Definition and Overview
Guillain-Barre syndrome (GBS) is an acute autoimmune polyneuropathy characterized by rapidly progressive, symmetrical, ascending muscle weakness that typically develops 2-4 weeks after a respiratory or gastrointestinal infection [1].
The annual incidence is 1-2 per 100,000, with a slight male predominance. It can occur at any age but shows bimodal peaks in young adults and the elderly [1]. GBS is the most common cause of acute flaccid paralysis worldwide since the eradication of polio.
Causes and Pathophysiology
Molecular mimicry is the central pathogenic mechanism. Structural similarity between microbial antigens and peripheral nerve gangliosides triggers cross-reactive autoimmune responses [2]. Campylobacter jejuni is the most commonly identified preceding pathogen (30%), followed by cytomegalovirus, Epstein-Barr virus, and Mycoplasma pneumoniae.
Autoantibodies attack myelin (demyelinating form, AIDP) or axonal membranes (axonal forms, AMAN/AMSAN). Anti-ganglioside antibodies (anti-GM1, anti-GD1a, anti-GQ1b) are detected in specific subtypes [2].
Classification
- AIDP (acute inflammatory demyelinating polyneuropathy): most common in Western countries (85-90%)
- AMAN (acute motor axonal neuropathy): common in Asia, associated with C. jejuni
- AMSAN (acute motor and sensory axonal neuropathy): severe axonal variant
- Miller Fisher syndrome: ophthalmoplegia, ataxia, areflexia triad; anti-GQ1b antibodies
Symptoms
Weakness typically begins in the legs and ascends to the arms, face, and respiratory muscles over days to weeks. Peak deficit usually occurs within 2-4 weeks [1].
Autonomic instability affects up to 70% of patients and includes tachycardia, bradycardia, blood pressure fluctuations, urinary retention, and ileus. Autonomic dysfunction is a major cause of mortality in the ICU setting [3].
Sensory symptoms include pain (particularly back and leg pain) and paresthesias. Cranial nerve involvement causes facial weakness and bulbar dysfunction.
Diagnosis
Cerebrospinal fluid (CSF) shows albuminocytologic dissociation (elevated protein with normal cell count), though this may be absent in the first week. Nerve conduction studies differentiate demyelinating from axonal subtypes [1].
Brighton criteria are used for diagnostic certainty. MRI may show gadolinium enhancement of nerve roots. Anti-ganglioside antibody testing supports subtype classification.
Treatment
Intravenous immunoglobulin (IVIG, 0.4 g/kg/day for 5 days) and plasmapheresis (5 exchanges over 2 weeks) are equally effective first-line treatments [4]. Treatment should begin within 2-4 weeks of symptom onset.
Respiratory function must be closely monitored; approximately 20-30% of patients require mechanical ventilation. Autonomic monitoring in ICU is essential for severe cases.
Early rehabilitation including physical and occupational therapy improves functional outcomes.
Prognosis
Approximately 80% of patients recover the ability to walk independently within 6 months. Complete recovery occurs in about 60% within 1 year. Mortality is 3-7%, primarily from autonomic complications and respiratory failure [4]. Poor prognostic factors include older age, preceding C. jejuni infection, rapid progression, and need for mechanical ventilation.