[A case of three-year-old boy with periodic apnea during waking and sleep, severe psychomotor retardation and hypotonia].

We presented a 3-year-old boy, a product of consanguineous parents, with periodic apnea during waking and sleep states, severe psychomotor retardation and hypotonia. According to polysomnographical recordings, he exhibited frequent central apneas which decreased in frequency and regularity in the stage REM. He showed abnormal background EEG, undifferentiated sleep stage and very short duration of stage REM. The initiation of breathing after apnea was often accompanied with generalized muscles contraction like a startle response. In the waking state the apnea induced generalized muscular hypotonicity and the decline of wakefulness. Arterial CO2 and O2 saturation was within normal limits. It was suggested that the malfunction of the brain stem responsible for the control of breathing, sleep-wakefulness cycle and determination of sleep stages was closely connected with the pathogenesis of abnormal breathing patterns.