Neurology_Medicine & Surgery

Question 1

Neuroanatomy - blood supply to the brain

Answer 1

Circle of Willis - perfuses brain

• Cerebral arteries - anterior, middle, posterior (all bordering the circle)
  
  • ACA - supplies anterior & medial brain (frontal lobe + medial motor & somatosensory cortices) –> behavioural changes, weakness legs > arms, mild sensory defect
  • MCA - supplies the lateral brain (lateral motor & somatosensory cortices, language - Broca & Wernicke’s, optic tracts) –> weakness face > arms > legs, aphasia (expressive/receptive), hemisensory defect, homonymous hemianopia
  • PCA - supplies inferior & posterior brain (affecting visual cortex and tracts) –> homonymous hemianopia, visual agnosia/prosopagnosia
• Major arteries giving rise to the circle of Willis:
  
  • Vertebral artery (from the spine)
  • Internal carotid artery (gives rise to A & M cerebral arteries)

Question 2

UMN vs LMN:

• Motorpathway name + route
• UMN & LMN lesion causes and signs

Answer 2

Corticospinal tract = voluntary motor pathway for body:

1. Cortex - primary motor cortex (posterior frontal cortex)
2. Medulla - tracts from PMC converge and cross over = pyramids
3. Spinal cord - UMN synapases with LMN
4. Peripheral nerves - LMN innervates muscle

UMN lesions

• Causes (anything affecting brain itself): stroke, SOL, MND, MS
• Signs: hypertonia, hyperreflexia, spasticity (velocity/direction-dependent), upgoing plantars, pronator drift
• NOTE: increased tone/reflexes as -ve feedback loop from the brain is removed

LMN lesions

• Causes (affect peripheral nerves): MND, trauma, polio, GBS
• Signs: hypotonia, hyporeflexia, muscle atrophy, fasciculations, fibrillations
• NOTE: reduced tone/reflexes because no nerve supply

Question 3

Intracranial bleeds - layers of the outer brain? types? Appearance on CT-head? Presentations?

Answer 3

Outer layers of the brain:

• Skull > dura mater (adherent to inside of skull) > arachnoid mater > pia mater > brain parenchyma

Types:

• Extradural haemorrhage- bleed between dura mater & skull
  
  • Most common = skull fracture of pterion (temple) –> trauma to middle meningeal artery
  • Hx: clear trauma –> transient LoC –> lucid interval –> ongoing headache –> reduced consciousness
  • Convex (EGG) appearance on CT-head as blood sealed in by dura ± soft-tissue oedema outside skull (trauma site)
  • Mx: A-E approach, refer to neurosurgery
    
    • Monitor GCS = deterioration
• Subdural haemorrhage - bleed between dura & arachnoid mater
  
  • Tearing of bridging veins going from outer surface of brain to dura mater
  • Common in elderly + alcoholics (both have cerebral atrophy)
  • Types: both concave (SICKLE) appearance on CT-head
    
    • Acute - assoc w/ trauma + blood white (hyperdense) on CT-head
    • Chronic - little/no Hx of head trauma e.g. fall several weeks ago and then not been normal since (elderly) + dark (hypodense) blood on CT-head
    • Reduced consciousness, if severe = focal neurology (esp. if midline shift)
  • Mx: A-E, neurosurgery referral
    
    • Monitor GCS, reverse Warfarin
• Subarachnoid haemorrhage - between arachnoid & pia matter
  
  • Caused by an aneurysm (berry) or trauma
  • Presentation: sudden-onset worst headache ever, photophobia, neck stiffness
  • LP 12hrs after Sx-onset (xanthochromia)
  • Mx: A-E approach
    
    • Monitor GCS and neuro obs
    • Discuss with neurosurgery
    • Other – fluids, monitor Na, nimodipine
  • Complications:
    
    • Vasospasm – presents like a stroke
    • Hyponatraemia – can be SIADH
    • Rebleed - coil ASAP if possible

Question 4

Headache - types? Ix? Mx?

Answer 4

Types:

• Tension - band-like, front of forehead, causes: dehydration, stress
• Cluster - intense pain behind/around eye (worse @night + lacrimation & ptosis during attack), daily clusters for 4-6wks then nothing for months, M>F
  
  • Mx: 100% O2 + nasal triptans
• Migraine - intense/throbbing, focal, aura, photophobia
  
  • Triggers: alcohol, chocolate, cheese, oestrogens (OCP)
  • Mx:
    
    • Acute - simple analgesia, dark room + Triptans (take as soon as Sx start)
    • Prevent - trigger avoidance + propranolol/ topiramate (anticonvulsant, terratogenic) /amitriptytline (TCA)
• Meningitis - generalised, moves down neck, neck stiffness + fever + rash (meningococcal)
  
  • Ix: CT-head, LP (type of meningitis), BC (causative organism)
  • Mx:
    
    • Suspected in primary care - IM/IV Benzypenicillin
    • Secondary care - IV Ceftriaxone ± Amoxicillin (infants/>50yrs)
    • If could be encephalitis (seizure/behavioural) - IV Aciclovir
• SAH - sudden-onset, worst headache ever ± neck stiffness, can get preceding sentinel bleed (minor), assoc w/ PCKD (Berry aneurysm in Circle of Willis)/Marfan’s
  
  • Ix: non-contrast CT –> LP for xanthochromia (after 12hrs)
  • Mx: nimodipine (CCB, give every 4hrs, reduces vasospasm in cerebral arteries)
• Giant cell (temporal) arteritis - vasculitis –> scalp tenderness, jaw claudication, vision loss, assoc w/ polymyalgia rheumatica (>50yrs)
  
  • Ix: ESR, temporal artery biopsy
  • Mx: high-dose Prednisolone (to prevent blindness, do not wait for biopsy)
• ​Trigeminal neuralgia - electric shock-like pain on touching face (extremely tender)
  
  • Divisions of trigeminal nerve (V2&3)
  • Ix: MRI brain
  • Mx: Carbamazepine (for pain), neurology referral
• Raised ICP - worse at night/on waking/coughing/straining ± N&V, visual disturbances
  
  • Mx: osmotic diuresis - mannitol/hypertonic saline
• Cerebral Venous Sinus Thrombosis (VTE in the brain) - papilloedema, 6th nerve palsy, seizures, Cushing’s reflex (HTN, bradycardia, Cheyne-Stokes breathing)
  
  • Ix: MRI w/ MR venography
  • Mx: LMWH
• Idiopathic intracranial HTN (IIH) - Obese, female, papilloedema, postural headache worse with straining, assoc w/ OCP
  
  • Ix: visual field testing, fundoscopy, MRI brain, LP (≥25 opening pressure)
  • Mx: acetazolamide (carbonic anhydrase inh), weight loss, LPs + VP/LP shunt, ophthalmology follow-up

Question 5

Cardiovascular accident (CVA) - Def? Presentation? DDx? Classification? Ix? Mx?

Answer 5

Def: better to use cardiovascular accident (CVA)

• Stroke ≥24hrs, TIA ≤24hrs

Presentation:

• Pyramidal weakness (flexors stronger than extensors in upper limb, opposite in lower limb), hypertonia, hyperreflexia
• Hemiplegic/scissor gait –> circumduction
• TIA: Amaurosis Fugax (black curtain)
  
  • If ≥2 in 1wk = high risk of stroke –> ADMIT
  • Aspirin 300mg + secondary prevention (as for stroke)

DDx:

• Cerebral lesion - 80% ischaemic, 20% haemorrhagic (reduced GCS & raised ICP)
• Neoplastic - SOL
• Rare: syphilis, Todd’s paralysis (post-ictal), migraine, MS, cerebral abscess, rheumatological (arteritis)

Classification: Bamford aka Oxford

• Total anterior circulation stroke: hemiplegia, homonymous hemianopia, higher cortical dysfunction
• Partial anterior circulation stroke: 2/3
• Lacunar circulation stroke: hemi-motor OR hemi-sensory stroke only
• Posterior stroke: cranial nerve problems, eye-movement disorder, cerebella presentation
  
  • Weber’s & Wallenberg’s (lateral medullary syndrome = posterior cerebellar artery infarct)

Ix:

• BEFORE Tx = CT-head - 80% strokes ischaemic, 20% haemorrhagic (wrong Tx will make it much worse) –> haemorrhage has an area of hyperdense (white) bleeding
• After initial Mx –> identify cause:
  
  • ​​Structural heart defect - echocardiogram
  • AF - ambulatory ECG (24hr tape if no obv sign of AF as outpatient)
  • Carotid atherosclerosis - carotid doppler –> carotid artery stenosis (70-99%) = carotid endarterectomy

Mx: A-E approach + URGENTLY contact stroke team –> dedicated stroke unit, if ischaemic:

• Immediately:
  
  • Aspirin 300mg OD + STOP anticoagulants (high risk of haemorrhagic transformation in first 2wks)
  • <4.5hrs since Sx onset: thrombolysis (Alteplase = tPA)
    
    • C/I: any sign of active bleeding, very high BP, recent surgery, raised ICP
  • >4.5hrs since Sx onset: conservative Mx:
    
    • BM - keep controlled <11 (sliding scale insulin)
    • NG tube (nutrition)
    • MDT - dietician, SALT, PT/OT
  • < 6hrs (sometimes up to 24hrs, depending on size, area, damage) –> thrombectomy (neurosurgery)
• After 2wks:
  
  • STOP aspirin –> start clopidogrel 75mg OD + consider anticoagulation (e.g. if AF) - DOAC/Warfarin
  • Manage vascular RFs (DM, HTN, QRISK etc.)

Question 6

Parkinson’s disease definition? Cardinal Sx? DDx? Ix? Mx? Complications?

Answer 6

Def: a neurodegenerative disease of dopaminergic neurones of substantia nigra (part of basal ganglia in the midbrain)

Cardinal Sx (from extrapyramidal involuntary dysfunction): resting tremor, rigidity (cogwheeling due to superimposed tremor), bradykinesia, postural instability

+ insomnia, hypomimia (mask face), depression, autonomic dysfunction

DDx:

• Benign essential tremor - bilateral, postural, FHx, alcohol improves it (in 50%)
• Drug-induced (anti-psychotic, metoclopramide) - drug chart
• MSA (multisystem atrophy) incl Shy-Drager (autonomic) - cerebellar signs
• PSP (progressive supranuclear palsy) - loss of downward gaze
• LBD (Lewy body dementia) - visual hallucinations
• Normal-pressure hydrocephalus - gait disturbance, cognitive impairment, impaired bladder control
• Other:
  
  • Corticobasal degeneration - single-arm signs, alien limb syndrome (myoclonus)
  • Wilson’s disease (copper) - motor

Ix: clinical Dx –> dopaminergic agent trial ± MRI scan/DAT scan

Mx: problem = lack of dopamine in substantia nigra –> aim of Tx is to increase dopamine here

• Dopamine agonist (cross BBB):
  
  • Good for younger patients to reduce time on levodopa (as get very sensitised)
  • Types:
    
    • Non-ergot - ropinirole, pramipexole - avoid below SEs = 1st line but still get dopamine dysregulation syndrome (hypersexuality & gambling)
      
      • SC Apomorphine for advanced disease
    • Ergot - cabergoline, bromocriptine –> retroperitoneal/pulmonary fibrosis
• ‘L-DOPA (levodopa) AND peripheral DOPA-decarboxylase enzyme (Carbidopa)’ = Sinemet/Medapar
  
  • Relevant physiology:
    
    • Substantia nigra contains dopaminergic neurones with DOPA decarboxylase (converts L-DOPA –> dopamine) - not happening as normal in Parkinson’s
    • Peripheral DOPA-decarboxylase in body
    • Chemoreceptor trigger zone (CTZ) –> triggers nausea & vomiting
  • Drug explanation:
    
    • If give L-DOPA by itself it will be broken down by peripheral DOPA-decarboxylase into dopamine - this can’t cross BBB to reach substantia nigra but can reach CTZ –> nausea/vomiting
    • Instead, give L-DOPA with peripheral DOPA-decarboxylase inhibitor to allow more L-DOPA to cross BBB to reach dopaminergic neurones in substantial nigra to be converted to dopamine (some still reaches CTZ –> SE of nausea/vomiting)
  • Other SEs: dyskinesia, on-off phenomena, postural hypotension
    
    • Amantadine - for dyskinesia secondary to levodopa
    • COMT inhibitors e.g. entacapone for tailing off betw/ doses of levodopa

Complications:

• Falls, cognitive impairment, depression
• Drool (SALT/glycopyrronium)
• Meds SEs (e.g. vomiting)

Question 7

Rigidity vs Spasticity

Answer 7

Rigidity (in Parkinson’s disease) = increased muscle tone, that is not velocity or direction-dependent

• In Parkinson’s get Cogwheeling = rigidity overlayed by tremor

Spasticity (in Stroke) = increased muscle tone, that is velocity or direction-dependent

• Flexors/extensors become imbalanced in strength - certain directions have increased muscle tone (not all) AND worse stiffness if move arm more quickly

Question 8

Dementia - Types?

Answer 8

Types:

• Alzheimer’s disease
  
  • ​Progressive decline in cognitive function
  • Tx: Acetylcholinesterase inhibitors (Donepezil)/NMDA receptor antagonists (Memantine)
• Vascular dementia
  
  • A stepwise decline in cognitive function
  • Background of vascular disease (IHD, PVD)
• Dementia with Lewy Bodies
  
  • ​Triad - dementia, hallucinations, parkinsonism
  • Balance - Parkinsonism = dopamine def vs hallucinations = dopamine excess
• Frontotemporal - personality changes, early onset
• Depressive pseudodementia - disinterested, low mood

Question 9

What are the nerve innovations for deep tendon reflexes in upper and lower limb neuro examination?

Answer 9

Nerve innovations:

• S1,2 - buckle my shoe - ankle jerk (Achilles tendon)
• L3,4 - kick the door - knee jerk (patellar tendon)
• C5,6 - pick up sticks - biceps, brachioradialis reflex
• C7,8 - lay them straight - triceps reflex

Question 10

MRC Power Scale

Answer 10

• 1 flicker
• 2 is moves with gravity removed
• 3 is movement against gravity
• 4 is reduced power against resistance
• 5 is normal

Question 11

Gait abnormalities vs normal

Answer 11

SUMMARY:

• Normal gait cycle: 1) heel strike 2) foot flat 3) mid stance 4) heel off 5) toe-off
• Antalgic gait - limping due to pain e.g. osteoarthritis, inflammatory joint disease, fracture, sciatica
• Hemi/Diplegic gait - uni/bilateral circumduction of leg - CNS lesion (bilateral is called a ‘scissoring gait’)
• Parkinsonian gait - shuffling gait, no arm swing - Parkinson’s/DLB/Antipsychotics
• Ataxic gait - wide/broad-based stance & imbalance - Cerebellar/Vestibular/Sensory neuropathy
  
  • NOTE: can’t do tandem walk
• Neuropathic gait - high-step gait (from foot drop) - motor neuropathy e.g. L5 radiculopathy (e.g. herniated disc), common peroneal neuropathy, MS, Charcot-Marie-Tooth disease
  
  • Can’t walk on heels
• Myopathic gait - waddling/Trendelenburg gait (hip sways to one/both sides - hip abductor muscles weak) - muscular dystrophy/myopathy
• Choreiform gait - involuntary movements - Basal ganglia disease e.g. Parkinson’s meds, Huntington’s, Wilson’s, Cerebral Palsy
• Stomping gait - sensory neuropathy (loss of proprioception & vibration sense = dorsal column disease)
  
  • Vibration –> proprioception (Romberg’s +ve) –> light touch (in order lost)
  • Causes: SACD (subacute combined degen cord - B12), Friedrich’s ataxia, Tabes/taboparesis & tabes dorsalis (syphilis),
• Marche à petit pas - small steps = normal pressure hydrocephalus

IN-DEPTH:

Normal gait cycle: 1) heel strike 2) foot flat 3) mid stance 4) heel off 5) toe off

Antalgic gait - limping due to pain

• Causes: osteoarthritis, inflammatory joint disease, lower limb fracture, nerve entrapment (sciatica)

Hemiplegic gait - unilateral circumduction of leg to prevent dragging foot

• CNS lesion –> unilateral weakness & spasticity (spastic flexion of upper limb vs extension of lower limb)
• Causes - UMN lesion:
  
  • Unilateral cerebral lesion e.g. stroke, SOL, trauma, MS
  • Hemisection of spinal cord (trauma)

Diplegic gait - bilateral circumduction of legs (scissoring gait_)_

• CNS lesion as above but bilateral clinical findings - spasticity worse in lower limbs vs upper limbs ± hyperreflexia, clonus, Babinski +ve, reduced power, sensory level if spinal cord pathology
• Causes:
  
  • Spinal cord lesion e.g. prolapsed intervertebral disc, spinal spondylosis, spinal tumour/infarct, transverse myelitis
  • Bilateral brain lesion - cerebral palsy, MS, bilateral brain infarcts, midline tumour (paraspinal meningioma)
  • MND - if also LMN findings (wasting, fasciculations)

Parkinsonian gait - shuffling gait

• Loss of dopaminergic neurones in substantia nigra of basal ganglia –> extrapyramidal dysregulation = rigidity, bradykinesia, resting tremor, postural instability
• Features of parkinsonian gait:
  
  • Initiation - slow to start walking
  • Step length - shuffling gait (short steps) & festinant gait (progressively smaller steps)
  • Arm swing - reduced (early feature)
  • Posture - flexed trunk & neck = stooped
  • Turning - postural instability
• Causes: Parkinson’s, Dementia w/ LBs, Parkinson’s plus syndromes (Multisystem atrophy & progressive supranuclear palsy), drug-induced (antipsychotics/emetics)

Ataxic gait - wide/broad-based stance (to maintain balance)

• Assoc w/:
  
  • Midline cerebellar disease (alcoholism/B12 def, MS, cerebellar stroke) - DANISH (dysdiadokokinesia, ataxia, nystagmus, intention tremor, slurred speech, hypotonia)
  • Vestibular disease (labyrinthitis, Meniere’s, acoustic neuroma) - vertigo, N&V
  • Sensory ataxia (peripheral neuropathy e.g. DM) - +ve Romberg’s, impaired proprioception, impaired vibration sense, lack of other cerebellar signs
• Features of ataxic gaint:
  
  • Stance - broad-based ataxic gait
  • Stability - staggering, slow, unsteady –> veer towards side of lesion
  • Turning - very difficult

Neuropathic gait - high-step gait (from foot drop)

• Weakness in muscles of distal limb (foot dorsiflexors) - damage to peripheral nerves providing motor innervation –> foot drop & dragging toes –> knee & hip flex excessively to compensate
• Other features: peripheral vascular disease, peripheral sensory impairment, reduced/absent reflexes
• Causes: motor neuropathy
  
  • Isolated common peroneal nerve palsy (trauma/compression)
  • L5 radiculopathy (disc prolapse)
  • Generalised polyneuropathy involving multiple nerves (DM, MND, Charcot-Marie Tooth disease)

Myopathic gait - waddling/Trendelenburg gait (hip sways to one/both sides)

• Weakness of hip abductors –> can’t stabilise pelvis –> tilts down towards unsupported side
• Assoc features: hard to stand from seat/squat/lying without arms, +ve trendelenburg’s sign (stand on one leg - if the hip on the side of the raised leg drops = +ve)
• Causes: muscular dystrophy, myopathy (e.g. in hyperthyroidism, Cushing’s, acromegaly, Polymyalgia rheumatica)

Choreiform gait - involuntary movements

• Oro-facial dyskinesia (grimacing/lip-smacking) & choreic mov of upper/lower limbs = dance-like/writhing @rest/mov
• Causes: Basal ganglia disease
  
  • Huntington’s, Sydenham’s chorea, Cerebal palsy (Choreiform type), WIlson’s disease, Dopaminergic meds (e.g. Parkinson’s)

Question 12

Cerebellar syndrome causes?

Answer 12

MAVIS:

• MS - eye (RAPD, INO), spastic paraparesis, catheterised
• Alcohol - peripheral neuropathy, liver signs
• Vascular (thromboembolic/haemorrhagic)
• Inherited (Friedrich’s ataxia)
• SOL
• Other: hypothyroidism & paraneoplastic syndrome

Question 13

MS - def? key features? DDx? Clinical courses? Ix? Mx? Poor prognostic features?

Answer 13

Def: evidence of damage to CNS that is separated in time & space

Key features:

• Profile: young, female (catheter & walking aid/wheelchair), eye & cerebellar signs
• Initial:
  
  • Ipsilateral visual disturbance - greying/blurring ± pain on eye mov/loss of red colours
  • Sensory phenomena - wetness/burning, uncomfortable band around the chest
    
    • Lhermitte’s sign - electric shock down neck and along spine & may radiate along limbs
    • Uthoff’s - neuro Sx worsen with increased temperature (hoff = hot)
• UMN Sx: hyperreflexia, hypertonia, pyramidal pattern (arm flexors stronger, leg extensors stronger)
• Dorsal column disease - reduced vibration, proprioception, Romberg’s +ve
• Eyes:
  
  • Internuclear ophthalmoplegia
    
    • Adduction paralysis and abduction nystagmus
    • From lesion in medial longitudinal fasciculus
  • Optic nerve damage:
    
    • Colour & visual acuity loss, RAPD
    • Central scotoma (central blindspot), optic atrophy
  • CN palsy (most commonly 6th - as longest)
• Cerebellar signs (imbalance, can’t tandem walk)

DDx:

• Cervical spondylosis - wo/ UMN signs but no cerebellar signs
• Subacute combined degeneration of the cord (SACD) - dorsal columns & cerebellar - if low B12
• Neuromyelitis optica aka Devic’s disease (IgG against aquaporin-4 channel) - optic neuritis & transverse myelitis but no cerebellar Sx

Clinical courses/patterns:

• Relapsing-remitting - steady decline + strong flair
• Primary progressive - steady decline without attacks
• Secondary progressive - initial relapsing-remitting becoming primary progressive
• Marburg variant - very severe, rapidly progressive

Ix:

• Bedside:
  
  • Fundoscopy (optic neuritis), full functional assessment (physio, OT)
  • Nerve conduction studies - visual evoked potentials (VEPs) - if single nerve lesion, delayed response
• Bloods - B12 (SACD), TFTs
• Imaging:
  
  • MRI (T2) head (lesions disseminated in time & space) - McDonald’s criteria
    
    • ​Periventricular white matter lesions
  • LP: IgG oligoclonal bands, high protein

Mx:

• Acute relapse: high-dose methylprednisolone (shortens acute attack) e.g. optic neuritis (painful eye mov + reduced visual acuity)
• Long-term - MDT approach (physio, OT, SALT)
  
  • Mobility - mobility aids, physio, OT
  • INF-beta = disease modifying
  • Spasticity –> Baclofen/Gabapentin (Dantrolene if CKD)
  • Bowel (laxatives) & bladder (oxybutynin, LT catheter)
  • Fatigue –> Amantadine
  • Emotional lability –> Amitriptyline

Poor prognostic features:

• Brainstem/cerebellar disease at onset
• >40yrs at onset
• Primary progressive MS (no resolution

Question 14

Wernicke’s encephalopathy - Def? Sx triad? Mx - in hypoglycaemia and without? Complication?

How does delirium tremens present?

Answer 14

Def: Acute presentation of thiamine (B1) def

Triad: confusion, ataxia, nystagmus

Complication = Korsakoff syndrome (chronic & permanent memory problems)

Delirium tremens: confusion, visual hallucinations, tachycardia, pyrexia

Question 15

Spinal cord injury - RFs? Ix? First Mx?

Answer 15

RFs: atherosclerosis, hypotension, aortic aneurysm, aortic dissection

Ix:

• Traumatic - CT-spine (bony injury/fracture)
• Non-traumatic - MRI spine (soft tissue injury)

Mx: spinal immobilisation, manage in tertiary neurosurgical centre

Question 16

What is Cushing’s triad? Indicates? Mx?

Answer 16

HTN, bradycardia, Cheyne-Stokes breathing

Indicates raised ICP (likely form herniation through foramen magnum)

Urgent referral to tertiary neurosurgical centre

Question 17

Most common cause of SAH?

High SAH suspicion but normal CT - Ix?

How do you reduce risk of ischaemia afterwards?

Answer 17

Berry aneurysm (85%)

LP in 12hrs for xanthochromia (yellow from bilirubin in CSF - RBC breakdown)

Nimodipine

Question 18

Neurology Ix depending on UMN/LMN signs?

Answer 18

ALL: involve MDT for full functional assessment (physio & OT)

UMN:

• Imaging (brain ± spinal cord)
• CSF (LP)
• Brain biopsy

LMN:

• Nerve conduction studies & electromyography (NCS & EMG)
• Bloods (metabolic, abs)
• Muscle/nerve biopsy

Question 19

GBS Ix? Mx?

Answer 19

Ix:

• Bloods (metabolic, abs), CT –> LP ± MRI spine (exclude other causes)
• Nerve conduction studies

Mx: ADMIT suspected cases - normally self-limiting course

• MDT - psychologist, SALT (if speech muscles affected)
• Plasmapheresis (plasma exchange)
• High-dose IVIG
• DVT prophylaxis

Question 20

MND - Presentation? DDx? Types of MND? Dx? Mx? Complications?

Answer 20

Presentation: mixed UMN/LMN (no sensory deficits, no eye involvement)

• UMN in lower limbs (spasticity, hyperreflexia, upgoing plantars)
• LMN in upper limbs (hypotonia, hyporeflexia, fasciculations, wasting)
• Bulbar/pseudo-bulbar tongue/speech (tongue fasciculations, palatal paralysis, nasal speech)
• NORMAL SENSORY EXAM

DDx mixed signs:

• Dual pathology (stroke + peripheral neuropathy)
• Conus medullaris lesion - painful, assoc with traumatic spinal injury/higher up mets)
• B12 def (subacute combined degen of spinal cord) = cofactor in myelination (as is folate)

Types:

• Amyotrophic lateral sclerosis (60%) - classic (UMN & LMN)
• Progressive Bulbar Palsy (30%) - CN 9-12 –> dysarthria (speech), dysphagia (swallowing)
• Primary Lateral Sclerosis - pure UMN onset
• Progressive Muscular Atrophy - pure LMN onset, ‘flail limb’ appearance

Dx: clinical, exclude other causes

• EMG/NCS (nerve conduction study) - chronic nerve root denervation
• Imaging - MRI (cervical, thoracic, lumbar spine) - exclude other causes

Mx: no cure - MDT approach

• Conservative - SALT (swallowing), physio & OT
• Sx-control:
  
  • Quinine - muscle cramp
  • Anticholinergics e.g. hyoscine patches - drooling
  • Exercise & nutrition
• Prognostic:
  
  • Riluzole - glutamate antagonist (extend life expectancy by 3-5 months)
  • NIV - if respiratory muscles no longer functioning

Complications: resp compromise, frontal lobe dementia (2%)

Question 21

How to remember nerve innervation of the diaphragm? Nerve associated?

Answer 21

C3,4,5 keep the diaphragm alive

Phrenic nerve

Question 22

Raised ICP - what is the Monro-Kellie Doctrine? Causes? Signs? Mx?

Answer 22

Monro-Kellie Doctrine: skull is a closed box, the sum of volumes of brain, CSF & IC blood is constant - increase in one should cause a decrease in one/both of others

• In brain there is little wiggle-room, the only weak point is the foramen magnum –> herniation = coning –> death

Causes: IC haemorrhage (IC blood), tumour, (brain vol), cerebral oedema (CSF)

Signs:

• Acute (pressure on brainstem): CUSHING’S TRIAD (HTN, bradycardia, irregular breathing) + reduced GCS
• Chronic: long-term headache

Mx:

• Conservative: sit up, hyperventilated (if intubated –> reduce pCO2 –> reduce vasodilation in brain)
• Medical: mannitol (osmotic diuretic), hypertonic saline –> both draw fluid out of brain –> reduce ICP
• URGENT neurosurgical input –> Burr hole surgery

Question 23

Cauda equina - def? Sx? Causes? Key Ix? Mx?

Answer 23

Def: compression of Cauda Equina (nerve fibres below L1-2)

Sx: can you feel it while you urinate/when you tug on catheter?

• Severe back pain
• Saddle anaesthesia (numb around the anus)
• Bladder/bowel dysfunction (urinary retention, faecal incontinence)
• Lower limb weakness
• Reduced anal tone (on PR exam)

Causes: large disc herniation, cancer, trauma, abscess, haematoma

• NOTE: if likely mets e.g. background of prostate cancer –> 16mg Dexamethasone (reduces swelling)

Ix: urgent MRI scan (+ PR exam)

Mx:

• In normal disc herniation (above cauda equina):
  
  • Get the patient to keep moving (or muscles will seize up)
  • Analgesia - PR Diclofenac (neuropathic pain) + Diazepam
• In cauda equina –> urgent referral to neurosurgery for decompression/laminectomy

Question 24

Spinal cord compression Ix & Mx for malignancy?

Answer 24

Ix: MRI whole spine (often multifocal lesions)

Mx:

• 1st line = surgical decompression (if localised, fit enough)
• 2nd line = radiotherapy (external beam radiotherapy)

Question 25

Meningitis & encephalitis - presentation? causes? Ix? Mx?

Answer 25

Meningitis:

• Presentation: headache, fever, photophobia, neck stiffness
• Causes:
  
  • Bacterial – N. meningitides, S. pneumo (TB; neonates/elderly – GBS/Listeria/E.coli) – Listeria also more common in alcoholics
  • Viral – enterovirus (Coxsackie, echovirus), mumps, HSV2
  • Fungal – cryptococcus neoformans (chr)
• Ix: A-E, BC, CT head, LP (CT first, if raised ICP –> LP would cause coning)
  
  • Kernig sign - flex knee & hip to 90 degrees –> extend knee (painful & limited extension)
  • Brudzinski sign - raise head while flat –> hip & knee flexion
• Mx: bacterial – IV ceftriaxone ± amoxicillin (Listeria - neonate/elderly)
  
  • IM BenPen for possible meningococcal infection (rash) in GP setting before sending to the hospital
  • Viral – supportive (self-limiting)
  • Altered consciousness (encephalitis?) –> add IV acyclovir

Encephalitis:

• Presentation: headache, fever, seizures, drowsiness, confusion (viral HSV1 affects temporal lobes –> affecting consciousness)
• Ix: BC, CT head, LP
• Mx: IV acyclovir ± anti-convulsants

Question 26

Sensory ataxia vs Cerebellar ataxia based on Romberg’s test?

Answer 26

Postural imbalance/swaying:

• When eyes open & closed = Cerebellar ataxia
• When eyes are closed = sensory ataxia (somatosensory nerve affected)
  
  • Dorsal column loss: Tabes dorsalis (syphilis), SCDC (B12), MS
  • Sensory peripheral neuropathy

Question 27

Spinal cord anatomy

Answer 27

Dark matter middle (cell bodies = synapses) –> white matter on the outside (neurone tracts)

Sensory pathways (ascending - goes up):

• Dorsal columns (posterior) - fine touch, vibration, proprioception
  
  • Sensory receptors - 1st order neurone up spinal column along ipsilateral side
  • At the medulla oblongata - synapses with 2nd order neurone that crosses the midline (decussation)
  • At the thalamus synapses with 3rd order neurone to the Primary Somatosensory cortex
• Spinothalamic tracts (anterior) - pain & temperature
  
  • Nociceptors (pain) - 1st order neurone to Substantia Gelatinosa within grey matter of spinal cord
  • Synapses with 2nd order neurone & immediately crosses midline (decussation) to ascend spinothalamic tract
    
    • NOTE: spinothalamic tracts decussate at the level the neurone enters the spinal cord
  • At the thalamus synapses with 3rd order neurone to the Primary Somatosensory cortex
• (Spinocerebellar tracts (lateral) - proprioceptive info to cerebellum)

Motor pathways (descending - goes down):

• Corticospinal tracts (anterior = trunk, neck, shoulders; lateral - limbs) - voluntary motor control (from primary motor cortex)
  
  • From the Primary Motor Cortex - UMN goes to the Medulla and crosses over (decussation)
  • At the anterior horn for each spinal level synapses with LMN–> muscle
  • NOTE: at any spinal level will be LMNs exiting the spine and UMNs that travel down further before synapsing with their respective LMN
    
    • SO cord pathology above the level of Cauda Equina –> some UMN & LMN signs

Question 28

Epilepsy - def? types & Tx? Status epilepticus def & Mx?

Answer 28

Def: tendency to have recurrent, unprovoked seizures

• Seizure = episodes of abnormal uncoordinated excessive brain activity
  
  • Provoked seizures = consequence of inf/drugs
  • Unprovoked = epilepsy

Types:

• Generalised (whole brain):
  
  • Tonic-clonic, Tonic, Atonic, Myoclonic –> Tx: Na Valproate (AVOID in girls/women of childbearing age)
  • Absence –> Tx: Ethosuximide/Na Valproate
• Focal - aware (conscious) OR impaired awareness (impaired consciousness)
  
  • Tx: Lamotrigine

Status epilepticus = >5mins/repeated seizures without full recovery in between

• 1st - IV lorazepam 4mg –> repeat
• 2nd - phenytoin infusion
• 3rd - general anaesthesia
• If no IV access –> rectal diazepam/buccal midazolam

Question 29

Lumbar disc herniation vs lumbar spinal stenosis - presentation? Ix? Mx?

Answer 29

Presentation

• Disc herniation - acute unilateral radiculopathy (pain & numb in specific dermatome/weakness in muscle group)
  
  • Straight leg raise +ve
  • Worse on flexion (bending over/sitting)
• Spinal stenosis - insidious neurogenic claudication (intermittent back pain worse on walking/standing) ± pain radiating down leg/leg paraesthesia
  
  • RFs: rev back injury/surgery, manual labour
  • Worse on extension (standing/walking)

Ix:

• Disc herniation - erect lumbar x-ray & MRI spine
• Spinal stenosis - plane x-ray, MRI (T2-weighted)

Mx: surgical decompression

Question 30

Brain anatomy “rules” summary - cerebellar, motor nerves, dorsal columns, spinothalamic tract

Clues to localisation - cortical, basal ganglia, cerebellar, nerve root

Answer 30

Cerebellar signs ipsilateral

Motor nerves travel laterally in brainstem & cross @medulla

Dorsal columns are posterior & cross @medulla

Spinothalamic tract is anterior in spinal cord & cross in spinal cord

Localisation:

• Cortical - UMN pyramidal signs (hypertonia, hyperreflexia, babinski)
• Basal ganglia - rigidity, tremor, bradykinesia
• Cerebellar - DANISH
• Nerve root (dermatome/myotome)/single nerve - LMN signs (hypotonia, hyporeflexia, fasciculations, wasting, sensory loss)

Question 31

Myotonic dystrophy - presentation? Assoc? Ix? Mx?

Answer 31

LMN presentation = muscle pathology

• Face:
  
  • Myopathic facies (sunken cheeks, bilateral ptosis, expressionless)
    
    • Wasting of facial & muscles of mastication
  • Frontotemporal balding
• Distal wasting, weakness w/ loss of ankle jerks
• Associations: cataracts, dysphagia, cardiac (cardiomyopathy, heart block), DM, hypogonadism (gynaecomastia/testicular atrophy)
• Exam - failure of immediate relaxation after voluntary contraction
  
  • Percussion myotonia - tap thenar eminence and thumb contracts
  • Slow-releasing grip - SHAKE HANDS (or make a fist and then spread fingers quickly or squeeze eyes shut and open quickly)

Ix:

• Conservative: full functional assessment (incl. SALT), lung function tests (NM resp insufficiency), ECG/echo (CMO/HB), slit lamp (cataracts)
• Bloods - BM (DM assoc), CK, genetic testing
• Imaging & invasive:
  
  • Electromyography (EMG) - ‘dive-bomber’ potentials
  • Muscle/nerve biopsy

Mx: MDT approach

• Phenytoin for myotonia, weakness has no Tx
• Genetic counselling - AD w/ genetic anticipation (trinucleotide repeat - worse severity/earlier presentation with each generation)
• Avoid statins (can cause myopathy)

Question 32

Ptosis causes?

Answer 32

Bilateral:

• MG
• Myotonic dystrophy
• Tabes dorsalis (syphilis) = Argyll-Robertson pupil

Unilateral:

• 3rd nerve palsy (down & out, dilated, ptosis)
• Horner’s syndrome (ptosis, meiosis, anhydrosis)

Question 33

Myasthenia Gravis Vs Lambert-Eaton Myasthenic Syndrome (LEMS)

Def? presentation? Assoc? Ix? Mx?

Answer 33

Myasthenia Gravis

• Def:
  
  • Chr AI disorder of post-synaptic membrane of NMJ in skeletal muscle
  • Abs to AChR on post-synaptic membrane
• Presentation:
  
  • Muscle fatiguability incl dysphagia, rarely SoB
  • Eyes - bilateral ptosis (and compensatory increased frontalis muscle activity = raised eyebrows), diplopia
  • Face - dysarthria (slurred speech), facial paresis
  • Curtain sign - when raising one upper eyelid the other one drops down
  • Assoc: thymomas (in the chest)
• Ix:
  
  • Abs: AChR (on post-synaptic membrane), MUSK abs
  • Serial pul funct tests (FVC & negative inspiratory force)
    
    • NOTE: do not wait for ABG findings - late in course
  • CT-chest (for thymoma)
• Mx:
  
  • Acetylcholinesterase inhibitors (Pyridostigmine) + IS (azathioprine)
  • IVIG/Plasmapheresis
  • Surgery - thymectomy
• Myasthenic crisis = acute respiratory failure - FVC <1L, negative inspiratory force (NIF) ≤20cm H2O, need mechanical ventilatory support
  
  • Accessory muscle use indicates sign inspiratory muscle weakness
  • Weak cough indicates sign expiratory muscle weakness
  • ABG often shows hypercapnia before hypoxia
  • Low threshold for endotracheal intubation (rapid deterioration of bulbar & resp muscles)
  • Mx: intubation + mechanical ventilation (& Mx above)

Lambert-Eaton Myasthenic Syndrome (LEMS)

• Def: rare AI disorder of NMJ
  
  • Pre-synaptic membrane Ab to voltage-gated Ca-channel receptors
  • 40% occur as paraneoplastic disorder assoc w/ SCLC
• Presentation:
  
  • Limb weakness - proximal legs –> proximal arms e.g. waddling gait
    
    • STRONGER WITH USE (vs MG get’s weaker with use)
  • Hyporeflexia, NO eye involvement (compared to MG)
  • Autonomic disturbance - dry mouth (& orthostatic hypotension, sweating, GI & urinary problems, visual blurring, sexual dysfunction)
  • Associated with: small cell lung cancer (SCLC)
• Ix:
  
  • Nerve conduction studies, EMG, serial PFTs
  • Ab testing (Voltage-gated Ca-channels & AChR-abs)
  • CT chest (SCLC)
• Mx: MDT support
  
  • Tx underlying cause, Amifampridine
  • IVIg/plasma exchange
  • Supportive care

Question 34

Hammertoes can be seen in what condition? Presentation? What do I need to check for to exclude DDx? DDx? Types? Ix? Mx?

Answer 34

Hammertoes - bilateral, symmetrical, distal wasting of small muscles of feet

• Advanced = dorsal guttering from distal wasting, wasting of extensor digitorum brevis at inferior border of lateral malleolus
• Similar can be seen in the hands = wasting of first dorsal interosseus

Sign of Charcot-Marie-Tooth disease aka hereditary motor & sensory neuropathy (HMSN)/peroneal muscular atrophy (PMA)

• Hx ankle sprains & scoliosis
• Motor & sensory losses (sensory milder) = classic peripheral neuropathy
  
  • LMN pattern of weakness:
    
    • Motor loss in anterolateral compartments of legs (ankle dorsiflexion & toe extension)
    • Absent reflexes (plantar reflexes show no response)
  • Sensory loss in glove & stocking distribution bilaterally
• Pes cavus ± palpable common peroneal nerve, thickened nerves @medial malleolus
• High stepping (foot drop) & ataxic gait
  
  • Test for foot drop = heel walking

What do I need to check for? NO scars over fibula (would indicate peroneal nerve damage from trauma e.g. car accident)

DDx:

• Common peroneal nerve palsy (inversion of foot normal)
• Sensory peripheral neuropathy: B12-def (SACD), Alcohol, DM, Hypothyroid (vitiligo?), HIV, drugs
• Motor peripheral neuropathy: lead poisoning

Types:

• Type 1 - demyelination, AD
• Type 2 - axonal, AD/AR
• Type 3 - demyelination, AR & presents as infant

Ix: full functional assessment, FHx, nerve conduction studies, genetic testing

Mx:

• Physio, walking aids with ankle & foot supports (e.g. foot splint)

Question 35

Wasting of hand muscles - distinguishing different nerves?

Answer 35

Hand muscle wasting - dorsal guttering = first to be affected in ulnar lesions

• First dorsal interosseous (next to thumb) = ulnar nerve
• Abductor policies brevis (thenar eminence) = median nerve
• Weakness of both - suspect T1 radiculopathy
• NOTE: ulnar nerve innervates most of the intrinsic muscles of hand except median nerve serves LOAF: 2 radial Lumbricals, Opponenes pollicis, Abductor pollicis brevis & Flexor pollicis brevis

Ulnar nerve palsy = claw hand @rest (4th & 5th fingers in extension at MCP, flexion at PIP/DIP)

• Commonest site of lesion = elbow (arthritis @wrist & elbow)
• Froment’s sign (weak adductor pollicis brevis –> thumb flexion) = +ve if thumb arches to hold paper = ulnar nerve palsy
• Ulnar paradox - higher lesion causes lesser deformity as lower lesions spares flexor digitorum profundus (causes flexion at DIP)

Median nerve palsy = sign of benediction on asking to close hand (thumb, index finger can’t close, middle finger can close partially)

• Look for sensation over thenar eminence –> if lost can’t be carpal tunnel syndrome (still median nerve palsy but arises proximally to carpal tunnel)
• Bilateral carpal tunnel syndrome causes: Acromegaly, Amyloid (periorbital purpura after sneezing), DM, Hypothyroid, pregnancy

Question 36

Muscle weakness causes by location?

Answer 36

Brain: stroke, SOL, MS

Spinal cord: MS, trauma, disc herniation/spinal stenosis, spinal cord infarct, syringomyelia

• MS - weakness & paraesthesia based on UMN demyelination, disseminated in time & space
  
  • Optic neuritis, periorbital pain, RAPD, INO (damage to medial longitudinal fasciculus)
  • Ataxia, vertigo, chr constipation, blaadder dysfunct
  • Lhermitte’s sign - electric shock down back on neck flexion
  • Unhthoff’s phenomenon - worsening of Sx with increased body temp e.g. exercise, hot shower
  • Ix: MRI (brain & spinal cord) + LP (oligoclonal bands), nerve conduction study (evoked potential)
  • Mx: methypred for flare, INF-b long-term
• Trauma - extremity weakness wo/ cortical signs/facial weakness e.g. hemisection of spinal cord (Brown-Sequard syndrome) - below level of lesion:
  
  • Ipsilateral hemiparesis & loss of vibration/proprioception
  • Contralateral loss of pain & temperature
  • At level of lesion - loss of sensation + flaccid paralysis of muscles supplied by this spinal cord segment
• Herniated disc/spinal stenosis - weakness at level of lesion & lower extremities + bladder/bowel dysfunction + sciatica
• Spinal cord infarct - occlusion of anterior spinal artery (complication of aortic surgery)
  
  • Affects anterior 2/3 spinal cord in affected segment
    
    • Sudden-onset bilateral flaccid paralysis –> developing into spastic paralysis after several days
    • Loss of pain & temp
    • Light-touch, vibration & proprioception-sense spared (dorsal columns not involved)
• Syringomyelia - developmental disorder
  
  • Syrinx (cavity) grows from centre of spinal cord & spreads outwards
  • Normally affects cervical cord but can extend into brainstem
  • Early - bilateral loss of pain & temp in cape-like distribution affecting neck, shoulders, upper arms
  • Late - as syrinx expands anterior horn cells affected –> bilateral flaccid paralysis

Anterior horn (motor neurone lesions): MND, poliomyelitis

• Poliomyelitis - enterovirus infection attacking anterior horn cells
  
  • 1-2wks prodrome (fever, headache, N&V)
  • Asymmetrical weakness + can develop years after inf (post-polio syndrome) + can take place after taking live-attenuated polio vaccine
• MND
  
  • Mixed UMN/LMN presentation
  • Ix (exclude other causes): EMG/NCS, MRI - whole spine
  • Mx: no cure - MDT approach (SALT (swallowing), physio & OT)
  • Sx-control:
    
    • Quinine - muscle cramp
    • Anticholinergics e.g. hyoscine patches - drooling
  • Prognostic:
    
    • Riluzole - glutamate antagonist (extend life expectancy by 3-5 months)
    • NIV - if respiratory muscles no longer functioning

Neuropathy: diabetic neuropathy

• Polyneuropathy (multiple nerves): DANG My THeRAPIST
  
  • Diabetic neuropathy (most common, T1/2)
    
    • Sensory - glove & stocking loss of sensation/paraesthesia
    • Motor - same distribution as above + CN palsies (3rd - pupil-sparing)
    • Autonomic - orthostatic hypotension, constipation, erectile dysfunction
  • Alcoholic neuropathy (2nd most common)
  • Nutritional (B1/6/12 def)
  • GBS (AIDP - acute inflam demyelin polyneuropathy)
    
    • AI demyelination of peripheral nerves
    • 2-4wks post-inf e.g. diarrhoea with C. jejuni
    • Ascending weakness in distal lower extremities over hrs/days (worst after 4wks)
    • Flaccid paralysis with reduced/absent deep tendon reflexes
      
      • Can involve diaphragm –> resp failure
      • Bilateral facial nerve palsy
      • Difficulty swallowing –> aspiration
    • Autonomic dysfunction - sweating, orthostatic hypotension, urinary retention
    • NOTE: sensory Sx rare
    • Ix:
      
      • LP (high protein, normal WCC)
      • NCS & EMG (reduced conduction velocity)
      • Serum abs (anti-glycolipid abs)
    • Mx:
      
      • Monitor FVC <1L, NIF <20cm H2O –> intubate + mechanical ventilation
      • Monitor BP –> IV fluids for hypo, Labetalol for hyper
      • IVIG, plasma exchange
  • M(y)-edications (colchicine, cisplatin, isoniazid –> niacin def)
  • Toxins (lead)
  • Hereditary - HMSN (CMT)
    
    • Progressive hereditary (AD) motor & sensory neuropathy (HMSN)
    • Distal back & lower extremity weakness:
      
      • Foot drop (damage to common peroneal nerve)
      • High-arch foot (pes cavus) - does not flatten with weight-bearing
      • Scoliosis
    • ± pain & sensory loss (can lead to foot ulcers)
    • Ix: nerve conduction study + EMG, genetic testing (electrophoresis/FISH)
    • Mx: physio, walking aids, foot & heel-support
  • Renal failure (uraemic nephropathy)
  • Amyloidosis
  • Porphyrias
  • Inf (HIV, syphilis)
  • Systemic (hypothyroidism)
  • Tumours (multiple myeloma)
• Mononeuropathy (one nerve):
  
  • Facial nerve palsy - not forehead-sparing, crying/sensitive to noise/abnormal taste (ant 2/3 tongue)
    
    • Idiopathic = Bell’s palsy
    • Secondary:
      
      • Lyme disease
      • Ramsay-Hunt syndrome - HZV reactivation in the geniculate ganglion, causes painful eruption in auditory canal
      • Tumours - acoustic neuroma, parotid
      • Bilateral palsy - Sarcoidosis, GBS
    • Tx: treat cause or if Bell’s palsy –> pred within 72hrs Sx onset + eye protection
  • Carpal tunnel syndrome - entrapment of median nerve in flexor retinaculum
    
    • Repetitive use of wrist –> numbness & tingling in lateral 3 fingers (& 1/2 4th finger) –> weakness of thenar muscles
    • Tinel’s sign - tap nerve at wrist
    • Phalen’s sign - reverse prayer sign for 60s
    • Ix: EMG, wrist USS, MRI wrist (imaging to detect SOL e.g. ganglion cyst)
    • Tx: immobiliser wrist (splint), CS injection, carpal tunnel release

Neuromuscular junction: MG/LEMS

• Myasthenia gravis (MG) - AI condition where Abs attach to NMJ post-synaptic nicotinic AChR in skeletal muscle
  
  • FATIGUABILITY with use
  • Initial - oculobulbar weakness (diplopia, ptosis, dysphagia, nasal voice)
  • Chr:
    
    • Asymmetrical proximal limb muscle weakness
    • Resp muscle failure
  • Assoc w/ thymic hyperplasia/thymoma
  • NOTE: normal sensation, normal deep tendon & pupillary reflexes
  • Ix:
    
    • Serological testing: AChR, MUSK abs
    • Repetitive nerve stimulation (CMAPs decrease)
    • CT chest - thymoma
    • Monitoring with serial pul funct tests (FVC & negative inspiratory force) if suspect myasthenic crisis
  • Mx:
    
    • Acetylcholinesterase inhibitors (Pyridostigmine) + IS (azathioprine)
    • Surgery - thymectomy
  • Myasthenic crisis = acute respiratory failure - FVC <1L, negative inspiratory force (NIF) ≤20cm H2O
    
    • Often trigger - meds/inf
    • Accessory muscle use/weak cough = sign. exp muscle weakness
    • Mx: intubation + mechanical ventilation (& Mx above)
      
      • IVIG/Plasmapheresis
      • Stop pyridostigmine (increases secretions –> aspiration risk), stop trigger (meds)
  • Cholinergic crisis - same presentation as above (resp muscle weakness) BUT cause = excess pyridostigmine –> overstimulation of AChR –> eventually stop working
    
    • Pyridostigmine also binds to nicotinic receptors –> cholinergic Sx - SLUDGE (Salivation, Lacrimation, Urination, Diarrhoea, GI cramps, Emesis)
    • Mx: intubation + mechanical ventilation
      
      • Atropine (anti-muscarinic) for Sx but does not address resp weakness
      • Reduce dose of pyridostigmine
• Lambert-Eaton myasthenic syndrome (LEMS) - AI condition where Abs target pre-synaptic voltage-gated Ca channels –> reduces release of ACh from presynaptic vesicles
  
  • Proximal muscle weakness - IMPROVES with use
  • Reflexes reduced/absent, ± autonomic Sx
  • Assoc w/ SCLC, Hodgkin’s lymphoma
  • Ix:
    
    • NCS, repetitive nerve stimulation (CMAPs increase)
    • Serological testing: VGCC abs
    • CT chest (SCLC)
  • Mx: Tx underlying cause, Amifampridine
    
    • IVIg/plasma exchange
    • Supportive care incl. intubation + mech ventilation (if resp compromise)

Myopathy: dermatomyositis

• Inflammatory: proximal muscle weakness & pain
  
  • Dermatomyositis - skin rash (heliotropic rash & Gottron’s papules)
  • Polymyositis
  • Assoc: ILD - in 10% patients
  • Ix: CK, ab panel (anti-Jo-1, ANA)
    
    • EMG, muscle MRI + muscle biopsy
  • Mx:
    
    • Induction: CS (PO/IV) ± IVIg
    • Maintenance: IS (methotrexate/azathioprine) ± IVIg
• Inherited:
  
  • X-linked - Duchenne’s & Becker’s muscular dystrophy
  • AD - Myotonic dystrophy
    
    • Myopathic facies (facial wasting) + frontal balding
    • Distal wasting & weakness + loss of ankle jerk
    • Assoc: cataracts, dysphagia, cardiac, DM, hypogonadism
    • Exam - failure of immediate relaxation after voluntary contraction
      
      • Percussion myotonia - thumb contracts tapping thenar eminence
      • Slow releasing grip on shaking hands
    • Ix: CK, genetic testing, EMG ‘dive-bomber’ potentials, muscle biopsy
    • Mx: MDT approach
      
      • Phenytoin for myotonia, weakness has no Tx
      • Genetic counselling - trinucleotide repeat -severity/earlier with each generation
      • Avoid statins (can cause myopathy)
• Endocrine:
  
  • Hypothyroidism - proximal muscle weakness & pain, deep tendon reflexes decreased, myoedema (swelling on percussion)
  • Also possible in Addison’s Cushing’s, Vit D def
• Meds - statins (proximal muscle weakness & pain), glucocorticoids (muscle weakness)
• Ix: serum CK, TSH lvls, EMG

Question 37

Idiopathic inflammatory myopathies (IIMs) - RFs? Presentation by type? Ix? Mx?

Answer 37

RFs:

• Exposure to high-intensity global UV radiation
• Treatment w/ lipid-lowering agents, D-penicillamine (Tx for RA)
• HIV, prev inf/vaccine

Presentation:

• Overall: insidious/acute symmetrical muscle weakness of proximal arm & leg –> difficulty getting out of chair/climbing stairs
• Dermatomyositis - acute, proximal muscle weakness + rash:
  
  • Heliotropic rash (purple discolouration of upper-eyelids)
  • Gottron’s papules (erythema over knuckles)
• Polymyositis - subacute, proximal muscle weakness, no rash
• Inclusion body myositis (IBM) - slowly, proximal & distal muscle weakness + muscle atrophy (quadriceps, distal wrist & finger flexor)
• Assoc:
  
  • ILD - in 10% patients with dermatomyositis/polymyositis
  • Malignancy (ovarian, pancreatic, NH lymphoma, lung, bladder)
  • AI disease

Ix:

• Bloods: CK, ANA/myositis ab panel (anti-Jo-1)
• Imaging: MRI of involved muscle, electromyogram (EMG), muscle biopsy

Mx:

• Induction: CS (PO/IV) ± IVIg
• Maintenance: IS (methotrexate/azathioprine) ± IVIg

Question 38

Proximal muscle weakness causes?

Answer 38

CONGENITAL MIND

• CONGENITAL - mitochondrial
• Metabolic - Cushing’s, hypothyroidism
• Inflammatory - dermato/poly/inclusion body myositis
• Neuromuscular - MG/LEMS
• Dystrophy - Becker

Question 39

UMN pattern of weakness - causes?

Answer 39

Bilateral = 3Ms

• MS
• MND (normal sensation)
• Myelopathy (sensory level) - SOL, cervical myelopathy, disc prolapse, transverse myelitis, syringomyelia

Unilateral:

• Intracranial - CVA, SOL, MS
• Brainstem - MS
• Spinal cord - trauma, SOL, haemorrhage

Question 40

Mononeuritis multiplex causes?

Answer 40

Vasculitis - GPA, EGPA, microscopic polyangiitis, polyarteritis nodosa

Rheum - RA, SLE, Sjogren’s, Sarcoidosis

Question 41

Causes of absent ankle jerk reflex AND extensor plantar response?

Answer 41

MND

B12 - SCDC (subacute combined degeneration of the spinal cord)

Friedrich’s ataxia (cause of cerebellar syndrome)

Syphilitic tabo-paresis