.), but if lesion is large enough then anterior spinothalamic tract can also be affected, although this is rare) - demonstrated in Brown-Sequard syndrome (Note: Because of the somatotopic organisation, damage to more lateral parts preferentially affects lower limb sensation, while more medial damage affects upper limb sensation)

Answer 306

- Test vibration/fine touch (eg. tuning fork) —> tests **DCML** - Test pain/temp. (eg. pinprick or cold tuning fork) —> tests **spinothalamic**

Answer 307

Right internal capsule lesion (most likely due to a stroke)

Answer 308

Lateral medullary syndrome (left brainstem lesion) - Face pain sensation = trigeminal nerve pathways - Body pain and temperature = spinothalamic tract

Answer 309

Complete transverse spinal cord lesion at T7 —> spinal cord trauma

Answer 310

Anterior spinal artery occlusion - Motor loss (corticospinal tract) and pain/temp loss (spinothalamic tract) —> anterior spinal cord - Vibration and proprioception preserved —> dorsal columns spared

Answer 311

Brown-Séquard syndrome (in this case it is a left spinal cord hemisection) - Right pain/temp loss = spinothalamic tract damaged —> lesion affects contralateral side (ie. left-sided lesion affects right side of body below the lvl of the lesion) - Left motor loss, vibration, proprioception = corticospinal and dorsal columns damaged —> lesion affects ipsilateral side (left side damage)

Answer 312

Dorsal column lesion (in this case left dorsal column lesion at or near L2) - **Touch and proprioception** = dorsal column involvement - Affecting left lower limb only —> localised lesion (Could be trauma, compression - eg. disc herniation or tumour affecting posterior part of cord)

Answer 313

Anterolateral lesion (spinothalamic tract damage) - in this case right-sided anterlateral lesion - **Pain and temp** = spinothalamic tract (anterolateral spinal cord) - **Spinothalamic fibres cross early** (within 1–2 segments of entry) - If L2 sensory symptoms → likely lesion around L1/L2 spinal cord

Answer 314

Small central cord lesion (probably T10 if hips affected) - "Cape-like" or band-like loss of pain/temp sensation —> think **central cord lesion**. - Central lesion affects **crossing spinothalamic fibres** at that level (before ascending) (Cause: Syringomyelia)

Answer 315

- **L2-L3 nerve root lesion** (but L2 dermatome mainly groin/upper thigh; lateral leg more L4/L5!). - Could also be **dorsal root ganglion** pathology (e.g., herpes zoster) (lesion will correspond with nerve root involved and its associated dermatome)

Answer 316

Brain tumour in parasagittal region (pressing the motor cortex for lower limbs) - Bilateral motor and sensory symptoms = central spinal or brain lesion. - Hyperreflexia = UMN (central) lesion. - Absent reflexes = LMN (peripheral) lesion

Answer 317

Supplies the anterior 2/3 of the spinal cord: - **Corticospinal tracts** —> motor tracts - **Spinothalamic tracts** —> pain and temperature tracts - **Anterior horn** (LMNs) Clinical relevance —> leads to loss of motor function (corticospinal), loss of pain and temp. sensation (spinothalamic), but preserved fine touch, vibration, and proprioception (dorsal columns spared)

Answer 318

Supply the posterior 1/3 of the spinal cord: - Dorsal columns (fine touch, vibration, proprioception)

Answer 319

- Supplies a large portion of the lower thoracic and lumbar spinal cord - Clinical relevance —> damage to this artery (e.g., during aortic surgery) can cause lower limb paralysis

Answer 320

—> Diagnosis = Transverse Myelitis - Time course (48hrs) —> suggests inflammatory/demyelinating process - Sensory level (T8) → Lesion is usually 1–2 levels below the clinical sensory level - Fits with MRI at T10–T11 - Normal power but proprioceptive ataxia → dorsal column dysfunction - T2 high signal on MRI spine → suggests inflammatory/demyelinating lesion

Answer 321

Opioid overdose - the parasympathetic nervous system causes the iris to contract, making the pupils small

Answer 322

1. Frontal cortex (in frontal lobe) → where you plan (”I want to move”) - Supplementary motor area (also in frontal lobe) → final step in planning (”Right, I really want to move”) 2. That then feeds into the primary motor cortex - part of brain involved in direct communication through the pyramidal tracts 3. That then sends a message down through the basal ganglia (extrapyramidal motor system) - basal ganglia acts as an ‘amplifier’ → makes small neural signal into a big neural signal 4. In doing this, it is still quite a jerky, poorly controlled signal → this is where the cerebellum comes in - the cerebellum smooths out those signals → turns a jerky, uncoordinated movement into a much smoother movement 5. That signal then travels down the spinal cord and at some point synapses with 2nd-order motor neurons 6. These 2nd-order motor neurons then feed out to the NMJ and the muscle itself

Answer 323

- C fibres (unmyelinated) - transmit signals slowly and produce dull and diffuse pain sensations - A-delta fibres (myelinated) - transmit signals fast and produce sharp and localised pain sensations Further type A: (Type 1 (slow twitch) - long, aerobic activities) (Type 2 (fast twitch) - short, fast bursts of activity, anaerobic)

Answer 324

- Blood is delivered to brain through 4 main arteries, two internal carotid arteries (anterior supply), and two vertebral arteries (posterior supply to the brain) - Anterior supplied by internal carotid arteries which form the ACA and MCA - Anterior connects with Posterior via posterior communicating artery - Posterior supplied by vertebral arteries which combine to form the Basilar artery (The brain also has a venous drainage system which drain into the venous sinuses)

Answer 325

- Formed by basilar artery, internal carotid artery, and middle cerebral artery - Safeguards the oxygen supply from interruption by arterial blockage - For example, if there is stenosis in one artery then other source arteries to the Circle of Willis can provide an alternative blood flow (collateral circulation)

Answer 326

Limbic system = a set of brain structures that controls emotions, memory, and behaviour . Hippocampus: - memory centre (forms and stores long term memories) - spatial awareness/orientation - neurogenesis occurs here (key brain structure for learning new things) . Amygdala: - plays a role in how we experience emotions (like fear, anger, anxiety, pleasure) - attaches emotional content to memories - fight or flight response occurs here

Answer 327

- FRONTAL - *tasks requiring executive function (planning, decision-making, problem-solving, and working memory) such as complex problem-solving scenarios* - PARIETAL - *two-point discrimination* - OCCIPITAL - *visual fields, colour recognition, identifying objects* - TEMPORAL - *ask pt to recall stories, identify sounds, or recognise familiar faces*

Answer 328

1. Invasion - Pathogen colonises nasopharynx - pathogen then invades bloodstream - bacteria then cross the blood-brain barrier (BBB) 2. Survival - bacteria evades immune responses to survive and proliferate - various mechanisms - antigenic variation, inhibition of complement activation, intracellular survival inside phagocytes, production of immunomodulatory molecules, and formation of biofilms 3. Replication and Tissue damage - bacteria multiply in the subarachnoid space - leading to increased ICP - Inflammatory response leads to damage of neuronal tissue and the BBB - results in symptoms

Answer 329

- sheath around optic nerve is connected with the subarachnoid space - therefore, raised CSF pressure flows into the optic nerve sheath --> increasing the pressure around the optic nerve behind the optic disc causing the optic disc to bulge forward

3C Neuro Flashcards

(364 cards)