Faculty Bibliography

Invasive intracranial monitoring with subdural grids has led to a greater appreciation of cortical function and the discovery of ictal onset either independently or in conjunction with deep structures. With the description of multiple subpial transections the armamentarium for surgical control of intractable seizures has been expanded. Utilizing invasive intracranial monitoring with subdural grids and strips, a large series of patients with intractable complex partial seizures originating in exquisite cortex, and in some cases additionally in deep structures, have undergone surgery. These patients would previously have been judged not to be candidates for surgical control of seizures. We will present 9-month or greater follow-up in an ongoing series of patients undergoing cortical resection and subpial transections in whom there has been a statistical improvement in control or alleviation of their seizure disorder. The report will specifically discuss outcomes as related to exquisite cortex, motor, sensory and language functions, as well as clinical results and EEG

We examined the contribution of the temporal neocortex to short-term memory (STM) in 15 patients with left hemisphere language dominance during intraoperative or extraoperative cortical mapping prior to left anterior temporal lobectomy. Recall errors were examined following stimulation during the acquisition, consolidation, and retrieval stages of a verbal STM task. Ten patients showed stimulation-induced recall errors, and five patients showed no significant memory errors. More patients showed errors following stimulation during consolidation than during acquisition or retrieval, possibly because of disrupted transfer of information from the temporal neocortex to the hippocampus. Patients with stimulation-induced recall errors did not differ significantly from patients without memory errors in terms of seizure, demographic, or neuropsychological variables. Patients with resection of sites showing stimulation-induced recall errors had greater postoperative decline in verbal memory than did patients with resection sparing these sites. We suggest that the left temporal neocortex contributes to verbal memory consolidation in patients with chronic epilepsy

Multiple subpial transections (MST) were made in language cortex in three patients with medically refractory partial epilepsy. All patients were mapped with extra-operative stimulation using subdural grids over the dominant temporal, frontal and parietal convexity. Two patients had anterior temporal lobectomy and MST in posterior language cortex. One patient who had undergone a previous frontal tumour resection had only MST over the frontoparietal convexity, including frontal and parietal language areas. Both patients with MST in the posterior language cortex had postoperative language dysfunction, which had improved significantly by 9 months after surgery. The patient with MST in frontoparietal language areas had improved language functions immediately postoperatively. The two men with anterior temporal lobectomies and MST are seizure-free at 1 year follow-up and the woman with frontoparietal MST has had a > 70% reduction in seizure frequency at 1 year follow-up

We identified seven patients with refractory partial epilepsy and sleep apnea. Treatment of the sleep apnea with nasal continuous positive airway pressure (CPAP), protriptyline, trazodone, acetazolamide, or tracheostomy reduced seizure frequency and severity in six patients. Success with CPAP depended largely on compliance. Four of five patients had a clear reduction in seizure frequency with the use of CPAP. Sleep apnea may exacerbate epilepsy by causing sleep disruption and deprivation, hypoxemia, and decreased cerebral blood flow. In epilepsy patients with risk factors (eg, obesity) or markers (eg, habitual snoring, daytime somnolence) for sleep apnea, a careful sleep history should be elicited and a polysomnogram obtained when indicated. Treatment of the sleep disorder can improve seizure control

After a 15-year hiatus, several new antiepileptic drugs have been approved or are under Food and Drug Administration investigation for use in the United States. This article reviews four of these new drugs--felbamate, gabapentin, lamotrigine, and vigabatrin. Although these drugs have been primarily developed for use in adults with partial seizures, they will also likely be used in children with partial epilepsy. Pediatric experience with several of these drugs has demonstrated safety and efficacy in other seizure types and epilepsy syndromes. These drugs will be an important addition to the therapeutic armamentarium for pediatric epilepsy. Additional studies are needed to fully explore the safety and efficacy of these drugs in a variety of pediatric epilepsies and to compare them to existing antiepileptic drugs

We treated 10 patients (aged 5-37 years) with medically refractory absence seizures with felbamate (FBM). Average duration of absence seizures was 16.2 years. All patients continued to have absence seizures at maximally tolerated doses of valproic acid and/or ethosuximide. At maximal FBM dosage (45 mg/kg/day or 3,600 mg/day), there was at least a 65% reduction in absence seizure frequency in eight patients; in four, there was a > 95% reduction. Mean duration of FBM therapy is 16.2 months (range, 5-31 months). Nine patients remain on FBM. Two patients are on FBM monotherapy; seven others are on FBM and one or two other antiepileptic drugs. FBM was discontinued in one patient who developed severe insomnia followed by a return to baseline absence seizure frequency after an initial good response, and an increase in generalized tonic-clonic seizures (GTCS). Three other patients also had a history of GTCS; in one there has been no significant change, whereas two have not had a GTCS during FBM therapy. Eight patients continue to have a clinically meaningful reduced absence seizure frequency, and eight patients reported fewer adverse effects with their current regimen including FBM. Tachyphylaxis to the antiabsence efficacy was observed in four cases. These preliminary findings suggest that FBM is useful in treating absence seizures

Nonepileptic seizures (NES) are common and are often diagnosed at epilepsy centers by video-EEG recording of both spontaneous and suggestion-induced episodes, but no study has evaluated provocative testing in a general seizure population. We studied consecutive patients with a tentative diagnosis of epilepsy using saline provocation during video-EEG recording, suggesting that this could produce a typical seizure. Of 52 patients, 40% had no response, 23% had responses unlike their seizures, and 37% had typical episodes (positive test). Patients whose usual episodes resembled complex partial seizures (CPS) were more likely to have NES than were patients with a history of generalized tonic-clonic seizures (GTC). Of patients with positive provocations, the primary physician predicted NES in 68% of cases. This preliminary study suggests that NES are frequent in a general neurology setting, and that saline provocation is a sensitive method of identifying NES