Do true remissions in myasthenia really exist? An electrophysiological study.

To answer the question whether true remissions in myasthenia gravis occurred, 20 patients were studied with a history of evident, typical myasthenia but in full clinical remission. Two control groups served as a comparison: one of 10 healthy volunteers and the other of 10 patients with generalized, presently active myasthenia. In 17 of the 20 patients in remission single-fibre EMG (SFEMG) abnormalities were found, indicating some subclinical disturbances of neuromuscular transmission (in 3 cases the results were overtly pathological, in 11 cases moderately pathological, and in 3 cases slightly pathological). The abnormalities found in the remission group were much less distinct than those in the group with clinically symptomatic myasthenia. A case illustrates these findings: a man in full remission following thymoma extirpation in whom the SFEMG revealed subclinical disturbances of the neuromuscular transmission. Three weeks later a full clinical relapse occurred. The results obtained suggest that in the majority of patients the remissions are only apparently complete. A pathological jitter in a patient in remission calls for special attention: the patient must be spared any immunological stimuli such as vaccination, injections of sera, infections etc.; no drugs can be given which may increase the neuromuscular block; an immunosuppressive course of treatment should be considered; prognosis should be reconsidered.