Somatosensory aura in mesial temporal lobe epilepsy: semiologic characteristics, MRI findings and differential diagnosis with parietal lobe epilepsy

INTRODUCTION: Somatosensory auras (SSAs) are more usually described in patients with parietal lobe epilepsy (PLE), producing more commonly a localized cutaneous tingling sensation, involving hands and fingers followed by tonic or clonic focal seizures. These usually originate in the contralateral hemisphere. Etiology includes dysplasias, tumours, ischemic or postencephalitic gliosis. However, other focal epilepsies, such as frontal and temporal, may also originate SSAs. Although this type of aura is reported as rare in patients with mesial temporal lobe epilepsy (MTLE), this association has not been systematically studied.OBJECTIVES: The aim of this article was to describe the cases of four patients with refractory MTLE and SSAs, reporting their clinical characteristics and MRI findings. We discuss the localizing and lateralizing value of SSAs, particularly in the context of MTLE. METHODS AND RESULTS: Four patients with refractory MTLE and SSAs followed-up in the outpatient's clinic at the Epilepsy Section, Universidade Federal de São Paulo, were submitted to presurgical evaluation and corticoamygdalohippocampectomy. MRI in all cases showed unilateral mesial temporal sclerosis (MTS). Regarding seizure semiology, tingling sensation involving the upper extremity was the most prevalent symptom. Three of the four patients had SSAs contralateral to the MTS. Following the SSAs all patients most of the time presented other symptoms such as autonomic or psychic auras evolving to psychomotor seizures. After surgical treatment, two of the patients presented infrequent auras, and two were rendered seizure-free. CONCLUSION: Although rare, SSAs can be present in MTLE. The characteristics of autonomic or psychic auras, psychomotor seizures, neuropsychological deficits, and typical neurophysiologic and MRI findings may help differentiate patients with MTLE from those with PLE

INTRODUÇÃO: Auras somatossensoriais (AS) são mais frequentemente descritas em pacientes com epilepsia de lobo parietal (ELP), produzindo sensação de formigamento cutâneo envolvendo mão e dedos seguida de sinais motores focais tônicos ou clônicos. Estas crises habitualmente originam-se no hemisfério cerebral contralateral. Displasias, tumores, patologias vasculares ou gliose pós encefalite constituem as etiologias mais prováveis. Outras epilepsias focais, como as de lobo frontal e temporal podem também originar (AS). Embora este tipo de aura seja considerada rara em pacientes com epilepsia mesial do lobo temporal (EMLT), esta associação ainda não foi sistematicamente estudada. OBJETIVOS: A proposta deste artigo foi descrever quatro casos de EMLT refratária ao tratamento clínico, apresentando AS, reportar as características clínicas comuns, achados de neuroimagem e estudar o valor localizatório e lateralizatório das mesmas. MÉTODOS E RESULTADOS: Quatro pacientes com EMLT refratária e AS acompanhados no ambulatório de Epilepsia, Universidade Federal de São Paulo, foram submetidos a avaliação pré-cirúrgica. Sensação de formigamento envolvendo a extremidade superior foi o sintoma predominante em todos. Em três (75%) as auras foram contralaterais à esclerose mesial temporal (EMT). Em todos as AS eram, com maior freqüência, seguidas por outras auras autonômicas e psiquícas e evoluiam para crises parciais complexas (crises psicomotoras). CONCLUSÃO: Embora raras, AS podem estar presentes em EMLT. A associação de auras autonômicas e psíquicas, presença de crises parciais complexas (psicomotoras), déficits neuropsicológicos distintos, além de achados neurofisiológicos e de neuroimagem podem diferenciar pacientes com EMLT daqueles com ELP.

Neurocysticercosis and microscopic hippocampal dysplasia in a patient with refractory mesial temporal lobe epilepsy

Estudos epidemiológicos sugerem que a neurocisticercose (NC) é a causa principal de epilepsia sintomática em países em desenvolvimento. A associação entre NC e epilepsia do lobo temporal mesial (ELTM) tem sido relatada por vários autores. Estudos recentes mostraram que a presença de NC não influência o perfil clínico e patológico em pacientes com ELTM e sugere que nem todas as lesões cisticercóticas são inevitavelmente epileptogênicas. No presente estudo, descrevemos uma mulher de 50 anos com crises epilépticas parciais associadas à NC que evolui para ELTM. A paciente foi submetida à corticoamigdalohipocampectomia para tratamento de epilepsia refratária. O estudo imunohistoquímico, utilizando marcadores neuronais, foi realizado em seções da formação de hipocampal. Além dos aspectos típicos da esclerose hipocampal, o exame microscópico demonstrou características celulares de malformação hipocampal, incluindo neurônios dismórficos e bilaminação focal da camada granular do giro denteado. Sugerimos que, neste caso, um transtorno do desenvolvimento reduziu o limiar para as crises epilépticas induzidas pela NC e contribuiu para o estabelecimento da epilepsia refratária.

Avaliação eletrofisiológica in vitro de drogas antiepilépticas em fatias hipocampais humanas provenientes de pacientes portadores de epilepsia do lobo temporal refratária ao tratamento medicamentoso / In vitro electrophysiological assessment of antiepileptic drugs in human hippocampal slices originating from patients with refractory temporal lobe epilepsy

The absence of a satisfactory response to antiepileptic drug (AED) therapy, is an unresolved problem in a significant number of epileptic patients. Mechanisms of intractability are not well understood but may include a combination of poor penetration of AED across a functionally altered blood-brain barrier owing to increased expression of multiple drug resistance transporters. Therefore, the aim of this work was to assess the in vitro efficacy of antiepileptic drugs through human hippocampal slices originating from patients with refractory temporal lobe epilepsy submitted to corticoamygdalohippocampectomy. Slices was prepared from a 1 cm3 block of the hippocampus body 30 min after resection. Briefly, hippocampal slices of 400 µM thickness was cut coronally. Extracellular field potentials was recorded from the st. Granulosum of the dentate gyrus. The antiepileptic drugs added in the bath were Carbamazepine, Topiramate and Phenytoin. The phenytoin was effective reducing the hyperexcitability (polispikes) in 60% of the experiments (n = 5). On the other hand, the carbamazepine promoted a decrease in evoked epileptiform activity in 37,5% of the cases (n = 8). The application of topiramate in the bath reduced in 30% the number of polispikes (n = 10). Our results showed that the phenytoin application resulted in a significant reduction in neuronal excitability, however, the carbamazepine and topiramate were not able to control of the hiperexcitability, suggesting that local neuronal alterations, as well changes in blood brain barrier, could be responsible for such behaviors.

Temporal lobe epilepsy with unilateral hippocampal sclerosis and contralateral temporal scalp seizure onset: report of four patients with "Buerned-out Hippocampus"

Patients with temporal lobe epilepsy (TLE) and unilateral severe hippocampal sclerosis (HS) may have contralateral temporal scalp onset. This has recently been called burned-out hippocampus, wich is believed to be a rare entity. In this study we report four patients with unilateral hippocampal clerosis and contralateral ictal onset registered by scalp electrodes. We discuss the importance of such cases in pre-surgical evaluation of patients with TLE, as well as possible strategies used for evaluation of these particular cases. We received charts from all patients with TLE submitted to pre-surgical evaluation, which included high resolution MRI and prolonged video-electroencephalogram (video-EEG) monitoring with scalp and sphenoidal electrodes, during a three-year period (2002-2004). We looked for patients who only had seizures that were clearly contralateral in location to the atrophic hippocampus. Four patients fulfilled the criteria above. Two of these patients had semi-invasive video-EEG monitoring with foramen ovale (FO) electrodes, which revealed seizures originating from the temporal lobe with the atrophic hippovampus, hence confirming false lateralization in the scalp-sphenoidal EEG. These patients were submitted to surgical tretament and had favorable prognosis after surgery. Burned-out hippocampus syndrome may not be as rare as it was previously believed.Further studies will be necessary before one can affirm tha patients with unilateral HS and scalp ictal EEG showing contralateral ictal onset may be operated without confirmation of the epileptogenic zone by invasive monitoring. In these patients, semi-invasive monitoring with FO electrodes might be an interesting alternative