[Paroxysmal dyskinesia during treatment with diphenylhydantoin]

Paroxystic-dyskinesias occurred in ten patients with encephalopathy and severe epilepsy associated with intellectual deficiences, during treatment of the epilepsy with diphenylhydantoin (DPH). The abnormal movements were usually paroxystic in nature and were mainly athetosic or choreic in nature affecting more particularly the facial region. None of the patients showed neurological signs during the attacks, which could have suggested an overdose of DPH, and the EEG showed no alterations. Blood levels of DPH were measured during the attacks in 9 of the patients and were within therapeutic limits in 6 cases. They were at toxic levels in the other 3 cases. All patients were receiving multiple therapy. The authors compare their findings with those in the published literature describing 46 such cases. Dyskinesias were usually observed in patients with encephalopaty. Of the 40 observations reported, blood levels of DPH were measured in 37 patients, and were found to be within normal therapeutic levels in 13 cases and at toxic levels in the other 24 patients. Clinical signs of an overdose were present in 26 cases. In all the cases reported by the authors, and in 28 cases described in published reports, the dyskinesias appeared when therapy was changed. Abnormal movements disappeared in 3 patients after an intravenous injection of diazepam. Experimental and biological arguments exist in favour of an action of DPH on the metabolism of cerebral mediators. The authors emphasize the need to investigate these dyskinetic manifestations which can be thought to be epileptic manifestations or signs of progressive encephalopathy.