Ascending weakness

Question 1

Describe the aetiology and pathophysiology of Guillain-Barre syndrome.

Answer 1

• 2/3 preceded by GI or URT
• Thought to be due to a process called molecular mimicry
• B cells create antibodies against the antigens on the pathogen that caused the preceding infection
• These antibodies match proteins on the nerve cells
• They may then target proteins on the myelin sheath of the motor nerve cell or nerve axon

Question 2

What pathogens are commonly implicated in GBS?

Answer 2

• Campylobacter (25-50% of cases)
• CMV
• EBV
• Haemophilus influenza
• Mycoplasma pneumoniae

Question 3

What are the clinical features of GBS?

Answer 3

• Progressive, ascending weakness +/- paraesthesia
• Severe back pain can occur
• Cranial nerve involvement, involving the facial and bulbar muscles
• Tendon reflexes gradually lost
• Respiratory muscle weakness requiring ventilation
• Autonomic involvement (cardiac arrhythmia, hypertension, hypotension)

Question 4

List the regional variants of GBS.

Answer 4

• Miller-Fisher syndrome
• Pharyngo-cervico-brachial pattern
• Acute oropharyngeal palsy (similar to diphtheria)
• Flaccid paraparesis variant
• Pure sensory variant
• Acute pandysautonomia

Question 5

What are the features of Miller-Fisher syndrome?

Answer 5

• Ophthalmoplegia
• Sensory ataxia
• Areflexia

Question 6

Which antibody is associated with Miller Fisher syndrome?

Answer 6

GQ1b

Question 7

What investigations should be carried out for GBS?

Answer 7

• Serology
• Immunoglobulin levels
• LP for CSF examination
• Nerve conduction studies
• EMG

Question 8

What are typical CSF findings in GBS?

Answer 8

Albuminocytologic dissociation: high protein + normal WCC

Question 9

What are typical nerve conduction study findings in GBS?

Answer 9

• Initially may be normal
• Delayed distal motor latencies
• Later in disease course will should widespread slowing in sensory and motor nerve
• Decreased motor nerve condution velocity
• Increased F wave latency

Question 10

What is the treatment of choice for GBS?

Answer 10

IVIG 0.4g/kg/day for 5 days

PLEX can also be given (IVIG and PLEX have no additional benefits)

• Corticosteroids do not help

Question 11

What factors are associated with worse outcomes in GBS?

Answer 11

• Older age
• Preceding diarrhoeal illness
• Severity and rapid rate of deterioration
• Electrically unexcitable nerves and muscle wasting
• Need for mechanical ventilation and ITU support