Clinical electroencephalographic variables suggesting extrapyramidal side effect risk.

Previous work has suggested that paroxysmal EEG dysrhythmias in psychiatric patients may be associated with an increased incidence of such diverse side effects as dyskinetic movements, extrapyramidal symptoms, iatrogenic seizures, and somatic/affective effects of oral contraceptives. The new analyses presented here extend these observations by using a large sample of 375 neuroleptically treated psychiatric patients with independently secured awake and asleep admission EEG studies. Those patients with minor paroxysmal EEG dysrhythmias are much more likely than normal EEG patients to receive anti-EPS medication during their treatment program. Furthermore, using data obtained from direct examination for EPS signs, neuroleptically treated patients with paroxysmal dysrhythmias as contrasted with those with normal EEGs, display statistically significant increases in EPS symptoms regardless of whether or not they are receiving concurrent anti-EPS medication at the time of examination. Prediction of side effect risk for the individual patient is not permitted by the strengths of associations reported for grouped data. However, it is suggested that future studies concerned with pharmacological side effect development in humans might benefit from stratification of samples by presence or absence of major and/or minor paroxysmal EEG patterns.