Neuropathy/myopathy Flashcards
Antibodies
a) Miller-Fisher
b) MMN with conduction block
c) Neuromyelitis optica
d) MG
e) LEMS
a) Anti- GQ1b
b) Anti- GM1
c) Anti- AQP-4
d) Anti- nAChR
e) Anti- voltage-gated presynaptic calcium channel
In patients with neuromuscular disease, what serial tests must be performed?
- Spirometry - FVC is particularly important
- may also do ABG
Scan to perform in:
a) LEMS
b) MG
c) GBS (if autonomic involvement)
a) CT thorax (SSLC)
b) CT thorax (thymoma)
c) ECG
Curative management of:
a) MG - acute, symptomatic, long-term
b) GBS - acute
a) - Acute/severe: IVIG or Plasmapheresis.
- Symptomatic: pyridostigmine.
- Long-term: DMARDs, or intermittent infusions of IVIG
b) IVIG or plasmapheresis
(note: steroids do NOT help recovery)
Supportive care for neuromuscular diseases (eg. MG, MND, GBS, muscular dystrophies)
- Airway and breathing - intubate and ventilate (NIV) if necessary
- Circulation - BP control (hypo - fluid bolus, hyper - labetalol/nitroprusside
- DVT prophylaxis, prevent pressure sores
- Pain management - gabapentin for neuropathic pain
- Rehabilitation - physio, SALT, mobilise
GBS: diagnosis
a) 2 clinical features required
b) Supporting clinical features
c) Investigations and findings
d) What syndrome may coexist?
e) What are the commonest causes of death in GBS?
f) Prognosis
a) Weakness and areflexia
b) - Onset over days to 4 weeks
- Recovery within weeks of progression stopping (if longer course, may be CIDP)
- Symmetrical, sensorimotor, CNs affected
- Autonomic dysfunction
- Preceding GI/resp infection (eg. campylobacter, EBV)
c) - U+Es (rule out differentials; may have SIADH)
- Antibody screen (eg. anti-GQ1b)
- LP: elevated CSF protein with no cell count elevation
- NCS: features of nerve conduction slowing or block
- Spirometry: low FVC predicts need for ITU admission and intubation/ventilation
- ECG: heart block, other arrhythmias
d) SIADH
e) - Respiratory failure
- Pulmonary embolism
- Pneumonia
f) ~ 75% recover fully
~ 20% have some persisting disability
~ 5% mortality
Peripheral neuropathy screen
a) Initial tests: FLUTE FUR
b) Others depending on the clinical scenario (go through VITAMIN C DEF)
a) FBC, Liver, U+E, Thyroid, ESR.
Folate (and B12), Urine (protein, glucose, ?toxicology, ?Bence Jones) Renal, Serology (coeliac, syphillis/HIV)
b) +/-Vasculitic screen, +/-EMG/NCS, +/-CSF study, +/-nerve biopsy
Differentiating Bell’s palsy from Ramsay-Hunt syndrome
RHS - pain, shingles rash
Myopathy (stair, chair and hair) causes:
a) Inherited
b) Inflammatory
c) Infective
d) Metabolic
e) Toxic
f) Drug-induced
a) Dystrophies, mitochondrial disease, glycogen storage
b) Poly/dermatomyositis, IBM, SLE, vasculitis;
PMR and RA (more pain than weakness)
c) HIV, toxoplasmosis, Coxsackie viruses, influenza, Lyme disease
d) Hyper/hypothyroidism, Cushing’s, diabetes, hypo/hyperparathyroidism, electrolyte disturbances (hypercalcaemia, hypokalaemia)
e) Alcoholic myopathy with myoglobinuria, paraneoplastic myopathy, protein malnutrition
f) Steroids, statins, zidovudine, clofibrate, colcichine
Two clinical syndromes where signs appear before symptoms
Myelopathy
Peripheral neuropathy
3rd nerve palsy:
a) What is the earliest sign in raised ICP? Why?
b) What is it compressed against?
c) Classical cause of pupil-sparing 3rd nerve palsy?
a) Fixed, dilated pupil. PSNS fibres on outside of the nerve
b) Apex of petrous part of temporal bone
c) Diabetes, other microvascular;
- Motor fibres are more central in the nerve axon - affected more by vascular injury (vs. compression of outer PSNS fibres)
Brain vs. spinal lesion:
- differentiating rules of thumb (pain, weakness, etc.)
Brain - headache, visual field defect, contralateral weakness
Spine - back pain, radiating leg pain, bilateral weakness
Spinal nerve roots: dermatome, myotome, +/- reflex
a) C5/C6
b) C7
c) C8/T1
d) L5
e) S1
a) Reg badge/thumb, shoulder abduction/elbow flexion, pronator/biceps reflex
b) Middle finger, elbow extension, triceps reflex
c) Medial hand/forearm, finger flexion/abduction
d) Big toe and dorsum, dorsiflexion
e) Little toe and sole, plantarflexion, calcaneal reflex
Three reasons to refer to neurosurgeon in context of back pain
- CES
- Progressive or severe neurological deficits
- Failure of conservative/medical management
Abnormal posturing:
a) DeCorticate - Explain. GCS motor score? Lesion site?
b) DecerEbrate - Explain. GCS motor score? Site?
a) Flexion towards Cord (C-shaped):
- lesion in Cortex or C-spine
- GCS motor score = 3
b) Extension
- Lesion in midbrain/pons (brainstem - more severe)
- GCS motor score = 2
Radiculopathies.
a) Differentiating between L5 and common peroneal nerve palsy
b) A C6/C7 disc would cause what root lesion?
c) Patellar reflex - tests what roots?
a) L5 - more severe (weak foot inversion and hip abduction)
b) C7
c) L2 - L4
3 gold standard tests for a myopathy
- 1 extra if dystrophy suspected
CK, EMG, muscle biopsy
Genetic testing
Causes of proximal myopathy.
Drugs eg steroids, statins Low vitamin D Cushings/ hypothyroid Alcohol Other?
Myasthenia gravis (MG).
a) Clinical features (symptoms, and signs o/e)
b) Examination findings
c) Initial investigations
d) Management
e) Main differential and management
f) Myasthenic crisis - clinical features, criteria and management
a) - Ocular symptoms: ptosis, diplopia
- Bulbar/facial muscles: dysarthria, facial droop, dysphagia
- Proximal myopathy
- Fatiguability - symptoms worse at end of day
b) Ice test.
- Crushed ice applied to eye for 3 minutes leads to improvement of ptosis in 90% patients
Fatiguability.
- Focus on finger above forehead level (cannot sustain for long due to extraocular muscle weakness)
- Count up to 50 (voice gets quieter)
Neurological.
- NO wasting, fasciculations or sensory loss; reflexes and tone are normal
c) - Bedside: FVC and negative inspiratory force
- Autoantibody screen: ACh-R (+ MuSK if ACh-R negative)
- Nerve conduction studies (normal)
- CT thorax (Thymoma)
- Edrophonium (Tensilon) test:
IV administration of short-acting cholinesterase inhibitor leads to transient improvement in symptoms; rarely done now due to risk of life-threatening bradycardia
d) Symptomatic:
- cholinesterase inhibitor (pyridostigmine)
Immune suppression:
- steroid, azathioprine
- plasmapheresis / IVIg
- Thymectomy
e) LEMS: usually associated with SCLC, treat the cause
f) Clinical features:
- Increasing SOB and use of accessory muscles (inspiratory weakness)
- Weak cough (expiratory weakness)
- ABG - hypercapnia (T2RF)
Criteria:
- FVC < 1 L, or
- negative inspiratory force (NIF) < 20 cm H2O
Management:
- Intubation and ventilation
Syringomyelia
a) What is it?
b) Causes
c) Typical presentation
d) If extending into brainstem - known as…?
e) What are Chiari malformations 1 and 2?
a) Tubular cyst (syrinx) within the central spinal cord (usually cervical);
b) CSF blockage:
- Main cause = Chiari malformation (note: type 2 malformations are associated with spina bifida)
- Other causes - SOL, arachnoiditis (following trauma, infection, inflammation, etc.)
c) - Usually presents in 20s - 30s
- Pain and temperature loss in cape distribution (upper chest and arms) - may lead to Charcot joints
- Later, affects vibration, light touch and motor nerves (generally LMN signs as affecting the anterior horn cells)
- Rarely, causes autonomic disturbance (eg. Horner’s) and bladder/bowel dysfunction
d) Syringobulbia
- Can cause CN palsies
e) - Type 1: cerebellar tonsils extend into spinal canal
- Type 2: cerebellar tonsils + brainstem + IVth ventricle
f) - Peripheral neuropathy screen
- MRI - shows syrinx +/- associated cause (eg. Chiari malformation)
- Do NOT do an LP - risk of coning
g) - Physio
- Symptom management - eg. neuropathic analgesics
- Surgery is only curative treatment
Footdrop: causes
- Central: ?MS, ?CVA
- Nerve root: L4/L5 lesion? (sparing of eversion?)
- Peripheral nerve: common peroneal nerve lesion (causes:
- Muscle: tibialis anterior
CMT.
a) What is it?
b) Classic pnset and features
c) Signs o/e
d) Investigations and findings
e) Management
f) What other inherited disease causes progressive sensory ataxia, ascending weakness and cardiac arrhythmias/ cardiomyopathy?
a) A group of inherited (usually autosomal dominant) sensorimotor neuropathies - caused by production of abnormal myelin and subsequent demyelination
b) - Onset usually in childhood
- Muscle weakness and wasting; distal muscles first (intrinsic muscles of foot), then hands, legs, thighs, etc.
- Glove and stocking sensory neuropathy; often causes sensory ataxia and steppage gait
c) Inspection.
- Pes cavus, hammer toes, finger curling, contractures, scoliosis
- Wasting of distal muscles
- Inverted champagne bottle leg appearance
Neurological.
- Gait - steppage common-
- Glove and stocking sensory neuropathy
- Areflexia (LMN signs)
- Peripheral weakness
d) - Peripheral neuropathy screen (FLUTE FURS)
- NCS - slowing (demyelination), reduced amplitude (axonal loss), conduction block (severe demyelination)
- ?genetic testing and nerve biopsy if uncertain
e) No cure. Symptomatic MDT management:
- Pain - especially neuropathic analgesia
- PT - tendon stretches, muscle strengthening, etc.
- Orthotic devices - ankle-foot orthoses, splints, etc.
- Orthopaedic surgery for contractures, scoliosis, etc.
- Genetic counselling
f) Friedreich’s Ataxia
MS.
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