Biomedical subjects

J R Gates

Publications and source records attributed to J R Gates.

41 records · Page 3Linked to original sources

PubMedDate not supplied

Methohexital (Brevital) effect on electrocorticogram may be misleading.

Intravenous (i.v.) methohexital (MTH, Brevital) was found to have an effect on the intraoperative electrocorticogram (ECOG) of 63 patients who had temporal lobectomies performed under general anesthesia for intractable complex partial seizures. In the preresection ECOG, MTH increased the frequency of spikes in 78%, the area of cortical spiking in 30% and induced seemingly "new" spike foci in 43%. Similar although less dramatic changes occurred in the final (i.e., postresection) ECOG. Whether these changes induced by MTH, specifically the new spike foci, are significant was assessed by correlating surgical results with the presence of "residual spikes" (i.e., after all resections, not spontaneously occurring but activated by MTH). Surprisingly, nine patients with residual "MTH-spikes" did not have any postoperative seizures whereas two had some. This raises the question of whether MTH effects are significant overall. Caution is advised in the use of MTH in intraoperative assessment of interictal spike fields, especially when new spike foci are activated. Further study of the possibility of false activation, with a larger series, is advised.

Cerebral Cortex↗

PubMedDate not supplied

Nonepileptic events in childhood.

The medical records of 27 children admitted to the MINCEP Epilepsy Program for evaluation of intractable epilepsy but later shown to have nonepileptic events by EEG with simultaneous video monitoring were reviewed. Four groups were identified: pure psychogenic events (5 patients), psychogenic events plus epileptic seizures (3 patients), pure nonepileptic physiologic events (5 patients), and nonepileptic physiologic events plus seizures (14 patients). Historical data, physical examinations, and neurodiagnostic evaluations (including previous EEGs, neuroradiologic evaluations, and neuropsychologic testing) were reviewed. Children in all groups, except for those with pure psychogenic seizures, had a history of multiple seizure types identified by parents or caretakers. A history of status epilepticus was obtained in 64% (of 22 patients), including 11 of 14 patients with physiologic events plus seizures. Abnormal findings on neurologic examination were common, especially in children with nonepileptic physiologic events. All but two patients had a history of interictal epileptiform abnormalities on previous routine EEGs. Based on identification of nonepileptic events, antiepileptic drugs (AEDs) were discontinued completely in eight patients (30%) and the total number of AEDs was reduced in nine others (33%). A diagnosis of nonepileptic events should be considered in all children with refractory seizures or multiple seizure types. Abnormal findings on routine (interictal) EEG may actually confound the diagnosis. Intensive neurodiagnostic EEG-video recording is the preferred method for distinguishing nonepileptic from epileptic seizures.

Adolescent↗

PubMedDate not supplied

Lack of pathologic changes in human temporal lobes after transcranial magnetic stimulation.

Most animal studies have failed to demonstrate pathologic changes in the brain after transcranial magnetic stimulation (TMS). Nevertheless, vacuolar lesions in the cortex of rats after TMS have been reported. We report the first histopathologic studies of human brains after TMS in 2 patients with epilepsy who underwent temporal lobectomies. They had been involved in a study to determine the speech-dominant hemisphere by TMS and had received approximately 2,000 stimuli centered over the resected temporal lobe. Histologic study of the surgical specimens did not show any lesions attributable to TMS in these 2 patients.

Adult↗

PubMedDate not supplied

Value of intraoperative EEG changes during corpus callosotomy in predicting surgical results.

The intraoperative transformation of generalized epileptiform discharges (GED) to lateralized epileptiform activity during the course of corpus callosum sectioning for intractable epilepsy in 37 patients was correlated with percentage of decrease in atonic-tonic seizures with "drops" at mean follow-up of 26 months (range 12-86 months). Twenty-seven (73%) patients had intraoperative interictal discharges, and 21 (78%) showed varying degrees of lateralization of GED during corpus callosum sectioning (two thirds to total). All patients experienced > 80% reduction in atonic-tonic seizures with drops. The group (n = 7) with largest decrease in GED had the greatest decrease in seizures (95.5%). Six patients without change in GED had 88% decrease in seizures, as did 14 patients (85-86%) with mild or moderate decreases in GED, but there was no statistically significant correlation between decrease in GED and seizure frequency after operation. Thus, although lateralization of GED after corpus callosum sectioning was evident in 78% of patients with GED, the degree of lateralization of GED did not correlate with degree of reduction of tonic-atonic seizures. Therefore, intraoperative surface EEG monitoring does not appear to be helpful at this time as a guide to extent of callosotomy.

Adolescent↗

PubMedDate not supplied

Routine EEG vs. intensive monitoring in the evaluation of intractable epilepsy.

Appropriate treatment of patients with intractable seizures requires precise identification of the type (or types) of seizure the patient experiences and correlation of this information with data from electroencephalography localizing the focus of the seizure in the brain. For such patients, the technique of "intensive monitoring" has gained rapid acceptance in the past several years as the investigative method of choice.Intensive monitoring usually entails prolonged electroencephalographic recording with simultaneous videotaping of the patient. Another common technique is prolonged monitoring of the patient's electroencephalogram (EEG) by radiotelemetry, during which time the patient is closely observed by trained personnel for suspected seizures.To compare the quality of information obtained from intensive monitoring with that from careful routine electroencephalography, the authors reviewed the medical records of 100 consecutive patients who had received both kinds of study after being referred for treatment in the special Epilepsy Treatment Unit of the University of Minnesota's Comprehensive Epilepsy Program (CEP).Success of each method was defined by ability to record an actual seizure. The routine EEG examination recorded actual seizures in 7 percent of patients in the study. With video EEG, following careful withdrawal of anticonvulsant drugs, seizures were recorded in 70 percent of patients. Telemetered EEG recorded seizure activity in 50 percent of those patients for whom the other two methods had failed to detect seizures.Intensive monitoring revealed that 60 percent of patients for whom the routine EEG study had recorded only one seizure type actually suffered from two or more types. Clinical diagnosis was changed in 84 percent of the patients. In this study, intensive monitoring was found to be far superior to the routine EEG examination as an aid to precise diagnosis of intractable seizure disorders.

Electroencephalography↗