颞叶内侧癫痫的两种术式对发作控制的对比分析

目的观察前颞叶切除术和选择性海马、杏仁核切除术对颞叶内侧癫痫的发作控制效果是否有差别。方法 2009年1月至2010年12月在我科行前颞叶切除术的67例颞叶内侧患者为A组;2011年6月至2013年5月在我科行选择性海马、杏仁核切除术的46例颞叶内侧患者为B组;统计分析两组术后1年发作控制为Engel I-II级和Engel III-IV级的人数。结果 A组Engel I-II级56例(83.58%),Engel III-IV级11例(16.42%);B组Engel I-II级40例(86.95%),Engel III-IV级6例(13.05%)。经χ2检验两组术后对MTLE发作的控制率无统计学差异,χ2=0.243,P0.05。结论前颞叶切除术和选择性海马、杏仁核切除术对颞叶内侧癫痫发作都能获得良好的控制,两者疗效无明显差异。     

Predictive value of MRI-identified mesial temporal sclerosis for surgical outcome in temporal lobe epilepsy: an intent-to-treat analysis

PURPOSE: Magnetic resonance imaging (MRI) accurately identifies mesial temporal sclerosis (MTS), but prediction of successful surgical outcome ranges from 62% to 96% in published studies. Prior investigations only used patients who had received anterior temporal lobectomy (ATL), potentially overestimating the predictive value of MRI-identified MTS (MRI-MTS). METHODS: The authors performed an intent-to-treat analysis of 90 consecutive patients assessed for possible ATL, including 13 who did not undergo ATL because of inconclusive intracranial ictal EEG. Four (31%) of these 13 patients had unilateral mesial temporal abnormalities on their MRIs. RESULTS: The positive predictive value of MRI-MTS for seizure cessation decreased from 0.69 to 0.63 after adjustment for these additional false positive results. Four previous studies had revealed a positive predictive value of 0.75 (0.72 after similar adjustment). CONCLUSIONS: The authors conclude that the predictive value of MRI-MTS for outcome from ATL may be overestimated by small retrospective studies of highly selected postoperative patients.     

前颞叶切除术或选择性海马杏仁核切除术治疗顽固性内侧颞叶癫痫患者神经心理功能改变的研究

目的 探讨前颞叶切除术(ATL)或选择性海马杏仁核切除术(SAH)治疗顽固性内侧颞叶癫痫(MTLE)患者神经心理功能的改变情况。方法 选择2010年1月-2014年12月来本院接受ATL或SAH治疗的MTLE患者60例; 根据MTLE手术部位分为左颞部MTLE组(n=35)和右颞部MTLE组(n=25); 利用神经心理功能评分系统(DST、VMPT、WMSLM、WMS视觉、BNT、视觉技能、Stroop、WCST、分类、VFT)对患者术前及术后1年神经心理功能进行评分,比较2组患者左右颞部手术前后神经心理测试及手术前后左右颞部神经心理测试差异。结果 60例MTLE患者中35例(58.33%)左颞部MTLE,25例(41.67%)右颞部MTLE; 2组患者在性别、年龄、手术方式、癫痫发作平均年龄、病程、术前WAIS评分方面无显著性差异(P>0.05); 2组患者左右颞部手术前后神经心理测试比较显示,右颞部MTLE组术后在最大学习得分、短时记忆得分、长时记忆得分、第5卡片时间、矫正、转换错误方面与术前比较有显著差异(P<0.05); 左颞部MTLE组术后在合计得分方面与术前比较有显著差异(P<0.05); 2组患者手术前后左右颞部神经心理测试比较显示,左颞部MTLE组在回忆得分、识别得分、短时记忆得分方面显著高于右颞部MTLE组(P<0.05)。结论 尽管ATL或SAH治疗顽固性MTLE患者会引起部分常见的认知副作用,但该手术治疗也可提高患者部分认知功能。     

Ictal spiking patterns recorded from temporal depth electrodes predict good outcome after anterior temporal lobectomy

PURPOSE: Investigators have shown that the presence of ictal spiking (IS) recorded from temporal depth electrodes is associated with mesial temporal sclerosis (MTS). We investigated the relation of IS to seizure control and pathology after anterior temporal lobectomy (ATL). METHODS: All patients undergoing intracranial ictal monitoring from a single institution since 1989 were identified. Those who did not undergo ATL or had postoperative follow-up of <1 year were excluded. All received at a minimum bilateral temporal depth electrodes. Ictal recordings were reviewed for the presence of IS, and the proportion of seizures with IS was determined for each patient. Outcome was determined by using Engel's classification. Surgical specimens were reviewed for pathology. Statistics used were chi2, Fisher exact test, and Wilcoxon rank sum. RESULTS: Forty patients with 571 seizures were reviewed. In 292 seizures from 32 patients, IS was seen. Outcomes were 24 class I (22 with IS), five class II (four with IS), three class III (one with IS), seven class IV (four with IS), and one lost to follow-up (with IS). Pathologic review revealed 25 with MTS, 22 of whom had IS. The presence of IS was associated with class I outcomes (p = 0.04), but not MTS (p = 0.06). Patients with class I outcomes had a significantly greater proportion of seizures with IS (mean, 0.58 +/- 0.3) compared with other outcomes (mean, 0.30 +/- 0.3, p = 0.02). CONCLUSIONS: The presence of IS and higher proportion of seizures with IS correlated with good seizure outcome after ATL. This information may be used in preoperative counseling.     

Preoperative IQ predicts seizure outcomes after anterior temporal lobectomy

PurposeIQ tests are frequently used in the preoperative neuropsychological assessment of candidates for anterior temporal lobectomy (ATL). We reviewed IQ test results and surgery outcomes to evaluate the roles of IQ tests in the preoperative work-up.MethodsA total of 205 adult patients who had undergone ATL and whose seizure outcomes were followed for 2 years after surgery were included. The short form WAIS-R was used to estimate intelligence. Multiple linear regression and logistic regression analyses were used to examine the variables for IQ and seizure outcomes.ResultsEducation, duration of epilepsy and gender were factors that accounted for 24.6% of the variance in the full-scale IQ (FSIQ) scores. The verbal IQ and performance IQ discrepancies at various magnitudes could not lateralize the seizure foci. Freedom of seizure was noted in 128 (62.4%) of the patients. Seizure outcomes, however, correlated with the preoperative FSIQ. After adjustment for variables that affect seizure outcomes, the FSIQ was an independent predictor of postoperative seizure outcomes (OR 1.04, 95% CI 1.01–1.06, p = 0.003). Of patients who had FSIQ lower than 70, 50% became free from seizures by 2 years after surgery.ConclusionsIn our study, IQ tests were unable to lateralize seizure foci but may serve as an independent predictor of postoperative seizure outcomes. Since a longer duration of epilepsy had deleterious effects on intelligence, earlier surgical intervention might better preserve neuropsychological function and, consequently, allow better seizure control after ATL. Nonetheless, patients with lower IQ scores could still benefit from ATL.     

Prognostic factors in anterior temporal lobe resections for mesial temporal lobe epilepsy: multivariate analysis

PURPOSE: Even though there have been several studies on the prognostic factors of temporal lobe epilepsy (TLE) after lobectomy, no studies have been performed for homogeneous mesial TLE. Furthermore, most studies on the predictors of outcome of epileptic surgery were based on univariate analyses and did not consider modern epileptic surgery investigation modalities such as brain magnetic resonance imaging (MRI) and positron emission tomography (PET). We attempted to identify the prognostic factors in anterior temporal lobectomy (ATL) for mesial TLE with multivariate analysis. METHODS: Ninety-three patients with mesial TLE (54 men and 39 women, mean age at surgery, 28.3 +/- 8.2 years) were included in the study. The primary outcome variable was the status of patients in the second postoperative year, classified as either seizure free (except aura), or not seizure free. Clinical, electroencephalographic, MRI, PET, Wada test, and pathological data were considered. RESULTS: Seventy-eight (84.0%) patients had remission of seizures. With univariate analysis, age at surgery (p < 0.001), epilepsy duration before surgery (p = 0.04), and ipsilateral hippocampal sclerosis on MRI (p = 0.02) were found to be significant. By using multivariate analysis, age at surgery (p = 0.001) and ipsilateral hippocampal sclerosis on MRI (p = 0.03) were found to be the most significant prognostic factors. CONCLUSIONS: Age at surgery and hippocampal sclerosis are independent prognostic factors for ATL in mesial TLE. These findings suggest that mesial TLE may be a progressive disorder, and surgical outcome is better when early ATL is performed.     

Impaired facial emotion recognition in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS): Side and age at onset matters

To define the determinants of impaired facial emotion recognition (FER) in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS), we examined 76 patients with unilateral MTLE-HS, 36 prior to antero-mesial temporal lobectomy (AMTL) and 40 after AMTL, and 28 healthy control subjects with a FER test consisting of 60 items (20 each for anger, fear, and happiness). Mean percentages of the accurate responses were calculated for different subgroups: right vs. left MTLE-HS, early (age at onset <6 years) vs. late-onset, and before vs. after AMTL. After controlling for years of education, duration of epilepsy and number of antiepileptic drugs (AEDs) taken, on multivariate analysis, fear recognition was profoundly impaired in early-onset right MTLE-HS patients compared to other MTLE patients and control subjects. Happiness recognition was significantly better in post-AMTL MTLE-HS patients compared to pre-AMTL patients while anger and fear recognition did not differ. We conclude that patients with right MTLE-HS with age at seizure onset <6 years are maximally predisposed to impaired fear recognition. In them, right AMTL does not further worsen FER abilities. Longitudinal studies comparing FER in the same patients before and after AMTL will be required to refine and confirm our cross-sectional observations.     

Hippocampal deformation-based shape analysis in epilepsy and unilateral mesial temporal sclerosis

PURPOSE: To assess shape changes in patients with mesial temporal sclerosis (MTS) and temporal lobe epilepsy (TLE), by using deformation-based hippocampal shape analysis. METHODS: We retrospectively reviewed magnetic resonance imaging (MRI) studies in 30 subjects with unilateral MTS (15 right-sided MTS, 15 left-sided MTS) and TLE. We defined the "average" hippocampus in the right- and left-MTS groups by generating a mean transformation for the 15 deformation images in each group. Further to quantify the difference between the hippocampi, we coregistered the mean transformation of the involved hippocampus (with MTS) to the contralateral hippocampus, considering the left- and right-MTS groups independently. We generated a color "flame" scale showing degrees of outward and inward deviation of the coregistered hippocampi. RESULTS: Both the right- and left-MTS groups showed similar shape changes, with maximal inward deformation in the medial and lateral hippocampal head and the hippocampal tail. However, more extensive involvement was seen in the lateral hippocampal body in the right-MTS group as compared with the left. CONCLUSIONS: Deformation-based hippocampal shape analysis shows specific regions of hippocampal surface anatomy that are most affected in MTS. This technique may aid in detection of clinically significant anatomic abnormalities of the hippocampus in patients with epilepsy.     

Good surgical outcome in discordant ictal EEG-MRI unilateral mesial temporal sclerosis patients

Purpose: Video electroencephalography (vEEG) monitoring of patients with unilateral mesial temporal sclerosis (uMTS) may show concordant or discordant seizure onset in relation to magnetic resonance imaging (MRI) evidence of MTS. Contralateral seizure usually leads to an indication of invasive monitoring. Contralateral seizure onset on invasive monitoring may contraindicate surgery. We evaluated long-term outcome after anteromesial temporal lobectomy (AMTL) in a consecutive series of uMTS patients with concordant and discordant vEEG findings, uniformly submitted to AMTL on the MRI evidence of MTS side without invasive monitoring.
Methods: We compared surgical outcome of all uMTS patients undergoing vEEG monitoring between January 1999 and April 2005 in our service. Discordant cases were defined by at least one seizure onset contralateral to the MRI evidence of MTS. Good surgical outcome was considered as Engel's class I. We also evaluated ictal SPECT concordance to ictal EEG and surgical outcome.
Results: Fifty-four patients had concordant (C) and 22 had discordant (D) scalp EEG and MRI. Surgical outcome was similar in both groups (C = 74% versus D = 86%). Duration of follow-up was comparable in both groups: C = 56.1 ± 20.7 months versus D = 59.8 ± 21.2 months (p = 0.83, nonsignificant). Discordant single-photon emission computed tomography (SPECT) results did not influence surgical outcome.
Discussion: Surgical outcome was not influenced by contralateral vEEG seizure onset or contralateral increased flow on ictal SPECT. Although vEEG monitoring should still be performed in these patients, to rule out psychogenic seizures and extratemporal seizure onset, a potentially risky procedure such as invasive monitoring may not only not be indicated in this patient population, but may also lead to patients erroneously being denied surgery.     

Surgery for temporal lobe epilepsy associated with mesial temporal sclerosis in the older patient: A long‐term follow‐up

Purpose: To assess the outcomes from temporal lobectomy for hippocampal sclerosis in patients 50 years or older. Controversy exists as to the suitability of older patients for epilepsy surgery, with most of the previous studies demonstrating a correlation between increasing age and poor outcome. However, the inclusion of temporal lobe epilepsy of multiple etiologies has confounded many previous studies of this age group. Methods: Twenty‐one patients aged 50 years or older (mean 54.9 years) at the time of surgery were included in the study group. All patients had a pathologic diagnosis of hippocampal sclerosis. A retrospective analysis was performed comparing seizure outcomes following a standardized anterior temporal lobectomy with those from 103 patients younger than 50 (mean age 34.7 years) operated upon over the same time period. The mean follow‐up period for the study was 9.57 years. Results: Twenty of the 21 patients in the older group (95.2%) had a satisfactory seizure outcome (Engel classes I and II) compared with 90.3% of the younger patients. There was no statistically significant difference in the outcomes between the two groups (p = 0.719). Across both groups of patients combined, there was no significant difference between the mean age in the patients with a satisfactory seizure outcome compared to those with an unsatisfactory outcome (38.3 vs. 34.7 years, p = 0.213). Discussion: Patients 50 years or older with intractable seizures from hippocampal sclerosis have seizure outcomes following temporal lobectomy that are comparable to young patients over the long term. Older patients should not be denied treatment on the basis of age.     

Outcome after cortico-amygdalo-hippocampectomy in patients with severe bilateral mesial temporal sclerosis submitted to invasive recording

IntroductionAlthough some degree of bilateral hippocampal involvement might be frequent in patients with temporal lobe epilepsy, severe bilateral mesial temporal sclerosis (MTS) is very rare. We present our experience while treating patients with severe bilateral MTS submitted to invasive recordings.MethodsNine adult patients were studied. All patients had simple and complex partial seizures. All patients had bilateral independent interictal temporal lobe spiking and non-lateralizing video-EEG findings. MRI showed severe bilateral MTS and no other brain lesion. All patients had severe verbal and non-verbal memory deficits. All patients were submitted to invasive recordings after bilateral subdural grids implantation. Cortico-amygdalo-hippocampectomy (CAH) was performed in all patients on the side suggested by invasive recording. Follow-up time ranged from 5 to 10 years.ResultsInvasive video-EEG showed exclusively unilateral seizure onset in seven patients; in two patients, seizures originating from both temporal lobes were found (80% of them originated from one side). Five patients were submitted to left and four to right CAH. Seven patients were rendered seizure-free after surgery (Engel I); the other two were rated as Engel II. There was no additional memory decline. There was no surgical morbidity or mortality. Pathological examination showed MTS in all patients.DiscussionGood surgical outcome (77% seizure-free patients) could be obtained even in this apparently unsuitable group of patients. All patients benefit from the procedure. We did not see any cognitive decline in our patients with severe bilateral MTS. Patients with severe bilateral MTS would need invasive recordings despite any findings during surface video-EEG.     

Outcome after corticoamygdalohippocampectomy in patients with refractory temporal lobe epilepsy and mesial temporal sclerosis without preoperative ictal recording

Purpose:   We report on the surgical outcome obtained in patients with refractory temporal lobe epilepsy with mesial temporal sclerosis (MTS) who were evaluated preoperatively without ictal recording and were submitted to corticoamygdalohippocampectomy.
Methods:   Two hundred twelve patients with refractory temporal lobe epilepsy were evaluated by means of clinical history, neurological examination, interictal electroencephalography (EEG), magnetic resonance imaging (MRI), and neuropsychological testing. MRI disclosed unilateral MTS in all patients. All patients were submitted to corticoamygdalohippocampectomy at the side determined by MRI.
Results:   Interictal EEG showed unilateral temporal lobe spiking in 176 patients; in 36 patients, bilateral discharges were found. Mean follow-up time was 2.7  years. One hundred ninety-four patients (92%) were classified as Engel's class I. Eighteen patients (8%) were rated as Engel's class II. Thirty-two out of 36  patients, in whom bilateral discharges were found, were in Engel's class I. Sixty percent of the patients had an improvement in memory function related to the nonoperated temporal lobe. Fifty-nine percent of the patients had a 10-point increase in general IQ postoperatively. Verbal memory decline was noted in three patients. Pathological examination showed MTS in all patients.
Conclusions:   It is possible to adequately select good surgical candidates for temporal lobe resection using MRI and interictal EEG alone. In patients with MRI-defined MTS, we should expect a 90% postoperative remission rate. Cognitive decline was very rarely seen in this patient population. The finding of MTS on MRI is the single most important prognostic factor for good outcome after temporal lobe surgery.     

不同术式选择对颞叶癫痫患者术后记忆功能影响的初步探讨

目的探讨不同术式选择对颞叶癫痫患者术后记忆功能的影响。方法 2009~2013年共248例海马硬化性颞叶癫痫患者在我院接受手术治疗,其中83例行标准前颞叶切除术(anterior temporal lobectomy,ATL),165例行选择性海马杏仁核切除术(selective amygdalohippocampectomy,SAH)。患者在术前、术后3个月及术后两年分别接受临床记忆功能评估。结果 ATL组和SAH组优势半球侧手术的患者临床记忆商数(memory quotient,MQ)在术后3个月(74.5±16.2,75.6±19.5)均有明显下降(P0.05),术后两年(75.1±14.1,76.1±17.6)略有恢复但仍然显著低于术前(82.9±15.8,83.2±21.2)(P0.05),其中SAH组术后3个月及术后两年相较术前MQ的减低程度都小于ATL组(7.6 vs.8.4;7.1 vs.7.8);ATL组和SAH组非优势半球侧手术的患者术后3个月的MQ(87.2±15.1,88.1±16.9)均高于术前(85.5±13.5,85.3±19.7),但无统计学意义,至术后两年时,两组患者的MQ(92.8±12.7,93.7±17.1)对比术前都有了显著的改善(P0.05),其中SAH组患者的改善幅度较ATL组略大(8.4 vs.7.3)。结论相比于ATL,SAH可能更有利于保护海马硬化性颞叶癫痫患者的术后记忆功能。     

The seizure outcome after amygdalohippocampectomy and temporal lobectomy

The aim of this study was to compare the seizure outcome of two different types of epilepsy surgery, selective amydalohippocampectomy (AHE) and anterior temporal lobectomy (ATLE) in patients with temporal lobe epilepsy. We included 114 patients who had mesio-temporal lobe epilepsy and hippocampal sclerosis or gliosis on histology. Patients had ATLE if the non-dominant hemisphere was affected or if the whole temporal lobe was atrophic. Patients had AHE if the dominant hemisphere was affected. Standardized seizure outcome at 1 year following surgery was used. Overall 40% of the 114 patients who had temporal lobe epilepsy surgery were seizure-free at 1-year (Engel's class Ia). A good outcome (Engel's classes I and II) was significantly more frequent in ATLE than in AHE. (66% and 44%, respectively, P  = 0.03). ATLE had a better seizure outcome than AHE.     

术前MRI检查与颞叶癫痫切除手术短期预后的关系

目的 评价术前MRI检查与难治性颞叶癫痫经过手术切除治疗后短期内预后关系. 方法 中国医科大学附属盛京医院神经外科自2009年1月至2010年12月共收治通过临床发作症状学以及视频脑电图诊断为颞叶癫痫的患者34例,按照MRI检查有无病灶分为2组,其中有病灶组18例,未发现病灶组16例.手术治疗后半年及1年,按照国际抗癫痫联盟(ILAE)术后疗效评估分类法判断2组患者不同预后情况. 结果 34例患者中术后半年达到ILAE-1级的有23例,占67.6％;术后1年达到ILAE-1级的有20例,占58.8％.其中有病灶组患者术后半年达到ILAE-1级的有16例,占88.9％;术后1年有14例,占77.8％;未发现病灶组患者术后半年达到ILAE-1级的有7例,占43.75％;术后1年有6例,占37.5％;差异均有统计学意义(P＜0.05). 结论 外科手术治疗对于颞叶难治性癫痫是一种有效的治疗方式;MRI检查阳性的颞叶癫痫患者宜积极行手术治疗.     

Tailored anteromedial lobectomy in the treatment of refractory epilepsy of the temporal lobe: long term surgical outcome and predictive factors

OBJECTIVE: To analyze long-term results and to determine prognostic factors on seizure outcome in a series of patients with temporal lobe epilepsy (TLE) who underwent anteromedial temporal lobectomy (AMTL). MATERIALS AND METHODS: From 1995 to 1998 forty-two patients suffering from non-lesional TLE underwent tailored AMTL at our Institution. We retrospectively reviewed surgical results and calculated predictive factors of good outcome in the long term. RESULTS: Sixty-four percent of patients were rendered seizure free (median follow up 60 months). Eleven cases (26.2%) had a significant reduction of disabling epileptic episodes. Poor seizure control was observed in four patients (9.5%). Overall surgical morbidity was 4.7%. Medial temporal sclerosis (MTS) was the most common histopathological finding (69% of cases). The presence of unilateral hippocampal abnormalities on qualitative MRI was significantly associated with excellent postoperative outcome (p<0.011). Qualitative preoperative MRI had a positive predictive value of 83% in detecting both MTS at pathological examination and excellent outcome. CONCLUSIONS: Tailored AMTL is a safe and effective procedure in the treatment of selected patients with medically refractory TLE. Data from preoperative qualitative MRI well correlated with histopathological findings. The presence of unilateral hippocampal atrophy on qualitative MRI was predictive of excellent outcome in the long-term follow up.     

Late-onset temporal lobe epilepsy with unilateral mesial temporal sclerosis and cognitive decline: A diagnostic dilemma

We present a patient with new onset temporal lobe epilepsy and cognitive decline in his sixth decade with unilateral hippocampal atrophy on structural brain imaging, compatible with mesial temporal sclerosis. This unusual clinical scenario presented a challenging differential diagnosis since it may overlap with primary cognitive disorders, including early-onset Alzheimer's disease and some forms of frontotemporal dementia, and the recently elucidated syndrome of non-paraneoplastic limbic encephalitis associated with voltage-gated potassium channel antibodies.     

术中皮层脑电图在颞叶癫痫手术中的应用

目的 探讨术中皮层脑电图(ECoG)在颢叶癫痫手术中的应用价值.方法 回顾性分析105例前颞叶切除手术患者的临床资料与ECoG的监测结果,统计对ECoG的影响因素及其对手术疗效的影响.结果 术前ECoG平均监测时间为72 min,结果显示:无异常11例、颢叶或前颞叶局限性放电73例、广泛痫性放电21例;术后ECoG平均监测时间为38 min,结果显示:无异常91例、颞叶后部痫性放电9例、广泛痫性放电5例.年龄与术前EcoG结果无明显相关性;而病程＜5年者术前EcoG痫性放电局限于前颞叶的比率较高,达到83.3%,且与另外两组差异有统计学意义.有6例(5.7%)根据术后ECoG结果行颞叶皮层后部扩大切除.术前ECoG显示痫性放电局限于前颞叶和术后ECoG正常与其他同期结果间的手术疗效差异有统计学意义,提示术后无癫痫发作.结论 颞叶癫痫患者ECoG监测可发现70%的痫波局限于前颞区,术前和术后ECoG监测结果可用于初步判断手术疗效,ECoG监测对颞叶癫痫手术具有一定的应用价值.     

Possible autoantibody-negative limbic encephalitis after anterior temporal lobectomy for hippocampal sclerosis

Purpose: Amnestic syndromes are acknowledged to be associated to bilateral hippocampal damage.

Materials and methods: We briefly report the case of a young man who underwent anterior left temporal lobectomy for a medically refractory temporal lobe epilepsy due to hippocampal sclerosis with an excellent seizure and neuropsychological outcome. Approximately 10 years later, he presented with a subacute severe global amnesia and neuroimaging findings of a damage involving the contralateral mesial temporal lobe structures.

Results: A diagnosis of a possible autoimmune encephalitis was made.

Conclusions: Due to its peculiarities (compared with other cases of bilateral temporal lesions, the damage occurred on two distinct occasions), this case might contribute to shed light on the issue of the possible contralateral reorganization of memory processes subserved by the mesial temporal lobe structures chronically involved in epileptogenesis.