SLEEP-APNEA IN WELL-CONTROLLED MYASTHENIA-GRAVIS AND THE EFFECT OF THYMECTOMY

We conducted overnight polysomnographic sleep studies of 16 patients ( 5 men and 11 women) with clinically well-controlled myasthenia gravis (MG). The subtypes of MG were IIA (3 patients), IIB (11 patients), IV (1 patient) and V (1 patient). Twelve patients were found on polysomno graphy to have obstructive and/or central types of the sleep apnoeas ( SA). Their mean age was 42.4, SD 16.4 years, and the mean duration of MG was 7.4, SD 6.96 years. SA was not detected in 4 patients whose mea n age was 30.8, SD 10.71 years and who had manifested MG for a mean du ration of only 0.9, SD 0.65 years. Thus, patients with a longer durati on of MG tended to have more SA. In 9 of the 12 SA patients, polysomno graphic studies were repeated following thymectomy. SA had resolved in 6 patients, but persisted in 3. These findings suggest that SA is a p ossible clinical manifestiation of MG and that nocturnal dysfunction o f both peripheral and central colinergic systems may be involved.