Neuro Flashcards
(152 cards)
1
Q
Which dermatomes supply which areas of the arm?
A
C5 = just below shoulder C6 = radial forearm. thumb and first finger C7 = middle two digits C8 = little finger and part of ulnar forearm T1 = ulnar top part of arm
2
Q
Which lumbar root controls the ankle jerk reflex?
A
S1
3
Q
Which cervical roots control the biceps and triceps reflexes?
A
C6 and C7
4
Q
What happens in Brown Sequard syndrome?
A
A hemisection of the spinal cord occurs causing ipsilateral loss of proprioception, fine touch and motor function and contralateral loss of pain and temperature
5
Q
Name 2 ascending spinal tracts and their functions
A
Spinothalamic = pain and temp laterally and crude touch and pressure anteriorly
Dorsal column medial lemniscus (DCML) = proprioception, fine touch and vibration
6
Q
Name 2 descending spinal tracts and their functions
A
Corticospinal = motor control of skeletal body muscles Corticobulbar = motor control of head and neck muscles
7
Q
Which spinal tracts are affected in Brown Sequard syndrome?
A
DCML (proprioception and fine touch) and Corticospinal (motor function) which decussate in brain
Spinothalamic = pain, temp, crude touch and pressure which decussates in spinal cord so causes contralateral symptoms
8
Q
List the symptoms that cerebellar dysfunction causes
A
D-ysdiadochokinesia A-taxia N-ystagmus I-ntention tremor S-lurred speech H-ypotonia
9
Q
What are the 3 layers of the meninges (from outer to inner)?
A
Dura mater
Arachnoid mater
Pia mater
10
Q
Where is CSF contained?
A
The sub arachnoid space
11
Q
How does CSF re enter circulation
A
Arachnoid granulations into the dura allow it to re enter circulation via the dural venous sinuses
12
Q
Describe the pathway of vessels in the circle of willis from bottom to top
A
Basilar artery (pontine arteries coming off)
Superior cerebellar artery
Posterior cerebral artery
Posterior communicating artery
Middle cerebral artery feeding into internal carotid
Anterior communicating artery
Anterior cerebral artery
13
Q
Which foramina do the 1st and 2nd CNs leave by?
A
Cribriform plate = olfactory
Optic canal = optic nerve
14
Q
Which CNs leave the brain via the superior orbital fissure?
A
Oculomotor (3)
Trochlear (4)
Ophthalmic (5)
Abducens (6)
15
Q
Which foramina do the mandibular and maxillary CNs leave by?
A
Maxillary = foramen rotundum Mandibular = foramen ovale
16
Q
Which CNs leave via the internal acoustic meatus?
A
Facial (7) and vestibulocochlear (8)
17
Q
Which foramina do the glosopharyngeal, vagus and accessory CN leave by?
A
Jugular foramen
18
Q
Which foramina does the hypoglossal CN leave by?
A
Hypoglossal canal
19
Q
Name some structures that make up the basal ganglia
A
Caudate nucleus, Lentiform nucleus (putamen and globus pallidus), claustrum, subthalamic nucleus and substantia nigra
20
Q
What is the role of glial cells?
A
Support, nourish and insulate neurones by removing waste products of metabolism
21
Q
Give 4 example of glial cells
A
Astrocytes, oligodendrocytes, microglia and ependymal cells
22
Q
What is CSF produced by?
A
Choroid plexus which covers both the lateral ventricles and the roof of the 3rd and 4th ventricles
23
Q
Give 4 roles of CSF
A
Buoyancy, protection, homeostasis and clearing waste
24
Q
What are some UMN signs?
A
Hypertonia, hyperreflexia, weakness/paralysis, spasticity and clonus
25
What are LMN signs?
Hypotonia, hyporeflexia, flaccid muscle weakness or paralysis, fasciculations and muscle atrophy
26
What causes Horners syndrome?
A lesion of the sympathetic chain supplying the eye
27
What triad of symptoms is Horner syndrome characterised by?
Ptosis (drooping of eyelid)
Anhidrosis (lack of sweating)
Miosis (constricted pupil on ipsilateral side)
28
What is MS?
A chronic inflammatory autoimmune disorder of the CNS causing multiple areas of demyelination within the brain and spinal cord (oligodendrocytes are targeted)
29
What are the patterns of MS?
```
Relapsing remitting (80%) symptoms come and go
Secondary progressive following on from relapsing remitting
Primary progressive (10-15%)
```
30
State some signs and symptoms of MS
Limb numbness, tingling and weakness
Visual = unilateral optic neuritis (acute pain in eye on movement), blurred vision or hemianopia
Brainstem demyelination = diplopia, vertigo, dysphagia or nystagmus
Autonomic symptoms = bladder symptoms, sexual dysfunction and loss of thermoregulation
Lhermittes sign = tingling electric shock shooting up spine
Uhthoffs phenomenon = symptoms worse in heat
31
What is the key diagnostic criteria of MS?
Lesions must be disseminated in both time and space
32
What is the management of MS?
Acute relapse = steroids eg IV methylprednisolone
| Frequent relapse = sc interferon beta, monoclonal abs, physio, muscle relaxants
33
What are the 2 types of stroke (CVA) and state causes of both
Ischaemic (85%) = small vessel occlusion, cardiac emboli eg due to AF, vasculitis
Haemorrhagic (15%) = trauma, aneurysm rupture, thrombolysis, SAH
34
What are common symptoms of an ACA stroke?
Leg weakness and sensory disturbance
Gait apraxia
Incontinence
Drowsiness
35
What are common symptoms of an MCA stroke?
Contralateral hemiplegia (more in arms)
Contralateral sensory loss
Hemianopia
Dysphasia
36
State some symptoms that may occur in a posterior circulation stroke
```
Very catastrophic
Motor deficits eg weakness, clumsiness and paralysis
Dysphagia
Visual disturbances
Altered consciousness
```
37
What are lacunar infarcts and what symptoms do they cause?
Small infarcts around the midbrain and internal capsule eg basal ganglia, thalamus and pons and cause pure motor or sensory signs
38
What is the management for an ischaemic stroke?
Thrombolysis within 4.5 hours of symptom onset
Give tissue plasminogen activator eg Alteplase
Start antiplatelet therapy eg Clopidogrel after
39
What is the management for a haemorrhagic stroke?
Control hypertension,
Frequent GCS monitoring
May need surgery
40
What are the most common type of primary brain tumours?
Gliomas (glial cell in origin) eg astrocytoma
41
Why are brain tumours not truly differentiated as benign or malignant?
All tumours even "benign" ones cause significant morbidity and mortality as are space occupying and increase the ICP
42
What are the 4 main symptoms of brain tumours?
Symptoms of raised ICP eg progressive headache, drowsiness, papilloedema (swelling of optic disc)
Progressive neurological deficit depending on area affected
Seizures
Lethargy/tiredness
43
What are the most common neoplasms that metastasise to the brain?
```
Non small cell lung cancer
Small cell lung cancer
Breast
Melanoma
Renal cell
GI
```
44
What is charcot marie tooth syndrome?
A group of inherited peripheral neuropathies causing muscle weakness starting from feet, sensory loss and spinal deformities
45
What are the main causes of bacterial meningitis in adults and children?
Streptococcus pneumoniae
Haemophilus influenzae
Neisseria meningitidis
46
What are common causes of viral meningitis?
EBV
Mumps
Herpes simplex
HIV
47
What are risk factors of meningitis?
Intrathecal drug administration, immunocompromised, crowding, IVDU, malignancy and diabetes
48
What are signs and symptoms of bacterial meningitis?
Non specific features eg fever, vomiting, rigors, headache, lethargy
Photophobia
Stiff neck
Meningococcal septicaemia = a non blanching petechial rash
Positive kernigs sign (resistance on passive knee extension when hips fully flexed)
Positive brudzinkis sign (hips flex on bending head forward)
49
How is bacterial meningitis diagnosed?
Blood cultures to see if septicaemia is present
| Lumbar puncture at L4 and CSF microscopy (give empirical abs if not done within 30 mins)
50
How is bacterial meningitis managed?
IV Ceftriaxone is initial treatment because is broad spectrum and crosses the BBB
If >50/immunocompromised add Amoxicillin to cover listeria
51
What further actions do you need to take if it is found that the cause of meningitis is N meningitidis?
Alert public health and give prophylaxis to close contacts - Rifampicin or Ciprofloxacin to eradicate nasopharyngeal carriage of the organism
52
What is encephalitis?
Inflammation of the brain parenchyma
53
What causes encephalitis?
Mainly viral causes eg Herpes simplex, mumps, HIV
54
How does encephalitis present?
Triad of fever, headache and altered GCS
May begin with prodrome phase = flu like illness then is acute rapid development of altered consciousness with confusion, drowsiness, coma and seizure
May have signs of meningitis eg fever, headache and neck stiffness
55
How is encephalitis managed?
Give antivirals eg Acyclovir to cover herpes simplex
56
What is the pathophysiology of herpes zoster (shingles)?
It affects the peripheral nerves
If reactivated in the dorsal root ganglion it travels down the affected nerve via the sensory root in dermatomal distribution
57
How does Herpes Zoster present?
Pre eruptive = pain and paraesthesia in a dermatomal distribution and may feel generally unwell
Eruptive phase = rash appears consisting of papules and vesicles, neuritic pain
58
What is the management of Herpes Zoster?
Oral antiviral therapy within 72 hours of rash eg Acyclovir
59
Name some types of dementia
```
Alzheimers disease
Vascular dementia
Lewy body dementia
Fronto temporal dementia
Parkinsons
```
60
How does Alzheimers disease present?
Insidious onset with steady progression
STM loss is most prominent early symptom
Slow disintegration of personality, intellect, language and visuospatial skills
61
How does Vascular dementia present?
Stepwise deterioration
| History of TIAs or strokes
62
How does dementia with lewy bodies present?
Fluctuating cognition
Impairment in attention or cognition before memory loss
Visual hallucinations and parkinsonian features
63
What drugs can be given in Alzheimers?
Acetylcholinesterases eg Donepezil, Rivastigmine
64
What is an epileptic seizure?
A convulsion or transient abnormal event from a paroxysmal discharge of cerebral neurones
65
What is the definition of epilepsy?
At least 2 unprovoked seizures occurring more than 24hrs apart
One unprovoked seizure and a probability for further seizures similar to general recurrence risk after 2 unprovoked
66
What are causes of an epileptic seizure?
```
2/3 are idiopathic
CVD eg cerebral infarction
Alcohol withdrawal
Cerebral tumour
CNS infections
Metabolic disturbances
Drugs eg cocaine
```
67
What are the elements of a seizure?
Prodrome = precedes seizure eg change in behaviour
Aura = part of seizure where patient is aware eg strange smell, deja vu or flashing lights
Ictus = the seizure itself
Post ictally = headahce, confusion, sore tongue
68
What are types of primary generalised seizures?
Generalised tonic clonic (grand mal) = no aura, loss of conc, tonic phase eg stiff limbs and clonic phase eg rhythmic jerking, may be incontinent and bite tongue and followed by confusion
Typical absence seizure (petit mal) = stare and pale for a few seconds
Myoclonic seizure = sudden isolated jerk of a limb, face or trunk
69
What is the jacksonian march symptom of epilepsy?
The seizure starts distally and moves more proximally and is more of motor origin (in frontal lobe seizures)
70
Which anti epileptic is first line for primary generalised tonic clonic seizure?
Lamotrigine
71
Which anti epileptic is first line for focal temporal seizure?
Carbamazepine
72
When are anti epileptics started?
Only if there is a high risk of recurrence
73
What advice should be given to patients with epilepsy?
Avoid swimming alone
Leave the door open when taking a bath
Inform the DVLA
74
What is Guillain Barre Syndrome (GBS)?
An acute inflammatory demyelination ascending polyneuropathy affecting the peripheral nervous system (schwann cells)
75
What is the aetiology of GBS?
75% have a preceding infection of resp/GI tract 1-3 weeks before eg campylobacter jejuni, HIV or EBV
76
How does GBS present?
An ascending pattern of progressive symmetrical muscle weakness "toes to nose"
In 20% respiratory and facial muscles are affected putting patients at risk of resp failure
77
How is GBS managed?
Monitor FVC hourly and if below 80% admit to ITU
IV immunoglobulins for 5 days and/or plasma exchange
AVOID CORTICOSTEROIDS as make it worse
78
What are common causes of migraines?
```
C-heese
H-angovers
O-rgasms
C-hocolate
O-ral contraceptive pill
L-ie ins
A-lcohol
T-umult (loud noise)
E-xercise
```
79
What are 2 different types of migraines?
With aura = progressive neuro deficits that recover completely eg hemianopia, paraesthesia, numbness
Without aura = usually have nausea/vomiting, photophobia or phonophobia (sounds) with headache
80
How are migraines managed?
Simple analgesia and anti emetics
Triptans eg sumatriptan
Beta blockers
Tricyclic antideps eg Amitryptiline
81
What is the most common primary headache?
Tension headache?
82
What are risk factors of a tension headache?
Stress, sleep deprivation, bad posture, hunger, eye strain, anxiety, noise
83
How do cluster headaches present?
Rapid onset of severe unilateral headache usually beginning around eye or temple
Pain is unilateral and localised
Ipsilateral cranial autonomic features eg lacrimation, rhinorrhoea (nasal discharge)
84
How are cluster headaches managed?
```
Acute = inhalation of 100% O2 and triptan (analgesics dont help)
Prophylaxis = CCB eg verapimil, steroids, reduce alcohol and stop smoking
```
85
How does trigeminal neuralgia present?
Severe paroxysms of knife like pain in one or more of the trigeminal nerve divisions
Pain usually shoots from mouth to angle of the jaw
Triggered by stimulation of a specific trigger zone eg by shaving, eating or talking
86
How is trigeminal neuralgia treated?
Anticonvulsants eg Carbamazepine
87
What causes trigeminal neuralgia?
Compression of the trigeminal nerve by a loop of a vein or artery
88
What is a subarachnoid haemorrhage (SAH)?
Spontaneous bleeding into the subarachnoid space (between arachnoid and pia mater)
89
What is the aetiology of SAHs?
Rupture of saccular berry aneurysms (80%) usually at branching points in the circle of willis
Congenital arteriovenous malformations eg fistula between arterial and venous systems (10%)
No cause found (15%)
90
How do SAHs present?
Sudden onset of a severe occipital "thunder clap" headache eg like being kicked in the head
Vomiting, collapse, seizures and coma
Meningeal irritation
91
How are SAH diagnosed?
Gold standard = Head CT showing star shaped lesion and hyperattenuation around circle of willis
Lumbar puncture = xanthocromia
92
How are SAH managed?
ABCDE
Give CCB eg Nimodipine to reduce cerebral artery spasm
Prevent re bleeding eg by neurosurgical clipping or endovascular coiling
93
What is a subdural haematoma?
An accumulation of blood in the subdural space (between dura and arachnoid mater) due to rupture of a bridging vein
94
What are causes of subdural haematomas?
Blunt head trauma with a latent interval after injury eg shaking baby syndrome
Clotting disorders
AV malformations
95
What are risk factors of subdural haematomas?
Infants eg due to abuse
Elderly as cerebral atrophy makes brains weaker
Alcoholism
96
How do subdural haematomas present?
Fluctuating levels of consciousness
Progressive headache
Raised ICP = vomiting, seizure and raised BP
97
What is shown on a CT head in a subdural?
Hyperdense crescent shaped collection of blood over one hemisphere like a banana
Shifting midline structures
98
How are subdural haematomas treated?
```
Surgical removal
IV Mannitol (diuretic) to reduce ICP
If chronic do burr holes
```
99
What is an extradural haemorrhage?
A collection of blood between the duramater and bone usually caused by a head injury
100
What causes extradural haemorrhages?
Usually due to a traumatic head injury which fractures the temporal or parietal bone
The fracture ruptures the underlying middle meningeal artery
101
How do extradural haemorrhages present?
Usually have a head injury with brief loss of conc or initial drowsiness followed by a lucid period of recovery and then a rapid decline once the ICP has built up
102
How do extradural haemorrhages appear on CT?
A lemon shaped haematoma adjacent to the skull
103
What is Huntingtons Chorea?
An autosomal dominant condition (with full penetrance) causing chorea and characterised by a lack of GABA
104
What are clinical manifestations of huntingtons?
Often a prodromal phase of mild psychotic and behavioural symptoms eg personality change, clumsiness and apathy
Chorea develops = relentless, progressive jerky involuntary movements
Causes dementia and eventually death
105
What is Lambert Eaton Myasthenic Syndrome?
A disorder of neuromuscular transmission caused by impaired presynaptic release of ACh
It causes proximal muscle weakness, autonomic symptoms eg dry mouth, impotence and postural hypotension and eyelid ptosis and mild diplopia
106
What causes lambert eaton myasthenic syndrome?
An autoimmune attack against P/Q type voltage gated calcium channels on PREsynaptic neurones
107
What are risk factors of lambert eaton myasthenic syndrome?
Cancer = 50% have SCLCs found
108
How is Lambert Eaton Myasthenic Syndrome differentiated from Myasthenia gravis?
Detection of ACh receptor antibodies characteristic of myasthenia gravis or malignancy
109
How is Lambert Eaton Myasthenic Syndrome treated?
IV 3,4-diaminopyridine which blocks K+ channels improving muscle strength
Immunosuppression by steroids if really severe
110
What is motor neurone disease (MND)?
A cluster of major degenerative diseases characterised by destruction of upper and lower motor neurones, cranial nerve nuclei and anterior horn cells in the brain and spinal cord
But no sensory loss, sphincter disturbance or affect on eye movements
111
What are the different types of MND?
Amyotrophic lateral sclerosis (AML) 80% = UMN and LMN tends to be focal and asymmetrical in onset
Progressive muscular atrophy (PMA) 10-20% LMN causing weakness and wasting
Progressive bulbar palsy (PBP) 10-20% LMN only lower cranial nerves
Primary lateral sclerosis (PLS) UMN least common
112
What is the management of MND?
Antiglutamatergic drugs eg Riluzole a Na channel blocker inhibiting glutamate release and slows progression very slightly
Treat symptoms
113
What is myasthenia gravis?
An autoimmune disease against nicotinic acetylcholine receptors in the neuromuscular junction
114
How does myasthenic gravis present?
Increasing muscular fatigue on sustained activity
Usually proximal limb muscles, extra ocular muscles and muscles of mastication, speech and facial expression
Ocular palsies, ptosis and diplopia
115
How is myasthenic gravis diagnosed?
Elicit fatiguability eg ask to count to 50 and voice will become less audible
Serum anti AChR raised in 90%
Tensilon test positive
116
How is myasthenia gravis treated?
Anti cholinesterase eg pyridostigmine to increase ACh in NMJ
Immunosuppression
Thymectomy
117
What is a complication of myasthenic gravis?
Weakening of respiratory muscles
118
What is Parkinsons disease?
A degenerative movement disorder characterised by a triad of rigidity, bradykinesia and a resting tremor due to reduced DA in the substantia nigra
119
Describe the signs and symptoms present in Parkinsons disease
```
Resting tremor (4-7Hz) often asymmetrical and most obvious in thumbs eg pill rolling
Rigidity "cog wheel"
Bradykinesia = progressive reduction in amplitude of receptive movements, face is expressionless, hypophonia (speech slow and quiet) and micrographia ( writing becomes small
Postural changes eg stooped, small shuffling steps and reduced asymmetrical arm swing
Other features = drooling of saliva, depression and constipation
```
120
How can Parkinsons be managed?
If <60 can use DA agonist eg pramipexole or ropinirole to treat motor features and delay starting L-dopa
Gold standard = Levodopa with a peripheral dopa decarboxylase inhibitor eg Madopar preventing peripheral conversion of Ldopa to DA and reducing side effects eg nausea
Over time efficacy is reduced
Monoamine oxidase B inhibitors (MAOIs) eg selegline inhibit MAO enzymes which usually breakdown DA so reduce DA breakdown
COMT inhibitors = similar mechanism as MAOIs
121
What nerve and spinal roots are affected in carpal tunnel syndrome?
Median nerve C6-T1
122
Which muscles does the median nerve innervate?
LL(2 lumbricals), O(opponens pollicus), A(abductor pollicus brevis), F(flexor pollicus brevis)
123
Which investigations are positive in carpal tunnel syndrome?
Phalens test = patient can only maximally flex wrist for 1 min
Tinnels test = tapping on nerve at wrist induces tingling
124
What causes wrist drop?
Radial nerve neuropathy (C5-T1)
125
What causes claw hand deformity?
Ulnar nerve neuropathy (C7-T1)
126
What causes foot drop?
Common peroneal/fibular nerve
127
What signs and symptoms are present in bells palsy?
```
Unilateral paralysis of the whole side of the face
Inability to close eye
Hyperacusis (due to noise sensitivity)
Dry mouth
Loss of taste in anterior 2/3 of tongue
```
128
How can you differentiate Bells palsy from a stroke?
Strokes = forehead sparing because there is bilateral innervation of the forehead so the contralateral lower face is affected only
Bells palsy = no forehead sparing and the whole side of the face is affected unilaterally as it affects the motor innervation after both of the hemispheres have joined
129
How do you manage Bells palsy?
Corticosteroids 1st line within 72 hours
Eye protection to prevent corneal injury due to dry eyes
If severe add antiviral
130
What are causes of cauda equina?
Herniation of lumbar disc eg at L4/5 or L4/S1
Tumours
Trauma
Infection
131
How does cauda equina present?
Flaccid paralysis = LMN signa
Lower limb neuro deficit or lower back pain
Saddle anaesthesia
Bladder/bowel dysfunction
132
What is syncope?
A transient LOC due to cerebral hypoperfusion
133
What are causes of syncope?
Vasovagal = emotional eg due to fear or pain or orthostatic stress eg prolonged standing
Situational syncope eg due to cough, sneeze or micturition
Orthostatic hypotension
Carotid sinus
Cardiac arryhthmias
Hypoglycaemia
134
What investigations are done for syncope?
Orthostatic BP (standing)
ECG
FBC
Tilt testing
135
What is the definition of a TIA?
A brief episode of neurological dysfunction due to focal brain, spinal cord or retinal ischaemia without infarction
Duration is no more than 24 hours
136
What risk score is conducted after someone has a TIA?
```
ABCD2
Age>60
BP>140/90
Clinical features - unilateral weakness (2) or speech disturbance without weakness (1)
Duration of symptoms >60 mins (2) and 10-59 mins (1)
Diabetes
>6 strongly predicts a stroke
>4 need assessment within 24 hrs
All should be seen within 7 days
```
137
What is Wernickes encephalopathy?
A neurological emergency resulting from thiamine (B1) deficiency usually caused by chronic alcohol consumption
138
How does Wernickes encephalopathy present?
```
Cognitive dysfunction eg loss of memory and confusion
Vision changes eg diplopia
Abnormal gait
Muscle weakness
Tachycardia
Asterixis
```
139
What is Wernicke Korsakoff syndrome?
A long term condition that develops when Wernickes encephalopathy is left untreated or not treated soon enough
Causes confusion, memory loss, changes in personality
140
What is strabismus (squint)?
A misalignment of the visual axis meaning the eyes aren't directed at an object at the same time
141
What is radiculopathy?
A neurological state in which conduction is limited or blocked along a spinal nerve or its roots
142
What is myelopathy?
An injury to the spinal cord due to severe compression of the cord itself
143
What causes sciatica (lumbar radiculopathy)?
Compression of the lumbosacral nerve roots L4-S1 forming the sciatic nerve
144
What are the clinical manifestations of sciatica?
Unilateral leg pain radiating below the knee to the foot or toes
Low back pain
Numbness or tingling in dermatome
Positive result on a straight leg test
145
What is hydrocephalus?
Build up of fluid in the brain/elevated CSF pressure
146
What are clinical features of hydrocephalus?
Levodopa unresponsive gait apraxia
Urinary/faecal incontinence
Cognitive impairment
147
What is non epileptic attack disorder?
A type of seizure that can look similar to epileptic seizures or fainting but isnt caused by abnormal discharges or blood pressure
They can happen when the brain cant handle thought, memories, emotions or sensations (overwhelming stress)
148
What are clinical manifestations of non epileptic attack disorder?
May have tonic clonic seziure like convulsions but movements aren't rhythmical
Dont lose conc
Last longer than epileptic seizures
149
What is narcolepsy?
A chronic condition caused by disruption of the sleep wake cycle and rapid eye movement intrusion in the wake state
150
What are clinical manifestations of narcolepsy?
```
Excessive daytime sleepiness
Cataplexy (generalised muscle weakness leading to partial or complete collapse)
Sleep paralysis
Poor memory and conc
Sleep attacks
```
151
What are the 3 components of GCS and the maximum scores for each?
Eye opening = 4 points
Verbal response = 5 points
Motor response = 6 points
152
What are bulbar palsy?
Signs and symptoms linked to impaired function of the lower cranial nerves typically caused by damage to LMNs eg due to tumours or brainstem strokes
