The communication skills, oral-motor function and respiration patterns of 20 girls with Rett syndrome were studied at the Crippled Childrens Division, Oregon Health Sciences University, Portland, OR. All patients showed a regression in speech and language function by the onset of Stage II Rett syndrome. Oral-motor tone of the cheeks, lips and tongue changed from hypotonicity in Stages I and III to hypertonicity in Stage IV in a direct relationship with postural tone. Three girls in Stage IV showed fasciculations of the tongue. Most girls in Stages III and IV showed tongue deviation to the left at rest. 
COMMENT. This study documents the differences in oral-motor function in the various stages of Rett syndrome. The same author has described abnormal chewing associated with tongue thrusting and involuntary undulating tongue movements in 11 of 13 girls with Rett syndrome . Feeding problems included difficulty in chewing and swallowing, choking and regurgitation.
An EEG study in 52 girls with Rett syndrome  showed that seizure discharges occurred in 43 patients and were not related to the onset of clinical seizures. They consisted of sharp waves or spikes, focal or multifocal, mainly limited to the central and midtemporal regions of one or both hemispheres. Light sleep enhanced the presence of discharges. Periodical hyperventilation seen frequently during EEG recordings in this study was not associated with any consistent EEG change. Sleep spindles were conspicuously absent in all records. The authors find the EEG features helpful in confirmation of the diagnosis of Rett syndrome in the appropriate clinical setting.