EEG and respiration in Rett syndrome.

Forty-four EEGs of 16 girls with Rett syndrome are reviewed. The ages of the girls at the time of the EEG examination ranged from 8 months to 20 years. The normal and abnormal EEGs were scattered among the ages. Eight girls showed a pseudoperiodic pattern, the short bursts of high-amplitude slow waves tending to be associated with apnoea and the lower-amplitude faster rhythms with normal breathing or with hyperventilation. The mechanism of the abnormal breathing pattern, which was present solely in the waking state, is discussed. We suggest that the alternating apnoea and hyperventilation are a behaviourally determined breathing pattern, a pastime which is often pleasurable. The need to treat the idiosyncratic breathing is questionable.