Once the efficacy of plasmapheresis in treating myasthenia gravis was demonstrated, evaluation was begun of its value in other diseases, including those without known cause and for which there is no effective treatment. Among these is amyotrophic lateral sclerosis. Unlike myasthenia, in amyotrophic lateral sclerosis there are no known antibodies to be removed; circulating factors have been reported, but with controversy and uncertain significance. Among the evidence cited are deposits of immune complexes in renal glomeruli and excessive serum complement consumption [41, toxic effects of serum on cultured neurons [5], and neuroelectric blocking activity in serum from patients with motor neuron disease. To help establish whether circulating factors play a role in amyotrophic lateral sclerosis, we evaluated the use of plasmapheresis in 10 patients with motor neuron disease.

All patients had unequivocal evidence of lower motor neuron disease (wasting and fasciculation), and 9 also had upper motor neuron signs. None had atypical features either clinically or in laboratory studies including electromyography and cerebrospinal fluid examination. Seven patients were unable to walk. Four of them ultimately died, none for reasons related to plasmapheresis; autopsy was obtained in 2 cases and confirmed the diagnosis in both. To evaluate the effects of treatment, we used a modification of the Norris scoring system [2]. For plasmapheresis we used a Haemonetics Model 30 intermittent cell separator. Exchanges were carried out by venipuncture using an arm vein or femoral vein. In each