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Flashcards in More neuropathies Deck (17):
1

Myasthenia gravis signs on examination

Inspection: thymectomy scar
Eyes: Bilateral ptosis, worse on sustained upwards gaze. Complex ophthalmoplegia.
Facial movements: myasthenia snarl on smiling (can't lift corners of mouth).
Voice: nasal, deterioration - ask patient to count to 50.
Limbs: fatiguability - repeatedly flap arm.

2

Completion of myasthenia gravis examination

Spirometry for respiratory muscle function

3

Investigations for myasthenia gravis

Antibodies: Anti-nAChR, Anti-mAChR
EMG: reduced response to titanic train of impulses
Tension test: improvement with edrophonium (anticholinesterase)
TFTs: Graves in 5%
CT mediastinum: thymoma in 10%

4

Conditions associated with myasthenia gravis

Patient <50yo, female:
AI disease - DM, RhA, Graves, SLE
Patient >50yo, male:
Thymoma

5

Acute management of myasthenia gravis

Plasmapheresis or IVIg
Monitor FVC: consider ventilation

6

Chronic management of myasthenia gravis

Pyridostigmine
Immunosuppression: steroids and azathioprine
Thymectomy: benefit even if no thymoma

7

Pathophysiology of Lambert-Eaton myasthenia syndrome

Antibodies against voltage-gated calcium channels
Often paraneoplastic e.g. SCLC

8

Symptoms in Lambert-Eaton myasthenia syndrome

Lower limb girdle weakness
Weakness improves on repetitive testing

9

Investigation to differentiate LEMS from MG

Tensilon test (edrophonium) will improve muscle strength in MG but not in LEMS

10

Differential for bilateral ptosis

Myasthenia gravis
Myotonic dystrophy
Congenital
Senile
Bilateral Horner's (rare)

11

What is Miller-Fisher subtype of Guillan-Barre Syndrome

More pronounced ophthalmoplegia + ataxia + areflexia

12

Pathophysiology of Guillan Barre Syndrome

Antibody cross-reactivity between microorganism and gangliosides (found on peripheral nerves)
There is also an axonal type: AMAN ("Chinese paralytic syndrome")

13

Common organisms causing Guillan Barre syndrome

Bacteria: Campylobacter jejuni, mycoplasma
Viruses: CMV, EBV

14

Features of Guillan Barre syndrome

Symmetrical ascending flaccid paralysis
Sensory disturbance: paraesthesia
Autoimmune neuropathy: labile BP

15

Investigations for Guillan Barre syndrome

Evidence of infection, e.g. stool MC+S
Anti-ganglioside antibodies
Lumbar puncture: very high CSF protein
Nerve conduction studies: demyelination

16

Management of Guillan Barre syndrome

1. Supportive: "AAAA"
ABCDE: ITU if FVC <1.5L
Analgesia: NSAIDs, gabapentin
Autonomic: may need inotropes, catheter
Antithrombotic: TEDS, LMWH
2. Immunosuppression: IVIg, plasma exchange
3. Physiotherapy (prevent flexion contractors)

17

Prognosis in Guillan-Barre syndrome

85% complete recovery
10% unable to walk unaided at 1 year
5% mortality