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Preoperative clinical, EEG, and imaging findings do not predict seizure outcome following temporal lobectomy in childhood.

Although certain clinical, electroencephalographic (EEG), magnetic resonance imaging (MRI), and pathologic findings in adults with intractable temporal lobe epilepsy predict seizure outcome following temporal lobectomy, predictors of seizure outcome have not been studied systematically in pediatric temporal lobectomy series. We retrospectively analyzed preoperative clinical, EEG, and neuroimaging findings with reference to seizure outcome (seizure free or non-seizure free) in 33 children (mean age, 9.3 years) who underwent tailored temporal lobe resections for intractable temporal lobe epilepsy. Trends were apparent with (1) younger age at seizure onset, younger age at surgery, shorter duration of epilepsy, localized unilateral temporal lesions on MRI, and right-sided surgery more frequently associated with a seizure-free outcome, and (2) significant prior history, daily preoperative seizures, generalized motor seizures, mental retardation, and localized unilateral temporal epileptiform EEG activity more frequently associated with a non-seizure-free outcome. However, none of these findings, alone or in combination, correlated with postoperative seizure status at a statistically significant level. Submitting the four variables generally considered to be most predictive of favorable outcome (ie, normal intelligence, unilateral ictal and interictal EEG discharges, and focal temporal MRI lesion) to a multiple-cutoff procedure did not predict seizure freedom. Our data indicate that predictors of outcome of temporal lobectomy in adults may not apply in children, perhaps due to inherent neurobiologic differences in the etiology and expression of temporal lobe epilepsy, and should therefore not be used as sole determinants of surgical candidacy in children.

Adolescent↗

Quantitative magnetic resonance characterization of mesial temporal sclerosis in childhood.

OBJECTIVE: To investigate whether quantitative MR techniques can be used to distinguish between mesial temporal sclerosis in patients with a history of prolonged febrile convulsion and in patients without such a history. METHODS: Quantitative hippocampal T2 relaxometry, hippocampal volumetry, and single voxel (1)H-MRS data were acquired from 16 children who subsequently underwent temporal lobe resections for intractable temporal lobe epilepsy and histologically were shown to have sclerosis of the horn of Ammon. Eight children had a history of prolonged febrile convulsion in early childhood and eight children had other or no associations. RESULTS: Patients with a history of prolonged febrile convulsion had smaller hippocampi (p = 0.02) and prolonged T2 relaxation time (p = 0.03) ipsilateral to the seizure focus when compared with patients without such a history. There was also more side-to-side asymmetry of T2 relaxation time (p = 0.004) and hippocampal volume (p = 0.02) in the patients with a history of prolonged febrile convulsion than in those with other or no associations. No differences between the groups were identified using (1)H-MRS. CONCLUSIONS: These data support the view that there are at least two types of mesial temporal sclerosis. There may be several pathogenetic pathways from initial insult to later mesial temporal sclerosis, and these pathways are, at least in part, dependent on the initial insult.

Adult↗

Predicting memory decline following epilepsy surgery: a multivariate approach.

BACKGROUND: While some patients experience a decline in memory function following an anterior temporal lobe resection, there is considerable individual variation in the extent, nature, and direction of postoperative memory change. Patients with surgically remediable temporal lobe epilepsy differ in etiology, the extent and type of underlying pathology, and on demographic and epilepsy-related variables, all of which may have an impact on their pre- and postoperative neuropsychological functioning. This study examined the relationship between these variables and postoperative memory decline. METHODS: Logistic regression was used to examine the effects of age, laterality of surgery, age of onset of epilepsy, underlying pathology and preoperative level of memory function on postoperative verbal learning in 288 patients who had undergone an anterior temporal lobe resection. One hundred twenty-five patients underwent a right temporal lobe resection (RTL), 163 patients underwent a left temporal lobe resection (LTL). RESULTS: In the group as a whole, 25% of the patients demonstrated a significant postoperative deterioration in verbal learning. Postoperative deterioration in verbal learning was significantly associated with higher levels of preoperative function in both the RTL and LTL groups. Older age at the time of the operation and a lower verbal IQ were additional significant predictors for the RTL group. The presence of cortical dysgenesis was a significant predictor of postoperative decline in the LTL group. The logistic regression models accurately identified 3/4 of those who experienced a postoperative decline in memory, using a cutoff of 0.25 or above to identify high risk. CONCLUSIONS: Our analyses suggest that the majority of patients with a high risk of significant postoperative memory decline can be reliably identified preoperatively. These models are valuable tools helping patients make an informed decision regarding surgery.

Epilepsy↗

Surgical treatment of children with medically intractable epilepsy--outcome of various surgical procedures.

Outcome after temporal lobe resection, extratemporal resection, and corpus callosotomy was studied in 33 children aged 15 years or less with medically intractable epilepsy. Seizure-free control was achieved in 67% (6/9) of pediatric patients versus 67% (60/90) of adult patients receiving temporal lobe resection and in 33% (4/12) of pediatric patients versus 25% (7/28) of adult patients receiving extratemporal resection. Among patients suffering from drop attacks and generalized convulsive seizures, 42% (5/12) of pediatric patients versus 25% (6/24) of adult patients receiving corpus callosotomy became seizure-free. The most prominent histological diagnoses in temporal lobe resections were three cases of mesial temporal sclerosis, four of ganglioglioma, and two of neuronal migration disorders. Neuronal migration disorders were the main histology in extratemporal resections. Four of five patients with behavioral problems treated by corpus callosotomy exhibited improved hyperactivity and/or attention deficits. There was no surgical morbidity or mortality. The outcome of pediatric patients was at least as favorable as that of adult patients, and improvement of behavioral disturbances could be expected after surgery. Surgical treatment is an effective and safe procedure for children with medically intractable epilepsy.

Adolescent↗

Long-term seizure outcomes following epilepsy surgery: a systematic review and meta-analysis.

Assessment of long-term outcomes is essential in brain surgery for epilepsy, which is an irreversible intervention for a chronic condition. Excellent short-term results of resective epilepsy surgery have been established, but less is known about long-term outcomes. We performed a systematic review and meta-analysis of the evidence on this topic. To provide evidence-based estimates of long-term results of various types of epilepsy surgery and to identify sources of variation in results of published studies, we searched Medline, Index Medicus, the Cochrane database, bibliographies of reviews, original articles and book chapters to identify articles published since 1991 that contained > or =20 patients of any age, undergoing resective or non-resective epilepsy surgery, and followed for a mean/median of > or =5 years. Two reviewers independently assessed study eligibility and extracted data, resolving disagreements through discussion. Seventy-six articles fulfilled our eligibility criteria, of which 71 reported on resective surgery (93%) and five (7%) on non-resective surgery. There were no randomized trials and only six studies had a control group. Some articles contributed more than one study, yielding 83 studies of which 78 dealt with resective surgery and five with non-resective surgery. Forty studies (51%) of resective surgery referred to temporal lobe surgery, 25 (32%) to grouped temporal and extratemporal surgery, seven (9%) to frontal surgery, two (3%) to grouped extratemporal surgery, two (3%) to hemispherectomy, and one (1%) each to parietal and occipital surgery. In the non-resective category, three studies reported outcomes after callosotomy and two after multiple subpial transections. The median proportion of long-term seizure-free patients was 66% with temporal lobe resections, 46% with occipital and parietal resections, and 27% with frontal lobe resections. In the long term, only 35% of patients with callosotomy were free of most disabling seizures, and 16% with multiple subpial transections remained free of all seizures. The year of operation, duration of follow-up and outcome classification system were most strongly associated with outcomes. Almost all long-term outcome studies describe patient cohorts without controls. Although there is substantial variation in outcome definition and methodology among the studies, consistent patterns of results emerge for various surgical interventions after adjusting for sources of heterogeneity. The long-term (> or =5 years) seizure free rate following temporal lobe resective surgery was similar to that reported in short-term controlled studies. On the other hand, long-term seizure freedom was consistently lower after extratemporal surgery and palliative procedures.

Adolescent↗

Use of MR imaging for quantitative evaluation of resection for temporal lobe epilepsy.

The postoperative magnetic resonance imaging studies of 40 patients who underwent surgery for medically refractory temporal lobe epilepsy were reviewed. A method for quantifying the resection of four specific medial temporal lobe structures--amygdala, uncus, hippocampal formation, and parahippocampal gyrus--was used to correlate postoperative seizure control with the degree to which those structures had been resected. Satisfactory postoperative seizure control was found to be strongly dependent (P less than .01) on the performance of at least partial resection of all four medial temporal lobe structures. The total amount of tissue removed did not necessarily correlate with the clinical outcome in individual cases, however, as long as some portion of all four medial structures had been resected. Two complicating factors--the presence of posterior or bilateral independent electroencephalographic foci and a history of meningoencephalitis--each negatively influenced surgical outcome (P less than .01). In cases with a complicating factor and inadequate medial resection, the outcome was invariably poor.

Adult↗

Cerebellar hemorrhage arising postoperatively as a complication of supratentorial surgery: a retrospective study.

OBJECT: Postoperative cerebellar hemorrhage as a complication of supratentorial surgery is an increasingly recognized clinical entity. So far, it has remained unclear whether this complication constitutes an intraoperative or postoperative event. The observation of such cases prompted the authors to analyze retrospectively their series of supratentorial craniotomies. The aim of this study was to determine the incidence of cerebellar hemorrhage and its temporal relationship to supratentorial surgery. METHODS: The authors reviewed discharge notes and reports on postoperative computerized tomography (CT) scans for 1650 patients who had undergone supratentorial craniotomy between January 1998 and February 2001. The retrospective study led to the identification of 10 patients who had sustained cerebellar hemorrhage as a complication of supratentorial surgery. Because it was routine to perform CT scanning following craniotomy, an early CT scan obtained within the 1st postoperative hour (mean 24 minutes after wound closure) was available in eight of the 10 patients. In seven of these patients no hemorrhage was found immediately after surgery, and in only one patient was there the suspicion of cerebellar hemorrhage. In the whole series of 10 patients, cerebellar hemorrhage was detected during the later postoperative course, after a mean interval of 7 hours and 35 minutes (range 1 hour and 49 minutes-144 hours) following surgery. The incidence of cerebellar hemorrhage was 0.6% of all patients who underwent supratentorial surgery. Among patients suffering from epilepsy the incidence was 4.6%, and in those patients who underwent temporal lobe resection it was 12.9%. CONCLUSIONS: The authors have demonstrated that cerebellar hemorrhage as a complication of supratentorial surgery arises not as an intraoperative event, but as a postoperative event. Resective nontumorous temporal lobe procedures place patients at particular risk for this complication. Evidence suggests that the complication might be precipitated by postoperative suction drainage.

Adult↗

The extent of resection of FDG-PET hypometabolism relates to outcome of temporal lobectomy.

A significant minority of patients undergoing surgery for medically refractory non-lesional temporal lobe epilepsy (TLE) continue to have seizures, but the reasons for this are uncertain. Fluorodeoxyglucose (FDG) PET shows hypometabolism in a majority of patients with non-lesional TLE, even in the absence of hippocampal atrophy. We examined whether the extent of resection of the area of FDG-PET hypometabolism influenced outcome following surgery for non-lesional TLE. Twenty-six patients who underwent temporal lobectomy for medically refractory TLE with at least 12 months follow-up were studied. The preoperative FDG-PET was compared with 20 non-epileptic controls using SPM99 to identify regions of significant hypometabolism (P < 0.0005, cluster > 200). This image was then co-registered to the postoperative MRI scan. The volume of the FDG-PET hypometabolism that lay within the area of the resected temporal lobe was calculated. The volume of temporal lobe resected was also calculated. Patients with a good outcome had a greater proportion of the total FDG-PET hypometabolism volume resected than those with a poor outcome (24.1% versus 11.8%, P = 0.02). There was no significant difference between the groups in the volume of temporal lobe resected (P = 0.86). Multivariate regression demonstrated that the extent of resection of the hypometabolism significantly correlated with outcome (P = 0.03), independent of the presence of hippocampal sclerosis (P = 0.03) and total brain volume of hypometabolism (P = 0.45). The extent of resection of the region of hypometabolism on the preoperative FDG-PET is predictive of outcome following surgery for non-lesional TLE. Strategies that tailor resection extent to regional hypometabolism may warrant further evaluation.

Adult↗

Hippocampal MRI volumetrics and temporal lobe substrates in medial temporal lobe epilepsy.

Forty-nine consecutive patients undergoing anteromedial temporal lobe resection for medically intractable temporal lobe seizures, and averaging 2 yr (range 6 mo to 4 yr) postoperative follow-up, were selected for a retrospective study. This study correlated magnetic resonance imaging (MRI) derived hippocampal volumetrics, preoperative demographics, postoperative seizure control, and tissue analysis, including hippocampal CA (cornu ammonis) field neuronal, and glial cell counts, and immunohistochemistry (IHC) evidence for dentate sprouting and reorganization. These measures were compared in hippocampi with or without an adjacent presumptive epileptogenic temporal lobe mass. Mesial temporal sclerosis (MTS) was defined as > 50% neuronal cell loss averaged across all CA fields with NPY (neuropeptide-y) and somatostatin reorganization. These patients may or may not include granule cell sprouting as determined by dynorphin staining. Patients were divided into two groups based on CA field neuronal cell counts, one averaging > 50% cell loss and one averaging < 50% cell loss. For the MTS group (N = 38), 89% had significant volumetric atrophy of the ipsilateral hippocampus, 74% had dentate reorganization, and complete seizure control was seen in 76% of these patients. In one subgroup of the < 50% cell loss group, patients with medial temporal lobe epilepsy caused by a mass in the medial temporal lobe (mass group) (N = 6), 33% demonstrated significant volumetric atrophy of the hippocampus ipsilateral to the mass, 0% had dentate sprouting, and seizures were completely controlled in 67%. For the second subgroup of the < 50% cell loss group, patients without mass lesions (N = 5) who were classified as the paradoxical medial temporal lobe epilepsy group (paradoxical group), 20% had ipsilateral hippocampal atrophy, 0% had dentate reorganization, and complete seizure control was seen in 60% of these patients. In conclusion, for the MTS group, hippocampal atrophy proven by MRI volumetrics was highly predictive of significant neuronal cell loss and an excellent indicator of success. However, in patients who had a foreign mass, hippocampal atrophy was not necessarily indicative of significant neuronal cell loss and MRI volumetrics was not a factor in the determination of a successful outcome. Furthermore, patients without mass lesions who have normal volumetrics but demonstrate hippocampal disease through invasive electrode monitoring, are likely to have paradoxical medial temporal lobe epilepsy, seizures beginning at a later age, and a lower, but not insignificant, success rate than the classical mesial temporal sclerosis group.

Adolescent↗

Parenchymal lesions in pharmacoresistant temporal lobe epilepsy: dual and multiple pathology.

OBJECTIVES: Dual pathology is reported in 5-30% of temporal lobe resections performed in pharmacoresistant epilepsy. Dual pathology may be of importance for surgical planning and also for the understanding of the pathogenesis of epilepsy. We describe the frequency of dual or multiple pathology, i.e. more than one histopathological diagnosis, in adults with temporal lobe resections. MATERIAL AND METHODS: Surgical specimens from 33 consecutive patients with resections including mesial as well as neocortical temporal structures were reviewed. All histopathological findings were recorded. Post-mortem specimens from 11 control subjects were also reviewed. RESULTS: Dual or multiple pathology was found in almost half of the epilepsy patients (48%). Hippocampal sclerosis was found in 25 patients (76%), malformations of cortical development in 15 (46%), of which 12 (36%) were microdysgenesis, and low-grade tumours in seven (21%). Apart from mild gliosis, there were no histopathological changes in the control specimens. CONCLUSION: Dual or multiple pathology was a common finding in this group of adults with temporal lobe resections. In order to increase our understanding of how aetiological factors may combine in the development of seizures, we consider it relevant and important to report all histopathological findings in epilepsy surgery series.

Adult↗

Cognitive consequences of two-thirds anterior temporal lobectomy on verbal memory in 144 patients: a three-month follow-up study.

Previous studies have shown that left temporal lobectomy for intractable epilepsy can lead to verbal memory deficits. However, patients with left temporal lobe epilepsy (LTLE) frequently have impaired verbal memory preoperatively. The present analysis of 144 patients who underwent temporal lobe resections for either left (n = 68) or right (n = 76) temporal lobe epilepsy (LTLE, RTLE) addressed the questions of (a) whether a left two-thirds anterior temporal lobectomy (ATL) increases deficits in these qualitative aspects of verbal memory already impaired preoperatively, and (b) whether other aspects of verbal memory are additionally affected. We also evaluated possible determinants of preoperative abilities and postoperative changes, using multiple regression analysis. Preoperatively, patients with LTLE differed from patients with RTLE only in poorer performance on measures of long-term consolidation/retrieval (delayed recall). This is related to hippocampal pathology and seizure severity. Only left temporal lobe resections resulted in significant deterioration in verbal learning and memory. Acquisition over learning trials and recognition deteriorated most markedly, whereas performance in long-term consolidation/retrieval showed only minor changes. Preoperative performance levels, chronological age, the extent of the en bloc resection, preoperative performance on figural memory, and preoperative seizure severity were valuable determinants of postoperative changes in acquisition and recognition. In contrast, changes in consolidation/retrieval related only to preoperative ability. Left two-thirds ATL leads to new impairment in addition to preexisting memory deficits. The finding that left temporal lobectomy affects verbal acquisition and recognition more than long-term consolidation/retrieval, including the different determinants of these changes, most likely reflects the differential effects of surgery on mesial temporal and neocortical temporal functions.

Adult↗

Contribution of medial versus lateral temporal-lobe structures to human odour identification.

To investigate possible distinct contributions of different temporal-lobe structures to odour identification, the University of Pennsylvania Smell Identification Test was administered monorhinally to seizure-free patients who had undergone one of three types of temporal-lobe resection practised in three different institutions for surgical treatment of epilepsy. The resections were neocorticectomy (Dublin), selective amygdalohippocampectomy (Zurich), or anterior temporal-lobe resection with encroachment on amygdala and hippocampus (Montreal). Resections, analysed from MRI scans, showed unexpected encroachment on medial structures in most patients of the neocorticectomy groups, and largest amygdala and hippocampal resections in the amygdalohippocampectomy groups. Impaired odour identification was observed in all patient groups, irrespective of surgical approach, with greatest impairment in the nostril ipsilateral to the resection. The finding of deficits in all three surgical groups suggests that damage in the anterior temporal area, perhaps in piriform cortex, is sufficient to disrupt performance on this task; it may be that function is disrupted in the medial temporal-lobe region by disconnection when the periamygdaloid area is damaged, even when amygdala and hippocampus are left intact. An alternative explanation for our results is that damage in any one of these areas disrupts a complex network involving several distinct temporal-lobe structures.

Adolescent↗

Odor perception in temporal lobe epilepsy patients with and without temporal lobectomy.

The investigation employed monorhinic (single nostril) olfactory testing to decide whether patients with unilateral anterior temporal lobe resection (N = 16) and patients with unoperated temporal lobe epilepsy (N = 18) have impaired ability to detect, remember, and identify odors. A shape memory task accompanied the odor memory task for comparison. The lobectomy patients showed a minor bilateral depression of absolute sensitivity but still fell within the clinically normal range. The lobectomy patients showed impairment of odor recognition memory but strictly via the nostril ipsilateral to the resected lobe. A similar ipsilateral-contralateral asymmetry characterized the performance of these patients in odor identification. In that case, however, performance via the contralateral nostril showed some impairment too. Nonsurgery patients also exhibited some impairment in odor identification, but bilaterally. Finally, both groups of patients fell somewhat below normals in recognition memory for amorphous shapes. The various results implied that temporal lobe epilepsy alone takes some toll on olfactory information processing and that temporal lobe resection exacerbates the problem, but only on the side of surgery.

Adult↗

Seizure control and extent of mesial temporal resection.

Controversy exists about the extent of mesial temporal lobe resection that improves seizure control in patients with temporal lobe epilepsy. In this retrospective study, 70 patients with mesial temporal seizure activity (without evidence of tumor or vascular malformation) were surgically treated and followed for at least 2 years. The extent of mesial temporal resection was based on the findings of interictal and ictal discharges using depth electrodes, which were inserted preoperatively or intraoperatively by the orthogonal approach to the amygdaloid and hippocampal regions. Only the amygdala was resected along with the limited lateral neocortex if no epileptiform activity involved the hippocampus. The amount of hippocampal excision was determined by the extent of interictal seizure activity. The following groups became seizure free: all 8 patients with only amygdalar resection; 6 of 10 patients with amygdalar and < or = 1 cm hippocampal resection; 23 of 38 with 1-2 cm hippocampal removal, and 11 of 14 with > 2 cm hippocampal excision. In cases where there was no hippocampal resection, neuropsychological outcome compared favorably with controls. Our results suggest that although most patients with temporal lobe epilepsy require hippocampal resection of varying degrees, there is a subset in whom the amygdala may be the crucial element of a mesial temporal epileptogenic network. These patients can undergo a surgical resection sparing the hippocampus without compromising seizure outcome.

Adult↗

[Analysis of postoperative seizure recurrence after 65 temporal lobe partial resections].

Sixty-five patients (aged between 3 years 5 months and 60 years) suffering from medically resistant temporal lobe epilepsy (TLE) were operated on over a period of 33 months in Bethel Epilepsy Center. Thirty-three patients had mesial TLE and 32 patients had TLE of different etiology. The postoperative follow-up lasted 2 years in 30 patients and was on average 13.2 months or at least 8 months in the 35 patients who did not have their last examination 2 years after surgery. Many of the patients (70.9%) were seizure-free; 92.3% achieved a rewarding improvement in seizure frequency and quality of life. Reduction of medication was the cause for relapse in 10 patients, in 6 patients incomplete resection, and in 5 patients the prognosis was not good even before surgery. The cause remained unclear in 4 patients. Freedom from seizures was achieved again by renewed medication or by repeated operation in 10 of 25 patients.

Adolescent↗

Two-year follow-up of intelligence after pediatric epilepsy surgery.

Research findings concerning cognitive effects of pediatric epilepsy surgery form an important basis for decisions about surgery. However, most follow-up studies have been of limited duration. In this study, a 2-year follow-up of intelligence was undertaken. Risk factors were analyzed. Included were 38 patients aged 3 to 17 years. Surgery was left in 19 patients and right in 19 patients. Types of surgery included temporal lobe resection (n = 23), extratemporal or multilobar resection (n = 8), and hemispherectomy (n = 7). The Wechsler Scales of Intelligence were administered presurgically, 6 months postsurgically, and 2 years postsurgically. No significant change in verbal or performance intelligence quotient (IQ) was demonstrated on a group level. Lateralization, type of surgery, age at surgery, sex, and presurgical IQ did not affect outcome. Across assessments, IQ scores of left-hemisphere patients were lower than those of right-hemisphere patients. Scores of patients in the hemispherectomy group were lower than those of the extratemporal or multilobar resection group, which were lower than the temporal lobe resection group. Scores improved significantly in six patients and deteriorated in seven. In conclusion, epilepsy surgery in children and adolescents does not, in general, have a significant impact on cognitive development in a 2-year perspective. In individual patients, poor seizure control and extensive surgery for Rasmussen's encephalitis were related to a deterioration of IQ.

Adolescent↗

The amygdala and sexual drive: insights from temporal lobe epilepsy surgery.

The aim of this study was to explore the relationship between the amygdala and human sex drive. We compared amygdalar volume in groups of patients with or without sexual changes after temporal lobe resection and in age-matched neurologically normal subjects. Forty-five patients with intractable temporal lobe epilepsy who underwent surgical resection in the Comprehensive Epilepsy Program at the Austin and Repatriation Medical Centre completed a semistructured interview and questionnaire relating to sexual outcome after surgery. Volumetric analyses of both amygdalae were conducted on the patients' preoperative T(1)-weighted magnetic resonance imaging scans and those of 46 neurologically normal controls. Patients who reported a postoperative sexual increase had a significantly larger amygdalar volume contralateral to the site of their resective surgery than patients with a sexual decrease or no change than control subjects. There was a significant positive relationship between contralateral amygdalar volume and the maximum degree of sexual change. We have demonstrated a relationship between contralateral amygdalar volume and sexual outcome in patients undergoing temporal lobe resection. This finding provides evidence for an important role of the amygdala in regulating human sexual behavior. A larger contralateral amygdala may contribute to the expression of increased or improved sexuality after temporal lobe resection.

Adult↗

Epilepsy surgery.

Surgical therapy of epilepsy, although still underutilized, is presently well accepted and performed world-wide with increasing frequency. In the last decade the following changes have been noticed: non-invasive pre-surgical evaluation is increasingly carried out in close collaboration with referring centres so that often no (or only a very short) hospitalization is necessary in highly specialized epilepsy centres for this purpose. Stereoelectro-encephalography (SEEG) is used less often in invasive evaluation while the subdural strip and grid electrode-techniques are used more often. There is a general trend for a more flexible and collaborative multidisciplinary and multi-method approach utilizing the whole spectrum of modern diagnostic facilities in a more patient-oriented and therefore more cost-effective way. The main objective of the pre-surgical evaluation is to determine the onset area of the patient's spontaneous habitual seizures. The primary epileptogenic zone is not necessarily synonymous with the so-called lesional zone, although in the great majority of patients they are related. In a small percentage of candidates for epilepsy surgery additional special examinations are necessary to prevent and/or predict the degree of post-operative deficits. At present selective Amytal tests are often used but these invasive procedures might be replaced in the future by functional PET and functional MR studies. Surgery in patients with epilepsy can be categorized into: (i) lesion-oriented surgery (lesionectomy sensu stricto), (ii) epilepsy-oriented lesional surgery, (iii) surgery for epilepsy sensu stricto. Surgery is performed with a 'curative (= causal)' or a 'palliative' intention. Furthermore surgery can be categorized into standardized epilepsy surgery (such as anterior temporal lobe resection, selective amygdalohippeocampectomy, anterior callosotomy); and individually tailored surgical interventions. It is obvious that also so-called standardized operations are tailored to some degree, usually based on pre-operative findings as well as on intraoperative corticography and/or other intra-operative neurophysiological tests (functional mapping). Individually tailored operations comprise smaller topectomies and larger resections. Surgery for temporal lobe epilepsy still prevails. For mesial temporal lobe epilepsy more selective operations, such as the selective amygdalohippocampectomy, are increasingly performed. Today the majority of patients suffering from this syndrome can be evaluated non-invasively (or 'semi-invasively' with the foramen ovale electrode technique) in combination with MRI (including volumetry of the hippocampus) and PET or SPECT. In general one has the impression that extratemporal resections without a lesion are performed less often. But, if a morphological abnormality is present, pre-surgical evaluation (using grids), and surgery making use of 'functional mapping' are increasingly offered from more and more centres. Anterior callosal sections and functional hemispherectomies have also witnessed a renaissance. The most important standardized operations are reviewed.

Amygdala↗