RETT-SYNDROME - CHARACTERIZATION OF SEIZURES VERSUS NON-SEIZURES

Epileptic seizures are reported to occur frequently in Rett syndrome ( RS). We evaluated the hypothesis that many events classified as seizur es in RS represent other paroxysmal, non-epileptic events; thus, the o verall incidence of seizures in RS is overestimated. We conducted vide o/polygraphic/EEG monitoring sessions (8-120 h duration) in 82 RS fema les (ages 2-30 years). Fifty-five patients (67%) had a history of seiz ures and 43 (52%) were receiving anticonvulsants. All had abnormal EEG s, These abnormalities included epileptiform findings, the frequency o f which ranged from 60% of patients in clinical stage IV to 97% of pat ients in clinical stage III. During monitoring, electrographic seizure s were recorded in only 13 patients (16%) and included both partial an d generalized events. Clinical events correlating with EEG seizure dis charges were identified by parents during only 5 of these recordings. The parents of 23 (42%) of the 55 patients with a history of seizures identified events during monitoring that they felt were representative of the child's typical 'seizures', but which were not associated with EEG seizure discharges. These 'non-seizure' events included episodes of motor activity, such as twitching, jerking, head turning, falling f orward, and trembling, as well as episodes of staring, laughing, pupil dilatation, breath holding and hyperventilation. These studies confir m that the occurrence of epileptic seizures is overestimated in RS, an d further suggest that actual seizures may be under-recognized. Video/ EEG monitoring can provide definitive information regarding the need f or anticonvulsant therapy in RS. (C) 1998 Elsevier Science Ireland Ltd .