Breathing impairment in Rett syndrome.

Four patients with Rett syndrome had prominent abnormalities of breathing during active wakefulness, characterized by prolonged apnea intermixed with irregular and frequent respiratory movements. The apneic periods were associated with severe drops in O2 saturation, which assumed a periodic pattern. Respiration was regular during sleep and quiet wakefulness. These respiratory patterns seem characteristic of Rett syndrome and are probably related to impairment of the behavioral control system of respiration. These severe hypoxic episodes could contribute to permanent neurologic damage and secondary neurochemical changes.