Different clinical manifestations of hyperammonemic encephalopathy.

Valproate is an effective anticonvulsant. Although it is usually well tolerated, it has been associated with many neurological, hematopoietic, hepatic, and digestive system side effects. Among these side effects, hyperammonemia without clinical or laboratory evidence of hepatotoxicity is rare and is an important clinical consideration. The aim of this article was to evaluate the reasons for the unexpected symptoms observed in seven patients with epilepsy patients during valproate treatment. We evaluated seven adult patients with localization-related epilepsy who presented with different acute or subacute neurological symptoms related to valproate-induced hyperammonemic encephalopathy. Four of the seven patients had acute onset of confusion, decline in cognitive abilities, and ataxia. Two had subacute clinical symptoms, and the other patient had symptoms similar to those of acute toxicity. These unusual clinical symptoms and similar cases had not been reported in the literature before. Serum ammonia levels were elevated in all seven patients. After discontinuation of valproate, complete clinical improvement was observed within 5-10 days. On the basis of our work, we suggest that the ammonia levels of a patient who has new neurological symptoms and has been taking valproate must be checked. Clinicians should be aware that these clinical symptoms may be related to valproate-induced hyperammonemic encephalopathy. The symptoms have been observed to resolve dramatically after withdrawal of the drug.

Surgery in temporal lobe epilepsy patients without cranial MRI lateralization.

High resolution MRI is very important in the evaluations of patients with intractable temporal lobe epilepsy in preoperative investigations. Morphologic abnormalities on cranial MRI usually indicate the epileptogenic focus. Intractable TLE patients who have normal cranial MRI or bilateral hippocampal atrophy may have a chance for surgery if a certain epileptogenic focus is determined. We evaluated the patients who were monitorized in Gazi University Medical Faculty Epilepsy Center from October 1997 to April 2004. Seventy three patients, who had a temporal epileptogenic focus, underwent anterior temporal lobectomy at Ankara University Medical Faculty Department of Neurosurgery. Twelve of them (16, 4%), did not have any localizing structural lesion on cranial MRI. Of the 12 patients examined 6 had normal findings and 6 had bilateral hippocampal atrophy. Of these 12 patients, 6 (50%) were women and 6 (50%) were men. The ages of patients ranged from 7 to 37 (mean: 24.5). Preoperatively long-term scalp video-EEG monitoring, cranial MRI, neuropsychological tests, and Wada test were applied in all patients. Five patients, whose investigations resulted in conflicting data, underwent invasive monitoring by the use of subdural strips. The seizure outcome of patients were classified according to Engel with postsurgical follow-up ranging from 11 to 52 (median: 35.7) months. Nine patients (75%) were classified into Engel's Class I and the other 3 patients (25%) were placed into Engel's Class II. One patient who was classified into Engel's Class II had additional psychiatric problems. The other patient had two different epileptogenic foci independent from each other in her ictal EEG. One of them localized in the right anterior temporal area, the other was in the right frontal lobe. She was classified in Engel's Class II and had no seizure originating from temporal epileptic focus, but few seizures originating from the frontal region continued after the surgery. In conclusion, surgery was successful in all 12 patients. We think that patients with no MRI lateralizing or localizing lesion should undergo epilepsy surgery after detailed presurgical evaluations, including invasive monitoring.