Characterisation of breathing and associated central autonomic dysfunctionin the Rett disorder

Aim-To investigate breathing rhythm and brain stem autonomic control in pat ients with Rett disorder. Setting-Two university teaching hospitals in the United Kingdom and the Ret t Centre, Sweden. Patients-56 female patients with Rett disorder, aged 2-35 years; 11 control s aged 5-28 years. Design-One hour recordings of breathing movement, blood pressure, ECG R-R i nterval, heart rate, transcutaneous blood gases, cardiac vagal tone, and ca rdiac sensitivity to baroreflex measured on-line with synchronous EEG and v ideo. Breathing rhythms were analysed in 47 cases. Results-Respiratory rhythm was normal during sleep and abnormal in the waki ng state. Forced and apneustic breathing were prominent among 5-10 year old s, and Valsalva breathing in the over 18 year olds, who were also most like ly to breathe normally. Inadequate breathing peaked among 10-18 year olds. Inadequate and exaggerated breathing was associated with vacant spells. Res ting cardiac vagal tone and cardiac sensitivity to baroreflex were reduced. Conclusions-Labile respiratory rhythms and poor integrative inhibition in R ett disorder suggest brain immaturity. Linking this to an early monoaminerg ic defect suggests possible targets for the MECP2 gene in clinical interven tion. Exaggerated and inadequate autonomic responses may contribute to sudd en death.