Therapeutic plasma exchange for acute inflammatory demyelinating syndromes of the central nervous system.

Idiopathic inflammatory demyelinating diseases (IIDDs) of the central nervous system, of which multiple sclerosis is the prototype, represent a family of monophasic, recurrent or progressive diseases with overlapping clinical and pathological manifestations. While most patients recover spontaneously or following a brief course of high-dose corticosteroids, occasional patients, particularly those with fulminant severe IIDDs, such as the Marburg variant, do not respond to corticosteroids and have severe, residual neurological deficits. While it is widely believed that IIDDs are mediated by T lymphocytes, as is experimental allergic encephelomyelitis, additional, possibly humoral, factors may be essential to generate the extensive demyelination seen in these conditions. Anecdotal reports over the past two decades have suggested that patients with acute, severe neurological deficits resulting from IIDDs, who fail to improve after high-dose intravenous corticosteroids, may benefit from plasma exchange. A randomized, sham-controlled, crossover study has recently been completed at the Mayo Clinic, which addresses these observations.