Guillain–Barré Syndrome - Classification

Classification

Six different subtypes of Guillain–Barré syndrome exist:

• Acute inflammatory demyelinating polyneuropathy (AIDP) is the most common form of GBS, and the term is often used synonymously with GBS. It is caused by an auto-immune response directed against Schwann cell membranes.
• Miller Fisher syndrome (MFS) is a rare variant of GBS. Accounting for approximately 5% of GBS cases, it manifests as a descending paralysis, proceeding in the reverse order of the more common form of GBS. It usually affects the eye muscles first and presents with the triad of ophthalmoplegia, ataxia, and areflexia. The ataxia predominantly affects the gait and trunk, with the limbs relatively spared. Anti-GQ1b antibodies are present in 90% of cases.
• Acute motor axonal neuropathy (AMAN), also known as Chinese paralytic syndrome, attacks motor nodes of Ranvier and is prevalent in China and Mexico. It is probably due to an auto-immune response directed against the axoplasm of peripheral nerves. The disease may be seasonal and recovery can be rapid. Anti-GD1a antibodies are present. Anti-GD3 antibodies are found more frequently in AMAN.
• Acute motor sensory axonal neuropathy (AMSAN) is similar to AMAN but also affects sensory nerves with severe axonal damage. Like AMAN, it is probably due to an auto-immune response directed against the axoplasm of peripheral nerves. Recovery is slow and often incomplete.
• Acute panautonomic neuropathy is the most rare variant of GBS, sometimes accompanied by encephalopathy. It is associated with a high mortality rate, owing to cardiovascular involvement, and associated dysrhythmias. Frequently occurring symptoms include impaired sweating, lack of tear formation, photophobia, dryness of nasal and oral mucosa, itching and peeling of skin, nausea, dysphagia, and constipation unrelieved by laxatives or alternating with diarrhea. Initial nonspecific symptoms of lethargy, fatigue, headache, and decreased initiative are followed by autonomic symptoms including orthostatic lightheadedness, blurring of vision, abdominal pain, diarrhea, dryness of eyes, and disturbed micturition. The most common symptoms at onset are related to orthostatic intolerance, as well as gastrointestinal and sudomotor dysfunction (Suarez et al. 1994). Parasympathetic impairment (abdominal pain, vomiting, constipation, ileus, urinary retention, dilated unreactive pupils; loss of accommodation) may also be observed.
• Bickerstaff's brainstem encephalitis (BBE) is a further variant of Guillain–Barré syndrome. It is characterized by acute onset of ophthalmoplegia, ataxia, disturbance of consciousness, hyperreflexia or Babinski's sign. The course of the disease can be monophasic or remitting-relapsing. Large, irregular hyperintense lesions located mainly in the brainstem, especially in the pons, midbrain and medulla, are described in the literature. Despite severe initial presentation, BBE usually has a good prognosis. Magnetic resonance imaging (MRI) plays a critical role in the diagnosis of BBE. A considerable number of BBE patients have associated axonal Guillain–Barré syndrome, indicative that the two disorders are closely related and form a continuous spectrum.