Polysomnographic and computerized electroencephalographic studies in myoclonic petit mal epilepsies

The study included 203 epileptic absences: 1. Simple; (30 cases); 2. Myoclonic petit mal absences (62 cases); 3. Amyotonic-akinetic absences (41 cases); 4. Temporal lobe absences (62 cases); 5. "Hybrid" absences in Lennox-Gastaud disease (13 children). This paper presents only the myoclonic petit mal absences (57 cases). Correlations of the clinical, EEG and polysomnographic data were found by several methods: a. The patients were video-monitored on an infrared closed-circuit TV screen: b. The Hjorth's NSD parameters were computed on a Siemens-Elema Mingograph; c. The EEG graphoelements were morphologically analyzed every second throughout the discharges, by means of an original technique; d. Computerized EEG mappings (CEM) were performed for various periods, also including the sequential ones, second by second, all along the epileptic discharges; e. 8 hours of continuous polysomnographic recordings. The peculiar electroclinical features of the five types of absences have been emphasized. Regarding the myoclonic petit mal absences, the discharges of polyspikes and waves manifested an evident increase in the number and duration within the LSWS stages and during the transition from the wakefulness state to sleep and from the LSWS to the wakefulness, and a transformation in slow polyspikes and waves complexes during the stages III and IV. The CEM were always asymmetrical during sleep and the maximal amplitudes were seen on the anterior and posterior temporal regions. In all the REM stages, the polyspikes and waves disappeared.