Neocortical Temporal Epilepsy Research Articles

Author response: Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology.

Objective: To assess the diagnostic accuracy and prognostic value of functional MRI (fMRI) in determining lateralization and predicting postsurgical language and memory outcomes. Methods: An 11-member panel evaluated and rated available evidence according to the 2004 American Academy of Neurology process. At least 2 panelists reviewed the full text of 172 articles and selected 37 for data extraction. Case reports, reports with Results and recommendations: The use of fMRI may be considered an option for lateralizing language functions in place of intracarotid amobarbital procedure (IAP) in patients with medial temporal lobe epilepsy (MTLE; Level C), temporal epilepsy in general (Level C), or extratemporal epilepsy (Level C). For patients with temporal neocortical epilepsy or temporal tumors, the evidence is insufficient (Level U). fMRI may be considered to predict postsurgical language deficits after anterior temporal lobe resection (Level C). The use of fMRI may be considered for lateralizing memory functions in place of IAP in patients with MTLE (Level C) but is of unclear utility in other epilepsy types (Level U). fMRI of verbal memory or language encoding should be considered for predicting verbal memory outcome (Level B). fMRI using nonverbal memory encoding may be considered for predicting visuospatial memory outcomes (Level C). Presurgical fMRI could be an adequate alternative to IAP memory testing for predicting verbal memory outcome (Level C). Clinicians should carefully advise patients of the risks and benefits of fMRI vs IAP during discussions concerning choice of specific modality in each case.

Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

To assess the diagnostic accuracy and prognostic value of functional MRI (fMRI) in determining lateralization and predicting postsurgical language and memory outcomes. An 11-member panel evaluated and rated available evidence according to the 2004 American Academy of Neurology process. At least 2 panelists reviewed the full text of 172 articles and selected 37 for data extraction. Case reports, reports with <15 cases, meta-analyses, and editorials were excluded. The use of fMRI may be considered an option for lateralizing language functions in place of intracarotid amobarbital procedure (IAP) in patients with medial temporal lobe epilepsy (MTLE; Level C), temporal epilepsy in general (Level C), or extratemporal epilepsy (Level C). For patients with temporal neocortical epilepsy or temporal tumors, the evidence is insufficient (Level U). fMRI may be considered to predict postsurgical language deficits after anterior temporal lobe resection (Level C). The use of fMRI may be considered for lateralizing memory functions in place of IAP in patients with MTLE (Level C) but is of unclear utility in other epilepsy types (Level U). fMRI of verbal memory or language encoding should be considered for predicting verbal memory outcome (Level B). fMRI using nonverbal memory encoding may be considered for predicting visuospatial memory outcomes (Level C). Presurgical fMRI could be an adequate alternative to IAP memory testing for predicting verbal memory outcome (Level C). Clinicians should carefully advise patients of the risks and benefits of fMRI vs IAP during discussions concerning choice of specific modality in each case.

Evaluation of Ictal Consciousness in Temporal and Extra Temporal Epilepsy: Observations from a Tertiary Care Hospital in India.

Background and PurposeDifferences in consciousness during seizures depend on the location of the seizure onset.MethodsThe present study evaluates ictal consciousness using the ictal consciousness inventory (ICI) in drug refractory mesial temporal (MTLE), neocortical temporal (NTLE) and extra temporal epilepsy (ETLE). This was a cross sectional cohort study with 45 patients with mesial temporal epilepsy, 47 with extra temporal and 11 patients with neocortical temporal epilepsy. The ICI a 20 item questionnaire was used to calculate the scores for level (L, question 1–10) and content (C, question 11–20) of consciousness.ResultsThe patients in mesial temporal group had higher ICI-L scores, p = 0.0129 as compared to the extra temporal group, but no difference was observed in the content of consciousness. The ICI-L and C scores were not different in the mesial temporal and the neocortical temporal group (p = 0.53 and 0.65) respectively.ConclusionsPatients with mesial temporal epilepsy had a higher level of consciousness than the extra temporal group but there was no difference in the content. Also there was no difference in the level and content of consciousness between mesial and the neocortical temporal group.

Ictal onset on intracranial EEG: Do we know it when we see it? State of the evidence.

A major limitation of intracranial electroencephalography (iEEG) is recording from a confined region. This may falsely localize seizure onset if the distinction between ictal onset zone, proximity, and spread is unclear, or if the ictal rhythm is not clearly identified. Delineation of the ictal onset zone is crucial for surgical success. We appraised the evidence to determine whether specific iEEG ictal patterns are associated with the ictal onset zone. We searched Embase for articles in English until September 30, 2014, with MeSH keywords related to intracranially implanted electrodes and seizures. Two authors independently screened abstracts, reviewed full text articles, and abstracted data. The association between seizure outcome and type of ictal onset pattern (IOP), and its extent, location, and spread were explored visually or by univariate analysis when sufficient data were provided. Methodologic quality of each study was assessed. We reviewed 1,987 abstracts from which 21 articles were analyzed. Fifteen IOPs were reported. Low frequency high amplitude repetitive spiking (LFRS) was the most frequently reported IOP by studies that dealt with mesial temporal lobe epilepsy (mTLE) and investigated with depth electrodes. In neocortical epilepsy, low voltage fast activity (LVFA) was the most commonly described IOP. Delta activity was an infrequently reported IOP and was described mostly as a spread pattern. LFRS is associated with good surgical outcome in mTLE and has a strong relation with mesial temporal pathology and its severity. LVFA is associated with neocortical temporal epilepsy and focal LVFA is associated with better surgical outcome. Electrodecrement may be associated with regional or widespread onsets. Rhythmic delta is a propagation rhythm rather than an IOP. Focal IOPs and slower propagation times are associated with better outcomes. The quality of the studies is suboptimal and there are methodological problems. Interobserver agreement is poorly documented.

Multimodal presurgical evaluation in children with focal cortical dysplasia

WCN 2013 No: 1499 Topic: 1 — Epilepsy Pharmacologic and genetic aspects of resistant epilepsy in children in Uzbekistan N.M. Tuychibaeva, M.I. Sigatullina, A.V. Prokhorova. Tashkent Medical Academy, Uzbekistan; Tashkent Institute of Postgraduate of Medical Education, Tashkent, Uzbekistan Objectives: To develop methods of detection for the frequency and influence of polymorphism of cytochrome Р450 genes on pharmacologic and genetic action of antiepileptic drugs (AED). Identify the role of these genetic markers in individual responses to AED and development of pharmacologic resistance in epileptic patients. Material and methods: The research is based on studying the results of treatment of patients (n= 20)with resistant epilepsy. The control group included 25 volunteers of Uzbek nationality adjusted by sex and age. Results and conclusions: 1. Minimum level of gene variety of marker CYP2C9 in children was determined with not very high frequency of heterozygosis. Reduction of frequency of heterozygote genotype, absence of adverse genotype Т/Т and simultaneous increase in the share of individuals with normal homozygous С/С genotype among apparently healthy patients can be related to selective advantage of C allele. 2. Frequency of CYP2C9 polymorphism in pharmacoresistant patients considerably exceeded that in the control group indicating the association between development of resistance to AED and the genetic marker. The obtained statistically insignificant difference is most likely caused by the small amount of patients in the groups. 3. The genotypic variant distribution analysis of polymorphic marker 9896 C-G of CYP2E1 gene showed that among patients with the resistant epilepsy and the controls, the share of people with mutant genotypes had almost identical frequencies (20%). The risk of development of resistance to AED in carriers of the genotype was statistically insignificant (N0.05). doi:10.1016/j.jns.2013.07.103 Abstract — WCN 2013 No: 1513 Topic: 1 — Epilepsy Symptomatic versus idiopathic temporal lobe epilepsies: Findings from a cohort of 75 patients Y. Hizem, A. Nasri, M. Ben Djebara, Y. Sidhom, I. Abdelkefi, A. Gargouri-Berrechid, R. Gouider. Department of Neurology/Research Unit 03/UR/08-09, Research Unit 12SP21, Razi Hospital, Tunis, Tunisia Introduction: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy. Twomain varieties have been described in TLE: mesial and lateral or neocortical temporal epilepsy. Objective: To determine clinical, electrical and radiological differences between mesial and neocortical variants of temporal lobe epilepsies in idiopathic versus symptomatic groups. Methods: Retrospective study of clinical, electrical and radiological features in four groups: mesial symptomatic (MSTLE), neocortical symptomatic (NSTLE), mesial idiopathic (MITLE) and neocortical idiopathic (NITLE). Results: Total of 75 patients: 24 MSTLE, 33 NSTLE, 14 MITLE and 4 NITLE. The mean age of onset was respectively: 11.54, 22.63, 9.78 and 15.7 years. History of febrile seizures is found in 66% inMSTLE. Themain types of seizures are automatisms and visceral sensory auras in MTLE symptomatic (75% and 58% respectively) and idiopathic (43% and 71% respectively). Psychic auras are the most frequent type in NSTLE (42%) and language alterations in NITLE (100%). spike-waves are common in mesial group. Pharmaco-resistance is more frequent in MSTLE (54%) and NITLE (50%). In the symptomatic group, brain MRI shows association of other temporal lobe abnormalities to mesial sclerosis in 46%. Conclusion: Our study shows earlier age of onset with a higher frequency of febrile seizures and pharmaco-resistance in MSTLE group. The Symptomatic group of TLE is characterized by older age and higher frequency of background EEG abnormalities. Some features are shared between the symptomatic or idiopathic variants and others depend on the mesial or neocortical localization. doi:10.1016/j.jns.2013.07.104 Abstract — WCN 2013 No: 1511 Topic: 1 — Epilepsy Multimodal presurgical evaluation in children with focal cortical dysplasia WCN 2013 No: 1511 Topic: 1 — Epilepsy Multimodal presurgical evaluation in children with focal cortical dysplasia M. Sigatullina, G. Garcia, J. Muchart, M. Rebollo, J. Aparicio, F. Sanmarti. Epilepsy Unit, University Hospital Sant Joan de Deu, Barcelona, Spain Objective: To evaluate the effectiveness of multimodal presurgical evaluation in patients with focal cortical dysplasia (FCD). Methods and subjects:We performed preand postsurgical evaluation in 20 patients withmalformations of cortical development (MCD) aged from 2 months till 17 years old. All of them underwent continuous video-EEG, MRI, 18 FDG-PET and SISCOM investigations. Results: There were operated 20 patients with MCD with preand postsurgical evaluation. Themean age at neurosurgerywas 6.5 years. 18 patients had different types FCD and 2 had hemimegalencephaly. The mean period between epilepsy onset and neurosurgery was 6 years. In 15 (75%) patients the presurgical MRI (1.5 T) detected FCD correlated with focal rhythmic epileptiform discharges during video-EEG register. In 5 patients (25%) with negative MRI, 18 FDG-PET and SISCOM were useful to complete the preoperative study. Surgical procedures included 6 temporal, 10 extratemporal, 2 multilobar resections and 2 functional hemispherotomies. Brain histological analysis confirmed the diagnosis ofMCD in all cases. The outcome after 1 year of neurosurgery, according Abstracts / Journal of the Neurological Sciences 333 (2013) e1–e64 e27

Pseudotemporal Ictal Patterns Compared With Mesial and Neocortical Temporal Ictal Patterns

This study analyzes falsely localizing pseudotemporal ictal EEG patterns, to test if it is possible to differentiate them from those in "true" temporal lobe epilepsy. We retrospectively studied 33 patients who had epilepsy surgery and a favorable outcome (Engel I), belonging to three groups: 10 patients (37 seizures) with pseudotemporal ictal patterns (PT), 12 patients (45 seizures) with mesial temporal epilepsy because of hippocampal sclerosis (HS), and 11 patients (41 seizures) with neocortical temporal epilepsy (NT). Ictal EEGs were analyzed visually according to predetermined criteria and by using a source localization program (BESA5.1). The topographies of interictal discharges were compared among the three groups. Ictal patterns and locations overlapped across all the groups. The initial onset patterns in NT were less likely to localize to one temporal region as compared with the other groups (P < 0.008). Rhythmic temporal theta as later pattern was seen significantly more frequently in HS than in NT (P < 0.001). All seizures in PT spread to the contralateral side compared with 73 of 86 (85%) of "true temporal" seizures (P < 0.05). Source analysis of the ictal discharge and topographic distribution of interictal discharges were not able to separate the three groups. Pseudotemporal ictal patterns are morphologically indistinguishable from true temporal ictal patterns. Although statistically more common in hippocampal sclerosis, rhythmic theta pattern can be seen as a result of propagation from extratemporal sites.

PET imaging of brain 5-HT1A receptors in the preoperative evaluation of temporal lobe epilepsy

[(18)F]MPPF PET has previously been used to identify the epileptic lobe in temporal lobe epilepsy (TLE) patients at the group level. This study aims to validate the visual analysis of [(18)F]MPPF PET in the assessment of individual TLE patients for their suitability to undergo temporal lobe resection. Forty-two patients suffering from TLE and 18 control subjects matched for age and gender were prospectively enrolled for [(18)F]MPPF PET. Four subtypes were defined according to the presurgical evaluation: mesio-TLE (MTLE, 32 patients), temporal neocortical epilepsy (NC, five patients), temporo-perisylvian epilepsy (T+, three patients) and temporal epilepsy without further information (t, two patients). Parametric binding potential (BP(ND)) images were obtained using a simplified reference tissue model. Three examiners, who were blinded to other data, visually interpreted each scan and delineated areas of decreased [(18)F]MPPF BP(ND). Statistical parametric mapping (SPM) analysis of MPPF BP(ND) images was also performed. Visual analysis showed a low rate of disagreement between the three examiners (7%). PET scans were considered normal in four patients (9.5%). In the remaining 38 patients (90.5%), areas of focal BP(ND) decrease were identified. A specific pattern was encountered in the MTLE subgroup, consisting of a BP(ND) decrease involving hippocampus, amygdala and temporal pole altogether. Combining the results from the presurgical investigations and the surgical outcome, we estimated that the area of BP(ND) decrease coincided with the epileptogenic zone in 40% of patients in the MTLE subgroup and 33% in the other TLE subtypes. This relatively low precision was due to 47% of patients who showed BP(ND) decreases in the insula ipsilateral to the epileptogenic lobe. The SPM analysis had much lower sensitivity (67%) to detect BP(ND) decreases in the epileptogenic temporal lobe, but revealed areas of increased BP(ND) outside the epileptogenic zone and bitemporal BP(ND) decreases of undetermined clinical significance, which were undetectable by visual analysis, in 29% of patients. In conclusion, visual analysis of [(18)F]MPPF BP(ND) images helps in the correct identification of the epileptogenic temporal lobe in all patients showing BP(ND) decreases, with a false negative rate inferior to 10% and no false positives in control subjects. All TLE patients with [(18)F]MPPF BP(ND) decreases involving hippocampus, amygdala and temporal pole together, with or without extension to the ipsilateral insula, were good candidates for anterior temporal lobectomy. All these patients became seizure free after surgery, even when the clinical presentation was not that of a typical MTLE, or when MRI failed to detect hippocampal atrophy.

Temporal Lobe Epilepsy: Clinical Semiology and Neurophysiological Studies

Most partial epilepsy crises originate in the temporal lobe. Two main syndromes have been described in temporal lobe epilepsy (TLE): mesial temporal epilepsy and neocortical temporal epilepsy. In recent years, the number and types of drugs used to control the crises have significantly increased, but almost 30% of patients do not have complete control of their epilepsy. In those cases, surgery is an efficient therapeutic option, especially in the case of mesial temporal sclerosis. Before surgery, wide and complex neurophysiological studies are needed to precisely delineate the epileptogenic area. The clinical and neurophysiological aspects of TLE that may be useful for understanding this pathologic entity are reviewed.

Spectroscopic evidence of hippocampal abnormalities in neocortical epilepsy

Lesional neocortical epilepsy (NE) can be associated with hippocampal sclerosis or hippocampal spectroscopic abnormalities without atrophy (dual pathology). In this study, magnetic resonance spectroscopic imaging (MRSI) was used to determine the frequency of hippocampal damage/dysfunction in NE with and without structural lesion. Sixteen patients with NE [seven temporal NE (NE-T), nine extratemporal (NE-ET)] and 16 controls were studied with a 2D MRSI sequence (Repetition time/echo time (TR/TE) = 1800/135 ms) covering both hippocampi. Seven NE patients had MR visible lesions (NE-Les), nine had normal MRI (NE-no). In each hippocampus, 12 voxels were uniformly selected. In controls, mean (+/- SD) NAA/(Cr + Cho) values for each voxel were calculated and voxels with NAA/(Cr + Cho) < or = (mean in controls--2SD in controls) were defined as 'pathological' in patients. Eight of 16 NE patients had at least two 'pathological' voxel (mean 2.5, range 2-5) in one hippocampus. Four were NE-Les and four NE-no. Three (43%) NE-T patients, had evidence for hippocampal damage/dysfunction and five (56%) had NE-ET. The ipsilateral hippocampus was affected in six of eight NE patients. Evidence for unilateral hippocampal damage/dysfunction was demonstrated in 50% of the NE patients. The type of NE, i.e. NE-Les or NE-no, NE-T or NE-ET, had no influence on the occurrence of hippocampal damage/dysfunction.