Subacute sclerosing panencephalitis with unusual ocular movements: polygraphic studies.

A 5-year-old child with subacute sclerosing panencephalitis had continuous involuntary ocular movements while awake. At this stage of illness, stereotyped periodic EEG complexes over the two hemispheres were asynchronous. Polygraphic studies showed three diffrent types of ocular movements, each apparently related to the degree of phase shift between the EEG complexes from the two hemispheres. The involuntary ocular movements in one direction were always preceded by periodic EEG complexes from the contralateral hemisphere. Overnight polygraphic studies revealed early disruption of non-rapid eye movement (NREM) sleep patterns and preservation of rapid eye movement (REM) sleep, even in a late stage of illness.