The epidemiology of inflammatory polyradiculoneuropathy. A critical review of the distribution, characteristics and outcome of the disease. Plasmapheresis Study Group.

An outline of the principal reports dealing with the definition, distribution, course and treatment of the inflammatory polyradiculoneuropathies, including the Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP), is given. Current diagnostic criteria for GBS are reaffirmed while the diagnosis of CIDP lacks proper standardization. Then, the boundaries between the two disorders are ill-defined. While GBS is rare and homogeneously distributed across developed and developing countries, the prevalence rate of CIDP is unknown. Several antecedent events have been implicated in the pathogenesis of GBS; yet, except for the swine-flu vaccine, the relation between infectious or toxic agents and the occurrence of the disease is purely anecdotal. The only factors known to influence the outcome of GBS are age, severity of opening symptoms, abnormal electrophysiologic characteristics of peripheral nerve function, and plasmapheresis. However, responders and non-responders to current treatment are far from defined. Although similarities have been found between experimental allergic neuritis and experimental allergic encephalomyelitis, the degree of CNS impairment in patients with inflammatory polyradiculoneuropathies needs further refinement. To provide a tentative answer to some of the unsolved questions on inflammatory polyradiculoneuropathies, a multicenter cohort study on newly diagnosed patients submitted to standard clinical and laboratory evaluation, and given common therapeutic regimes, is awaited.