Polygraphic recordings in subacute sclerosing panencephalitis. A study of the pathophysiology of the periodic EEG complexes.

Polygraphic whole night recordings were performed in 10 patients with SSPE. In most cases sleep states could not be classified according to the usual criteria, but two different states with differing EEG patterns were always seen. A significant correlation was obtained between EEG complexes and phase of the respiratory cycle in 8 out of 9 patients, irrespective of the sleep state. Slowing of heart rate for one R-R interval was observed to occur during the onset of the complex in 7 patients in both sleep states, and in 2 patients only in one state. Periodic occurrence of complexes was stable throughout the night. This stability seems to be maintained by a mechanism regulating the duration of an interval according to the duration of the preceding one. It is suggested that diffuse involvement of subcortical structures rather than a localized change is responsible for the generation of the EEG complexes in SSPE.