Phenytoin withdrawal and seizure frequency.

We withdrew phenytoin from 17 inpatients maintained on combination therapy with carbamazepine for complex partial seizures and analyzed seizure occurrence in relation to plasma levels and time from initiation of withdrawal. The ratio of maximum to mean weekly seizure frequency did not vary with initial level or rate of withdrawal. The week with most frequent seizures began a median of 10 days after phenytoin levels became undetectable, and mean daily seizure frequency was higher at undetectable than at falling levels for the entire 2- to 10-week study period.

The effect of carbamazepine on cerebral glucose metabolism.

We used positron emission tomography with 18F-2-deoxy-D-glucose to study the effect of carbamazepine on local cerebral metabolic rate for glucose (lCMRGlc) in 9 patients with complex partial seizures. Twenty regions of interest were evaluated. Seven control patients had serial scans without a drug change.

Carbamazepine and its epoxide: relation of plasma levels to toxicity and seizure control.

We studied the relation of plasma levels of carbamazepine (CBZ) and carbamazepine 10,11 epoxide (CBZ-E), and their ratio to drug toxicity and seizure control in 7 patients with complex partial seizures. CBZ-E/CBZ increased with increasing CBZ levels and was higher when patients were taking phenytoin or valproic acid. There were weak correlations between CBZ, CBZ-E levels, toxicity scores, and seizure control when patients were taking CBZ alone, but not when other drugs were given as well.

Complex partial seizures. Correlation of clinical and metabolic features.

We compared metabolic patterns on 18F-2-deoxyglucose positron emission tomography (PET) with closed circuit television and simultaneous electroencephalographic ictal recordings of complex partial seizures in 48 patients. Closed circuit television and electroencephalographic data and PET scans were scored by "blinded" raters. Of the 48 patients, 26 had unilateral temporal; three, frontal; ten, ipsilateral frontotemporal; one, frontoparietal; and five, temporoparietal hypometabolism; and three had widespread hypometabolism affecting frontal, temporal, and parietal lobes.

Antiepileptic drugs and cerebral glucose metabolism.

Using PET with [18-F]-2-deoxyglucose (FDG), we studied the effects of antiepileptic drugs on cerebral glucose metabolism. Serial scans were performed before and after the test drug was added to or removed from the patient's regimen. At least 3 weeks elapsed after achieving steady-state plasma levels when drugs were added, or after plasma levels were undetectable when drugs were tapered, before repeat scans were obtained.

Seizures during barbiturate withdrawal: relation to blood level.

We studied 21 patients with complex partial seizures during phenobarbital (PB) or primidone withdrawal. Blood levels were measured daily, and seizure frequency was monitored by nursing staff and EEG-video telemetry. Patients were monitored for one week of baseline and for five weeks after PB tapering was initiated (withdrawal).