Age-related occurrence of signs and symptoms in the Rett syndrome.

The occurrence of signs and symptoms in the Rett syndrome (RS) was analyzed in a series of females born 1945-87 (median age 17 1/2 years) and fulfilling the diagnostic criteria for classic RS. For general information, data from 91 girls and women were used (group A), while the more detailed analyses were based on three age related subgroups: the youngest 20, born 1980-87 (group B); the 34 girls born 1970-79 (group C); and the oldest 37, born 1945-69 (group D). Data from group A indicated a developmental stagnation (stage I) at median age 11 (5-24) months and loss of ability to use acquired skills (stage II) at 19 (12-36) months. Group B displayed subtle prodromes in the first months of life, and later in infancy gross motor delay with insufficient equilibrium control. Development invariably came to a definite break at a crucial stage of maturation and was followed by a remarkable "awakening" and return of interest to act and interact (stage III). Loss of skills belonged to the triad contact/communication, hand use/skill, and babble/words. By age 2 1/2 years, apraxia and involuntary and stereotyped movements, were found in all. Seizures, hyperventilation and spells of screams and laughter were more frequent in group C (94%, 65% and 71%, respectively), and breathholding, bloating and drooling in group D (73%, 43% and 81%, respectively). Plantar flexion and abiotrophy of feet, as well as peroneal weakness and scoliosis, increased with age and was found in 89%, 86%, and 89%, respectively. The sequence of events described, emerged as subtle insufficiency and more or less abruptly turned into loss. Conversely to known progressive encephalopathies, the deterioration was followed by excess of activity, only years later to turn into restriction.