Guillain Barre Syndrome
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Introduction
Guillain-Barre Syndrome, or GBS, is a heterogeneous set of acute, rapidly progressive polyradiculoneuropathies. It has three subtypes:
- acute inflammatory demyelinating polyneuropathy (90%)
- acute motor-sensory axonal neuropathy
- acute motor axonal neuropathy
Annual incidence is 1-2/100,000. An estimated 3500 cases of GBS are seen in North America annually.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis. To get students thinking.
Causes and Risk Factors
There is a bi-modal distribution, with peaks in young adulthood and elderly patients.
Events which can precede GBS:
viral infections
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bacterial infections
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vaccinations
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Molecular mimicry is an attractive suggestion for GBS, but it has been difficult to uncover the antigen.
C jejeuni lipooligosaccharide can result in anti-ganglioside titres.
Pathophysiology
Acute inflammatory demyelinating polyneuropathy is a focal inflammation and demyelnation of nerve roots and distal perihperal nerve fibres, resulting in conduction slowing or block.
Acute motor or motor-sensory axonal neuropathy is focal axonal degeration of ventral or ventral/dorsal roots.
Variable lymphocytic infiltration is typically seen around endoneurial vessels and throughout endoneurial space.
T cells can recruit macrophages which contribute to Schwann cell demyelination, either directly or through cytokine production.
Demyelination can occur anywhere in the PNS, but is most often clustered around spinal roots with significant edema.
Proximal demyelination can be associated with distal degeneration.
Often a break in the blood nerve barrier, and complement/immunoglobulin binding may create pores that induce calcium influx, activation of phospholipase A, and subsequent demyelination.
Can also have axonal degeneration without loss of myelin.
Deposition of circulating factor on the axons can cause acute conduction block.
Signs and Symptoms
- history
- physical exam
History
The dominant initial complaint is of weakness, often leading to paralysis. Weakness may begin in feet and ankles but often spreads to proximal arms and legs and, ominously, respiratory muscles.
paresthesias usually occur first may begin in the toes and ascend upwards, occasionally involving the face and trunk. Pain can also occur, usually deep and poorly localized.
Dysarthria and difficulty swallowing can occur.
Hearing, vision, and smell are not affected.
Motor
Motor weakness tends to begin in proximal muscles of the legs and ascends.
Loss of deep tendon reflexes (DTRs)
UMN findings may be present
Sensory
paresthesiae are usually distal and symmetric
objective sensory loss with vibration and proprioreception
Autonomic
blood pressure deregulation (hypertension; orthostatic hypotension)
cardiac arrhythmias
bladder dysfunction
Miller-Fisher variant
opthalmoplegia
ataxia
areflexia
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
CSF analysis: albuminocytological dissociation (increased protein with normal white cell count) seen in demyelination
- often absent in first few days, and absent in 10% of all GBS
Diagnostic Imaging
EMG/NCS can show conduction block, differential slowing, or focal slowing; (motor > sensory)
decreased F wave
EMG should be done 2-4 weeks after onset of symptoms to assess for axonal loss.
Differential Diagnosis
Treatments
Supportive Care
Admit all patients with suspected GBS, who risk rapid detioration.
Phrenic nerve involvement leads to respiratory failure in 30% of patients; monitor VC and intubate if <15ml/kg
Dysautonomia requires ICU management:
- paroxysmal hypertension: short-acting beta blockers
- orthostatic hypotension: isotonic fluid replacement
- cardiac arrhythmias: fluid replacement; transvenous pacing
Pain
ASA
antidepressants and anticonvulsants ineffective
Anti-immune therapy
IVIg
plasmapheresis within first week has no effect on mortality or relapse, but leads to more rapid improvement, less intensive care.
Consequences and Course
Progression can be fast, over a matter of hours, but can continue for up to 4 weeks
Half of patients reach maximum weakness after two weeks
A longer progression suggests a subacute or chronic inflammatory polyneuropathy
Typical course sees maximal symptoms at 2-3 weeks, and considerable resolution at 4-6 weeks.
Long term outcomes
75% recover without serious residual deficit, with maximal recovery by 18 months
7-15% have permament, substantial deficits (bilateral foot drop, intrinsic hand muscle weakness, sensory ataxia, dysesthesiae)
5% die (15-20% if in ICU)
Resources and References
Topic Development
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