Temporal Lobectomy For Intractable Epilepsy Research Articles

Amygdala lesions are associated with improved mood after epilepsy surgery.

Neuroimaging studies in healthy and clinical populations strongly associate the amygdala with emotion, especially negative emotions. The consequences of surgical resection of the amygdala on mood are not well characterized. We tested the hypothesis that amygdala resection would result in mood improvement. In this study, we evaluated a cohort of 52 individuals with medial temporal lobectomy for intractable epilepsy who had resections variably involving the amygdala. All individuals achieved good post-surgical seizure control and had pre- and post-surgery mood assessment with the Beck Depression Inventory (BDI) ratings. We manually segmented the surgical resection cavities and performed multivariate lesion-symptom mapping of change in BDI. Our results showed a significant improvement in average mood ratings from pre- to post-surgery across all patients. In partial support of our hypothesis, resection of the right amygdala was significantly associated with mood improvement (r = 0.5, p = 0.008). The lesion-symptom map also showed that resection of the right hippocampus and para-hippocampal gyrus was associated with worsened post-surgical mood. Future studies could evaluate this finding prospectively in larger samples while including other neuropsychological outcome measures.

Functional MRI, resting state fMRI, and DTI for predicting verbal fluency outcome following resective surgery for temporal lobe epilepsy.

Predicting cognitive function following resective surgery remains an important clinical goal. Each MRI neuroimaging technique can potentially provide unique and distinct insight into changes that occur in the structural or functional organization of "at-risk" cognitive functions. The authors tested for the singular and combined power of 3 imaging techniques (functional MRI [fMRI], resting state fMRI, diffusion tensor imaging) to predict cognitive outcome following left (dominant) anterior temporal lobectomy for intractable epilepsy. METHODS; The authors calculated the degree of deviation from normal, determined the rate of change in this measure across the pre- and postsurgical imaging sessions, and then compared these measures for their ability to predict verbal fluency changes following surgery. The data show that the 3 neuroimaging techniques, in a combined model, can reliably predict cognitive outcome following anterior temporal lobectomy for medically intractable temporal lobe epilepsy. These findings suggest that these 3 imaging modalities can be used effectively, in an additive fashion, to predict functional reorganization and cognitive outcome following anterior temporal lobectomy.

Seizure Types and Frequency in Patients Who “Fail” Temporal Lobectomy for Intractable Epilepsy

Temporal lobectomy can lead to favorable seizure outcomes in medically-refractory temporal lobe epilepsy (TLE). Although most studies focus on seizure freedom after temporal lobectomy, less is known about seizure semiology in patients who "fail" surgery. Morbidity differs between seizure types that impair or spare consciousness. Among TLE patients with seizures after surgery, how does temporal lobectomy influence seizure type and frequency? To characterize seizure types and frequencies before and after temporal lobectomy for TLE, including consciousness-sparing or consciousness-impairing seizures. We performed a retrospective longitudinal cohort study examining patients undergoing temporal lobectomy for epilepsy at our institution from January 1995 to August 2010. Among 241 TLE patients who received temporal lobectomy, 174 (72.2%) patients achieved Engel class I outcome (free of disabling seizures), including 141 (58.5%) with complete seizure freedom. Overall seizure frequency in patients with persistent postoperative seizures decreased by 70% (P < .01), with larger reductions in consciousness-impairing seizures. While the number of patients experiencing consciousness-sparing simple partial seizures decreased by only 19% after surgery, the number of individuals having consciousness-impairing complex partial seizures and generalized tonic-clonic seizures diminished by 70% and 68%, respectively (P < .001). Simple partial seizure was the predominant seizure type in 19.1% vs 37.0% of patients preoperatively and postoperatively, respectively (P < .001). Favorable seizure outcome was predicted by a lack of generalized seizures preoperatively (odds ratio 1.74, 95% confidence interval 1.06-2.86, P < .5). Given important clinical and mechanistic differences between seizures with or without impairment of consciousness, seizure type and frequency remain important considerations in epilepsy surgery.

C-C4-01: Functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI): An Efficient, Non-invasive Alternative to Conventional Pre-surgical Planning in Neurosurgery

Jennifer Robinson, PhD1, Batool Kirmani, MD1, Manjit Sanghera, PhD1, Jacqueline Phillips-Sabol, PhD1, Daniel Cruz, PsyD1, Charles Wright, MD1 and Gerhard Friehs, MD, PhD1 1Scott & White Memorial Hospital

Basal Ganglia Location of Subependymal Giant Cell Astrocytomas in Two Infants

Subependymal giant cell astrocytomas are benign tumors that constitute one of the primary features of tuberous sclerosis. Two infants with tuberous sclerosis had very unusual subependymal giant cell astrocytomas, confirmed on biopsy in one of the infants. In both cases, contrast-enhanced cranial magnetic resonance imaging suggested a calcified intra-axial mass with diffuse basal ganglia involvement extending into the lateral ventricle. Computed tomography confirmed calcification in both cases. The first patient had right temporal lobectomy for intractable epilepsy. Biopsy of the basal ganglia lesion in that case suggested subependymal giant cell astrocytoma. In infants, subependymal giant cell astrocytomas can present with unusual morphology and may feature diffuse basal ganglia involvement and severe calcification.

Temporal lobectomy: Resection volume, neuropsychological effects, and seizure outcome

Objective The goal of the work described here was to evaluate relationships among resection volume, seizure outcome, and cognitive morbidity after temporal lobectomy for intractable epilepsy. Methods Thirty patients with mesial temporal sclerosis were evaluated pre- and postoperatively with the Wechsler Adult Intelligence Scale III, Wechsler Memory Scale III, and three-dimensional coronal spoiled gradient recall acquisition MRI. Preoperative whole-brain volumes were calculated with Statistical Parametric Mapping. Resection volume was calculated by manual tracing. Systat was used for statistical analysis. Results All resections included the temporal tip, at least 1 cm of the superior temporal gyrus, and 3 to 5 cm of the middle and inferior temporal gyri. Left were significantly smaller than right temporal resections. Seizure-free patients had significantly larger resections. Immediate verbal memory was significantly worse after left temporal lobectomy. Surgical outcome and resection volume did not affect postoperative neuropsychological results. Conclusions Dominant temporal lobe resections are associated with immediate verbal memory deficits. Larger resection volume was associated with improved seizure control but not worse cognitive outcome.

Transient symptomatic vasospasm following antero-mesial temporal lobectomy for refractory epilepsy

Arterial vasospasm has rarely been reported following temporal lobectomy for intractable epilepsy. A 31-year-old patient presented with a global aphasia 2 days after a left dominant anteromesial temporal lobectomy for intractable epilepsy. Magnetic resonance imaging on 5th post-operative day revealed severe narrowing of M1 segment of the left middle cerebral artery (MCA) and Transcranial Doppler (TCD) ultrasonography an increased velocity of the MCA that suggested a severe vasospasm. The patient received continuous intravenous hyperhydratation and nimodipine; aphasia improved within 24 h and resolved completely within 6 weeks, associated with velocity reduction on control TCD. Transient vasospasm is a likely underestimated cause of focal deficit following temporomesial resection that deserves appropriate treatment.

The Family Pictures subtest of the WMS-III: Relationship to verbal and visual memory following temporal lobectomy for intractable epilepsy

This study examined the extent to which the Family Pictures (FP) subtest of the Wechsler Memory Scale–Third Edition (WMS-III) is related to verbal memory measures and right mesial temporal integrity. Epilepsy patients who underwent temporal lobectomy did not differ in the extent to which FP scores changed from before to after surgery, although postoperative FP performance was worse in those who underwent right temporal lobectomy than in those who underwent left temporal lobectomy. FP was most strongly related to the Logical Memory subtest from the WMS-III. Results suggest that FP measures both verbal and visual memory and is minimally sensitive to lateralization of temporal lobectomy.

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.

Rey Complex Figure: Figural and spatial memory before and after temporal lobectomy for intractable epilepsy

Reliable neuropsychological markers of right temporal integrity have proven elusive. Specifically it is unclear whether figural and spatial aspects of visual memory are differentially affected by right temporal lobe epilepsy (TLE) and subsequent resection. To investigate this we used the modified Rey Complex Figure (RCF) scoring system devised by Brier et al. (1996) to obtain separate indices of figural and spatial memory in TLE surgery candidates. We extended on their study by examining presurgical performance and change following right and left temporal lobectomy (RATL, n = 38, LATL, n = 42) in individuals from a cross-institutional sample with and without hippocampal sclerosis (HS(+)/HS(-)). Contrary to expectation neither figural nor spatial RCF recall were differentially sensitive to RTLE, right HS, or subsequent resection. Presurgically, laterality effects on both figural and spatial memory indices were not found although HS(-) individuals significantly outperformed HS(+) individuals on both measures. Following surgery the largest decrements in both figural and spatial recall were observed among LATL HS(-) participants. We concluded that RCF recall is a poor marker of right temporal lobe function and suggest it may be a "surrogate" measure of left temporal lobe function possibly due to the verbalizability of many of its components.

Surgical Treatment for Extratemporal Epilepsy.

Partial seizures of extratemporal origin may present unique challenges in the patient with medically refractory seizures. The efficacy of an extratemporal focal cortical resection may be less effective than an anterior temporal lobectomy for intractable epilepsy. The potential operative complications may be increased in individuals with extratemporal epilepsy because of functional cerebral cortex involvement and the need for a large cortical resection to significantly reduce seizure tendency. Partial seizures of extratemporal origin are predominantly associated with frontal lobe epilepsy. The most effective treatment for intractable partial epilepsy is a focal cortical resection with excision of the epileptogenic zone, that is, an area of ictal onset and initial seizure propagation. The preoperative evaluation and operative strategy in patients with partial epilepsy of extratemporal origin associated with pharmacoresistant seizures is determined by the anatomic localization of the epileptogenic zone and the presence of a substrate-directed disorder. The goals of surgical treatment in extratemporal epilepsy include rendering the patient seizure-free, avoiding operative morbidity, and allowing the individual to become a participating and productive member of society. Before surgical treatment, the individual with extratemporal epilepsy will require a comprehensive preoperative evaluation, including routine electroencephalogram (EEG), long-term EEG monitoring, neuropsychologic studies, and magnetic resonance imaging (MRI). Patients with a normal MRI study, conflicting preoperative evaluation, or involvement of suspected functional cerebral cortex would require chronic intracranial EEG monitoring. The rationale for intracranial EEG includes localization of the ictal onset zone or intraoperative functional mapping, or both. Two-fluorodeoxyglucose positron emission tomography studies are usually unremarkable in patients with extratemporal epilepsy and normal MRI scans. Subtraction ictal single photon emission computed tomography coregistered to MRI (SISCOM) study may be useful to demonstrate a localized cerebral perfusion alteration in patients with intractable partial epilepsy. The diagnostic yield of SISCOM has been confirmed in patients with extratemporal epilepsy undergoing surgical treatment. The results of the SISCOM study may tailor the placement of intracranial EEG electrodes and affect the operative strategy. Patients with extratemporal epilepsy overall are less favorable operative candidates than individuals with medial temporal lobe epilepsy. However, individuals with MRI-identified lesional pathology of SISCOM-identified perfusion alterations concordant with the epileptogenic zone may be considered for surgical treatment. Chronic intracranial EEG monitoring may be necessary to confirm the localization of the ictal onset zone before epilepsy surgery. Patients with normal neuroimaging studies and extratemporal epilepsy are unlikely to be rendered seizure-free with focal cortical resection and should be considered candidates for other alternative forms of treatment for intractable partial epilepsy. Patients with non-substrate-directed extratemporal epilepsy should undergo a preoperative evaluation and surgical treatment at a comprehensive epilepsy center with extensive experience in chronic intracranial EEG monitoring and contemporary neuroimaging procedures because of the inherently high acuity associated with the operative management clinical disorder.

Predictors of seizure outcome after temporal lobectomy for intractable epilepsy

To assess predictors of outcome of temporal lobectomy for intractable epilepsy. In 63 adult patients operated with anterior temporal lobectomy during 198892, we used logistic regression analysis to assess predictors of being seizure-free (Engel's class I) 2 years after surgery. As potential predictors, we included the following variables: gender, age at operation, age at onset of seizures, epilepsy duration, etiology, generalized vs not generalized seizures, seizure frequency, intelligence quotient, ictal electroencephalography, magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), side of resection, and extent of the resection. About 44% of the surgery patients were seizure-free (Engel's class I) 2 years after surgery. In multivariate analysis (n = 55), MRI pathology defined as atrophy in the temporal lobe, angioma, tumor or mesial temporal sclerosis (odds ratio, OR 7.4, 95%CI: 1.7-32.9) and extent of the hippocampal resection (increase of 1 cm) (OR 2.2, 95%CI: 1.1-4.6) predicted being seizure-free. Focal pathology in preoperative MRI and the extent of the hippocampal resection were the only significant predictors of being seizure-free after 2 years.

Pediatric Temporal Lobectomy for Epilepsy

Background: Temporal lobectomy in adults is an accepted form of treatment for patients with intractable complex partial seizures. There have been few long-term studies of children undergoing temporal lobectomy for epilepsy. Methods: We reviewed the pediatric cases of temporal lobectomy for intractable epilepsy performed by the Comprehensive Epilepsy Program at the University of Alberta Hospitals between 1988 and 2000. All patients had preoperative and postoperative clinical evaluations, seizure charts, drug levels, EEG, CT/MRI, long-term video EEG monitoring and neuropsychological testing. The patients were reassessed at 6 weeks, 6 months and 1 year postoperatively, then yearly. The duration of follow up was 1–10 years (mean 5 years). Results: Forty-two patients were studied (25 males and 17 females). Age at surgery ranged from 18 months to 16 years. The interictal EEG was abnormal in 38 of the 42 patients. Twenty-two patients had focal epileptic discharge and 1 had generalized epileptic discharge. Focal slowing was seen in 9 patients and diffuse slowing in 5 patients. CT scan was abnormal in 17 of 39 patients and normal in 22 of 39. MRI was abnormal in 34 of 42 patients and normal in 8 of 42. Pathology included brain tumors in 14 patients, mesial temporal sclerosis in 8, focal cortical dysplasia in 4, tuberous sclerosis in 4, dual pathology in 4, porencephalic cyst in 1 and normal pathology or gliosis in 6. Thirty-three of 42 patients (78%) were seizure-free following surgery and an additional 5 (12%) had a decrease in seizure frequency. Three patients had complications, but there were no deaths. Conclusion: Temporal lobectomy is a safe and effective treatment for children with intractable complex partial seizures. Seventy-eight percent of patients are seizure-free following the surgery and there are few complications. MRI is superior to CT scan for detection of temporal lobe pathology yet failed to detect abnormalities in some patients. The most common pathologies found were brain tumors, mesial temporal sclerosis and developmental lesions. In addition to seizure control, many patients experienced improvement in cognitive and psychosocial function following surgery.

Hippocampal, but not parahippocampal, damage in a case of dense retrograde amnesia: a pathological study

Damage limited to the hippocampus is believed to result in temporally graded retrograde amnesia (RA), with more severe RA occurring only as a result of additional damage to adjacent neocortical structures. Patient N.T. suffered dense, temporally ungraded, RA following a right temporal lobectomy for intractable epilepsy. Postmortem pathological examination revealed sclerosis of the unresected left hippocampus. Microscopic analysis of the parahippocampal areas and other temporal lobe regions undertaken in this study confirmed the absence of any significant pathology extending beyond the hippocampus. This further review of the pathological findings in N.T. is therefore not consistent with the postulated role of the hippocampus as a temporary memory store and suggests instead that the hippocampus is involved in the storage of remote memories as well as recent memories.

Rhythm and Melody in Children and Adolescents after Left or Right Temporal Lobectomy

Rhythm (a pattern of onset times and duration of sounds) and melody (a pattern of sound pitches) were studied in 22 children and adolescents several years after temporal lobectomy for intractable epilepsy. Left and right lobectomy groups discriminated rhythms equally well, but the right lobectomy group was poorer at discriminating melodies. Children and adolescents with right lobectomy, but not those with left temporal lobectomy, had higher melody scores with increasing age. Rhythm but not melody was related to memory for the right lobectomy group. In neither group was melody related to age at onset of non-febrile seizures, time from surgery to music tests, or the linear amount of temporal lobe resection. Pitch and melodic contour show different patterns of lateralization after temporal lobectomy in childhood or adolescence.

Pathology and Neuroimaging in Pediatric Temporal Lobectomy for Intractable Epilepsy

Objectives: Firstly, to study the pathology at surgery in children undergoing temporal lobectomy for intractable partial epilepsy. Secondly, to compare neuroimaging techniques (CT, MRI) in the preoperative detection of pathology. Lastly, to examine the surgical outcome in children. Methods: Forty-two pediatric patients undergoing temporal lobectomy for intractable epilepsy at the Comprehensive Epilepsy Program at the University of Alberta Hospital between the years 1988–1998 were studied. Patients had extensive preoperative investigations including CT and MRI. The pathology at surgery was reviewed and compared to preoperative neuroimaging. Charts were reviewed to determine surgical outcome. Results: Brain tumors were the most common pathology, found in 13/42 patients. Mesial temporal sclerosis (MTS) was found in 8 patients and dual pathology in an additional 5. Focal cortical dysplasia (FCD) was seen in 4 patients, 1 patient had a porencephalic cyst and 4 patients had tubers of tuberous sclerosis. Seven patients had no specific pathology detected. MRI was clearly more sensitive than CT in the detection of pathology. MRI was abnormal in 27/42 cases (64%), while CT scan was found to be abnormal in only 12/39 (31%). Surgical outcome was excellent, with 34/42 patients (80%) having an Engel class I outcome. One patient had significant improvement with an Engel class II outcome, 3 (7%) had little improvement (Engel class III) and 4 (10%) were unchanged (Engel class IV). Three patients (7%) had surgical complications. Conclusions: A wide variety of developmental pathology is seen following temporal lobectomy for intractable epilepsy of childhood. Brain tumors, FCD and MTS are common. MRI is superior to CT in the detection of pathology, which may be subtle in children. Surgical outcome is excellent, with most children being seizure free and few complications being seen.

Prognostic factors in the surgical treatment of medically intractable epilepsy associated with mesial temporal sclerosis.

To assess the prognostic factors determining seizure remission after temporal lobectomy for intractable epilepsy associated with mesial temporal sclerosis (MTS) at pathology. The clinical and investigative features of 116 consecutive patients who had temporal lobe surgery for drug-resistant epilepsy and MTS at pathology were assessed using actuarial statistics and logistic regression analysis. At a median follow-up of 63 months the probability of achieving at least a 1-year period of continuous seizure freedom was 67%. Factors contributing to a favourable outcome were interictal EEG localization to the operated lobe and the absence of secondarily generalized seizures. These were also selected in the multivariate analysis, although at lower statistical significance (P=0.08 and 0.09, respectively). Perinatal complications were associated with a significantly worse outcome but overall, complicated febrile convulsions and congruent neuropsychological deficits were not significantly predictive variables. The present findings may aid in the non-invasive presurgical assessment of patients with intractable TLE and clinical and neuroimaging evidence of MTS.

Significance of cerebellar atrophy in intractable temporal lobe epilepsy: a quantitative MRI study.

To determine the incidence of cerebellar atrophy (CA) in patients with intractable temporal lobe epilepsy, whether any clinical factors are significantly associated with CA, whether CA is unilateral or asymmetric and whether this feature has any relationship to the side of epileptogenicity, and whether the presence of CA is related to epilepsy surgery outcome. We developed a magnetic resonance imaging method of measuring the presurgical volumes of the cerebellar hemispheres of 185 patients who underwent temporal lobectomy for intractable epilepsy and of 80 control subjects. In addition, cerebellar volumes were normalized to the total brain volumes. CA was determined as being present when the measured volume was smaller than two standard deviations from the mean value found in control subjects. Both absolute and normalized cerebellar volumes were found to be significantly reduced in the epilepsy patients compared with the control subjects. Without normalization of the cerebellar volumes, CA was present in 25.9% of the epilepsy patients; with normalization, it was present in only 16.2%. The atrophy was symmetric between the cerebellar hemispheres, and there was no significant difference in volume between the hemisphere ipsilateral and the hemisphere contralateral to the side of the temporal lobectomy. The duration of epilepsy was significantly longer and the age at onset of epilepsy was younger in patients with CA than in those without CA. The presence of CA was not associated with the outcome of temporal lobectomy. CA is symmetric and common in patients with intractable temporal lobe epilepsy. However, the results suggest that the atrophy in one third of patients with CA also proportionately affects the cerebral hemispheres. The duration of epilepsy and the age at onset of epilepsy are associated with the occurrence of CA. Seizure control after temporal lobectomy is not influenced by the presence of CA.

Generalised cerebral atrophy following temporal lobectomy for intractable epilepsy associated with mesial temporal sclerosis

Studies of post-operative imaging data have mainly concentrated on brain atrophy following radiotherapy and/or chemotherapy. We have investigated the effect of conventional surgery on the unresected brain tissue based on the comparison of magnetic resonance images acquired pre- and post-operatively in 13 subjects with a history of mesio–temporal epilepsy. The pre- and post-operative scans were co-registered prior to volumetric analysis. The total brain volume (TBV) was calculated by semi-automated segmentation, and the total volume loss was the difference between the post-operative and pre-operative TBV. The total volume of resection was determined by manual delineation in the post-operative scan. The atrophy volume in the post-operative scan was calculated as the difference between the total volume loss and the resection volume. In 6 cases, there was generalised cerebral atrophy of the order 4–5% of the total brain volume. In addition to the automated volumetric technique, the images were assessed by two expert neuroradiologists. There was complete correspondence between their assessment and the automated technique. The causes and significance of this phenomenon are unknown but it requires further investigation as it may be related to seizure control and neuropsychological changes following epilepsy surgery.

Cognition and behavior after temporal lobectomy in pediatric patients with intractable epilepsy

The increased use of surgical intervention for intractable epilepsy during childhood has resulted in a critical need for information concerning possible cognitive and behavioral changes in pediatric patients after surgery. In this pilot study, comprehensive neuropsychologic evaluations were completed on nine children who had a temporal lobectomy for intractable epilepsy before 16 years of age. Performances before and after surgery were compared using cognitive and behavioral measures. Repeated measures analysis of variance did not indicate differences in performance on the basis of laterality of surgery, although the number of left (n = 5) vs right (n = 4) temporal resections was small. Paired comparison t tests, which included all patients, did not suggest marked changes in cognitive functioning after surgery, although decreases in delayed verbal memory were evident. Positive effects on quality of life during the first year after surgical intervention were suggested by reduced internalizing symptoms and increased social interaction. Replication of this study is recommended with a larger number of patients and multicenter collaboration.