Station 3: Neurology Flashcards
General inspection findings of isolated ulnar nerve neuropathy?
- wasting of the dorsal interossei “guttering” of the hands, and hypothenar eminence
- ulnar claw: flexion of the interphalangeal joints of the 4th and 5th digits
- sparing of the thenar eminence
cause: look for scars around the wrist or near the elbow
if suspecting ulnar neuropathy, what other important negatives?
rule out medial/ nerve palsies or C8/T1 nerve root problem
Power findings in ulnar neuropathy?
weak
- finger abduction (dorsal interossei)
- Froment’s sign positive (weakness of adduction of the thumb, adductor policis)
test finger flexion of the 5th finger for flexor digitorum profundus involvement (more proximal lesions may result in weakness of IP joint flexion)
test for wrist flexion at ulnar side (flexor carpi ulnaris)
ulnar paradox?
the higher the level of injury to ulnar nerve, the less obvious the “clawing”
if ulnar nerve injured more proximally, the ulnar half of the flexor digitorum profundus muscle may be affected. As a result, flexion of the IP joints of the 4th and 5th fingers is weakened, which reduces the claw-like appearance of the hand.
sensory testing in ulnar neuropathy?
medial 1.5 fingers affected
what is the anatomical course of the ulnar nerve?
begins from the medial cord of the brachial plexus (C8, T1)
enters the forearm via the cubital tunnel (medial epicondyle and olecranon proocess) and motor supply to the flexor carpi ulnaris and ulna half of the flexor digitorum profundus
gives off a sensory branch just above the wrist
and enters the Guyon’s canal and supplies the sensory medial 1.5 fingers and hypothenar as well as motor to all intrinsic muscles of the hands except LOAF (lateral two lumbricals, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis)
what does ulnar nerve supply in terms of motor function?
motor to all muscles of the hands except the LOAF:
- lateral two lumbricals.
- opponens pollicis.
- abductor pollicis brevis.
- flexor pollicis brevis
forearm: flexor carpi ulnaris (wrist flexion and adduction) and flexor digitorum profundus to 4th/5th fingers
level of ulnar lesions and its clinical correlation?
wrist- hypothenar eminence wasting, froment’s positive, weakness of finger abduction, pronounced claw and loss of sensation
elbow- less pronounced claw, loss of terminal flexion of the DIPJ and loss of flexor carpi ulnaris tenon on the ulnar flexion of the wrist
how do you differentiate ulnar nerve palsy vs T1 lesion?
motor- wasting of the thenar eminence will be seen for T1
sensory- loss of T1 dermatomal distribution
what is the ulna claw hand?
- hyperextension of the 4th and 5th MCPJ associated with flexion of the IPJs of the 4th and 5th fingers
due to the unopposed long extensors of the 4th/5th fingers in contrast to the IF and MF
what is froments sign?
asked to grasp piece of paper between thumbs and the lateral aspect of the index finger
affected thumb will flex as the adductor policis muscles are weak
-> pt trying to compensate by using the flexor pollicis longus supplied by the median nerve
causes of ulnar nerve palsy?
- compression or entrapment (Cubital tunnel at elbow; Guyon’s canal at the wrist)
- trauma (fractures or dislocation- cubitus valgus leads to tardive ulnar nerve palsy)
- surgical
- mononeuritis multiplex
- infection: leprosy (thickened nerves, hypopigmented hypoaesthetic patches)
- ischaemia- vasculitis
- inflammatory -CIDP
ix of ulnar nerve palsy?
- blood ix to rule out DM if no obvious cause
- Xrays of the elbow and wrist KIV C spine
- EMG (axonal degeneration for chronic)
- Nerve conduction studies: can help to locate level and monitor
mx of ulnar nerve palsy?
education and avoidance of resting on elbow
PTOT
Medical: NSAIDs
Surgical decompression with anterior transposition of the nerve
causes of sensory predominant peripheral neuropathy?
DM
Alcohol
Metabolic: B1, B6, B12 deficiency
CKD
Infective: Leprosy
causes of motor predominant peripheral neuropathy?
inflammatory: GBS, amyloid, sarcoid, hiv
drugs: lead poisoning, dapsone, organophosphate
metabolic: DM, porphyria
Congenital: charcot-marie-tooth (HSMN type 1)
PAN
causes of mononeuritis multiplex? (ie involvement of 2 or more peripheral or cranial nerves by the same disease)
Endocrine: DM, Acromegaly
Infiltrative: Amyloidosis, Sarcoidosis
Autoimmune: RA/SLE, PAN, Sjogren, GPA, eGPA
Neoplastic: Carinomatosis
Infection: Leprosy, Lyme, HIV
causes of thickened nerves?
CIDP
Charcot-Marie Tooth Disease (HMSN)
Acromegaly
Amyloidosis
Others:
Sarcoidosis
Leprosy
Neurofibromatosis
Refsum Disease (Retinitis pigmentosa, optic atrophy, cerebellar and deafness, cardiomyopathy and ichthyosis)
Dejerene-Sottas disease (hypertrophic peripheral neuropathy)
Causes of sensorimotor peripheral neuropathy?
- DM
- Alcohol
- Endocrine: Hypothyroidism
- Uraemia (CKD)
- Sarcoidosis
- Inflammatory: Vasculitis
- Paraneoplastic
- Immune mediated: CIDP
- Congenital: HSMN
- Drugs: Vincristine, Cisplatin, Gold, Amiodarone
Drugs causing sensory peripheral neuropathy?
isoniazid, chloroquine, metronidazole
causes of peripheral neuropathy with autonomic dysfunction?
GBS
infection: botulism, Chagas disease, HIV
porphyria
paraneoplastic
DM
Amyloidosis
Demyelinating causes of peripheral neuropathy?
CIDP
Multiple myeloma
HSMN Type 1 and 3
HIV
POEMs disease
Multifocal motor neuropathy
Hereditary neuropathy with pressure palsy
Screening for causes of peripheral neuropathy during neuro examination?
- features of DM: diabetic dermopathy
- thickened nerves or hypopigmentation patches (leprosy)
- parotidomegaly, dupuytrens (ETOH)
- sallow (uraemia)
- pallor (B12 deficiency)
- cachexia, toe clubbing (paraneoplastic)
- symmetrical deforming polyarthropathy (RA)
- clinical features of acromegaly, hypothyroidism
gait in peripheral neuropathy?
sensory ataxic gait
- may be high stepping
causes of peripheral neuropathy (mixed/ sensory/ motor)
DAMIT BICH
Drugs: Isoniazid, chloroquine, nitrofurantoin, gold, penicillamine, cyclosporin A, phenytoin, vincristine
Alcohol
Metabolic: DM, uraemia (CKD), porphyria
Infectious: Leprosy, HIV, botulism
Inflammatory: GBS, CIDP
Tumour: paraproteinaemia (MM), Paraneoplastic (Lung Ca)
B12, B6, B1
Infiltrative: Amyloid, sarcoid
Congenital: HMSN, porphyria
Hormonal: Acromegaly, Hypothyroidism
causes of a painful peripheral neuropathy?
DM, Alcohol, B12 deficiency
Carcinoma, Porphyria, Arsenic
types of neuropathy in DM?
- glove and stocking symmetrical sensory neuropathy
- predominantly motor, asymmetrial (DM amyotrophy)
- mixed motor and sensory peripheral neuropathy
- mononeuropathy
- mononeuritis multiplex
- autonomic neuropathy
neurological complications of alcohol?
wernicke’s (Confusion, ophthalmoplegia, ataxia)
korsakoffs psychosis (anterograde amnesia, confabulation)
cerebellar degeneration
central pontine myelinolysis
epilepsy
myopathy and rhabdomyolysis
peripheral neuropathy
nerve conduction studies in diabetic peripheral neuropathy?
axonal loss
Further examination if patient presents with ptosis?
- visual acuity
- pupils: miosis (horners), mydriasis (CN III)
- EOM (down and out: CN III, complex: MG?)
- fatiguability: MG
DDx unilateral ptosis?
Horner’s syndrome
3rd Nerve Palsy
Myasthenia gravis
Previous tarsorraphy/ congenital ptosis
Muscle - local orbital infiltration/ pathology, dystrophia myotonica
DDx Bilateral ptosis?
Myasthenia gravis
Myotonia dystrophy
GBS/ Miller Fisher
Motor Neuron Disease
Oculopharygneal dystrophy
Thyroid eye disease
Senile ptosis/ congenital ptosis
Mitochondrial dystrophy e.g. CPEO, Kearn Sayre syndrome
Tabes dorsalis
Nuclear 3rd nerve palsy
Syringomyelia with bilateral Horner’s syndrome
Esotropia
6th nerve palsy
DDx exotropia
3rd nerve palsy
4th nerve palsy
DDx complex ophthalmoplegias?
Central cause:
Intranuclear ophthalmoplegia
Wernicke’s encephalopathy
Nerves: Miller Fisher
NMJ:
Myasthenia gravis
Myopathies:
Thyroid eye disease
CPEO/ Kearn-Sayre synrome or Ragged Red Fiber Myopathy
Glass eye/ trauma
cause of unilateral facial droop? + Long tract signs
UMN lesion
- pontine and above
unilateral facial droop + VIII nerve involvement?
neurolocalisation
Internal auditary canal
unilateral facial droop + 5th/6th/8th CN involvement
neurolocalisation?
Cerebellopontine angle lesion
unilateral facial droop + cerebellar involvement; neurolocalisation?
middle cerebellar peduncle
Approach to CN examination, if no obvious signs on general inspection. what to think of?
visual fields
RAPD (with fundoscopy)
EOM restriction
Myasthenia Gravis
Bulbar/ pseudobulbar palsy
Cranial nerve examination: general inspection. What can be suggestive of underlying defect?
- Ambulation aids: ?LL weakness
- Supplemental O2
- NG tube ?CN 9/10/12 lesion
- Urine catheters ?cauda equina, neurogenic bladder, myelopathy
- IV fluids/drugs
then look more closely:
any ophthalmoplegia?
ptosis?
facial asymmetry?
abnormal speech?
limb asymmetry/ posturing
tremors
fasciculations
CN exam: checking CN 1
olfactory nerve
- ask “any problems with your sense of smell?”
CN exam: checking CN 2?
optic nerve
- check visual acuity grossly (how many fingers?)
- pupillary reflexes (direct, consensual, accommodation)
- RAPD?
CN exam: checking CN 3/4/6?
Oculomotor, Trochlear, Abducens
- check ROM of eyes (diplopia, ophthalmoplegia)
- in presence of complex ophthalmoplegia or ptosis, check for fatiguability
CN exam: CN 5 testing?
Trigeminal nerve
- pin prick sensation over forehead, maxilla, chin
- “bite your teeth” -> feel for bulk masseters
- “open your mouth” -> feel for strength of pterygoids and see if jaw moves to one side (displaced to the side of weakness)
CN exam: CN 7 testing?
- “Look up” -> loss of wrinkling of forehead (frontalis) = LMN lesion
- “Close your eyes as tight as possible, don’t let me open them” -> bell’s phenomenon, unable to bury eyelashes
- “show me your teeth” -> facial droop, loss of nasolabial fold
- “puff out your cheeks”
additional:
lacrimation - lesion proximal to geniculate nucleus if affected
taste over tip of tongue
salivary gland
hyperacusis - paralysis of stapedius muscle
CN exam: CN 8 testing?
“I’m going to say something into your ear, please repeat the words after me”
- Rinne’s test: place 256Hz tuning fork on mastoid, then in line with ear
- Weber’s test: place 256Hz tuning fork on forehead
Rinne’s positive = AC>BC. negative: BC > AC (conductive HL)
Weber’s test: localizes to side with conductive HL, localizes away from side with SNHL
CN exam: testing for CN 9/10 nerves
Glossopharyngeal, vagus nerves
“open your mouth and say AH”
-> look for deviation of uvula and palatal weakness
CN IX: mainly sensory function
CN X: mainly motor function in the mouth
CN exam: testing CN XII nerve?
Hypoglossal nerve
stick out tongue (deviation, wasting, fasciculations)
move it left to right
CN exam: testing CN XI accessory nerve?
“push your head against my hand” test SCM ->feel for SCM contraction/bulk
shrug shoulder and feel for trapezius contraction/bulk
CN exam: how to screen for cerebellar and UL signs?
Cerebellar:
Nystagmus, finger-nose test (intention tremor), dysdiadochokinesia, upper limb rebound, heel shin test, toe finger test, gait (ataxia)
UL and LL:
Hemiplegia, pyramidal signs
CN exam: how to say you will complete your examination?
- fundoscopy
- visual field defect
- proper assessment of visual acuity with snellen’s chart
- check the corneal reflex: afferent CN V1, efferent VII
- check gag reflex: afferent CN IX, efferent X
CN II lesion: how may different pathologies present?
- homonymous hemianopia: optic tract/radiation lesion
- superior homonymous quadrantonopia: contralat temporal lobe lesion
- inferior homonymous quadrantonopia: contralat parietal lobe lesion
- bitemporal hemianopia: optic chiasm lesion
- monocular blindness: pre-chiasmal lesion
CN III: how may different pathologies present?
- pupils normal: ischaemic CN III palsy
- pupils fixed and dilated: PCOM aneurysm
- DDx OAS, SOFS, CSS, Benedikt’s syndrome, MG (excluded if pupillary reflex abnormal)
CN V lesion: how may different pathologies present?
ganglion/sensory root lesion: total loss of sensation in all 3 divisions
post-ganglionic lesion: total loss of sensation in 1 division (usually ophthalmic division a/w CN III, IV, VI palsies due to lesion in cavernous sinus)
Brainstem/upper cervical cord lesion:
- dissociated sensory loss of face: ie. loss of temp/sensation but retention of touch and propioception sensations of face
CN VI lesion: how may different pathologies present?
nerve tract:
- cavernous sinus (may p/w isolate CN VI if early)
- clivus lesino
- NPC/meningeal lesino
- GBS/MFS- check reflexes
- ischaemic
- false localising sign
NMJ: MG
Local/muscle: infiltrative orbital process, tumour thyroid eye disease
DDx: OAS, SOFS, CP angle
Causes of UMN CN VII lesion?
contralateral cortical or subcortical lesion:
vascular: stroke
Tumours
-> if detected, examine UL and look for hemiparesis on same side of facial weakness
-> check for xanthelasma, DM signs, BP
Causes of LMN CN VII lesions?
infection: HSV (bell’s palsy), zoster, lyme disease
Connective tissue/ infiltrative: sarcoid, amyloidosis, Sjogrens, behcets
Neoplasm
Brainstem (infarct/ haemorrhage) - a/w gaze palsy
MS
can organize by site of lesion:
brainstem: infarct/bleed, MS, abscess/tumour, syringobulbia
base of skull lesion: infective, tumour, infiltrative
CPA lesion:
Acoustic neuromas
Meningiomas
neurofibroma
Petrous temporal bone/ facial nerve canal:
Bells palsy
Ramsay Hunt syndrome
Fractures
otitis media
Parotid gland: tumour, surgery, sarcoidosis
mononeuritis multiplex
causes of isolated CN II palsy?
ischaemic
PCOM aneurysm
causes of isolated CN IV palsy?
trauma
decompensated squint
causes of single CN VI palsy?
- false localising
- ischaemic
- NPC
- meningeal
- cavernous sinus pathology
causes of CN VII isolated palsy?
Bells palsy
Parotid tumour
Middle ear disease
trauma: # to mastoid area
Causes of isolated CN XII palsy?
hypoglossal canal
base of skull pathology
carotid artery dissection
ALS (bilateral wasted tongue)
CN III palsy?
- abnormal EOM (down and out pupil)
- abnormal light reflex
- abnormal dilated pupils (may be normal in ischaemic CN III palsy)
causes of isolated CN III palsy?
- Posterior communicating artery aneurysm
- Medical CN III palsy
cavernous sinus syndrome?
CN III, IV, V1, V2, VI
superior orbital fissure syndrome?
CN III, IV, V1, VI
Orbital apex syndrome?
CN II, III, IV, V1, VI
CN III palsy + long tract signs?
midbrain pathology
CN III palsy + signs of peripheral neuropathy?
GBS/ Miller Fisher syndrome
Signs of Horner’s syndrome
miosis
partial ptosis
enophthalmos
slight elevation of lower eyelids
+/- anhidrosis depending on level of lesion
Causes of Horners syndrome + what to examine for?
- Pancoast tumour:
- tracheal deviation, supraclavicular dullness, wasting of small muscle of hands, clubbing, loss of pain sensation in UL
- scars of cervical sympathectomy
- enlarged LNs
- carotid and aortic aneurysms
- examine for signs of brainsteam vascular disease or demyelination
- nystagmus, cerebellar signs, cranial nerves, pale optic discs
Suspected myasthenia gravis: what to examine?
Test for fatiguability
- prolonged upward gaze
- superio-lateral gaze
-> Normal pupils, normal light reflex, EOM may be abnormal
Test for bulbar weakness
Test for proximal limb weakness
Examine for associated signs:
- thyroid goitre, retrosternal extension
- retrosternal thymoma
- RA hands
- vitiligo
Horner’s syndrome:
degree of anhidrosis according to location of lesion
central lesion (1st order neuron): anhidrosis over head, upper trunk and arm
proximal to superior cervical ganglion (2nd order neuron): anhidrosis over face only
distal to super cervical ganglion (3rd order neuron): none
approach to unilateral ptosis?
- rule out pseudoptosis
- droopy eyelids - muscle
- myotonic dystrophy - neuromuscular
- Myasthenia gravis - nerve
- III nerve palsy
- horner’s syndrome
approach to unilateral horner’s syndrome?
- examine the other cranial nerves
- cavernous sinus syndrome
- superior orbital syndrome
- lateral medullary syndrome
- syringobulbia
- multiple sclerosis (INO, cerebellar, RAPD) - neck
- scars: trauma/ surgery
- neoplasia
- carotid aneurysm
- cervical rib - upper limbs (examine in this sequence)
- pronator drift then cerebellar signs (lateral medullary syndrome)
- wasting of ipsilateral small muscles of the hands (T1)
- clubbing
- sensory loss T1
- dissociated sensory loss (syringomyelia)
- contralateral loss to pain and temp (lateral medullary syndrome)
- axilla (trauma to brachial plexus) - chest
- pancoast tumour: tracheal deviation, dullness, auscultation
- ask for loss of sweating and level
what medications can help to delineate the site of lesion clinically?
adrenaline 1:1000 to both eyes (denervation hypersensitivity)
- abovev the superior cervical ganglion (peripheral) = dilates the affected eye
- below/ proximal to superior cervical ganglion or a normal eye = no effect
cocaine 4%
- dilates normal eyes
- no effect on the affected side if above/ distal to superior cervical ganglion
how do you delineate the site of lesion clinically via loss of sweating?
central lesion (1st order): loss of sweating in head, upper trunk and arm
neck, proximal to superior cervical ganglion (2nd order): loss of sweating in face
neck, distal to superior cervical ganglion: sweating intact (3rd order)
causes of horner’s syndrome?
Hypothalamus/ brainstem:
stroke, pontine glioma, coning of temporal lobe
cervical cord (C8-T2: intermediolateral column):
syringomyelia, multiple sclerosis, tumour
superior mediastinum (2nd order nerves exixt the spinal cord and synapses at the superior cervical ganglion):
pancoast lesion (SCC lung), trauma to brachial plexus
neck (carotid sympathetic plexus and superior cervical ganglion):
neoplasia, trauma, surgery (cervical sympathectomy), carotid aneurysm, carotid dissection (triad of pain, ipsilateral horner’s, cerebral/retinal ischaemia)
idiopathic
congenital - heterochromia of iris (grey blue on affected side)
migraine- causes intermittent horner’s syndrome
approach to bilateral ptosis?
muscular (usually no wrinkling of the forehead):
myotonic dystrophy
ocular myopathy
oculopharyngeal dystrophy
chronic progressive external ophthalmoplegia (mitochondrial/Kearns sayre)
Neuromuscular:
myasthenia gravis
Nerve:
bilateral 3rd CN palsy (rare)
bilateral Horners’ (syringomyelia)
tabes dorsalis
miller fisher syndrome
examination approach in bilateral ptosis?
- general screen for myotonic dystrophy, fascioscapular dystrophy
- screen for myasthenia gravis
- check CNs:
> III, Horner’s
> Argyll Robertson pupils (Tabes)
> Ophthalmoplegia (kearns sayre)
> bulbar palsy (syringomyelia) - Neck
- Upper Limbs:
> ataxia (kearns sayre, miller fisher)
> Syringomyelia: flaccid and wasted ULs, dissociated sensory loss, spastic paraparesis
> Areflexia (miller fisher) - complete examination by fundoscopy for retinitis pigmentosa (CPEO)
Examination of myasthenia gravis, sequence?
- eyes
- ptosis with fatiguability
- variable strabismus and diplopia that occurs after some time
- check for hyperthyroid and thyroid eye disease
- check for anaemia
- check for malar rash of SLE
- face
- VII power
- assessment of speech: count to 1 to 20, nasal voice (bulbar palsy)
- masseter weakness but pterygoids normal
- check neck for goitre and scars
- ULs
- normal deep tendon reflexes (Miller fisher/ lambort eaton are reduced)
- normal sensation
- fatiguability with weakness
- RA and SLE features - Thymectomy scar and plasmapheresis line
associations of Myasthenia gravis:
endocrine: Thyroid, DM, pernicious anaemia
CTD: RA, SLE, polymyositis
Request for:
negative inspiratory force
drug history: antibiotics/ drugs that can worsen MG
temperature chart for fever - can ppt weakness
what is myasthenia gravis?
- autoimmune condition with antibodies targeting the post synaptic Ach receptors of the neuromuscular junction
- resulting in progressive muscle weakness with use of the muscle and recovery of strength after a period of rest
- weakness experienced once number of receptors is 30% or less
how common is the thymus involved in myasthenia gravis ?
75% of cases:
of which 15% are thymomas and 85% are thymic hyperplasia
usual age for myasthenia gravis?
2 peaks
20 to 30 years old with female predominance
> 50 years old with male predominance
features of myasthenia gravis on presentation
ptosis, diplopia
dysarthria, difficulty swallowing (isolated bulbar muscle involvement in ~20%)
generalised weaness or reduced exercise tolerance
respiratory failure in 1%
tends to affect extra ocular muscles first then facial to bulbar and then limbs and truncal
what may exacerbate myasthenia gravis or precipitate a crisis?
- non compliance to meds
- infection
- emotions/ stress
- drugs
what drugs may exacerbate MG crisis?
antibiotics: aminoglycosides, tetracyclines, macrolides, fluoroquinolones
cardiac: BBs, CCBs (verapamil)
others: chloroquine, procainamide, Lithium, Mg, prednisolone, quinine, penicillamine
what is a cholinergic crisis?
not the same as myasthenic crisis
results from excess of cholinesterase inhibitors such as neostigmine and pyridostigmine
causes flaccid paralysis and SLUDGE (miosis, salivation, lacrimation, urinary incontinence, diarrhoea, GI hypermotility and emesis)
ix to do for suspected myasthenia gravis?
Bloods:
- AChR Ab (+ve in 80% with generalised MG, only +ve in 50% with ocular involvement only, also present in 90% of patients with penicillamine induced MG)
- anti striated muscle Ab
- Anti MUSK Ab (muscle specific kinase)
- FBC to rule out infection
Imaging:
- CXR: thymus (Anterior mediastinal mass), aspiration pneumonia
- CT for thymus
Tensilon test: for diagnosis
Ice pack test
Electrodiagnostic studies:
- repetitive nerve stimulation test
- single fibre nerve EMG
what is the ice pack test in myasthenia gravis?
ice applied with glove to eyelids for 2 mins
improvement in ptosis (positive in 80%)
what is the tensilon test in myasthenia gravis?
can help to distinguish from cholinergic crisis
- edrophonium (half life 10 min)
- look for objective improvement in ptosis
- cardiac monitoring for bradycardia and astystole (Rx with atropine if any)
- 1mg test dose and up to 10mg
- in cholinergic crisis, will get increased salivation etc
repetitive nerve stimulation test in myasthenia gravis?
shows a decrease in the compound muscle action potential by 10% in the 4th to 5th response to a train of nerve stimuli
single fibre nerve EMG in myasthenia gravis?
evidence of neuromuscle blockade with increased jitter
how do you grade the severity of weakness in myasthenia gravis?
Myasthenia Gravis Foundation of America
- Grade 1: affects ocular muscles only
- Grade 2: mild weakness affecting muscles other than ocular muscles
> 2A: limbs/ axial muscles
> 2B: respiratory and bulbar muscles
- Grade 3: moderate weakness
- Grade 4: severe weakness
- Grade 5: intubation required
Osserman’s grading
I: ocular
II A: mild generalised with slow progression
II B: Moderate generalised
III: acute fulminant MG
IV: late severe MG (Takes 2 years to progress from I to II)
Management of myasthenia gravis?
crisis: ABC approach
tx exacerbating factor:
stop exacerbating medications, treat infection if any, treat fever with antipyretics
oral pyridostigmine
steroids, azathioprine, cyclosporine (to maintain remission)
plasmapheresis
IVIG
Thymectomy
complications of myasthenia gravis?
myasthenic crisis
- severe exacerbation of MG
- 10% require intubation
treatment complications
- cholinergic crisis
- cx of medications
what is Lambert Eaton syndrome?
myasthenic disorder associated with malignancy such as small cell Lung Ca
affects the proximal (thigh/pelvic girdle) and truncal musculature, bulbar muscles rarely involved
improves with exercise
presence of Abs to calcium channels
approach to examination upon detection of facial asymmetry (CN VII palsy)
- test CN VII functions:
> look up (frontalis)
> close eyes (orbuclaris oculi) attempt to open
> look for exposure keratitis, tarsorraphy
> nasolabial fold, show teeth, blow against closed lips
> look for drooling of saliva - determine LMN or UMN, unilateral or bilateral
2A UMN unilateral:
examine UL and look for hemiparesis on same side of the facial weakness
check for xanthelasma, DM signs and BP
2B LMN unilateral
- examine other CN
- VI nerve and contralateral weakness in brainstem lesions
- CPA lesion (V, VI, VII, VIII with cerebellar)
- other CN involvement non comforming type: mononeuritis multiplex, MG
- look at palate for vesicles
- examine the parotids and for surgical scars
- mastoid tenderness
- examine neck for cervical LNs
- Upper limbs: contralateral hemiparesis, ipsilateral cerebellar
ask to examine:
otoscopy for vesicles in ear canal and otitis media
for hyperacusis
for loss of taste in anterior 2/3 of tongue
urine dip for glucose and BP (mononeuritis multiplex)
if noted to have bilateral rather than unilateral facial weakness?
rule out MG
rule out myotonic dystrophy or fascio scapular humeral dystrophy
bilateral LMN VII:
> look for V VI VIII
> examine parotids (sarcoidosis, amyloidosis)
> examine tongue (scrotal tongue for MR syndrome)
> examine UL for GBS, MND, leprosy, lyme (radiculopathy) and bilateral cerebellar signs if suggestive of bilateral CPA tumours
rare: melkerssson rosenthal syndrome, mobius syndrome
what is the course of the facial nerve?
VII nerve nucleus lies in the pons in close proximity to VI nerve nuclei
VII leaves the pons with VIII via cerebellopontine angle
VII enters facial canal and enlarges to become the geniculate ganglion
A branch is given off to the stapedius muscle and the greater superficial petrosal branch goes to the lacrimal glands
the chorda tympani which supplies taste sensation to anterior 2/3 of tongue joins the VII nerve in the facial canal
VII nerve exits the skull via stylomastoid foramen through the parotids and branches into 5: temporalis, zygomatic, buccal, mandibular, cervical
what are the causes of bilateral LMN VII nerve palsies?
after ruling out MG and myopathies
bilateral CPA tumour as in NF type 2
Bilateral Bell’s palsy
bilateral parotid enlargement (Sarcoidosis- uveoparotid fever or Heerfordt’s fever)
GBS, MND, Lyme disease
Rare: Rosenthal Melkersson syndrome (triad of VII palsy with facial oedema and plication of the tongue), Mobius syndrome (congenital facial diplegia, oculoparalysis from III and VI and infantile nuclear hypoplasia)
what is Bell’s phenomenon?
refers to the upward movement of the right eyeball with incomplete closure of the right eyelid in an attempt to close the right eye
why are the muscles of the upper face spared in an UMN lesion?
the upper facial muscles are preserved in an UMN lesion as there are bilateral cortical representations of these muscles
what is bell’s palsy?
an idiopathic facial paralysis, believed to be due to viral-mediated cranial neuritis from HSV
typically presents with abrupt onset weakness with worsening the following day, associated with facial or retroauricular pain, hyperacusis and excessive tearing
what is ramsay hunt syndrome?
- herpes zoster infection of the geniculate ganglion
- presents with vertigo, hearing loss, facial weakness, pain in the ear with vesicles seen on the external auditory meatus and palate
what is facial synkinesis?
attempt to move one group of facial muscles results in movement of another group
occurs as a result of anomalous regeneration of the facial nerve
e.g nerve fibres that innervate facial muscles innervating lacrimal glands -> tearing on mastication (crocodile tears)
ix of facial nerve palsy?
target ix according to history and physical examination
bloods e.g. Lyme disease
Imaging
Management of Bell’s palsy?
- educate
- lubricating eye drops, eye patch, taping eyes closed
- physiotherapy
Meds:
PO pred 1mg/kg/d for 7-10 days and PO aciclovir 400mg 5x/d for 7 days (within first 72h)
regular follow up to look for resolution and exclude new developing signs suggestive of other conditions
surgical (tarsorraphy) for chronic non resolving cases
how would you educate or counsel patient with Bell’s palsy?
common condition
course:
improvement onset 10d - 2mo
plateau 6w-9mo
residual signs
- synkinesis in 50%
- face weakness 30%
- contracture 20%
- blepharospasm: may occur years after paralysis
synkinesis in facial nerve - can be treated with?
synkinesis may be due to anomalous regeneration of nerve
may be treated with botulinum
what are associated signs with better prognosis in bells palsy?
incomplete paralysis
early improvement
slow progression
younger age
normal salivary flow
normal taste
normal NCS, electrogustometry
examination approach to visual field defects
general inspection:
acromegaly
hemiparesis
dysphasia
visual fields
- introduce
- sit about arms length
- “can you see my whole face”
- test gross VA- counting fingers (wear specs!)
- test gross visual fields using finger movements as well as for visual inattention
- test using white hat pin from all quadrants
if single eye defect for visual field, examination approach?
proceed with fundoscopy:
BRAO, haemorrhages, chorioretinitis
optic atrophy, glaucoma, RP
single eye visual defect with constricted field (tunnel vision)
> chronic papilloedema
chronic glaucoma
retinitis pigmentosa
chorioretinitis
hysteria (visual field does not widen as object is brought further away from the patient compared to organic cause)
single eye visual field defect: scotoma? causes
retinal haemorrhage or infarct (paracentral or peripheral scotomas)
- does not cross the horizontal midline
optic nerve (pale in atrophy, normal in retrobulbar neuritis, pink/swollen in papillitis) resulting in central scotoma
- compression: tumour, aneurysm, paget’s
- glaucoma
- neuritis: MS, ischaemia (temporal arteritis, idiopathic, C/BRAO), toxic (methanol), B12 deficiency, Hereditary (Friedrich’s ataxia, LHON), 2’ retinitis pigmentosa
totally blind in one eye causes?
retina
optic nerve lesion
single eye altitudinal visual field defect (ie. superior or inferior)?
retinal infarcts
ischaemic optic neuropathy
bitemporal visual field defect causes
upper > lower= inferior chiasmal
- pituitary tumour
- suprasellar meningioma
lower > upper
- craniopharyngioma
others: aneurysm, metastasis, glioma
homonymous hemianopia - causes?
infarcts/ haemorrhages/ tumour
left homonymous hemianopia = right cerebral lesion and vice versa
incongruous: optic tract
congruous:
upper quadrantonopia: temporal lobe
lower quadrant: parietal lobe
macula sparing (test with red hat pin):
occipital cortex
no macula sparing: optic radiation
note any DM dermopathy, xanthelasma. AF. hemiparesis (causes / RF for stroke)
ix of bitemporal hemianopia?
- lateral skull XR: enlarged sella turcica, calcification for craniopharyngioma
- CT or MRI head
- formal field perimetry
- serum prolactin
- screen for hypopituitarism
- IGF1: screen for acromegaly if suspected
what signs to mention when patient has a unilateral homonymous hemianopia?
incongruous/ congruous
macula sparing or not
if any: hemiparesis,
dysphasia, visual inattention
look for CVRF- DM dermopathy, xanthelasma, AF
tumour - cachexia, clubbing for metastatic disease
request for full neurological examination to evaluate for stroke/ SOL
ix of homonymous hemianopia?
CT head
formal field testing, perimetry
examination findings for right INO?
left eye can abduct with nystagmus, right eye fails to adduct on leftward gaze
right eye is able to independently adduct
saccadic eye movement - horizontal saccade is abnormal with the right eye lagging behind the left eye
Internuclear ophthalmoplegia:
what examination finding can help to neurolocalise?
convergence intact: pons
convergence not intact: midbrain
what else to examine for if internuclear ophthalmoplegia is picked up?
eye movements
convergence
proceed with other CN examination:
- multiple sclerosis (RAPD)
- myasthenia gravis
limbs:
- multiple sclerosis: may have cerebellar signs
- CVA: DM dermopathy, xanthelasma, AF
request for fundoscopy: optic atrophy
what causes a right INO?
lesion is in the right medial longitudinal fasciculus that connects the ipsilateral third nerve innervation to the right medial rectus to the left gaze center
causes of INO?
multiple sclerosis
brainstem infarction
pontine glioma
infections: Lyme disease, syphilis, viral
drug intoxication: TCAs, phenytoin, CMZ
trauma
myasthenia gravis (pseudo INO due to EOM weakness)
ix of internuclear ophthalmoplegia?
as per possible aetiologies:
MG
MRI brain
Lipid panel, fasting glucose
Lyme disease titre
VDRL
drug levels
what is wall eyed bilateral INO? (webino syndrome)
- due to bilateral MLF damage
- bilateral INO with exotropia and failure of convergence
- lesions in the pons and midbrain
- due to MS/ brainstem infarct, gliomas, wernicke’s
what is fisher’s one and a half syndrome?
ipsilateral horizontal gaze palsy (ie. both eyes can’t look right) and ipsilateral INO (ie. left eye can look left, right eye cannot adduct)
- due to lesion in MLF and adjacent gaze center
causes of conjugate upward vertical gaze palsy?
midbrain lesion:
MS (demyelination), vascular (infarct, haemorrhage, aneurysm), tumour
causes of conjugate downward vertical gaze palsy?
lesion in midbrain or foramen magnum
- arnold chiari malformation, dandy walker
- acquired lesion (tumour, vascular, demyelination, abscess)
features of parinaud’s syndrome?
loss of vertigal gaze (usually upward gaze affected)
+
nystagmus on convergence (particularly with upward gaze and saccades upward)
+
light near dissocation (poor bilateral pupillary constriction in response to light, but preserved constriction with convergence)
+ bilateral lid retraction
parinaud syndrome -causes?
lesions affecting structures in the dorsal midbrain
most often: pineal region tumors, brainstem hemorrhage, and ischemic infarction
MS
features of progressive supranuclear gaze palsy in parkinsons plus disease?
loss of downward gaze, then upward gaze then horizontal gaze
can be overcome by doll’s reflex
loss of saccadic (frontal lobe) and pursuit movements (occipital lobe)
isolated CN III palsy - what to examine for upon completion of eye/ CN examination?
look for intortion of the affected orbit by asking patient to look down and medially of affected eye (if affected, implies 4th nerve palsy)
rule out:
thyroid eye disease, MG
Superior orbital syndrome and cavernous sinus syndrome
proceed with
- neck for LNs
- examine upper limbs for cerebellar, hemiplegia, EPSE, areflexia
- look for DM dermopathy
isolated CNIII palsy: what to request for on completion of examination?
- corneal reflex (Reduced or absent)
- visual fields (bitemporal hemianopia)
- fundoscopy for optic atrophy (MS), DM or hypertensive changes
- visual acuity
- blood pressure
- urine dipstick
- temperature chart
- headache or pain
what is the course and anatomy of the 3rd CN?
- nuclear portion at the midbrain
- fasicucular intraparenchymal portion: close to the red nucleus, emerges from the cerebral peduncle
- fascicular subarachnoid portion: meninges, PCA aneurysm
- fasiculular cavernous sinus portion: sella turcica between the petroclinoid ligament below and interclinoid above
- fascicular orbital portion: superior orbital fissure
what are the causes of an isolated 3rd nerve palsy?
Brainstem:
- infarct, haemorrhage, tumour, abscess, MS
peripheral:
- subarachnoid portion: PCA aneurysm, meningitis, infiltrative
- cavernous sinus lesions
- orbital
- mononeuritis multiplex, MG, Miller fischer
features of a third nerve nucleus lesion?
will also have contralateral ptosis and elevation palsy
as axons from the third nerve nucleus also innervate the contralateral superior rectus and the contralateral levator palpebrae
emergency causes of third nerve palsy?
coning (raised ICP)
giant cell arteritis
aneurysm
how would a patient present with thrid nerve palsy? (symptoms)
diplopia
ptosis
symptomatic glare from failure of constriction of pupil
blurring of vision on attempt to focus of near objects due to loss of accommodation
pain in certain aetiologies: DM, PCA aneurysm, migraine
causes of a dilated pupil?
- III nerve palsy
- optic atrophy (direct light and accommodation absent with intact consensual reflex)
- Holmes Adie Pupil (myotonic pupil)
- Mydriatic eye drops
- Sympathetic overactivity
why does a PCA aneurysm result in pupillary involvement whereas conditions such as DM or hypertension spares the pupil?
the pupillary fibres are situated superficially and prone to compression whereas ischaemic lesions tends to affect the core of the nerve thus sparing the pupillary fibres
ix of isolated CN III palsy?
imaging: CT, MRI
Angiogram
Bloods:
Fasting blood glucose
ESR
TFT
screen for myasthenia if suspected
LP
mx of 3rd nerve palsy?
medical third nerve palsy
- education: watchful waiting, avoid driving/ heavy machinery/ climbing high places
- treat underlying conditions such as DM/ hypertension
- most spontaneously recover within 8 weeks
- symptomatic treatment: NSAIDs for pain, eye patch for severe diplopia and prism glasses for mild diplopia
surgical 3rd nerve palsy - surgery
Features of sciatic neuropathy?
Weak knee flexion (hamstrings)
- knee extension and hip adduction normal
Weak ankle dorsi and plantar flexion-> foot drop
Weak foot inversion and eversion
Wasting of peroneus and anterior tibialis muscle
Loss of ankle reflex and plantars absent, knee jerk intact
Everything below knee except medial aspect of leg and foot may be numb
features of progressive supranuclear palsy on MRI brain?
atrophy and hyperintensity of the midbrain and red nucleus
“hummingbird” sign: atrophy of the midbrain results in a profile of the brainstem (in the sagittal plane) in which the preserved pons forms the body of the bird, and the atrophic midbrain the head, with beak extending anteriorly towards the optic chiasm.
Features of L5 radiculopathy?
Weakness of hip abduction and internal rotation,
Weak foot dorsiflexion (foot drop)
loss of foot inversion and eversion
plantar flexion preserved
Loss of ankle reflex
Sensory loss over dorsum of foot and lateral calf + big toe
Features of common peroneal nerve palsy?
Weak ankle and toe dorsiflexion, foot eversion
Wasting of anterior tibialis muscles
Foot inversion and plantar flexion normal (innervated by posterior tibial nerve)
Reflexes all normal
Sensory loss over lateral calf and dorsum of foot
Features of palsy of deep peroneal nerve
Deep branch supplies the ankle +
toe dorsiflexion (foot drop)
- eversion spared (supplied by superficial branch)
Normal reflexes
Sensory loss only over first interdigital web space
