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Intraoperative electrocorticography and successful focus resection in a case of Sturge-Weber syndrome.

This paper reports a surgically treated case of Sturge-Weber syndrome (SWS) in which the epileptic foci and haemangiomatosis were successfully resected under monitoring of intraoperative electrocorticography. The patient was a 19-month-old female infant who was referred to our hospital because of frequent hemi-tonic-clonic convulsions that were resistant to anticonvulsant therapy. Serial MRI showed progressive atrophy in the left fronto-parieto-temporal lobe, and gyral enhancement by gadolinium corresponded to venous haemangiomatosis of SWS. Three-dimensional reconstruction of the MR images was performed using the Viewing Wand System. Conventional EEG taken before the operation showed slow activity in the left frontal lobe. Intraoperative ECoG revealed spike focus at the posterior temporal cortex to the margin of the haemangiomatosis. Lesionectomy with lobar corticectomy of the total frontal and parietal lobe and part of the temporal lobe was performed. The epileptogenic focus detected by ECoG in the posterior temporal lobe was also resected. In post-excisional ECoG, epileptogenic activities had disappeared. The patient had hemiparesis and hemihypesthesia just after the surgery, but gradually recovered from the paresis and almost has normal motor function except for right-hand clumsiness up to 1 year after Surgery. The present study demonstrated that lobar corticectomy of the haemangiomatosis-affected cortex with resection of the neighbouring epileptogenic focus is a good surgical alternative even if a haemangiomatosis of the SWS affected multilobar corti of the hemisphere.

Electroencephalography↗

The role of the intracarotid amobarbital procedure in evaluation of patients for epilepsy surgery.

PURPOSE: To examine the role of the intracarotid amobarbital procedure (IAP) in the presurgical evaluation of patients with medically refractory localization-related epilepsy. METHODS: We retrospectively studied 111 patients who underwent cortical resective surgery at our center between 1991 and 1996. In patients with mesial temporal lobe epilepsy (mTLE), a presurgical determination of the epileptogenic zone was compared with localization based on IAP memory asymmetry scores, and with ultimate localization after resective surgery. In patients with neocortical or mesial frontal epilepsy, the IAP was evaluated for evidence of unilateral or bilateral poor memory performance. RESULTS: Of 68 patients with mTLE localized by noninvasive tests, 60 had concordant lateralized memory deficits on IAP. Eight patients had lateralized memory deficits on IAP that were discordant with noninvasive tests and with localization as determined by surgical outcome. All 11 mTLE patients requiring invasive EEG monitoring were correctly lateralized by IAP, including one patient in whom the noninvasive evaluation otherwise provided false lateralization. Of 32 patients with neocortical or mesial frontal lobe epilepsy, 21 displayed memory deficits on IAP. Of 10 patients with bilateral deficits, five had mesial frontal lobe epilepsy. In 13 patients with lateralized memory deficits, seven underwent electrode implantation in the mesial temporal lobe, and four ultimately underwent resection of an epileptogenic mesial temporal lobe in addition to a neocortical resection. CONCLUSIONS: In patients with mTLE, lateralized memory deficits on IAP usually confirm localization provided by noninvasive tests. However, in mTLE not well lateralized by the noninvasive evaluation, and in neocortical or mesial frontal epilepsy, the IAP may provide information regarding localization that ultimately alters surgical management.

Adolescent↗

Surgical treatment of temporal lobe epilepsy associated with subcortical ectopic gray matter under the guidance of intraoperative electrocorticography.

We describe a dual pathology presenting as intractable temporal lobe epilepsy associated with subcortical ectopic gray matter. The patient was a 28-year-old male with a 12-year history of refractory temporal lobe epilepsy. Preoperative diagnostic imaging revealed right hippocampal sclerosis, in addition to subcortical ectopic gray matter extending from the posterior end of the inferior horn of the right lateral ventricle to the cerebral parenchyma in the temporoparietal lobe. As surgical therapy for epilepsy, right anterior temporal lobectomy with amygdalohippocampectomy was initially performed. Intraoperative electrocorticography (ECoG) was extremely useful at this point in determining the range of excision of ectopic gray matter after resection of mesial temporal lobe structures. Based on ECoG findings, about 50% of the ectopic gray matter was excised. As of 2 years postoperatively, the patient has remained seizure free with no medication. In cases concomitantly manifesting hippocampal sclerosis and subcortical ectopic gray matter, epilepsy may be associated with dual pathology. This case report raises the potentially important issue of the possible presence of areas of structural abnormality that are non-epileptogenic.

Adult↗

[History of epilepsy surgery at The Hospital for Sick Children in Toronto, Canada].

OBJECTIVE: To review the development of epilepsy surgery for pediatric patients with intractable epilepsy at The Hospital for Sick Children in Toronto, Canada. METHODS: We retrospectively collected and reviewed published papers regarding pediatric epilepsy surgery since 1930's. RESULTS: First, McKenzie started a hemispherectomy for children. Hendrick established anatomical hemispherectomy for pediatric patients with hemiparesis and intractable seizures since 1964. Hoffman performed anterior temporal lobectomy and neocortical temporal resection for lesional tempolal lobe epilepsy with or without mesial temporal sclerosis since 1974. Thereafter, multimodal neuroimaging studies of CT scan, MRI, and XenonCT, SPECT and PET have been used to identify and remove the epileptogenic lesion and zone. In 1996, magnetoencephalography (MEG) was introduced to localize interictal spike sources and somatosensory evoked fields for children with intractable seizures. Snead and Rutka started subdural grid electrodes that were constructed by scalp video EEG, MRI and MEG findings. The clustered MEG spike source coregistered with the intraoperative neuronavigation system delineated the epileptogenic zone requiring completely excision for neocortical lesional epilepsy from 2000. CONCLUSION: The pediatric epilepsy surgery at the Hospital for Sick Children has been progressing from anatomical hemispherectomy to complete clusterectomy of MEG spikes sources that localized the epileptogenic zone. Cortical excision, lobectomy, hemisphelotomy, corpus callosotomy and vagal nerve stimulation have been applied to appropriate seizure types identified by advanced neurodiagnostic modalities. We furthermore develop non-invasive methods for localizing and understanding the epileptic network in pediatric epilepsy patients with developing brain.

Canada↗

Adult-onset temporal lobe epilepsy associated with smoldering herpes simplex 2 infection.

A 40-year-old man with chronic genital herpes simplex infection developed partial complex temporal lobe seizures of insidious onset, with EEG and MRI evidence of a unilateral temporal lobe destructive, atrophic process. Extensive workup did not reveal an infectious etiology. Three years of escalating number and severity of daily seizures with memory loss led to temporal lobectomy. Histologic study revealed active, low-level viral infection in the resected hippocampus and temporal lobe cortex, with immunohistochemical evidence for infection by herpes simplex 2, principally in neurons. In situ hybridization confirmed the presence of herpes simplex virus in neurons. Anticonvulsant-resistant seizure episodes began to recur several times daily soon after surgery, but the addition of acyclovir to the treatment regimen resulted in a substantial reduction in seizure occurrence, maintained for the subsequent 2.5 years.

Acyclovir↗

Changes in regional cerebral blood flow beyond the temporal lobe in unilateral temporal lobe epilepsy.

PURPOSE: Single photon emission computed tomography (SPECT) is widely used to evaluate functional abnormalities during the epileptic event. Changes in regional cerebral blood flow (rCBF) are well defined in patients with temporal lobe epilepsy (TLE) undergoing surgical resection. Nonetheless, the interpretation of ictal abnormalities in CBF beyond the temporal lobes has not been carefully addressed. METHODS: We assessed 4 patients with pathologically proven unilateral TLE who had significant ipsilateral frontal hypoperfusion in ictal studies with no other abnormalities but chronic epilepsy accounting for such findings. Patients were assessed as candidates for surgery by interictal EEG, neuropsychological studies, brain magnetic resonance imaging, scalp electrode video-EEG monitoring, and ictal SPECT. RESULTS: Characteristic hyperperfusion was evident over the temporal lobe ipsilateral to the EEG focus, with significant hypoperfusion over the frontal region in 3 patients. In patient 4, frontal hypoperfusion was not statistically significant. CONCLUSIONS: SPECT demonstrated relative rCBF changes beyond the epileptogenic zone in unilateral TLE. Our findings provide further insight into the pathophysiological changes underlying this condition.

Adult↗

Distinct electrophysiological alterations in dentate gyrus versus CA1 glial cells from epileptic humans with temporal lobe sclerosis.

Previous studies have characterized the electrophysiological properties of astrocytes in the CA1 region of hippocampi resected from patients with intractable temporal lobe epilepsy (TLE). However, the properties of hilar astrocytes from such patients have not been studied although astrocytes display regional heterogeneity and a non-uniform response to injury. Thus, we performed patch-clamp recordings of putative astrocytes in hilar and CA1 regions of surgically removed epileptic hippocampi with and without sclerosis (mesial TLE, MTLE patients, and paradoxical TLE, PTLE patients, respectively), and non-epileptic, non-sclerotic hippocampi (tumor patients). Our data show that the current profile of hilar astrocytes undergoes significant changes in MTLE but not in PTLE or tumor hippocampi. In particular, inwardly rectifying K(+) (K(IR)) and outwardly rectifying K(+) currents were reduced, inward Na(+) currents and membrane resistances were increased in putative astrocytes from MLTE cases compared to PTLE and tumor cases. Because the conductance of K(IR) channels in cell-attached patches (approximately 34pS) from MTLE tissue was not altered, a reduction in the number of K(IR) channels likely accounts for the decrease in whole-cell K(IR) conductance. Presumed astrocytes in the CA1 region from each patient group displayed intercellular coupling and a passive current profile; these characteristics were never observed in hilar glial cells. No apparent changes in the current profile of coupled CA1 glial cells could be detected between MTLE, PTLE and tumor tissues. Additionally, CA1 glial cells expressed a high density of 34pS K(IR) channels. These data suggest that K(+) buffering via K(IR) channels may be functionally compromised in hilar astrocytes of epileptic and sclerotic (MTLE) human hippocampi. By contrast, CA1 astrocytes retained their intercellular coupling and K(IR) channel expression necessary for K(+) buffering.

Dentate Gyrus↗

Malignant transformation of a gangliocytoma/ganglioglioma into a glioblastoma multiforme: a molecular genetic analysis. Case report.

A gangliocytoma/ganglioglioma with no atypical or malignant features was subtotally resected from the right temporal lobe of a 16-year-old woman. A second resection was performed 8 years later to treat a locally recurrent lesion with increased cellularity that was diagnosed as a World Health Organization Grade II ganglioglioma on the basis of neuropathological examination. Molecular analysis of the recurrent tumor revealed a TP53 gene mutation, but no amplification of the epidermal growth factor receptor (EGFR) gene. Radiotherapy (60 Gy) was administered after the second resection. The patient returned 1 year later with a second focal recurrence. The specimen obtained during the third resection of tumor exhibited exclusively astrocytic differentiation, cellular pleomorphism with multinucleated cells, high mitotic activity, and endothelial proliferation. Therefore, the tumor was diagnosed to be a glioblastoma multiforme (GBM). Molecular analysis of tumor DNA from the second recurrent tumor demonstrated the presence of the TP53 mutation, which previously had been observed in the first recurrent tumor, but again no evidence of EGFR amplification. Findings demonstrate that the presence of TP53 mutation in progressed gangliogliomas should be interpreted as a progression-associated mutation rather than a consequence of treatment. This is the first report to indicate that the molecular pathways of gangliocytomas/gangliogliomas progressing to become GBMs may parallel those of diffuse astrocytomas progressing to become GBMs.

Adolescent↗

Management of low-grade gliomas: results of resections without electrocorticography.

Low-grade gliomas associated with chronic seizures constitute a distinct clinicopathologic group of tumors that arise in young hosts, are based in gray matter of limbic or adjacent cortex, and usually have an indolent course. The most important factor in achieving long-term seizure control in these patients is complete removal of the lesion, to tumor-free margins. For low-grade gliomas in the temporal lobe, additional mesial temporal resection may be required, but there is no evidence that it need be based on ECoG. Using this procedure to define the epileptogenic zone for surgery may result in resections that are larger than necessary. The decision on extralesional hippocampal resection should be based on evaluation of the structural and functional status of the hippocampus by considering several variables, including seizure history, proximity of the tumor to the hippocampus, and the neuropsychologic profile of the patient, especially with regard to memory function.

Astrocytoma↗

Hippocampal resections and the use of human tissue in defining temporal lobe epilepsy syndromes.

From the clinical perspective, a continued analysis of the hippocampus in animal models of epilepsy as well as in human material will be critical to finally understanding MTLE. Through the continued evolution of surgical feedback to our preoperative localization studies, and from our basic science studies on resected tissue, we propose that 1) the hippocampus is critical to developing medial temporal lobe excitability, and that the inhibitory hilar interneurons which suffer most during developmental injury are likely to be involved in this process; 2) the hippocampus is not the only potentially hyperexcitable medial temporal lobe structure, but seems to function (both normally and pathologically) in a recurrent loop consisting of the entorhinal cortex, amygdala, and temporal neocortices; and 3) hypotheses derived from animal model studies, and data obtained directly from analysis of human tissue can be used to refine epilepsy classifications.

Animals↗

Magnetic resonance imaging-based computer-assisted stereotactic resection of the hippocampus and amygdala in patients with temporal lobe epilepsy.

In patients with medically intractable complex partial seizures of temporal lobe origin, stereotactic amygdalohippocampectomy can now provide excellent results. Target structures can be accurately identified and completely resected with use of a carbon dioxide laser. In a series of 18 patients who underwent this computer-interactive procedure, all experienced a cessation or dramatic reduction in frequency of seizure activity. Because the inferior optic radiations are disrupted with use of the posterolateral approach, nondisabling postoperative visual field deficits always ensue. In addition, two of our patients who underwent left-sided procedures had transient minor speech problems, perhaps attributable to postoperative swelling of the lateral temporal lobe. Patients in whom a surface electroencephalogram discloses a posterior temporal focus of seizure activity are candidates for stereotactic amygdalohippocampectomy.

Adolescent↗

Robotic long-distance telementoring in neurosurgery.

OBJECTIVE: To test the feasibility of long-distance telementoring in neurosurgery by providing subspecialized expertise in real time to another neurosurgeon performing a surgical procedure in a remote location. METHODS: A robotic telecollaboration system (Socrates; Computer Motion, Inc., Santa Barbara, CA) capable of controlling the movements of a robotic arm, of handling two-way video, and of audio communication as well as transmission of neuronavigational data from the remote operating room was used for the telementoring procedures. Four integrated services digital network lines with a total speed of transmission of 512 kilobytes per second provided telecommunications between a large academic center (Halifax, Nova Scotia) and a community-based center (Saint John, New Brunswick) located 400 km away. RESULTS: Long-distance telementoring was used in three craniotomies for brain tumors, a craniotomy for an arteriovenous malformation, a carotid endarterectomy, and a lumbar laminectomy. There were no surgical complications during the procedures, and all patients had uneventful outcomes. The neurosurgeons in the remote location believed that the input from the mentors was useful in all of the cases and was crucial in the removal of a mesial temporal lobe glioma and resection of an occipital arteriovenous malformation. CONCLUSION: Our initial experience with long-distance robotic-assisted telementoring in six cases indicates that telementoring is feasible, reliable, and safe. Although still in its infancy, telementoring has the potential to improve surgical care, to enhance neurosurgical training, and to have a major impact on the delivery of neurosurgical services throughout the world.

Academic Medical Centers↗

[Patient aged 45 with refractory epilepsy of the temporal lobe since early childhood].

INTRODUCTION: Temporal lobe epilepsy is the most frequent of the epilepsies related with localization and one of the most refractory to pharmacological treatment. Temporal lobectomy curbs seizures in many of these patients, which improves their quality of life. CASE REPORT: Patient aged 45 who, during early infancy, started to suffer simple partial seizures that later went on to become generalised. These were well under control by adolescence but at 23 they became complex partial seizures that were resistant to different antiepileptic drugs. The patient was submitted to a complete presurgical evaluation and a left anterior temporal lobectomy was performed at the age of 44. After surgery he evolved favourably. The final diagnosis was that he was suffering from mesial temporal sclerosis, associated with a subcortical neuronal heterotopy of the parahippocampal region. We discuss the semiology and the aetiology with regard to this patient and in a general sense, and we also define the foundations upholding the decision to perform surgery, the areas that make up the epileptogenic zone, and the neurophysiological and neuropsychological tests, and the structural and functional neuroimaging that are used to measure those areas. Likewise, the different techniques that can be used in resection of the temporal lobe are analysed. We also set out an etiopathogenic hypothesis according to the histopathological results and comment on a number of related general aspects. CONCLUSIONS: Progress in physiopathological knowledge, the development of diagnostic and surgical techniques, and its high efficiency and low morbidity have consolidated temporal lobectomy as a radical form of treatment for temporal lobe epilepsy that should be performed as early as possible once resistance to medication has been observed.

Diagnosis, Differential↗

Activation of electrocorticographic activity with remifentanil and alfentanil during neurosurgical excision of epileptogenic focus.

BACKGROUND: Opioids are known to stimulate surface electroencephalographic activity in patients with temporal lobe epilepsy. The objective of the current study was to compare the electrocorticographic activation effects of the newer short-acting opioid remifentanil with those of alfentanil during epilepsy surgery under general anaesthesia. METHODS: Thirteen patients undergoing temporal lobe epilepsy surgery under general anaesthesia received alfentanil 30 microg kg(-1) and remifentanil 1 microg kg(-1) as i.v. boluses in sequence. The design was a randomized double-blind cross-over study. After opening the dura, electrocorticogram (ECoG) electrode contact strips were placed over the temporal and supratemporal neocortex and depth electrodes were inserted in the amygdala and hippocampus. Alfentanil 30 microg kg(-1) or remifentanil 1 microg kg(-1) were administered randomly in a blinded fashion. The ECoG was recorded continuously before and after the injection of each drug. The interictal epileptiform activity (spikes and sharp waves) above baseline was analysed. RESULTS: Both drugs increased epileptiform activity especially that recorded from depth electrodes in the temporal limbic structures. No epileptiform activity was recorded from the electrodes overlying the supratemporal neocortex before or after drug administration. The more potent activator was alfentanil, which caused an increase in activation from baseline of 99.8% compared with 67.4% for remifentanil. In addition, alfentanil activated the epileptiform activity in 3 patients in which remifentanil had no effect. There were no changes in heart rate after the opioid boluses. Both remifentanil and alfentanil caused significant reductions in blood pressure at 3 and 5 min after administration. CONCLUSION: We conclude that at the doses used in this study, alfentanil is the better opioid for intraoperative activation of the ECoG in neurosurgical patients undergoing resection of a temporal lobe epileptic focus. This pharmacological activation of epileptiform activity assists in localizing and confirming the site of surgical excision. Neither alfentanil nor remifentanil activated epileptiform activity in non-epileptic brain tissue.

Adult↗

Monstrocellular heavily lipidized malignant glioma.

A man of 32 years was admitted with a 3-month history of temporal lobe epilepsy. CT-Scan showed a well-circumscribed area of heterogenous contrast enhancement in the right temporal lobe. Gross total resection was performed but the tumor recurred: the patient died 6 months after the onset of symptoms. There was no autopsy. Histology revealed a highly pleomorphic neoplasm with extensive zones of necrosis. Monster cells, up to several hundred micrometers in diameter, with multiple and/or multi-lobed nuclei were numerous and showed emperipolesis for polymorphonuclear, mononuclear, and small tumor cells. Abundant mitoses were observed. Tumor cells of all sizes had ground-glass or vacuolated cytoplasm which obscured their glial nature. GFAP was demonstrated in some neoplastic cells. Reticulin fibers were confined to perivascular areas where mononuclear inflammatory cells were sometimes noted. Vascular proliferation was mild. Electromicroscopic study revealed that the cytoplasms of the tumor cells contained abundant lipid droplets, numerous mitochondria, and glio-filaments. Such a tumor has been reported recently as "malignant glioma with heavily lipidized tumor cells". This rare entity, previously reported as xanthosarcoma of the brain, represents a subgroup of primitive monstrocellular cerebral tumors.

Adult↗

Randomized trials and collaborative research in epilepsy surgery: future directions.

BACKGROUND: Although randomized controlled trials (RCTs) are the gold standard for evaluating therapeutic interventions, surgical RCTs are particularly challenging and few have been done in the field of epilepsy surgery. We assess the level of RCT activity in epilepsy surgery and propose feasible alternatives to develop sustainable research initiatives in this area. METHODS: We undertook a systematic review of the world literature to assess the level of RCT activity in epilepsy surgery. Previous personal experience with RCTs in epilepsy surgery and examples of successful Canadian multicentre research networks were reviewed to propose initiatives for sustainable, valid research in epilepsy surgery. RESULTS: We identified 12 RCTs in epilepsy surgery, including 692 patients, of whom 416 were involved in vagus nerve stimulation, 16 in various brain electrostimulation procedures, 180 in comparisons of different surgical techniques, and 80 in a comparison of medical versus surgical therapy. Most studies were of short duration (median=3 months, range 3-12 months). In the area of resective surgery, only temporal lobe epilepsy has been subjected to any type of RCT comparison. All RCTs have been done within the last 13 years. There were no multicentre Canadian surgical studies. CONCLUSIONS: The adoption of RCTs in epilepsy surgery has been slow and difficult worldwide. Because of its universal health care system and its well established epilepsy surgery centres, Canada is in a strong position to create a national epilepsy surgery research initiative capable of undertaking high quality, sustainable research in epilepsy surgery.

Electric Stimulation Therapy↗

Psychometric properties and factor structure of the Wechsler Memory Scale-Revised in a sample of persons with intractable epilepsy.

The Wechsler Memory Scale-Revised (WMS-R) is used routinely as a presurgical assessment of memory for clients considering elective resection of the temporal lobe and/or hippocampus for the relief of intractable temporal lobe epilepsy. This research investigated the psychometric properties of the WMS-R in a population of people with epilepsy. The sample consisted of 181 patients with a diagnosis of epilepsy who underwent a complete neuropsychological examination as a routine part of their investigation. The results confirm that the WMS-R has acceptable levels of reliability as measured by internal consistency. A factor analysis revealed a consistent three-factor structure: Visual Memory, Verbal Memory, and Attention/ Concentration factors. Multiple regression analysis, however, indicated that the Visual Memory index was susceptible to a number of influences, throwing into question whether it is a pure measure of nonverbal memory functioning.

Adolescent↗

Auditory and visual P300s in temporal lobectomy patients: evidence for modality-dependent generators.

The P300 component of the event-related brain potential (ERP) was studied in epileptic patients with unilateral resections of medial temporal lobe areas of the brain. The patients and controls were tested in an oddball paradigm in two conditions: counting and reaction time. Both auditory and visual stimuli were used to elicit ERP activity in different blocks. Despite the reported presence of locally-generated auditory and visual P300-like potentials in these areas, no evidence was found of any surgically-related hemispheric asymmetries in the scalp distribution of the P300 or Slow Wave for stimuli in either modality. Moreover, compared to normal controls, there were no significant reductions in overall P300 amplitude in the patients. The patients did show a double dissociation in their frontal ERP activity: the left temporal lobectomy patients showed apparent decreased frontal auditory P300 amplitudes but normal visual P300 amplitudes, whereas the right temporal lobectomy patients showed the opposite pattern. These results appeared to be due to the presence of a long-duration slow wave rather than to alterations in P300 amplitude. These data do not support the presence of a significant contribution by a hippocampal/amygdala generator to the activity of the scalp-recorded P300 in the oddball paradigm. Topographic comparisons on normalized amplitudes revealed significantly different scalp distributions as a function of stimulus modality, event probability, and task for both the P300 and Slow Wave components. These data indicate that the amplitude variations associated with each experimental variable are due to the activity of a separate underlying neural source. The sources of task and probability effects on P300 and Slow Wave amplitude each appeared to be modality-independent generators. The nature of the third, modality-related generator is less clear. These results uphold the tenets of the model of P300 amplitude proposed by Johnson (1986) and argue against the idea that the P300 is a unitary phenomenon.

Adult↗