Sleep apnea and cognitive dysfunction in myasthenia gravis.

19 middle-aged patients with myasthenia gravis (MG) and 10 age, sex and education-matched controls underwent overnight polysomnography and neuropsychological testing, in order to test the hypothesis of whether cognitive dysfunction and REM-sleep disturbance in MG are related to nocturnal respiratory problems or caused by CNS-involvement. We observed in 60% of the myasthenics central type of sleep apneas and hypopneas with resulting oxygen desaturations occurring during REM-sleep, but no decrease of REM sleep. In neuropsychological testing, we found normal vigilance performance but decreased memory function in the myasthenics. In comparison with patients without sleep apnea, myasthenics with sleep apneas had an impaired memory function.