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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.

Adolescent↗

Increased neuronal beta-amyloid precursor protein expression in human temporal lobe epilepsy: association with interleukin-1 alpha immunoreactivity.

Levels of immunoreactive beta-amyloid precursor protein and interleukin-1 alpha were found to be elevated in surgically resected human temporal lobe tissue from patients with intractable epilepsy compared with postmortem tissue from neurologically unaffected patients (controls). In tissue from epileptics, the levels of the 135-kDa beta-amyloid precursor protein isoform were elevated to fourfold (p < 0.05) those of controls and those of the 130-kDa isoform to threefold (p < 0.05), whereas those of the 120-kDa isoform (p > 0.05) were not different from control values. beta-Amyloid precursor protein-immunoreactive neurons were 16 times more numerous, and their cytoplasm and proximal processes were more intensely immunoreactive in tissue sections from epileptics than controls (133 +/- 12 vs. 8 +/- 3/mm2; p < 0.001). However, neither beta-amyloid precursor protein-immunoreactive dystrophic neurites nor beta-amyloid deposits were found in this tissue. Interleukin-1 alpha-immunoreactive cells (microglia) were three times more numerous in epileptics than in controls (80 +/- 8 vs. 25 +/- 5/mm2; p < 0.001), and these cells were often found adjacent to beta-amyloid precursor protein-immunoreactive neuronal cell bodies. Our findings, together with functions established in vitro for interleukin-1, suggest that increased expression of this protein contributes to the increased levels of beta-amyloid precursor protein in epileptics, thus indicating a potential role for both of these proteins in the neuronal dysfunctions, e.g., hyperexcitability, characteristic of epilepsy.

Adolescent↗

Characterization of hemorrhagic complications after surgery for temporal lobe epilepsy.

OBJECTIVES: To assess the significance of symptomatic hemorrhagic complications occurring after different temporal resections for temporal lobe epilepsy (TLE) and to compare this data to findings with postoperative hematomas after temporal surgery for mostly glial or metastatic tumors. PATIENTS AND METHODS: Patient charts were retrospectively reviewed for 442 patients who underwent surgery for refractory TLE between 1995 and 2000. Procedures were 247 transsylvian amygdalohippocampectomies (AH), 40 transcortical AH, 57 anterior temporal lobectomies (ATL), 23 lesionectomies plus AH, and 75 lesionectomies without AH. All patients with delayed awakening or new neurological deficits due to hemorrhages were included in the study. An identical procedure was performed to detect symptomatic hemorrhages after 208 procedures for temporal tumor resection during the same time period. RESULTS: Symptomatic postoperative hemorrhages were found in 17 patients (3.8 %) undergoing epilepsy surgery, while the incidence was 3.0 % in a group with space-occupying temporal tumors (six patients). Hemorrhages showed a characteristic distribution after epilepsy surgery: in eight patients they were located remote from the site of surgery in the upper cerebellar vermis and foliae. Five typical hemorrhages associated with dysphasia were found in the left frontal operculum, only three patients had hematomas in the resection cavity, and one was located epidurally. Two patients had more than one location of hemorrhage. Transsylvian AH and ATL had a similar risk for postoperative hemorrhage, whereas none was found after lateral lesionectomies or transcortical AH. Intraoperative manipulations were associated with opercular hemorrhages; the only predisposing factor for resection site hematomas was older age, whereas cerebellar hemorrhages were associated with cerebrospinal fluid (CSF) loss during AH and ATL. There was no mortality in the TLE group, and 0.75 % permanent mild deficits. Seizure outcome did not differ from the rest of the group (82.5 % satisfactory seizure control). In contrast, all intraaxial hematomas after tumor surgery (N = 4, incidence 1.9 %) were located in or adjacent to the resection cavity. Prognosis was much worse with parenchymal hemorrhages after tumor surgery: three of four patients died, one survived with a severe hemiparesis, only two patients with extraaxial hematomas (incidence 1 %) had a complete recovery. The 3 % incidence of symptomatic hemorrhages was only insignificantly lower compared to the TLE group, patients with tumor surgery were older than TLE patients (49 versus 33 years), and in five of six patients only incomplete tumor resection was achieved. CONCLUSION: Although associated with a low permanent morbidity, features of postoperative hemorrhages after TLE surgery are characteristically different to complications after surgery for other indications, which has to be kept in mind for patient counseling and obtaining informed consent.

Adolescent↗

Language activation distributions revealed by fMRI in post-operative epilepsy patients: differences between left- and right-sided resections.

OBJECTIVE: To reveal differences of cerebral activation related to language functions in post-operative temporal lobe epilepsy (TLE) patients. METHODS: Right (RTL) and left temporal lobe (LTL) resected patients, and healthy controls were studied using functional magnetic resonance imaging (fMRI). Only patients with complete left-hemispheric language dominance according to the intracarotid amytal procedure (IAP) were included. Language-related activations were evoked by performing word generation and text reading language tasks. Activation lateralization and temporo-frontal distribution effects were analysed. RESULTS: For word generation, only LTL patients showed reduced left lateralized activation compared to controls, due to a decrease in activation in the left prefrontal cortex and an increase in the right prefrontal cortex. For reading, the left-hemispheric lateralization in RTL patients increased because of enhanced activity in the left prefrontal cortex, whereas for LTL patients the activation became bilaterally distributed over the temporal lobes. Lateralization results between pre-operative IAP and post-operative fMRI were highly discordant. Significant temporo-frontal distribution changes manifested from the reading but not from the word generation task. CONCLUSION: The cerebral language representation in post-operative LTL epilepsy patients is more bi-hemispherically lateralized than in controls and RTL patients. Post-operative temporo-frontal and interhemispheric redistribution effects, involving contralateral homologous brain areas, are suggested to contribute to the cerebral reorganisation of language function.

Adult↗

Resective surgery for medically intractable epilepsy associated with schizencephaly.

Four adults with unilateral (three cases) or bilateral (one case) closed schizencephaly, medically intractable epilepsy, and otherwise normal neurological examinations are presented. Three were examined preoperatively with magnetic resonance imaging and one with computerized tomography. Scalp electroencephalographic (EEG) studies in all four patients and electrocorticography via intracranial electrodes in two showed seizure origin in the cleft regions in two patients and in the ipsilateral temporal lobe in the other two. Temporal lobectomy was performed in the two patients with temporal lobe foci. Resection of superficial pachygyria around the cleft was performed in one patient. The authors conclude that the abnormal cortical mantle lining schizencephalic clefts may be epileptogenic. Alternatively, temporal allocortex may become the source of seizures. Therefore, these patients require careful EEG monitoring of the entire ipsilateral hemisphere as well as the cleft region.

Adult↗

Inferior temporal sulcus approach for amygdalohippocampectomy guided by a laser beam of stereotactic navigator.

OBJECTIVE: To describe a surgical technique for a minimally invasive transcortical transventricular amygdalohippocampectomy via the inferior temporal sulcus (ITS) using a stereotactic navigator. METHODS: Seven patients with medically intractable mesial temporal lobe epilepsy underwent an amygdalohippocampectomy via the ITS. By use of a laser-guided navigation system, the epileptogenic foci of the mesial temporal lobe were resected through a small linear operative route that was made by a brain speculum inserted from the ITS to the anterolateral floor of the temporal horn in the lateral ventricle. RESULTS: All patients completed at least a 1-year follow-up (range, 14-45 mo) after surgery and had improved neuropsychological parameters as a result of the operation. All patients became seizure-free after surgery. A Humphrey visual field perimeter detected no hemianopsia. CONCLUSION: Combined with the stereotactic navigation system, the ITS approach provides the least invasive amygdalohippocampectomy that preserves optic radiation. This approach seems beneficial especially in patients in whom the epileptic lesions are limited to the anterior mesial temporal lobe.

Adolescent↗

[The surgery of epilepsy].

INTRODUCTION: At the present time the surgery of epilepsy is a safe, effective therapeutic option which should be offered to the patient with drug resistant epilepsy at the right moment to prevent the irreversible negative consequences of uncontrolled seizures. DEVELOPMENT: All patients with drug resistant epilepsy should be surgically assessed. In recent years the concept of surgically remediable syndrome has been introduced to refer to conditions in which surgical treatment gives excellent results: mesial temporal sclerosis, circumscribed neocortical lesions, Sturge Weber syndrome and infantile hemiplegic epilepsy are good examples in which prolonged, unnecessary delay of surgery should not occur. This type of surgery should be undertaken in centres with suitable trained multi disciplinary teams with adequate resources and preestablished guidelines. The clinical history, surface electroencephalogram monitoring, directed magnetic resonance, functional neuroimaging with SPECT and PET and neuropsychological studies are the basis for pre surgical diagnosis. These and other investigations should be done following the guidelines of each centre and the complexity of the disorder in each case. CONCLUSION: Anteromesial resection of the temporal lobe, selective amigdalo hippocampectomy, neocortical resection, hemispherectomy or a variation of it, section of the corpus callosum and multiple sub pial transection are the most usual surgical techniques since good results are obtained with them in suitable cases.

Adult↗

Temporal-lobe seizures with additional foci treated by resection.

The authors describe the use of temporal lobectomy following careful and repeated electroencephalogram (EEG) evaluation (with implanted electrodes in otherwise unresolvable cases) in the epileptic group characterized by automatisms (psychomotor seizures) with temporal epileptiform activity complicated by EEG foci in the opposite temporal lobe or by extratemporal activity. They found that this can render a significant number of patients (between 25% and 50%) either seizure-free or with significant and useful reduction in their seizure frequency. The cure and improvement rates of cases followed up after temporal resection with or without prior study with implanted electrodes were approximately equal. However, the implanted electrodes permitted surgical treatment of certain cases which would have been rejected on the basis of evidence derived from the scalp recordings alone. Of 28 of these 34 patients with persisting EEG epileptiform activity in the postoperative period, only one had such activity in a different location in a follow-up period of 6 years. No evidence of spreading epileptic activity or appearance of "mirror foci" was seen during a follow-up period averaging 8.2 years. Seizure remission up to 15 years with eventual recurrence of the original seizure type may occur following surgical therapy. Follow-up studies of surgical epileptic treatment of less than 3 to 5 years are of doubtful value.

Adolescent↗

Surgical options for uncontrolled epilepsy.

Surgical management of refractory epilepsy has undergone many modifications since it was instituted for the treatment of post-traumatic seizures many decades ago. Localization of onset of all seizures to a single resectable area of brain by various noninvasive and invasive recording methods is a complicated and controversial area, but guidelines are available. Success is correlated with accurate location and complete resection of the focus. When this is accomplished, resective surgery for epilepsy can provide cure or over 95 per cent reduction in seizure frequency in 60 to 90 per cent of patients undergoing these procedures. Although most often applied to temporal lobe foci, resections may be done in any cerebral lobe in the dominant or nondominant hemisphere with appropriate modifications of the evaluation and surgical procedure. When patients have unlocalizable or unresectable foci, depending on their exact pattern of seizures, electrical abnormalities, and neurologic status, other procedures may be used for surgical control of seizures. These include hemispherectomy, corpus callosum section, or stereotaxic procedures. The risks of all evaluation and surgical approaches are well balanced by the benefits obtained in a large proportion of patients.

Cerebral Decortication↗

[Functional neurosurgery for epilepsy].

Introduced at the end of the last century, epilepsy surgery is indicated in patients with intractable partial seizures and based on the resection of the epileptogenic cerebral tissue from which ictal discharges originate. Palliative procedures include seizure spread pathways interruption (callosotomy, multiple subpial transections) and chronic stimulation of the vagus nerve. Complete preoperative investigations including seizure observation, clinical tests, video-EEG, MRI and functional MRI, and PET-scan are performed in order to identify the epileptogenic zone. In difficult cases, invasive seizure monitoring through depth electrode implantation (SEEG) is performed. Resections for temporal lobe seizures are associated with favorable outcome: 60 to 90% of patients will be seizure-free after surgery. A less favorable outcome is observed after extra-temporal resections: 40 to 60% seizure-free patients. A better outcome is observed after surgery for epilepsy associated with an image-defined lesion, most often a tumor, rather than for cryptogenic epilepsy. Tumors associated with chronic partial epilepsy are indolent, most of them are dysembryoplastic neuroepithelial tumors (DNET). Outcome after palliative procedures are more variable, depending on the etiology of epilepsy.

Epilepsy↗

Functional neuroimaging predicts individual memory outcome after amygdalohippocampectomy.

We examined memory-related activity within to-be-resected medial temporal lobe (MTL) structures in 12 epilepsy patients with PET before amygdalohippocampectomy and studied the reallocation of memory functions to the contralateral MTL before and after surgery. Learning tasks were designed to activate predominantly the right or left MTL. Those patients who significantly activated to-be-resected ipsilateral MTL structures during the ipsilateral learning task (i.e. the left MTL during verbal learning or the right MTL during nonverbal learning) experienced a postoperative memory decline. Preoperative activation in the contralateral MTL during the ipsilateral learning task positively correlated with the postoperative outcome for ipsilateral memory. There was no significant postoperative reallocation of ipsilateral memory functions to the contralateral MTL.

Adolescent↗

Anatomic dissociation of auditory and visual naming in the lateral temporal cortex.

BACKGROUND AND OBJECTIVE: Visual object naming traditionally has been used to identify cortical areas essential for naming (i.e., word retrieval), and investigators have found critical naming sites in the middle and posterior temporal region in most patients. Based on clinical observation, empirical findings, and the pathophysiology of temporal lobe epilepsy, the authors hypothesized that naming sites identified from auditory cues might also be relevant, and that within the temporal region, these sites would be anatomically distinct and located anterior to naming sites based on visual cues. METHODS: Twenty patients requiring resective surgery involving the left (language dominant) temporal lobe underwent pre-resection language mapping using direct cortical stimulation. Visual and auditory naming were tested at lateral temporal sites extending from 1 cm from the anterior tip to the parietal operculum. RESULTS: Auditory naming was consistently disrupted by stimulation in the anterior temporal lobe, whereas both auditory and visual naming were impaired by stimulation in the posterior temporal region. CONCLUSIONS: This pattern may explain why word finding difficulties sometimes arise or worsen following surgical procedures in which the anterior temporal region is resected without language mapping, or when resection is based on mapping that identifies language cortex exclusively using visual tasks. These results suggest that utilization of auditory based naming tasks might improve pre-resection identification of essential language cortex during direct stimulation cortical mapping, as well as noninvasive localization of dysfunction during presurgical cognitive testing.

Auditory Perception↗

Specific memory impairment in a multiple disabled male with fragile X syndrome and temporal lobe epilepsy.

Evaluation of the cognitive repercussions of an epileptic disorder and its treatment are important issues in clinical follow-up. This especially holds true for temporal lobe epilepsy (TLE) where resective surgery can be a valid treatment option. However, in patients where TLE coexists with another neurocognitive disorder, questions can arise about the precise nature of the neuropsychological deficits. The aim of the present study was to evaluate memory impairments, found in a male aged 12 years who had the dual pathology of fragile X syndrome and refractory TLE. Memory functions of this child were compared with those of a male aged 11 years 7 months with fragile X syndrome matched for intellectual functioning as indicated by highly comparable verbal (5 y 5 mo vs 5 y 9 mo) and non-verbal (7 y 2 mo vs 6 y 1 mo) cognitive age equivalents. Performance on each neuropsychological measure was evaluated twice, separately with normative data based on chronological age and on verbal or non-verbal cognitive level. A specific, distinguishable profile of task performance could be found only when controlling for general level of cognitive functioning. This made it possible to accurately evaluate neuropsychological abilities before and 6 months after anterior temporal lobe resection even in this male with a complex neurological pathology.

Abnormalities, Multiple↗

[Psychomotor epilepsy--a comparison of CT and MR in 100 patients].

The value of CT and MR was studied in 100 patients with temporal lobe epilepsy. Axial CT scans were obtained before and after contrast injection. Coronary MR scans were carried out with T1-(SE 400/30, GE 315/14) and T2-weighted sequences (SE 1600/30 + 70). A circumscribed lesion was demonstrated in fifteen patients by CT and in 25 patients by MR. With the exception of a small area of calcification, all lesions seen on CT could also be recognized on MR. In four patients CT, MR and pathologic specimen could be compared following partial resection of temporal lobe. Localized glial reactions, which were not seen on CT, produced a signal difference on MR. Better sensitivity and improved demonstration of the temporal lobes makes MR the method of choice in the diagnosis of temporal lobe epilepsy.

Adolescent↗

Olfactory learning: convergent findings from lesion and brain imaging studies in humans.

The role of temporal lobe structures in olfactory memory was investigated by (i) the examination of odour learning and memory in patients who had undergone resection from a temporal lobe (including primary olfactory regions) for the treatment of intractable epilepsy; and (ii) the examination of brain function during odour memory tasks as assessed via PET imaging of healthy individuals. In order to study different stages of odour memory, recognition of a 'list' of odours was tested after a first exposure, again after four exposures and once more after a 24 h delay interval. Patients with resection from a temporal lobe performed significantly less well than control subjects on all trials, and no significant differences were noted as a function of side of resection, indicating that there is not a strong hemispheric superiority for this task. The PET data yielded different levels of activity in piriform cortex (primary olfactory cortex), in relation to the 'no-odour' baseline scan, depending on the type of processing: no increase in activity noted during odour encoding, a small increase bilaterally during short-term recognition and a larger increase bilaterally during long-term recognition. These findings, together with findings in animal studies, suggest that piriform cortex may have an active role in odour memory processing, not simply in odour perception. Taken together, the findings from the lesion study and functional brain imaging of healthy subjects suggest that olfactory memory requires input from left and right temporal lobe regions for optimal odour recognition, and that, unlike with verbal or non-verbal visual material, there is not a strong functional lateralization for olfactory memory.

Adult↗

[Pathophysiology of medial temporal lobe epilepsy: role of cerebral dysgenesis].

We studied the incidence of cerebral dysgenetic lesions(CD) in 39 operated patients with medial temporal lobe epilepsy(MTLE) who had hippocampal sclerosis. Four patients had CD, such as menigocele at the ipsilateral temporal fossa, schizencephaly in the ipsilateral peri-Rolandic area, focal cortical dysplasia in the ipsilateral inferior temporal gyrus and periventricular nodular heterotopia at the bilateral inferior horns of the lateral ventricle. Histological examinations of the resected lateral temporal lobes from 29 MTLE patients revealed the presence of microdysgenesis (microscopic cerebral dysgenesis) in 28 patients, including heterotopic white matter neuron(24 cases), molecular layer neuron(14), oligodendroglial cell cluster(11), dilated perivascular space(10). These findings suggest that the congenital factors, as well as hippocampal sclerosis, may be involved in the development of MTLE.

Adult↗

PET and SPECT in epilepsy.

Positron emission tomography (PET) measures regional cerebral metabolism and blood flow. PET imaging has been quite successful in identifying focal epileptogenesis as an area of hypometabolism between attacks. PET has proven to be an important diagnostic tool in selecting patients with partial epilepsy, in particular with foci in the temporal lobe, for resective surgery. Because of the high costs and complexities of PET, this technology has been confined to a limited number of centers. Single photon emission computed tomography (SPECT) can also be used for noninvasive functional imaging of the brain because it demonstrates regional cerebral blood flow which is linked to cerebral metabolism. SPECT uses conventional and readily available equipment and radiopharmaceuticals. Emphasizing the outstanding UCLA experience with PET, the presently available data on the usefulness of these functional imaging techniques in the context of surgical treatment of the epilepsies are reviewed.

Adult↗

Surgery of intractable temporal lobe epilepsy presented with structural lesions.

BACKGROUND: Structural lesions are found in about 30% of surgical specimens resected for intractable temporal lobe epilepsy (TLE). Detailed presurgical evaluations can identify the epileptogenic foci, the structural lesions and their correlation. Different surgical approaches have variable seizure control outcomes. METHODS: The preoperative investigations for the intractable TLE consisted of serial electroencephalogram (EEG) recordings, long-term EEG/video monitoring with sphenoidal electrodes, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), positron emission tomography with fluorodeoxyglucose (FDG-PET) and neuropsychological assessment. Among the 217 patients who underwent anterior temporal lobectomy (ATL) for TLE at Taipei Veterans General Hospital between 1987 and 1998, 47 (21.7%) had structural lesions in the resected specimen. The patients were divided into neoplastic (n = 35) and vascular (n = 12) groups, based on the pathological findings. RESULTS: In the neoplastic group, the interictal scalp-sphenoidal EEG recordings were abnormal in all 35 cases and lateralizing in 30 (85.7%). MRI revealed tumor growth within the temporal lobe in 26 patients (74.3%). FDG-PET was performed on 17 patients. Fifteen (88.2%) of them revealed unilateral mesial temporal lobe hypometabolism. In the vascular group, the interictal EEG tracings revealed unilateral mesial temporal lobe spikes in 11 patients (91.6%). MRI revealed abnormal enhanced lesions within the temporal lobes in all 12 patients. FDG-PET was available for 7 patients, 6 (86%) of whom had unilateral mesial temporal lobe hypometabolism. At the last follow-up (range 2-10 years, with a mean period of 4.2 years), 25 patients (73%) in the neoplastic group became and remained seizure-free postoperatively, 3 (9%) had fewer than 3 attacks per year. Among the vascular group, all 12 patients became and remained seizure-free after surgery. CONCLUSIONS: For intractable TLE with structural lesions, detailed presurgical evaluations are mandatory to identify the concordance of the lesions and the epileptogenic foci. Standard ATL with removal of the lesion may offer good seizure control postoperatively.

Brain Neoplasms↗