Poor presurgical performance on both verbal and visual memory measures is associated with low risk for memory decline following left temporal lobectomy for intractable epilepsy

Studies have shown a lower risk for verbal memory decline following dominant anterior temporal lobectomy (ATL) among patients with poor, presurgical verbal memory scores. It is unclear however, if the risk of decline is increased in patients who also have reduced visual memory. Objective and subjective memory outcome following left ATL was examined in twelve patients with reduced presurgical visual and verbal memory scores. Only one patient demonstrated a meaningful decline in memory scores, with a decline in visual memory following surgery. Presurgically, this patient demonstrated poor memory bilaterally on Wada testing and small discrepancy in hippocampal volumes. She was also one of two patients who continued to have seizures post-surgery. This preliminary study suggests that patients with unilateral, left TLE and poor verbal and visual memory are unlikely to show meaningful memory declines following left ATL, particularly if they demonstrate expected patterns on Wada testing, hippocampal volume discrepancy (left < right), and postsurgical seizure-freedom.     

Resection extent versus postoperative outcomes of seizure and memory in mesial temporal lobe epilepsy

OBJECTIVES: To investigate the effects of the resection of hippocampus and temporal neocortex on postsurgical seizure and memory outcomes in mesial temporal lobe epilepsy (mTLE) patients. METHODS: Sixty-eight mTLE patients underwent pre- and postsurgical brain magnetic resonance imaging (MRI). The patients were divided into seizure-free group (SF, N=54) and non-seizure-free group (NSF, N=14). The resection length of hippocampus was determined by the difference between presurgical and postsurgical hippocampus lengths in MRIs. The lengths of resected temporal gyri were measured on three-dimensional MRI reconstruction. Among SF group, 37 patients performed pre- and postsurgical neuropsychological tests. The postsurgical memory decline (PMD) was calculated by subtracting postsurgical memory score from presurgical one in verbal and visual memory tests. RESULTS: The resection length of hippocampus in SF was significantly longer than in NSF (32.7 +/- 7.7 mm versus 25.1 +/- 7.3 mm, t-test, p=0.002), regardless of intersubject difference in the extent of hippocampal sclerosis (logistic regression, p=0.003) while the resection lengths of the lateral temporal gyri were not different between SF and NSF. Overall postsurgical change of verbal or visual memory was not significant. However, regression analysis showed a significant correlation between the resection length of inferior or basal temporal gyrus and verbal PMD (p<0.001) in left TLE patients with seizure-free outcome. CONCLUSION: More resection of hippocampus may predict a better postsurgical seizure-free outcome. The larger resection of inferior or basal temporal gyrus seems to be related to a postsurgical verbal memory decline in left TLE patients.     

Memory, emotional and vocational impairments before and after anterior temporal lobectomy for complex partial seizures

PURPOSE: To assess the pre- and postsurgical frequency of memory, emotional, and vocational impairments in patients who underwent anterior temporal lobectomy (ATL), and to assess the relationship between emotional disturbance and memory abilities after ATL. METHODS: Retrospective analysis of data was performed on 90 patients with medically intractable complex partial seizures who underwent ATL between 1981 and 2003. Patients were evaluated an average of 5 months before surgery and 11.3 months after surgery. RESULTS: A moderate to high frequency of memory impairment (44.4%; verbal or nonverbal), emotional disturbance (38.9%) and unemployment (27.8%) existed in the same individuals both before and after surgery. There were small to moderate rates of new onset memory (18.9%), emotional (11.1%), and vocational (7.8%) difficulties after surgery often regardless of seizure control outcome. Patients who underwent left-ATL and had emotional disturbance after surgery had the lowest verbal memory test scores. CONCLUSIONS: Results highlight the importance of taking into account emotional status when assessing memory abilities after ATL. Results replicate the finding of moderate to high frequencies of memory impairment, emotional disturbance, and unemployment both before and after ATL. Results provide support for the rationale that cognitive, psychiatric and vocational interventions are indicated to mitigate the problems that exist before and persist after ATL.     

Evaluating the contributions of state-of-the-art assessment techniques to predicting memory outcome after unilateral anterior temporal lobectomy

PURPOSE: Although anterior temporal lobectomy (ATL) is an effective treatment for many patients with medically refractory temporal lobe epilepsy (TLE), one risk associated with this procedure is postsurgical decline in memory. A substantial number of past studies examined factors that predict memory decline after surgery, but few have investigated multiple predictors simultaneously or considered measures that are currently in use. METHODS: This study compared the relative contributions made by presurgical neuropsychological test scores, MRI-based hippocampal volumetric analysis, and Wada test results to predicting memory outcome after ATL in a group of 87 patients. RESULTS: Logistic regression analyses indicated that noninvasive procedures (neuropsychological testing and MRI) made significant contributions to improving the prediction of memory outcome in this sample. The results from the Wada procedure did not significantly improve prediction once these other factors were considered. The only exception was in predicting memory for visual information after a delay, in which Wada results improved prediction accuracy from 78% to 81%. CONCLUSIONS: Current neuropsychological tests and MRI volumetric measures predict changes in verbal and visual memory after ATL. The relatively small change in correct classification rates when Wada memory scores are considered calls into question the benefits of using Wada test results to predict memory outcome when the results of noninvasive procedures are available.     

Individual Memory Change After Anterior Temporal Lobectomy: A Base Rate Analysis Using Regression-Based Outcome Methodology

Summary: Purpose: To characterize patterns of base rate change on measures of verbal and visual memory after anterior temporal lobectomy (ATL) using a newly developed regression-based outcome methodology that accounts for effects of practice and regression towards the mean, and to comment on the predictive utility of baseline memory measures on postoperative memory outcome. Methods: Memory change was operationalized using regression-based change norms in a group of left (n = 53) and right (n = 48) ATL patients. All patients were administered tests of episodic verbal (prose recall, list learning) and visual (figure reproduction) memory, and semantic memory before and after ATL. Results: ATL patients displayed a wide range of memory outcome across verbal and visual memory domains. Significant performance declines were noted for 25–50% of left ATL patients on verbal semantic and episodic memory tasks, while one-third of right ATL patients displayed significant declines in immediate and delayed episodic prose recall. Significant performance improvement was noted in an additional one-third of right ATL patients on delayed prose recall. Base rate change was similar between the two ATL groups across immediate and delayed visual memory. Approximately one-fourth of all patients displayed clinically meaningful losses on the visual memory task following surgery. Robust relationships between preoperative memory measures and nonstandardized change scores were attenuated or reversed using standardized memory outcome techniques. Conclusions: Our results demonstrated substantial group variability in memory outcome for ATL patients. These results extend previous research by incorporating known effects of practice and regression to the mean when addressing meaningful neuropscyhological change following epilepsy surgery. Our findings also suggest that future neuropsychological outcome studies should take steps towards controlling for regression-to-the-mean before drawing predictive conclusions.     

Neuropsychological Profile in Children with Posterior Fossa Tumors with or Without Postoperative Cerebellar Mutism Syndrome (CMS)

Cerebellar mutism syndrome (CMS) is a common surgical sequela in children following posterior fossa tumor (PFT) resection. Here, we analyze the neuropsychological features associated with PFT in children, focusing particularly on the differential profiles associated with the presence or absence of CMS after surgery. We further examine the effect of post-resection treatments, tumor type, and presence/absence of hydrocephalus on surgical outcome. Thirty-six patients diagnosed with PFT (19 with and 17 without CMS) and 34 age- and gender-matched healthy controls (HCs) were recruited. A comprehensive neuropsychological evaluation was conducted in all patients postoperatively and in HCs, including an assessment of general cognitive ability, motor skills, perception, language, memory, attention, executive functions, and academic competence. CMS was found to be a clinical marker of lower neuropsychological profile scores across all cognitive domains except auditory-verbal processing and visual memory tasks. PFT patients not presenting CMS exhibited milder impairment in intellectual functioning, motor tasks, reasoning, language, verbal learning and recall, attention, cognitive executive functions, and academic competence. High-grade tumors were associated with slower processing speed and verbal delayed recall as well as alterations in selective and sustained attention. Hydrocephalus was detrimental to motor functioning and nonverbal reasoning. Patients who had undergone surgery, chemotherapy, and radiotherapy presented impaired processing speed, verbal learning, and reading. In addition to the deleterious effects of PFT, post-resection PFT treatments have a negative cognitive impact. These undesired consequences and the associated tumor-related damage can be assessed using standardized, long-term neuropsychological evaluation when planning rehabilitation.     

A comparison of two fMRI methods for predicting verbal memory decline after left temporal lobectomy: Language lateralization versus hippocampal activation asymmetry

Purpose: Language lateralization measured by preoperative functional magnetic resonance imaging (fMRI) was shown recently to be predictive of verbal memory outcome in patients undergoing left anterior temporal lobe (L‐ATL) resection. The aim of this study was to determine whether language lateralization or functional lateralization in the hippocampus is a better predictor of outcome in this setting. Methods: Thirty L‐ATL patients underwent preoperative language fMRI, preoperative hippocampal fMRI using a scene encoding task, and pre‐ and postoperative neuropsychological testing. A group of 37 right ATL (R‐ATL) surgery patients was included for comparison. Results: Verbal memory decline occurred in roughly half of the L‐ATL patients. Preoperative language lateralization was correlated with postoperative verbal memory change. Hippocampal activation asymmetry was strongly related to side of seizure focus and to Wada memory asymmetry but was unrelated to verbal memory outcome. Discussion: Preoperative hippocampal activation asymmetry elicited by a scene encoding task is not predictive of verbal memory outcome. Risk of verbal memory decline is likely to be related to lateralization of material‐specific verbal memory networks, which are more closely correlated with language lateralization than with overall asymmetry of episodic memory processes.     

Changes in individual and group spatial and verbal learning characteristics after anterior temporal lobectomy

Purpose:   To evaluate the effects of anterior temporal lobectomy (ATL) on individual and group spatial and verbal learning and memory abilities as a function of side of surgery and seizure control outcome.
Methods:   We evaluated pre- and postsurgical learning and memory abilities of 75 left-hemisphere language dominant individuals who underwent ATL (33 left, 42 right) using the 8-trial Nonverbal Selective Reminding test and the 12-trial Verbal Selective Reminding test.
Results:   Reliable change index methods indicated that 40.5% of individuals who underwent right-ATL had a clinically significant decline in spatial memory, and 62.5% of individuals who underwent left-ATL had a significant reduction in verbal memory. Growth curve analyses indicated that both side of surgery and poor seizure outcome independently affected the learning slope in the best fitting models. Left-ATL reduced the slope, but did not affect the overall shape, of verbal learning across trials. On the other hand, poor seizure control outcome affected the slope of spatial learning regardless of the side of surgery.
Discussion:   Results demonstrate both individual and group declines in spatial memory and learning after ATL. Results suggest that individuals who undergo right-ATL should be counseled regarding the likelihood of a decline in spatial memory and learning abilities after ATL. Results also suggest that individuals with poor seizure control after ATL should be referred for rehabilitation services given the significant declines in spatial and verbal memory that occurred in our sample regardless of side of surgery.     

Determining empirically based self-reported cognitive change: development of reliable change indices and standardized regression-based change norms for the multiple abilities self-report questionnaire in an epilepsy sample

PURPOSE: Reliable change indices (RCIs) and standardized regression-based (SRB) change score norms were calculated for a measure of self-reported cognitive function, the Multiple Abilities Self-Report Questionnaire (MASQ), in patients with complex partial seizures. Establishment of such standardized change scores could be useful in determining the magnitude and direction of self-appraised cognitive change after epilepsy surgery or other treatment interventions. The primary study objective was to calculate RCI and SRB values for the MASQ. A secondary objective was to report SRB change scores in patients who had undergone anterior temporal lobectomy (ATL) and to assess relationships between self-reported cognitive change, seizure outcome, objective memory test performance, and mood. METHODS: The MASQ was administered to 36 patients with complex partial seizures on two occasions (mean test-retest interval, 6 months). This group did not have major psychopathology and were on stable antiepileptic drugs. RCI and SRB change scores were calculated. Adjustments for baseline ratings, age, education, gender, age at seizure onset, and seizure duration were made with the SRB method. A confidence interval cutoff score (90% level) was calculated for the five MASQ cognitive domains (Language, Visual Perception, Verbal Memory, Visual-Spatial Memory, Attention/Concentration). MASQ SRB scores were computed for a second sample of 50 patients who had undergone ATL. RESULTS: Test-retest reliabilities for the MASQ domains ranged from a low of 0.63 (Attention/Concentration) to a high of 0.87 (total score). Baseline MASQ score was the single largest contributor to the regression equations. Left and right ATL groups demonstrated similar magnitudes of self-reported cognitive change across all five MASQ domains. Individual base rate change distributions were similar across four of the five domains. with a higher proportion of right ATL patients reporting worsening attention function. Both postoperative mood and SRB-based verbal memory outcome were significantly correlated to self-reported cognitive change in the patients who had undergone ATL. CONCLUSIONS: SRB methodology provides a standardized technique with which to establish patient perception of cognitive change and may be of use when examining change across individual- and group-level ratings of cognitive functioning in clinical and research settings. These techniques also provide a common metric for direct comparison between subjective self-report ratings of cognitive function and objective cognitive test instruments.     

Verbal memory outcome in patients with normal preoperative verbal memory and left mesial temporal sclerosis

PURPOSE: Previous studies have shown that structural integrity (i.e., presence/absence of mesial temporal sclerosis (MTS)) of the left mesial temporal lobe is associated with verbal memory outcome following left anterior temporal lobectomy (ATL). However, the functional integrity of the left temporal lobe, as exemplified by preoperative verbal memory performance, has also been associated with verbal memory outcome following surgery. We investigated the risk of verbal memory loss in patients with known structural abnormality (i.e., left mesial temporal sclerosis by MRI) and normal preoperative verbal memory performance who undergo left ATL. METHODS: Seventeen patients with left temporal lobe epilepsy, MRI-based exclusive left MTS, and normal preoperative verbal memory were identified. Normal verbal memory was defined as performance on both Acquisition (learning across trials 1-5) and Retrieval (long delayed free recall) portions of the California Verbal Learning Test (CVLT) above a T score of 40 (>16%ile). Postoperative verbal memory outcome was established by incorporating standardized regression-based (SRB) change scores. RESULTS: Postoperative declines across both CVLT Retrieval T scores and Acquisition T scores (average 20% and average 15% declines from baseline scores, respectively) were measured for the group. The average CVLT Retrieval SRB change score was -2.5, and the average CVLT Acquisition SRB change score was -1.0. A larger proportion of patients demonstrated postoperative declines on Retrieval scores than Acquisition scores (64.7% vs 17.6%, respectively). CONCLUSIONS: Even in the presence of left MTS, patients exhibiting normal presurgical verbal memory are at risk for verbal memory declines following ATL. These results suggest that the functional integrity of the left mesial temporal lobe may play an important role in the verbal memory outcome in this patient group.     

Cortical gene expression: prognostic value for seizure outcome following temporal lobectomy and amygdalohippocampectomy

Whole genome analyses were performed to test the hypothesis that temporal cortical gene expression differs between epilepsy patients rendered seizure-free versus non-seizure-free following anterior temporal lobectomy with amygdalohippocampectomy (ATL/AH). Twenty four patients underwent ATL/AH to treat medically intractable seizures of temporal lobe origin (mean age 35.5 years, mean follow-up 42.2 months); they were then dichotomized into seizure-free and non-seizure-free groups. Tissue RNA was isolated from the lateral temporal cortex and gene expression analysis was performed. Whole genome data were analyzed for prognostic value for seizure-free outcome following ATL/AH by logistic regression. Genes that could distinguish seizure outcome groups were identified based on providing an accuracy of >0.90 judging by area under the receiver operating characteristic curve, AUC, with a P value of the slope coefficient of <0.05. Four genes and seven RNA probes were with prognostic value for post-operative seizure-free outcome. Gene expression associated with seizure-free outcome included relative down-regulation of zinc finger protein 852 (ZNF852), CUB domain-containing protein 2 (CDCP2), proline-rich transmembrane protein 1 (PRRT1), hypothetical LOC440200 (FLJ41170), RNA probe 8047763, RNA probe 8126238, RNA probe 8113489, RNA probe 8092883, RNA probe 7935228, RNA probe 806293, and RNA probe 8104131. This study describes the predictive value of temporal cortical gene expression for seizure-free outcome after ATL/AH. Four genes and seven RNA probes were found to predict post-operative seizure-free outcome. Future prospective investigation of these genes and probes in human brain tissue and blood could establish new biomarkers predictive of seizure outcome following ATL/AH.     

Cognitive changes in people with temporal lobe epilepsy over a 13-year period

ObjectivesThe aims of our study were to evaluate cognitive decline in people with temporal lobe epilepsy over a period of 13 years and to determine what clinical and treatment characteristics may have been associated with these.Materials and methodsThirty-three individuals with temporal lobe epilepsy underwent the same neuropsychological assessment of verbal and nonverbal memory, attention, and executive functions using the same cognitive test battery as one used 13 years ago. Long-term verbal and nonverbal memory was tested four weeks later. Results were compared with those carried out 13 years earlier.ResultsThere was no significant change in verbal and verbal–logical memory tests; however, nonverbal memory worsened significantly. Long-term verbal memory declined for 21.9% of participants, long-term verbal–logical memory for 34.4%, and long-term nonverbal memory for 56.3%. Worsening of working verbal and verbal–logical memory was associated with longer epilepsy duration and lower levels of patients' education; worsening of verbal delayed recall and long-term verbal–logical memory was associated with higher seizure frequency. Decline in long-term nonverbal memory had significant association with a longer duration of epilepsy. The worsening of reaction and attention inversely correlated with the symptoms of depression.ConclusionOver a 13-year period, cognitive functions did not change significantly. Good seizure control and reduced symptoms of depression in this sample of people with temporal lobe epilepsy were associated with better cognitive functioning. The predictors of change of cognitive functions could be complex and require further study.     

Presurgical language fMRI activation correlates with postsurgical verbal memory decline in left-sided temporal lobe epilepsy

We analysed the association of presurgical language fMRI activations and postsurgical verbal memory changes in 16 left-sided mesial temporal lobe epilepsy patients with initially intact memory. Patients with severe verbal memory decline after surgery (n = 9) had stronger presurgical fMRI activations within the left posterior temporal lobe, compared to those with no decline (n = 7). Language fMRI activation may predict verbal memory outcome, even in patients with a high risk of postsurgical memory deterioration.     

Material-specific memory changes after anterior temporal lobectomy as predicted by the intracarotid amobarbital test

Summary: Purpose: The intracarotid amobarbital test (IAT) has been shown to predict verbal memory changes after anterior temporal lobectomy (ATL). Seeking to extend these findings, we examined two questions: (a) What is the relationship between material‐specific aspects of IAT memory and material‐specific memory changes after ATL? and (b) Which IAT memory score(s) optimally predict memory changes after surgery, the memory score after injection ipsilateral to the seizure focus, the memory score after injection contralateral to the seizure focus, or the IAT asymmetry score, comprising the ipsilateral minus contralateral injection scores? Methods: Seventy left hemisphere language‐dominant patients undergoing ATL for treatment of medically refractory seizures were administered a verbal and visuospatial recognition memory test before surgery and 3 weeks after surgery. IAT memory recognition scores for words and designs were used to predict verbal and visuospatial memory changes after surgery. Results: After surgery, left ATL patients declined in verbal memory, whereas right ATL patients declined in visuospatial memory. IAT total recognition memory scores (collapsed across all types of materials) and IAT word memory scores were associated with postoperative verbal memory decline. This relationship was significant for the IAT ipsilateral injection memory scores and the IAT hemispheric asymmetry scores. IAT memory performances were not related to visuospatial memory changes. Conclusions: Results indicate IAT memory measures to be related to postoperative verbal, but not visuospatial, memory change. A specific relationship was found between postoperative verbal memory change and IAT verbal memory after injection ipsilateral to the seizure focus, when relying primarily on the contralateral hemisphere. This finding is consistent with the functional reserve model of memory change in ATL.     

Long-term cognitive outcome of hemiconvulsion-hemiplegia-epilepsy syndrome affecting the left cerebral hemisphere

Long-term cognitive outcome following hemiconvulsion–hemiplegia–epilepsy (HHE) syndrome has been poorly studied, with little attention to the implications of side of involvement in HHE. This retrospective study describes language lateralization and cognitive performance in five patients with HHE syndrome affecting the left cerebral hemisphere. All of the patients had to have intracarotid sodium amytal testing (IAT) to be included in this study. The mean age of the patients was 30.2 years (range: 13–50). All patients had their hemiconvulsive seizures before age 1½ years (range: 6–13 months). All patients had right-sided hemiatrophy of the body, left mesial temporal sclerosis, and seizures originating from the left temporal lobe. The habitual seizures began at a mean age of 4.5 years (range: 1.5–12 years). Performance on tests of intelligence, verbal memory, and visual memory was examined. Language was represented in the right cerebral hemisphere in three patients, the left hemisphere in one patient, and both hemispheres with predominance on the right side in the fifth patient. Intellectual functioning was in the borderline to extremely low range among the patients with right hemispheric or bilateral representation for language. These patients were variably impaired on measures of verbal and visual memory. The patient with left hemispheric representation for language performed in the average range on tests of intellectual functioning and verbal memory, whereas scores on visual memory were variable. This study demonstrated that reorganization of language to the right cerebral hemisphere or its bilateral representation is common in patients with HHE syndrome affecting the left cerebral hemisphere, and is associated with poor cognitive outcome.     

Cognitive consequences of coexisting temporal lobe developmental malformations and hippocampal sclerosis.

OBJECTIVE: To characterize patterns of cognitive functioning in a well-defined group of patients with MRI-identified coexisting left temporal lobe developmental malformations (TLDM) and mesial temporal sclerosis (MTS), and to examine neuropsychological outcome in this dual-pathology group following epilepsy surgery. METHODS: Cognitive functioning in patients with left TLDM and MTS (n = 15) was compared with patients with isolated left MTS (n = 40). TLDM and MTS were identified by high-quality MRI protocol. Patients were administered a battery of neuropsychology tests as part of their presurgical workup for possible epilepsy surgery. Unilateral temporal lobe resection was performed on 10 of the dual-pathology patients and 34 of the isolated MTS patients. Postoperative cognitive performance was also assessed. RESULTS: Both groups displayed impairments in verbal and visual memory, language, and academic achievement. Performance on measures of psychometric intelligence, executive function, and attention were not impaired and were similar between groups. Presence of dual pathology was associated with a significantly less efficient verbal encoding strategy on the word list learning task. Postoperatively, declines were noted for both groups across tasks of verbal memory and language. Groups were not different significantly in terms of neuropsychological outcome after surgery. CONCLUSION: Patients with coexisting TLDM and MTS have impaired cognitive functioning similar to MTS patients-in particular, with regard to episodic memory and language deficits. Temporal lobe resection produces similar cognitive changes in both groups.     

Memory outcome 2 years after anterior temporal lobectomy in patients with drug-resistant epilepsy

PURPOSE: Memory decline is often observed after anterior temporal lobectomy (ATL), particularly in patients with dominant hemisphere resections. However, the follow-up length has been 1 year or less in most studies. Our aims were to examine postoperative memory changes over a longer period and to identify baseline demographic and clinical predictors of memory outcome. METHODS: We administered material-specific memory tests at baseline, and 1 and 2 years after surgery to 82 consecutive right-handed patients (52% males) who underwent ATL for drug-resistant temporal lobe epilepsy (TLE) (35 left, 47 right) after a non-invasive presurgical protocol. Repeated measures multivariate analysis of variance (RM-MANOVA) was used to examine the relationship between changes in memory tests scores over time and side of TLE and pathology. Also, standardized residual change scores were calculated for each memory test and entered in multiple linear regression models aimed at identifying baseline predictors of better memory outcome. RESULTS: RM-MANOVA revealed a significant change in memory test scores over time, with an interaction between time and side of surgery, as 2 years after surgery patients with RTLE were improved while patients with LTLE were not worse as compared with baseline. Pathology was not associated with changes in memory scores. In multiple regression analysis, significant associations were found between right TLE and greater improvement in verbal memory, younger age and greater improvement in visuospatial memory, and male gender and greater improvement in both verbal and visuospatial memory. CONCLUSIONS: Our results suggest that the long-term memory outcome of TLE patients undergoing ATL without invasive presurgical assessment may be good in most cases not only for right-sided but also for left-sided resections.     

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

Prediction of post-surgical seizure relief and potential cognitive deficits secondary to anterior temporal lobectomy (ATL) are important to pre-surgical planning. Although the intracarotid amobarbital test (IAT) is predictive of post-ATL seizure outcome, development of non-invasive and more precise means for determining post-ATL seizure relief are needed. We previously reported on a technique utilizing functional MRI (fMRI) to evaluate the relative functional adequacy of mesial temporal lobe structures in preparation for ATL. In the present study, we report follow-up outcome data on eight temporal lobe epilepsy (TLE) patients 1-year post-ATL who were evaluated pre-surgically using IAT and fMRI. Functional memory lateralization using fMRI predicted post-ATL seizure outcome as effectively as the IAT. In general, asymmetry of functional mTL activation favouring the non-epileptic hemisphere was associated with seizure-free status at 1-year follow-up. Moreover, when combined, fMRI and IAT provided complementary data that resulted in improved prediction of post-operative seizure control compared with either procedure alone.     

Memory functions following surgery for temporal lobe epilepsy in children

Surgical treatment appears to improve the cognitive prognosis in children undergoing surgery for temporal lobe epilepsy (TLE). The beneficial effects of surgery on memory functions, particularly on material-specific memory, are more difficult to assess because of potentially interacting factors such as age range, intellectual level, left-handedness, type of surgery and seizure outcome. This study investigated memory functions in 20 right-handed children who had left or right-temporal lobe surgery - including hippocampectomy - and became seizure-free. The neuropsychological evaluation included tests measuring verbally and visually mediated episodic memory, everyday memory as well as attention/working memory and language/semantic memory. We also assessed the relationships between age of seizure onset, general cognitive ability and memory functions. Children with TLE showed poor memory efficiency before surgery that tended to improve about 1 year after surgery. We found a material-specific memory effect, especially after surgery-9 (out of 12) children with left TLE had worse verbal memory results while 5 (out of 8) with right TLE had worse visual memory results. Post-operatively, most children had poor everyday memory performance on the Rivermead Behavioural Memory Test. No significant relationship was observed between episodic memory scores and age of epilepsy onset but children with early onset remained with lower Performance IQ values, Rey's figure copy scores and naming performances after surgery. Surgery significantly improved all the attention/working memory scores, some verbal episodic memory tasks and naming test performances. A different pattern of episodic and semantic memory limitations related to left or right TLE was observed.     

Preoperative FDG-PET temporal lobe hypometabolism and verbal memory after temporal lobectomy

OBJECTIVE: To examine the relationship of preoperative fluorodeoxyglucose (FDG)-PET asymmetry in temporal lobe metabolism and memory outcome after anterior temporal lobectomy (ATL). METHODS: In a university-based epilepsy surgery center, 60 ATL patients (27 left, 33 right) were divided into two groups: no/mild (n = 21) or moderate/ severe (n = 39) asymmetry in temporal lobe hypometabolism as determined by FDG-PET. All patients were nonretarded, at least 18 years of age, left-hemisphere speech dominant, without MRI abnormalities other than hippocampal atrophy, and with unilateral temporal lobe origin of intractable complex partial seizures. Neuropsychological measures of intelligence and verbal and visual memory function were assessed preoperatively and 6 months postoperatively. RESULTS: Left ATL patients with no/mild asymmetry in FDG-PET temporal lobe metabolism exhibited significantly greater verbal memory decline compared with left ATL patients with moderate/severe hypometabolism. There was no significant relationship between PET asymmetry and pre- to postsurgical IQ change. No significant relationship was observed between extent of PET hypometabolism and memory outcome for right ATL patients. CONCLUSIONS: FDG-PET asymmetry can be added to the preoperative clinical markers that appear useful in predicting verbal memory decline after left ATL.