As mentioned earlier, children with Rett syndrome seem to develop normally as infants, then regress or lose skills. Many persons with Rett syndrome also experience a period of stability.
Health care providers, relying on consensus criteria, view the onset of symptoms in four stages:
Early Onset Phase—Development stalls or stops. Sometimes, the slowing or stopping is so subtle that parents and health care providers don’t notice it at first.
Rapid Destructive Phase—The child loses skills (regresses) quickly. Purposeful hand movements and speech are usually the first skills lost. Breathing problems and stereotypic hand movements usually also start during this stage.
Plateau Phase—Regression slows, and other problems may seem to lessen or improve. Seizures and movement problems are common in the stage. Most people with Rett syndrome spend most of their lives in Stage 3.
Late Motor Deterioration Phase—Individuals with Rett syndrome may become stiff or lose muscle tone; some become immobile. Scoliosis may be severe and require bracing or surgery. Stereotypic hand movements and breathing problems seem to lessen.