Temporal lobe epilepsy with sensory aura: interictal glucose hypometabolism

Patients with mesial temporal lobe epilepsy (mTLE) exhibit marked depressions of the regional cerebral glucose metabolism (rCMRGlu) in the mesiotemporal region. We hypothesised that patients with temporal lobe epilepsy (TLE) who have a bilateral somatosensory or acoustic ( = temporolateral/SII-) aura can be differentiated from mTLE by rCMRGlu depressions primarily involving temporo-perisylvian locations. We therefore used this ictal semiology as a clinical criterion to define a subgroup of such patients and measured the rCMRGlu in 16 patients with TLE as evident from interictal and ictal EEG-video monitoring. Clinically, they presented with medically refractory complex partial seizures and were subjected to presurgical evaluation. The pattern of the interictal rCMRGlu in the TLE patients was different from that observed in patients with mTLE and showed significant depressions ipsilateral to the epileptic focus in mesial temporal and lateral temporal regions but spared the thalamus. The neocortical metabolic depressions were spatially more extended in right than in left TLE patients. Magnetic resonance images (MRI) were either normal (n = 5) or revealed unilateral or bilateral hippocampal atrophy/sclerosis (n = 7), or temporal or extratemporal focal cortical dysplasia (n = 4). The selected TLE patients presented here comprise a heterogeneous group showing most pronounced metabolic depressions in the lateral temporal cortex. Thus, our data suggest that non-invasive metabolic imaging can assist in identifying the neocortical symptomatogenic zone in putative temporo-perisylvian lobe epilepsy.     

Ictal SPECT in children with partial epilepsy due to focal cortical dysplasia

We studied the usefulness of ictal single-photon emission computed tomography in the presurgical evaluation of children with partial epilepsy resulting from focal cortical dysplasia. Fifteen children, age 1-18 years, were identified with partial epilepsy caused by focal cortical dysplasia (confirmed by histology) who underwent subtraction ictal single-photon emission computed tomography during presurgical evaluation. All children later underwent surgery at the Cleveland Clinic Epilepsy Center between 1996 and 2000. The findings of ictal single-photon emission computed tomography and brain positron emission tomography were classified as localized when "localizing and concordant" with the surgical resection site, nonconcordant when "localizing but not concordant" with the surgical resection, or nonlocalized when "no well-localized region of ictal hyperperfusion was observed on the difference image". In 15 patients, age 1.5-18 years (median age 8 years), epilepsy was classified as frontal in 7, posterior temporal/occipital in 3, temporal in 2, multilobar in 2, and parietal in 1. Of 15 patients, preoperative magnetic resonance imaging revealed focal cortical dysplasia in 11, positron emission tomography was localized in 9, and ictal single-photon emission computed tomography was localized in 8 patients. In 4 patients with normal magnetic resonance imaging but scalp electroencephalographic findings of partial epilepsy, ictal single-photon emission computed tomography and positron emission tomography were localized in 3 each. Fourteen patients were monitored for 6-39 months (mean 20 months). Six of 7 patients (85%) with localized ictal single-photon emission computed tomography compared with 4 of 7 (57%) with nonconcordant/nonlocalized ictal single-photon emission computed tomography had no seizures at follow-up. In 4 patients with normal magnetic resonance imaging, 3 patients with localized ictal single-photon emission computed tomography were free of seizures compared with 1 with nonconcordant ictal single-photon emission computed tomography who continued to have seizures. Ictal single-photon emission computed tomography is a useful adjunctive test in presurgical evaluation of children with refractory partial epilepsy due to focal cortical dysplasia, especially when brain magnetic resonance imaging is normal.     

Generalized nonconvulsive status epilepticus in symptomatic partial epilepsy

A 6-year-old male with cortical dysplasia who developed secondarily generalized nonconvulsive status epilepticus is reported. He had partial epilepsy since the age of 10 months. On electroencephalography, almost continuous left frontocentral/anterior temporal spikes were observed at 3 years of age, which lasted until 6 years of age, when he developed nonconvulsive status epilepticus. Nonconvulsive status epilepticus lasted for more than 7 days. Electroencephalography during nonconvulsive status epilepticus documented almost continuous generalized polyspike-wave complexes suggestive of generalized nonconvulsive status epilepticus. On magnetic resonance imaging, abnormal gyration was observed in the left frontal lobe. Histopathologic analysis of the resected left frontal lobe revealed cortical dysplasia. The present case demonstrates that continuous focal epileptiform discharges caused by cortical dysplasia in the frontal lobe can develop into secondarily generalized nonconvulsive status epilepticus.     

Medically refractory epilepsy associated with temporal lobe ganglioglioma: characteristics and postoperative outcome

OBJECTIVES: To define the postoperative seizure outcome and its predictors in patients with ganglioglioma-related temporal lobe epilepsy (TLE). PATIENTS AND METHODS: We reviewed the pre- and post-surgical evaluation data of 23 patients with temporal lobe ganglioglioma, who had completed >or=1 year of postoperative follow-up. They comprised 4.9% of the patients with TLE and 67.6% of the tumoral TLE operated in a developing country epilepsy center during an 8-year period. RESULTS: Median age at surgery was 20 years; median duration of epilepsy prior to surgery was 9 years. Magnetic resonance imaging (MRI) revealed tumor in mesial temporal location in 18 patients (78.3%) and in the lateral location in 2; in the remaining 3, involved both mesial and lateral regions. EEG abnormalities were localized to the side of lesion in the majority. Mesial temporal lobe structures were included in the resection, if they were involved by the tumor; otherwise, lesionectomy alone was performed. During a median follow-up of 4 years, 19 (82.6%) patients were completely seizure-free. Epileptiform abnormalities persisting in the 1-year postoperative EEG predicted unfavorable seizure outcome. CONCLUSION: We emphasize that, in patients with temporal lobe ganglioglioma, when the seizures are medically refractory, surgery offers potential for cure of epilepsy in the majority.     

Magnetic resonance imaging-based volume studies in temporal lobe epilepsy: pathological correlations

We performed a prospective study correlating magnetic resonance imaging volume measurements of the hippocampal formation with histopathology in 24 patients with intractable partial epilepsy who subsequently underwent an anterior temporal lobectomy for their seizure disorder. Patients with mass lesions verified pathologically were excluded from this study. In 71% of patients, quantitative hippocampal formation atrophy correctly lateralized the temporal lobe of seizure origin; in 29%, the volume study was indeterminant. The severity of the pathological alterations in the hippocampus correlated with the hippocampal formation volume determination. Mesial temporal sclerosis was identified in the surgically excised temporal lobe in 15 patients. The magnetic resonance imaging volume studies indicated hippocampal atrophy in the temporal lobe resected in 14 of the 15 patients. Magnetic resonance imaging-based volume measurements of the hippocampal formation increase the diagnostic yield of magnetic resonance imaging scanning in patients with intractable partial epilepsy related to mesial temporal sclerosis.     

Focal fast rhythmic epileptiform discharges on scalp EEG in a patient with cortical dysplasia.

A distinctive scalp electroencephalographic (EEG) pattern of focal fast rhythmic epileptiform discharges (FREDs) in a 23-year-old man with symptomatic localization related epilepsy is presented. Magnetic resonance imaging (MRI) of the brain revealed cortical dysplasia over the right temporal region where the peculiar EEG abnormality was detected. We suggest that this characteristic EEG pattern may be predictive of focal cortical dysplasia (FCD). A brief review of the rhythmic EEG abnormalities in FCDs is also presented.     

Magnetic resonance imaging and temporal lobe epilepsy

Surgical treatment is a well established option for patients with medically refractory temporal lobe epilepsy. Magnetic resonance imaging (MRI) has revolutionized the evaluation of these patients. New techniques can identify structural, metabolic and functional abnormalities associated with the epileptogenic zone. Mesial temporal sclerosis is the most common pathological finding and presents as hippocampal atrophy, which can be detected by visual inspection in most cases. Volumetric analysis of medial temporal structures offers the advantage of detecting bilateral abnormalities. Magnetic resonance spectroscopy can detect metabolic abnormalities associated with the epileptogenic focus. Functional MRI allows for the non-invasive evaluation of cognitive function, allowing for the localization of the neuroanatomic substrate of motor, sensory and cognitive functions. Intraoperative MRI-based image guided systems are a useful adjunct in the surgical treatment of this epileptic syndrome.     

MRI阴性的颞叶癫痫的外科治疗

目的 总结MRI阴性的颞叶癫痫的手术疗效.方法 对2004年4月至2009年12月间行前颞叶切除的并且MRI为阴性的32例颞叶癫痫患者的资料进行回顾性分析.包括术前检查、手术方式、术后病理及手术疗效.结果 Engel Ⅰ级为21例,占66％;EngelⅡ级为4例,占12％,EngelⅢ～Ⅳ级为7例,占22％,其中头皮视频脑电图痫波位于一侧颞叶的手术效果较好,86％可达到Engel Ⅰ级.结论 对MRI阴性的颞叶癫痫术前评估要更加全面,如检查结果趋于一致,手术效果良好,特别是癫痫样放电起源于一侧颞叶的手术效果更佳.     

术中1.5T核磁共振外科治疗难治性癫癎

目的探讨应用术中1.5T核磁共振(MRI)治疗难治性癫癎的手术效果。方法手术治疗难治性癫癎15例,利用术中1.5T核磁共振,术前常规行T1、T2及T1加强,及弥散张量成像,术中切除(切开)后行T1、T2及T1加强及弥散张量成像检查,以确定切除范围及功能区定位,其中5例术中MR检查后扩大切除。结果左侧枕叶局灶性皮质发育异常2例,左侧颞叶海绵状血管瘤4例,左侧颞叶海马硬化1例,右侧额叶胚胎发育不良性神经上皮肿瘤1例,右侧中央前回局灶性皮质发育不良1例,右侧颞叶海马硬化1例,右侧颞叶海绵状血管瘤1例,右侧颞叶胶质瘤1级1例,右侧中央后回海绵状血管瘤1例,胼胝体切开2例,engle分级:Ⅰ级11例,Ⅱ级4例。结论术中1.5T核磁共振对切除(切开)病灶及功能保护有指导意义。     

Electroclinical and magnetoencephalographic analysis of epilepsy in patients with congenital bilateral perisylvian syndrome

PURPOSE: Epilepsies in four patients with congenital bilateral perisylvian syndrome (CBPS) were studied electroclinically and by magnetoencephalography (MEG) to determine whether cortical dysplasia associated with this syndrome is epileptogenic. METHODS: We studied three women and one man (mean +/- SD age 30.8 +/- 3.4 years) with a diagnosis of CBPS based on magnetic resonance imaging (MRI). All had drug-resistant epilepsy. In addition to electroclinical analysis, the distribution of equivalent-current dipoles (ECDs) analyzed from MEG signals was examined. RESULTS: Patient 1 had left-sided parietal lobe epilepsy and ECDs clustered in the left temporoparietal lobe. Patient 2 had bilateral, independent temporoparietal lobe epilepsy, and ECDs were found in both hemispheres, with clustering in the right temporoparietal lobe but not in the left hemisphere. Patient 3 presumably had parietal lobe epilepsy with unidentified focus side and ECDs clustered in the left parietal and right temporal lobes. Patient 4 had symptomatic generalized epilepsy, and ECDs were observed in both hemispheres without clustering. In the three patients who had partial epilepsy (patients 1-3), clusters of ECDs overlaid the perisylvian dysplasia and were not found elsewhere. CONCLUSIONS: Patients with CBPS may have either symptomatic partial epilepsy or symptomatic generalized epilepsy, and those with partial epilepsy are likely to have temporoparietal foci. In addition, cortical dysplasia is closely related to the generation of partial seizures and may be epileptogenic per se. However, this study did not elucidate the relationship between cortical dysplasia and CBPS-generated generalized epilepsy.     

Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI

Purpose:   To determine the long-term efficacy of anterior temporal lobectomy for medically refractory temporal lobe epilepsy in patients with nonlesional magnetic resonance imaging (MRI).
Methods:   We identified a retrospective cohort of 44 patients with a nonlesional modern "seizure protocol" MRI who underwent anterior temporal lobectomy for treatment of medically refractory partial epilepsy. Postoperative seizure freedom was determined by Kaplan-Meyer survival analysis. Noninvasive preoperative diagnostic factors potentially associated with excellent surgical outcome were examined by univariate analysis in the 40 patients with follow-up of >1 year.
Results:   Engel class I outcomes (free of disabling seizures) were observed in 60% (24 of 40) patients. Preoperative factors associated with Engel class I outcome were: (1) absence of contralateral or extratemporal interictal epileptiform discharges, (2) subtraction ictal single photon emission computed tomography (SPECT) Coregistered to MRI (SISCOM) abnormality localized to the resection site, and (3) subtle nonspecific MRI findings in the mesial temporal lobe concordant to the resection.
Discussion:   In carefully selected patients with temporal lobe epilepsy and a nonlesional MRI, anterior temporal lobectomy can often render patients free of disabling seizures. This favorable rate of surgical success is likely due to the detection of concordant abnormalities that indicate unilateral temporal lobe epilepsy in patients with nonlesional MRI.     

A magnetization transfer imaging study in patients with temporal lobe epilepsy and interictal psychosis.

BACKGROUND: Findings from previous neuropathological and neuroimaging studies in patients with epilepsy and interictal psychosis have been inconclusive, and both focal and widespread brain abnormalities have been reported. Thus, further investigation with advanced in vivo magnetic resonance imaging (MRI) techniques, such as magnetization transfer imaging, capable of detecting more subtle brain abnormalities, is warranted. METHODS: Twenty patients with temporal lobe epilepsy and interictal psychosis were compared with 20 nonpsychotic patients. Patients were matched with respect to conventional MRI findings. Each group comprised of 10 patients with hippocampal sclerosis (6 left, 4 right) and 10 patients without focal lesions on MRI. A voxel-based analysis was used for the group comparisons. RESULTS: Voxel-based analysis revealed significant reductions of magnetization transfer ratio (an index of signal loss derived from magnetization transfer imaging) in the left superior and middle temporal gyri in the psychotic patients for the subgroup of patients with no focal lesions on MRI. There were no significant volumetric differences between the psychotic and nonpsychotic patients. CONCLUSIONS: Focal cortical magnetization transfer ratio abnormalities in the left temporal lobe unrelated to volume changes can be demonstrated in some temporal lobe epilepsy patients with interictal psychosis. Our findings might reflect subtle neuropathological abnormalities that are undetected by conventional MRI.     

Multimodality neuroimaging evaluation improves the detection of subtle cortical dysplasia in seizure patients

The purpose of this study is to investigate if multimodality neuroimaging evaluation increases the detection of subtle focal cortical dysplasia as part of an epilepsy surgery evaluation. Three patients with normal magnetic resonance imaging and histopathological findings of focal cortical dysplasia were reviewed. Their magnetoencephalography recordings were performed on whole-head magnetoencephalography system. Magnetic resonance images were re-evaluated with special inspection in limited regions guided by magnetoencephalography spike localization. Two patients had ictal and interictal single photon emission computed tomography study after administration of Tc99m ECD. In two patients we found tiny focal abnormalities including slightly increased cortical thickness and blurred gray-white matter junction at the locations of interictal events after re-evaluation of the MR images indicating focal cortical dysplasia. The third patient showed focal atrophic change. All patients are seizure free after surgery. Both ictal and interictal single photon emission computed tomography showed hyperperfusion in the dysplastic cortex regions. Multimodality neuroimaging study can improve the detection of focal cortical dysplasia. Normal magnetic resonance images should be re-evaluated for subtle signs of focal cortical dysplasia especially when magnetoencephalography recording demonstrate focal epileptic discharges.     

Parahippocampal epilepsy with subtle dysplasia: A cause of “imaging negative” partial epilepsy

Purpose: Lesion‐negative refractory partial epilepsy is a major challenge in the assessment of patients for potential surgery. Finding a potential epileptogenic lesion simplifies assessment and is associated with good outcome. Here we describe imaging features of subtle parahippocampal dysplasia in five cases that were initially assessed as having imaging‐negative frontal or temporal lobe epilepsy. Methods: We analyzed the clinical and imaging features of five patients with seizures from the parahippocampal region. Results: Five patients had subtle but distinctive magnetic resonance imaging (MRI) abnormalities in the parahippocampal gyrus. This was a unilateral signal abnormality in the parahippocampal white matter extending into gray matter on heavily T₁‐ and T₂‐weighted images with relative preservation of the gray–white matter boundary on T₁‐weighted volume sequences. Only one of these patients had typical electroclinical unilateral temporal lobe epilepsy (TLE); one mimicked frontal lobe epilepsy, two showed bitemporal seizures, and one had unlocalized partial seizures. All have had surgery; four are seizure‐free (one has occasional auras only, follow‐up 6 months to 10 years), and one has a >50% seizure reduction. Histopathologic evaluation suggested dysplastic features in the surgical specimens in all. Discussion: In patients with lesion‐negative partial epilepsy with frontal or temporal semiology, or in cases with apparent bitemporal seizures, subtle parahippocampal abnormalities should be carefully excluded. Recognizing the MRI findings of an abnormal parahippocampal gyrus can lead to successful surgery without invasive monitoring, despite apparently incongruent electroclinical features.     

The clinical spectrum of focal cortical dysplasia and epilepsy

Focal cortical dysplasia is an important pathologic substrate in patients with epilepsy, but its clinical spectrum has not yet been completely defined. We retrospectively studied 30 epilepsy surgery patients with focal abnormalities of neuronal migration as the only histopathologic finding in resected tissue. Patients comprised two clinical groups. Seventeen patients with extratemporal epilepsy had early (median age, 7.0 years) extratemporal resection or hemispherectomy for severe epilepsy (47% of patients with > 10 partial seizures a day) that began in infancy or early childhood (median age, 1.0 year), usually in the setting of mental retardation or developmental delay (59% of patients), and often with magnetic resonance imaging (MRI) evidence of focal neuronal migration abnormality (44% of patients). In contrast, 13 patients with temporal lobe epilepsy were significantly older at age of seizure onset (median, 8.0 years; p = 0.001) and surgery (median, 22.0 years; p = 0.001), with less severe epilepsy (no patients with an average of > 10 seizures a day; p = 0.004), and without mental retardation or MRI evidence of neuronal migration abnormality (p = 0.001). In both groups, positron emission tomography (PET) was more sensitive than MRI and showed focal hypometabolism in seven patients with normal MRI. Seizure-free outcome tended to be more common after temporal lobectomy (77%) than after extratemporal resection or hemispherectomy (53%). Pathologic abnormalities were more severe in patients with extratemporal epilepsy than in patients with temporal lobe epilepsy. The clinical spectrum of focal cortical dysplasia included not only infants and children with severe extratemporal epilepsy and mental retardation, but also older patients with temporal lobe epilepsy and at least boderline IQ. Preoperative diagnosis may be difficult in cases with less severe pathologic abnormality, but high-resolution MRI and PET can increase the yield.     

Language reorganization in early onset temporal lobe epilepsy

Behavioral and functional magnetic resonance imaging (fMRI) studies have consistently shown abnormalities of language function or cortical organization in patients with well-established temporal lobe epilepsy (TLE). However, whether these changes are present in new-onset TLE has not been studied to date. Studying such changes in new-onset TLE would provide valuable insight into the timing and factors that affect language deficits in TLE and may unmask fundamental differences in brain organization in persons who have TLE and those who do not.     

Assessment and surgical outcomes for mild type I and severe type II cortical dysplasia: A critical review and the UCLA experience

Recent findings on the clinical, electroencephalography (EEG), neuroimaging, and surgical outcomes are reviewed comparing patients with Palmini type I (mild) and type II (severe) cortical dysplasia. Resources include peer-reviewed studies on surgically treated patients and a subanalysis of the 2004 International League Against Epilepsy (ILAE) Survey of Pediatric Epilepsy Surgery. These sources were supplemented with data from University of California, Los Angeles (UCLA). Cortical dysplasia is the most frequent histopathologic substrate in children, and the second most common etiology in adult epilepsy surgery patients. Cortical dysplasia patients present with seizures at an earlier age than other surgically treated etiologies, and 33–50% have nonlocalized scalp EEG and normal magnetic resonance imaging (MRI) scans. 2-(¹⁸F)Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is positive in 75–90% of cases. After complete resection, 80% of patients are seizure free compared with 20% with incomplete resections. Compared with type I, patients with type II cortical dysplasia present at younger ages, have higher seizure frequencies, and are extratemporal. Type I dysplasia is found more often in adult patients in the temporal lobe and is often MRI negative. These findings identify characteristics of patients with mild and severe cortical dysplasia that define surgically treated epilepsy syndromes. The authors discuss future challenges to identifying and treating medically refractory epilepsy patients with cortical dysplasia.     

Focal cortical malformations can show asymmetrically higher uptake on interictal fluorine-18 fluorodeoxyglucose positron emission tomography (PET)

Interictal fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is a component of the presurgical evaluation of patients with medically intractable epilepsy, including patients with malformations of cortical development. The authors describe 3 cases of focal cortical malformations that displayed asymmetrically higher uptake on FDG-PET performed in the interictal state in patients undergoing evaluation for possible focal resection for refractory localization-related epilepsy. The evaluation included routine and prolonged video electroencephalography (EEG), magnetic resonance imaging (MRI), interictal FDG-PET with concurrent EEG, and single-photon emission computed tomography (SPECT). All 3 patients had focal cortical malformations on MRI corresponding to regions of asymmetrically higher uptake on FDG-PET. EEG confirmed that the FDG-PET studies were performed in the interictal state. The lesions included a large region of subcortical heterotopia in the right frontal lobe, a left temporal lobe dysplasia, and a region of subcortical heterotopia in the right occipital lobe. In both patients with subcortical heterotopia, there were other focal regions of cortical malformation that were not associated with abnormal or asymmetric uptake on FDG-PET. Previous reports describe decreased uptake on interictal PET in most cases of focal cortical malformations. Normal to increased uptake has been reported with band heterotopia. The authors demonstrate that other types of focal malformations of cortical development, including focal subcortical heterotopia and lobar dysplasia, can be associated with asymmetrically higher uptake on interictal FDG-PET.     

Surgical treatment of epilepsy associated with cortical dysplasia: 2012 update

Cortical dysplasia is the most common etiology in children and the third most frequent finding in adults undergoing epilepsy neurosurgery. The new International League Against Epilepsy (ILAE) classification grades isolated cortical dysplasia into mild type I (cortical dyslamination), severe type II (dyslamination plus dysmorphic neurons and balloon cells), and dysplasia associated with other epileptogenic lesions (type III). Multilobar type II lesions present at an earlier age and with more severe epilepsy compared with focal type I abnormalities, often in the temporal lobe, and these findings are reflected in types and age of operations for cortical dysplasia. Presurgical evaluation of patients with epilepsy from cortical dysplasia can be challenging. Interictal and ictal scalp electroencephalography (EEG) accurately localizes cortical dysplasia with 50-66% accuracy. Structural magnetic resonance imaging (MRI) is negative in roughly 30% of cases, most often linked with mild type I cases. FDG-PET can be 80-90% accurate, but is not 100% sensitive. Chronic intracranial electrodes are used in about 50% of cases with cortical dysplasia, but often do not capture restricted ictal-onset zones. About 60% of patients with cortical dysplasia are seizure free after epilepsy neurosurgery, with much higher rates of becoming seizure free with complete (80%) compared with incomplete (20%) resections. The most common reason for incomplete resection is the risk of an unacceptable neurologic deficit. Future challenges include better tools in identifying subtle forms of type I cortical dysplasia, and development of adjunctive treatments from basic research for those undergoing incomplete resections.     

Hippocampal sclerosis is a progressive disorder: a longitudinal volumetric MRI study

Twelve patients with refractory temporal lobe epilepsy and unilateral hippocampal sclerosis had repeat volumetric magnetic resonance imaging scans after a mean of 3.4 years to determine whether progressive hippocampal volume loss occurred. Seizure-free patients showed no change in hippocampal volume. Patients with continuing seizures had a decline in ipsilateral hippocampal volume that correlated with seizure frequency. Patients with medically refractory temporal lobe epilepsy and unilateral hippocampal sclerosis have progressive hippocampal atrophy.