Clinical EEG findings in mania.

Clinical EEG findings from 202 hospitalized manic patients repeated during 131 recurrences of mania were described. Results were considered in the light of current issues in the literature including the incidence of EEG abnormalities and minor variations, relationships between EEG and family history, EEG lateralization and longitudinal course of illness. The majority of patients had normal EEGs or mild nonspecific deviations compatible with effects of psychoactive medications. More definitive EEG abnormalities were observed in 16-percent. Microsleep occurred in 19 percent and small sharp spikes were found in 17 percent of those who drowsed, with lower incidences of 14 and 6 positive bursts and 6 Hz spike-and-slow-waves. Significant relationships between moderate or severe EEG abnormalities and negative familial loading were identified. Lateralized EEG abnormalities appeared in 9 percent of cases, involving the left side significantly more often than the right. With one exception EEG recordings during subsequent episodes did not suggest structural brain changes. Clinical EEG studies are useful in discriminating between primary and secondary affective disorders. They are also sensitive to effects of lithium and other psychoactive medications. The significance of EEG variations including microsleep and other atypical features continues to be elusive. Issues relating to heritability, hemispheric dysfunction and longitudinal course of illness merit further investigation.