Neurology Flashcards
In diplopia, which is the false image?
The outermost image is always false. Cover each eye in sequence. When the outermost image disappears, this is the eye with extraoccular muscle weakness.
What facies is this?
Acromegalic facies
Name the syndrome
Cushing’s syndrome
What facies is this?
Myaesthenia snarl - when asked to smile, the snarl is the result of contraction of the middle part of the mouth without contraction of the muscles on the sides of the mouth.
What is the facies? What are its features?
Frontal balding, bilateral ptosis, bilateral face weakness with thin facial muscles. AKA Hatchet Facies of myotonic dystrophy.
Which phase of nystagmus is pathologic?
The slow phase that follows the fast phase
What does cerebellar nystagmus look like?
Unilateral or bilateral. The slow phase drifts back to the centre during horzontal gaze, with the fast phase in the direction of gaze.
What are you looking for when you examine a patients head and scalp as part of a cranial nerve exam?
Craniotomy scars
Neurofibromata
Cushings syndrome
Acromegaly
Paget’s disease
Facial asymmetry and obvious ptosis
Proptosis
Skew deviation of the eyes
Obvious pupil inequality
Myaesthenia snarl
Myotonic hatchet face
What is strabismus?
Abdnormal resting alignment of the eyes (aka a ‘squint’)
What does peripheral vestibular nystagmus look like?
-Unidirectional, normally horizontal but occasionally has torsional element.
-It gets worse when the eyes move in the direction of the fast phase
-It improves when the eyes are allowed to move towards the slow phase.
-Abnormal head impulse test (rapidly, without hurting the pt, move their head and watch for loss of vestibulo-ocular reflex - eyes follow head and corrective saccade occurs)
-Nystagmus can be monocular and occur in the setting of weakness of the other eye.
-
What is the significance of vertical nystagmus?
Almost exclusively indicates a central disorder
What is Alexander’s Law?
States that the slow-phase velocity of the nystagmus caused by unilateral vistubular lesion increases with gaze in the beat direction. In other words, the nystagmus gets worse if gaze goes towards nystagmus.
What’s the most helpful feature for delineating congential nystagmus from other forms?
Patient doesn’t experience the world moving
What does multidirectional nystagmus in a gaze-evoked pattern suggest?
Generalised cerebeller dysfunction - more commonly caused by drug toxicitiy (e.g. anticonvulsants are a common cause).
What is tested by doing a jaw jerk?
Testing the reflex arc between cranial nerve 5 sensory components and motor components.
What are the three features of pseudobulbar palsy?
Dysphagia, dysarthria and emotional apathy.
Other possible features include sialorrhoea, dysphonia (hypernasal), glossoplegia, emotional lability, poverty of facial expression, pathalogical laughter, trismus, frontal release signs, cognitive impairment and seizures.
What is pseudobulbar palsy?
It’s a a collection of symptoms that results from bilateral corticobulbar tract lesions - upper motor neuron signs impacting the muscles of the face. Also referrerd to as bilateral upper motor neurone IX, X and XII nerve palsy.
What is the corticobulbar tract?
Fibres from the motor and pre-motor cotrex via the the cranial nerve nuclei that provide motor input to the muscles of the face + the trapezius and SCMs.
In a speech exam, what is the reason to do a jaw jerk?
If the patient presents with dysarthria without evidence of wasting, then a jaw jerk can be done to test the integrity of the corticobulbar tract. Bilateral corticobulbar tract defects will lead to a brisk jaw jerk. This will help to distinguish upper motor neuron defects (pseudobulbar palsy) from cerebellar disease.
What nerves are involved in the corneal reflex?
V1 opthalmic sensory branch, and the motor part of the 7th nerve
Why test light touch and pain over the 5th nerve regions?
A medullary or upper cervical lesion of the fifith nerve causes loss of pain and temperature sensation with preservation of light touch. A pontine lesion may cause loss of light with perservation of pain and temperature sensation.
What does a deviated uvular indicate?
A unilateral tenth nerve lesion on the side the uvular is pointing away from.
Regarding the rule of 4s, what are the four structures in the midline of the brainstem?
The midline structures all begin with M.
1. The motor pathway (corticospinal tract)
2. Medial lemniscus (continuation of the dorsal column - vibration, proprioception)
3. The medial longitudinal fasciulus
4. Motor nuclei of the cranial nerves (3, 4, 6 and 12)
Regarding the rule os 4s, what the four structures that sit in the lateral parts of the brain stem?
The lateral structures all begin with S (Side structures).
1. Spinocerebellar pathways
2. Spinothalamic pathway
3. Sensory nucleus of the 5th nerve.
4. Sympathetic pathway
What are the 4 cranial nerves that have nuclei in and above the midbrain?
1 and 2 have nuclei above the brainstem. Occulomotor and trochlear are in the midbrain. Trigeminal kind of extends up into the midbrain a bit as well.
What are the 4 cranial nerves that have nuclei in the pons?
Trigeminal, abducens, facial and vestibulocochlear. AKA 5/6/7/8
What 4 cranial nerves have nuclei in the medulla?
Glossopharyngeal, vagus, spinal accosory and hypoglossal nerves.
What deficits are likely to be found in a medial medullary syndrome?
Using the rule of 4s, the medial structures are:
1. The ‘medial leminiscus’ (proprioception and vibration) - this will cause contralateral vibration and proprioception loss
2. The medial motor nuclei (at the level of the medullar) - those that divide into 12. So, that leaves just nerve 12. This will lead to ipsilateral weakness of the tongue.
3. Motor pathways: weakness and upper motor neuron signs in the contralateral upper and lower limbs.
Note that they MLF is unaffected as it extends from the Pons to the Midbrain and is not involved in the medullar.
What cranial nerve nuclei are located medially in the brainstem?
Those that are 1. in the brainstem and 2. divide evenly into the number “12”
So - cranial nerves 3, 4, 6 and 12 are located medially.
What cranial nerve nuclei are located laterally in the brainstem?
Those that do not divide neatly into the number “12”.
So - cranial nerves 5, 7, 8, 9, 10, 11
What neurological deficits would you expect to find in a lateral medullary syndrome?
All lateral structures per the rule of 4s at the the level of the medullar:
1. Spinocerebellar dysfunction leading to ipsilateral ataxia of the arms and legs.
2. Spinothalamic dysfunction leading to contralateral sharp/dull dysfunction
3. Sympathic pathway involvement leading to an ipsilateral horners syndrome
4. The lateral meduallary CN nuclei may be affected - CN9 deficit will lead to ipsilateral sensation loss of the oropharynx, CN10 deficit will lead to ipsilateral pharyngeal arch weakness, and a CN11 deficit will cause ipsilateral trapezious and sternocleidomastoid weakness.
Do cranial nerve nuclei innervate contralateral or ipsilateral structures?
Ipsilateral
If you detect a lower 7th facial nerve palsy, what should you do next?
Check in the ear for VZV vesicles of ramsey hunt, look in the mouth fo vesicles also,
What are the components of a HINTS exam?
Head impulse, nystagmus, test of skew.
What is a normal head impulse test?
Normally, the vestibulo-ocular reflex allows a person to focus on a object whilst the head moves around. This is lost in peripheral vertigo syndromes, with the eyes having to perform a corrective saccade in order to keep focus on the face when quickly moving the head to the left or right.
What do tongue fasiculations and wasting indicate?
12th nerve palsy - peripheral
What is one-and-a-half syndrome?
Ipsilateral eye horizontal gaze paralysis (cannot adduct or abduct with horizontal gaze). Contralateral eye INO (cannot adduct beyond the midline with gaze). Convergence is normal.
In neutral gaze, the contralateral eye is slightly abducted (paralytic pontine exotropia).
Causes: 1) lesion in the 6th nerve nuclei AND the MLF on the same side OR 2) in the paramedian pontine reticular formation (PPRF - horizontal gaze centre) on the ipsilateral side to the paralysed eye.
Explain what goes wrong to cause an internuclear opthalmoplegia (INO).
The horizontal gaze centre at the top of the pons is caused the paramedian pontine reicular formation PPRF. When looking to the right, the PPRF stimulates the ipsilateral abducens nucleus which innervates the lateral rectus of the ipsilateral eye to look in that direction. Simultaneously, the interneurons from stimulated abducens nerve project to form the medial longitudinal fasciulous and synapse with the contralateral third nerve nucleus. This innervates the contralateral medial rectus and causes the contralateral eye to move in the same direction as the ipsilateral eye. Lesions of the medial longitudinal fasciculus interupt the communication to the contralateral eye from the ipsilateral abducens nucleus and so the contralateral eye does not adduct beyond the midline.
What is the structural reason that bilateral INOs occur frequently?
Becasue the 2x MLF tracts run very close to each either in the midline of the brainstem from the pons through the midbrain. Runs from the 6th to 3rd nerve nuclei.
Why is vergence maintained in an MLF lesion induced INO?
Vergence is coordinated by CNIII nuclei and doesn’t rely in the MLF connection between the 6th and 3rd nuclei.
What is an 8 and a half syndrome?
One and half syndrome with a lower motor 7th nerve palsy
What is the differential for a one and a half syndrome?
MS, stroke
Which parts of the 5th cranial nerve nuclei are responsible for sharp dull perception in the face, and which part is responsible for light touch perception?
The 5th nerve spans the pons and the medulla.
Isolated medullary 5th nucleus lesion - loss of pain, preserved light touch senstion of the face.
Isolated Pontine 5th nucleus lesions - loss of light touch, preserved pain sensation on the face.
What’s a good differential for Horner’s syndrome?
Carcinoma of the lung apex (usually SCC)
Neck issues - thyroid malignancy or trauma
Carotid arterial lesions - aneurysms, dissection, pericarotid tumours, cluster headaches
Brain stem lesions - vascular disease (lateral medullary syndrome, syngobulbia tumour)
Retro-orbital lesions
Syringomyelia
What should you check in the hands if you detect horners?
Clubbing, interosseus muscle wasting, C8/T1 abduction power
What causes an absent light reflex, but a normal accomodation reflex?
Midbrain lesions (neurosyphyllis) - Argyll Robertson pupils
Ciliary ganglion lesion
Parinaud’s syndrome
Bilateral anterior visual pathway lesions
Where is the PPRF?
The paramedian pontine reticular formation - is in the midline of the pons
Where is the rostral interstitial nucleus? What is it?
It’s the vertical gaze centre. It’s in the MLF.
What is the pathway for the accomodation reflex?
Afferent signal via CNII bilaterally to the lateral geniculate nucleus, thalamus, and cortical visual structures of the occipital lobe. Concious control or the reflexive presence of something close to the face leads to bilateral activation of medial recti via the third nerve nuclei, and parasympthetic stimulation of ciliary muscles leads to pupilary miosis via the endiger westphal nucleus.
What can cause loss of accomodation reflex but presence of light responsive pupils?
Occipital lobe lesions (cortical blindness) or a midbrain lesion
What is Adie’s syndrome?
A lesion in the efferent parasympathtic pathway to the ciliary ganglion, or between the ciliary ganglion and the iris. It leads to a dialted pupil that doesn’t respond to light or accomodation correctly. Pts often have decreased tendon reflexes. Commonly young woman.
What are the causes of an Argyll Robertson pupil?
Pupillary constriction to accomodation but not to light.
1. Syphilis
2. Diabetes mellitus
3. Alcoholic midbrain degeneration
4. Other midbrain disease
Where is the edinger westphal nucles located?
In the midbrain
What is tabes dorsalis?
Loss of vibration sensation and priprioception associated with neurosyphilis.
Clinically what is the difference between papilloedema an papilitis?
Papilitis is painful and swollen and has a greater impact on function. So, compared with with non-painful swelling (papilloedema), papilitis causes reduced visual acutiy, red desaturation, large central scotoma, pain on eye movement. Papilitis is a feature of optic neuritis, and is usually unilateral. Papilloedema is a feature of raised ICP, and is bilateral.
Differential for papilloedema?
Space occupying lesion
Hydrocephalus
-obstructive
- communicating
Retroorbital mass
Differential for papilloedema?
Space occupying lesion
Hydrocephalus
- obstructive
- communicating
–increased formation or decreased absorption
Retroorbital mass
Idiopathic intracranial hypertension
- idiopathic
- contraceptive pill
- Addison’s disease
- Drugs (nitrofurantoin, steroids, tetracycline vit A)
- Lateral sinus thrombosis
- head trauma
Hypertension (grade IV)
Central retinal vein thrombosis
Cerebral venous sinus thrombosis
High cerebrospinal fluid protein level (in e.g. GBS)
Causes of optic atrophy?
Chronic papilloedem or optic neuritis
Optic nerve pressure or division
Glaucoma
Ischaemia
Familial - retinitis, Leber’s disease, Friedreich’s Ataxia
What is Friedreich ataxia?
The most common hereditary ataxia, caused by mitochondrial protein (fraxin) triplet repeat (GAA) disease. Age at onset: depends on number of GAA repeats - most common in adolescence. Anticipation. Ataxia in all four limbs, reflexes lost in ~90% of patients, motor weakness involving the feet and legs first, then the arms later. Cerebellar dysarthria. Sensory loss in distal limbs. Dysphagia is common. Pes cavus. Cognition is usually preserved,
Causes of optic neuropathy with papillitis?
MS
Toxic - ethambutol, alcohol, nictotine, chloroquine
Metabolic - b12
Iscahaemia - Diabetes mellitus, TA, atheroma
Leber’s disease (mitochondiral disease)
Mononucleosis
Cataract causes?
Old age
Diabetes mellitus
Steroids
Hereditary and congenital causes
Glaucoma
Irradiation
Trauma
Causes of ptosis with normal pupil size?
Senile
Myotonic dystrophy
Fascioscapulohumeral dystrophy
Ocular myopathy
Thyrotoxic myopathy
Myasthenia gravis
Botulism
Snake bite
Congential
Fatigue
What are the features of a CNIII palsy?
Complete ptosis
Divergent strabismus (down and out)
Dilated and unreactive pupil
How do you check for a CNIV palsy in a patient with a CNIII palsy?
Ask the patient to look down and across the opposite side of the lesion, and look for intorsion. The CNIV innervates the superior oblique which causes intorsion.
What cranial nerves are impacted by lesions in the cavernous sinus?
CNII, CNIII, IV, V (occular and maxillary branches), and VI
What are the important non-CN structures in the cavernous sinus?
Veins, internal carotid artery, pituitary gland
Differential for CNIII opthalmoplegia?
Aneurysms (PICA)
Tumiour causing raised ICP
Nasopharyngeal carcinoma
Orbital lesions
Basal meningitis
CNIII nerve infarction - arteritis, diabetes
Trauma
Cavernous sinus lesions
Features of a sixth nerve palsy?
Lateral eye movement failure
Affected eye becomes deviated inwards in severe lesions
Diplopia - maximal when looking at the affected side
What are the examination findings found in pseudotumour cerebri?
AKA indiopathic intracranial hypertension or other causes of raised ICP.
Papilloedema
Changes in visual acuity
Enlarged blind spot
Pulsatile tinnitus
Bilateral cranial nerve IV palsy
Differentials of a bilateral sixth nerve palsy?
Trauma
Wernicke’s encepahlopathy
Raised ICP
Mononeuritis multiplex
Differentials for a unilateral sixth nerve palsy?
Central causes
- vascular
- tumour
-Wernicke’s encephalopathy
-MS (rare)
Periperhal
- diabetes
- trauma
- idiopathic
- raised ICP
What muscle is responible for downward gaze of the eye when it is adducted?
The superior oblique - innervated by the fourth nerve
What muscle is responsible for downward gaze when the eye is abducted?
The inferior rectus - innervated by the third nerve
What are the causes of jerky horizontal nystagmus?
Vestibular lesions
Cerebellar lesions
INO (in the unaffected side)
What are the causes of jerky vertical nystagmus?
Brain stem lesions
- upbeat -> floor of the fourth ventricle
- down beat -> foramen magnum lesion
Toxic
- phenytoin
- alcohol
What are the causes of pendular nystagmus?
Retinal (AMD, albinism)
Congenital nystagmus
How does supranuclear palsy affect gaze?
Loss of vertical upward and/or downward gaze.
How do you differentiate a supranuclear (higher centre) palsy loss of vertical gaze from ‘nuclear plasy’ (e.g. CNIII or vertal gaze centre lesions)
Dolls head eye movement reflexes in the vertical plane (i.e. able to fixate on an object) throughout neck flexion and extension.
Also, in PSP, both eyes are affected, pupils are often unequal, and there is no diplopia.
What are the occular findings in progressive supranuclear palsy (the Parkinson’s plus syndrome), as opposed to supranuclear palsy?
Downward gaze is lost first in PSP
–then upward gaze, then horizontal gaze as well
Saccades impaired before pursuit
Associated with pseudobulbar palsy (+jaw jerk), long tract signs, extrapyramidal signs, dementia and a rigid neck.
What is parinaud’s syndrome?
Loss of vertical upward gaze
Convergence-retraction nystagmus on attempted convergence
Pseudo-argyll robertson pupils (loss of light pupillary reflex, but constriction to near focus)
What causes parinaud’s syndrome?
Central lesisons impacting the dorsal (tectal) midbrain
- pinealoma
- MS
- vascular lesions
Peripheral
- trauma
- diabetes mellitus
- other vascular lesions
- idiopathic
- raised ICP
What does tectum mean in relation to the midbrain?
Tectum is latin for roof. It’s the dorsal part of the midbrain.
What’s the differenetial diagnosis of a 5th nerve palsy?
Central (pons/medullar/upper C spine)
- vascular, tumour, syringobulbia, multiple sclerosis
Peripheral (posterior fossa lesiosn)
-aneurysm, base of skull tumour (e.g. acoustic neuroma), chronic meningitis
Trigeminal ganglion (petrous temporal bone)
- meningioma, fracture of the middle fossa
Cavernous sinus
- tumour, aneurysm, thrombosis
Other
- SLE, Sjorgren’s, toxins, idiopathic
How to delinate between peripheral or central 5th nerve lesions?
Central lesions typically will impact all 3 territories, but only one modality
- light touch is lost in pontine lesions affectiving the 5th nerve nucleus, but pain is preserved
-pain is lost in lesions that impact the medullar or upper C-spine, but light touch is preserved
In peripheral lesions - both light touch and pain sensation will be lost. If the lesion is in the posterior fossa or at the trigeminal ganglion.
What are the upper motor neuron causes of a 7th nerve palsy?
MND, vascular or tumour.
What are the lower motor neuron causes of a 7th nerve lesion?
Pontine
- vascular, tumour, syningobulbia or MS
Posterior fossa
- acoustic neuroma or meningioma
Petrous temporal bone
-Bell’s palsy
-Ramsay Hunt
-Otitis media
-Fracture
Parotid
-tumour
-sarcoid
What can cause bilateral 7th nerve palsy?
GBS
Bilateral parotid disease (e.g. cancer or sarcoidosis)
Mononeuritis multiplex
What is Rinne’s test?
Tuning fork to the mastoid process behind the ear, then when it can no longer be heard, in front of the meatus of the external auditory canal. If it cannot be heard when its moved, the person has conduction deafness.
What is Weber’s test?
Place tuning fork on the forehead. Sound is heard in the middle of the forehead -> normal. Abnormal results - sound is louder in an ear with conduction deafness. OR sound is quiter in the ear with nerve deafness.
What’s the differential diagnosis for a unilateral twelth nerve palsy?
Central
- vascular (vertebral artery thrombus)
- motor neuron disease
- syringobulbia (fluid cavity in the spinal cord that involves the lower brain stem)
Peripheral
-aneurysm
- tumour
-Trauma
-Base of skull fracture
-Arnold-chiari malformation
—cerebellar tonsilar protrusion through teh foramen magnum. May be associated with cerebellar dysfunction.
What signs might be found in a patient with an Arnold-Chiari malformation?
CN IX, X, XI, XII dysfunction
Cerebellar ataxia
Upper motor neuron signs in the limbs
What causes bilateral 12th nerve palsy?
Motor neuron disease
Arnold-Chiari malformation
GBS
Polio
Differential for multiple cranial nerve palsies?
Nasopharyngeal carcinoma
Chronic meningitis - TB, sarcoidosis
GBS - especially the Miller-Fischer variant
Brain stem lesions - e.g. glioma
Arnold-chiari malformation
Trauma
Lesions in the base of the skull - cancer, meningioma, Paget’s disease
Mononeuritis multiplex (in the setting of diabetes, or PAN, or ANCA vasculitis)
Myopathies and other neuromuscular diseases
What is the classic disease association with bilateral CNVII palsies?
Neurosarcoidosis
What are the higher centres features unique to dominant parietal lobe lesions?
Gerstmann Syndrome:
Acalculia
Agraphia
Left-right disorientation
Finger agnosia
What is the unique higher centre feature of non-dominant parietal lobe disease?
Dressing apraxia
What higher centre features (cortical signs) are seen in non-dominant and dominant parietal lobe disease?
Sensory inattention
Visual inattention
Cortical sensory loss
-loss of graphaesthesia
-two-point discrimination
-joint position sense
-stereognosis
Constructional apraxia (intersecting pentagons)
Parietal lobe defects may also be associated mixed sensory deficits that respect the sensory homunculus of the postcentral gyrus, and visual field defects that correlate with suspected lesions sites (inferior quadrantanopias)
What would you look for in a higher centres exam features if you suspect temporal lobe disease?
Memory loss - short term and long term.
The non-cortical signs associated with temporal lobe include visual field defects (superior quandrantanopias).
What frontal lobe signs should be looked for in a higher centres exam?
Reflexes - grasp, pout, palmar, mental
Proverb misinterpretation
Smell
Fundi
Gait - unable to lift feet off the ground - a failure to initiate.
What is titubation?
A nodding movement of the head or the body. When a person with cerebllar diseases tries to stand still they sway at the waist. This is called titubation. Not to be confused with a positive rhomberg’s. There head will also bob up and down.
What is Foster Kennedy syndrome?
Visual loss due to compressive optic atrophy in one eye, and papilloedema in the contralateral eye due to raised intracranial pressure. Most commonly caused by frontal lobe meningiomas causing raised ICP. Pseudo FKS can be the result of optic nerve compression from the gyrus rectusm, or diabetic pappilopathy, or unilateral optic nerve hypoplasia.
What is a paraphrasia?
Using the incorrect word in a sentence