[The significance of rhythmic mid-temporal discharges (author's transl)]

Out of 50,000 EEG's those of 38 subjects contained rhythmic mid-temporal discharges (RMTD), corresponding to an incidence of 0,1%. The morphological features of RMTD are: 1. frequency: 5.5-6.5/sec 2. shape: monophasic and regular with occasionally interposed 12/sec. activity. 3. localisation: mid temporal, often spread to anterior, seldom posterior region. 4. occurence: bilateral, simultaneous, or alternating sides. They are closely linked to the drowsy state, occuring at the transition from A2 to B2 stage (IA2) and arising from a fairly desynchronized EEG. RMTD are commonly seen within REM periods, which are markedly fragmented with interspersed periods of drowsy patterns lasting 20-90 sec, during which the RMTD are seen. Occasionally they are strictly related to slow eye movements and periodic respiration. The RMTD are an individual feature, appearing in different persons with variing penetrance. Their occurence is favoured or inhibited to a certain degree by external circumstances. Slow and fast wave sleep in subjects with RMTD are disturbed. Both of them, especially the fast wave sleep are reduced in favour of markedly increased stages of drowsiness with RMTD, which sometimes last several minutes. In spite of such abnormal organisation of sleep the subjects feel recovered in the morning and sleep disturbances are not reported. RMTD could therefore be considered as "bioelectrical sleep disorder". We did not find any correlation between RMTD and clinical findings, in particular not with psychomotor or any other form of epilepsy.