Alfentanil-induced activation: a promising tool in the presurgical evaluation of temporal lobe epilepsy patients.

Pharmacologic activation of epileptic foci has been used experimentally with the hope that it may accelerate the presurgical evaluation of patients with medically intractable epilepsy. In this article, we will review the existing literature on these activating tests giving emphasis on the opioid analogs, and particularly alfentanil. Alfentanil is an opioid analog with rapid anesthetic effect, which has been known to trigger epileptiform discharges in epilepsy patients. 58 temporal lobe epilepsy (TLE) patients were studied with alfentanil activation during electrocorticography, at the Epilepsy Surgery Unit (ING, Brazil). An increase of the interictal epileptiform discharges was observed originating from hippocampal and parahippocampal regions (96.5%). To a lesser extent, alfentanil activated the basal and lateral temporal regions. Electrographic seizures were observed in 38%. In addition, we performed continuous video-EEG (VT/EEG) monitoring, with scalp and bilateral foramen ovale electrodes, in 12 TLE patients. The results of spontaneously observed seizures were compared with the electrographic changes following alfentanil activation (50-75 microg/kg, i.v.). In seven cases, alfentanil triggered focal electrographic seizures, ipsilaterally to the side generating the spontaneous seizures and in two patients it produced bilateral sequential activation of the temporal lobes. Ictal SPECTs during the alfentanil test showed hyperperfusion at the lateral temporal regions, ipsilaterally to the activated area or bilaterally. In summary, our study confirms the activating effect of alfentanil, and provides a strong evidence for its selective activating effect on the temporal lobes of TLE patients. The ictal SPECT during alfentanil activation did not offer any additional advantage for the localization of the ictal onset.

Corpus callosotomy in treatment of medically resistant epilepsy: preliminary results in a pediatric population.

We report the results of 34 patients who underwent corpus callosotomy between 1986 and 1989 with 28-65 months of postoperative follow-up (mean 42 months). Thirty-two patients had mental retardation and 26 had significant behavioral problems. Thirteen patients had total section, 8 had subtotal section with preservation of the posterior half of the splenium, and 13 had section of the anterior two thirds of the callosum. Satisfactory seizure control was achieved in 25 patients (73.5%) Atonic seizures, followed by tonic seizures, generalized tonic-clonic seizures (GTCs), and atypical absence seizures were most improved. Myoclonic and complex partial seizures (CPS) did not improve significantly. No deterioration in seizure status was observed postoperatively. Two patients developed previously unobserved simple seizures and CPS postoperatively, but they were not as disabling as the preoperative seizures. Among the patients with behavioral problems, 81% had significant decrease in aggressiveness, hyperactivity, and/or attention deficit. Patients who underwent total section had interhemispheric disconnection symptoms that improved progressively and did not interfere with daily life. Decreased speech output, dysarthria, and gait dyspraxia occurred after total callosal section and persisted in 5 of the 13 patients. Patients who underwent anterior two thirds or subtotal sections did not have such symptoms. Early postoperative complications consisted of aseptic ventriculitis (5), subdural hematoma (1), and wound infection (4) and resolved without sequelae.

[Interhemispheric disconnection syndrome following total callosotomy associated to anterior commissurotomy for the treatment of intractable epilepsy: a case report]. / Síndrome de desconexão inter-hemisférica após calosotomia total associada a comissurotomia anterior para tratamento de epilepsia resistente: relato de um caso.

The authors provide a brief review of the indication criteria of callosotomy for the treatment of medically intractable seizures. They report a surgical case with the classical picture of disconnection (split brain) syndrome, following a two-staged complete callosotomy plus anterior commissurotomy. The disconnection syndrome was more severe on the first 5 days post-operatively, improving quickly after the 11th day; there was almost complete functional recovery and a great reduction in seizure frequency.

Functional microsurgical partial callosotomy in patients with secondary generalized epilepsies. I. Disruption of bilateral synchrony of spike and wave discharges.

Fourteen patients with secondary generalized epilepsy suffering from multiform seizures (MS) not amenable to medication were submitted to partial section of the corpus callosum. In all patients, there was a partial disruption of the previous generalized bilateral synchronous epileptiform discharges (GBSD). The electroencephalographic findings after callosal section are discussed with respect to their implications in furthering our understanding of the mechanisms subserving the organization of GBSD.

Functional microsurgical partial callosotomy in patients with secondary generalized epilepsies. II. Mesial surface electrocorticography.

Eight patients with secondary generalized epilepsy not alleviated by medical treatment underwent partial callosotomy. During the surgical procedure, they had mesial surface ECoG recordings taken from both frontal and parietal lobes, using large flat multilead platinum electrodes, and simultaneously recordings from a number of scalp positions, using needle electrodes. In all cases studied, this approach demonstrated one or, more commonly, several focal areas of epileptiform activity discharging independently over the mesial aspects of one or both hemispheres. The findings were correlated with the pre- and postoperative EEG patterns, in the light of current concepts of generalized epilepsies.

Anterior zygomatic electrodes: a special electrode for the study of temporal lobe epilepsy.

The position of a surface electrode over the anterior zygomatic arch is described. Epileptiform activity recorded at this position is compared with that recorded by sphenoidal electrodes in 21 cases of temporal lobe epilepsy. In 100% of the cases abnormalities were detected with both electrodes, although in 11% of the cases the findings could not be definitely described as epileptiform in the anterior zygomatic electrodes.

On the dose equivalence of flurazepam and triazolam.

Flurazepam (30 mg), triazolam (0.5 mg) and placebo were given in the morning to 6 normal volunteers in a double-blind crossover study. Subjects were evaluated by a large battery of psychophysiological tests before and 1 and 5 hours after drug administration. Triazolam was significantly more sedative than flurazepam and both were significantly different from placebo. Slope-ratio assay analysis of the results from the present study pooled with those from a similar previous study (C. Gorenstein and V. Gentil, Psychopharmacology, 80: 376-379, 1983) indicated that these doses are non-equivalent. We suggest that dose-equivalence studies based on the present method should be carried out early in the development of new hypnotic drugs.

Efeito do cloridrato de quetamina em epilepticos cronicos. / Effect of ketamine hydrochloride in chronic epileptic patients

A quetamina foi utilizada para estimulacao de focos epilepticos durante a cirurgia para exerese de area epileptogenica em 3 pacientes com epilepsia temporal (grupo 2) e para o registro de atividade eletrica cerebral em 2 portadores de epilepsia focal (grupo 2). Nos tres pacientes do grupo 1, a droga desencadeou e agravou crises EEG e ECoG tipicas de epilepsia. Nos dois casos de epilepsia focal, houve desaparecimento das crises psico-motoras pre-existentes e individualizacao do foco original fenomenos que regrediram apos 20 e 30 minutos. Em todos os doentes houve aparecimento do tracado EEG tipico do efeito da droga. O periodo pos-operatorio dos casos do grupo 1 caracterizou-se por crises convulsivas generalizados e prolongadas, que cederam com altas doses de anticonvulsivantes. Nos do grupo 2, as crises de epilepsia focal reapareceram, acompanhadas de alucinacoes auditivas e visuais que regrediram em dois dias

Potencial evocado: generalidades. / Evoked potencials: generalities

Apos definir o metodo e conceituar brevemente os 3 tipos principais de potencial evocado (visual, auditivo e somatossensitivo), sao discutidos aspectos do registro do PE, bem como as caracteristicas gerais dos sistemas utilizados nesse registro, procurando-se ressaltar a importancia fundamental de cada laboratorio de eletrofisiologia clinica proceder a normalizacao do metodo, antes de sua utilizacao no exame de pacientes. Por fim, sao citados alguns exemplos mais comuns de patologias onde a avalicao pelos PE acrescenta importantes subsidios ao diagnostico

Potencial evocado visual por padrao reverso. / Visual evoked potencial pattern reversal

Em 10 individuos normais de ambos os sexos foram estudados potenciais evocados visuais por padrao reverso (PEV-PR) com diferentes angulos visuais. Apos os estimulos monoculares, foram obtidas curvas reprodutiveis, apresentando componentes de latencias bem definidas, negativo ao redor dos 75 ms (N75), positivo ao redor dos l00 ms (Pl00) e negativo ao redor dos 120 ms (N120). Os dados normativos obtidos mostraram-se concordantes com os referidos na literatura consultada, permitindo assim a utilizacao do estudo do PEV-PR na avaliacao objetiva de patologias das vias opticas. Sao discutidas constancia e variabilidade dos componentes, bem como alteracoes introduzidas pelos diferentes angulos visuais estudados

Potencial evocado auditivo:tronco cerebral (estudo normativo). / Auditory evoked potentials:brain stem (normative study)

Em 10 individuos normais, adultos, de ambos os sexos, foram estudados os potenciais evocados auditivos - tronco cerebral (PEA-TC) usando-se cliks monoaurais por rarefacao com 60dB nivel de sensacao; o registro foi realizado em um canal, entre o vertex e a orelha ipsilateral. Os picos positivos, proeminentes e constantes no vertex foram numerados em algarismos romanos de I a VII, de acordo com a ja classica nomenclatura proposta por Jewett. Foi dada enfase ao estudo das latencias interpicos (LIP), particularmente I-III (tempo de conducao bulbo-pontino), III-V (tempo de conducao ponto-mesencefalico), I-IV e I-V (tempo de conducao central). Foram discutidas constancia e variabilidade das ondas, assim como aspectos gerais relativos a amplitude e morfologia. Os dados normativos obtidos mostraram-se concordantes com os referidos na literatura medica consultada, permitindo assim a aplicacao clinica do estudo dos PEA-TC na avaliacao objetiva de patologias interessando primaria ou secundariamente as vias auditivas no tronco cerebral

Anterior callosotomy as a substitute for hemispherectomy.

Two patients with epilepsy and large hemispheric lesions underwent section of the frontal fibres of the corpus callosum for the treatment of seizures refractory to medical treatment. A severely retarded girl of 18 had encephalotrigeminal angiomatosis (Sturge-Weber syndrome) with multiple daily absences, tonic-clonic, myoclonic, atonic and adversive seizures since infancy. All types of fits--with the exception of adversive seizures and rare tonic-clonic fits--disappeared after anterior callosotomy. Another moderately retarded girl of 18 had an old cystic lesion over the entire territory of the left middle cerebral artery. She had had right hemiplegia since infancy and frequent brief absences and massive myoclonus triggered by unexpected sensory stimuli since the age of six years. Following anterior callosotomy there was an almost complete disappearance of the absences and a marked reduction of her startle myoclonus. Frontal callosotomy is a useful procedure in epileptics with large hemispheric lesions and carries less risk than hemispherectomy or total commissurotomy.

Anterior callosotomy in epileptics with multiform seizures and bilateral synchronous spike and wave EEG pattern.

Cerebral commissurotomy is a well established procedure in the treatment of epileptics refractory to drug therapy. Breeching of the ventricles in complete commissurotomy carries a certain morbidity. This has led others to perform operations in which the entire corpus callosum or only its anterior portion with or without the anterior commissure were sectioned. Sectioning of the anterior corpus callosum alone is justified by: a) frequent appearance in patients of seizures attributable to a frontal focus, b) clinical and experimental evidence that frontal discharges spread across the corpus callosum leading to subsequent generalized its, c) the attempt to understand the mechanisms involved in generalized seizures, d) even further reduced surgical morbidity and neuropsychological disability. Five epileptics were submitted to anterior callosotomy. The seizures in all of them suggested a frontal focus and consisted of absences, adversive, tonic, atonic, and tonic-clonic attacks. All patients were incapacitated by the frequency of seizures. Their EEGs showed paroxysms of bilateral synchronous slow spike and wave with uni-, or multiple (including bilateral symmetrical) focal accentuation. In two patients there were additional independent temporal lobe discharges. Neuropsychological evaluation showed cognitive deficits caused by inattention paroxysms and absences. After anterior callosotomy there was marked reduction in frequency of all types of seizures, the greatest improvement being in the reduction of frequency of absences. There was a marked decrease in physical, social and neuropsychological disabilities.