Surgery of Cerebrovascular Lesions Causing Intractable Epilepsy

OBJECTIVE: Traditionally, the main indications for surgery in vascular-related lesion were based upon reduction or control of seizures, reversal of symptoms of deficits related to mass effect, and prevention of hemorrhage or recurrent hemorrhage. However, the results of surgical treatment for seizure control are disappointing in some reports. Here we describe surgical strategies and our experience in treating patients with intractable seizures associated with vascular-related lesions according to sophisticated presurgical and intraoperative evaluation. METHODS: Twelve(4.5%) patients were selected for this study out of total 264 patients with resective epilepsy surgery at our epilepsy center during four years since 1992. All were treated with anticonvulsant agents but became refractory. These patients operated on under local or general anesthesia for resection surgery, underwent presurgical and intraoperative evaluation for identification of adjacent, beyond or remote epileptogenic area and the eloquent area. RESULTS: Of these 12 patients, vascular malformations(AVM, cavernous angioma) were 7, overt hemorrhage due to vascular lesion were 2 and intractable ongoing seizure after vascular surgery were 3. Other vascular lesion including occlusive disease, moyamoya disease or previous hemorrhage were excluded in this study. The location of the lesion was mainly temporal and peri-Rolandic areas, and dual pathology was verified in 2 cases of 6 temporal lesion. The surgical outcome(class I;7, II;3, III;1, IV;1) was excellent by Engel's classification. CONCLUSION: Control of seizures related to vascular lesions remains strong indication for surgical resection. For this reason, careful presurgical evaluations are essential to evaluate the remote epileptogenic area, especially in temporal lesion. Intraoperative acute recording(ECoG) and functional mapping by electrical stimulation or SSEP are important for maximal resection of epileptogenic area with minimal sequellae.

Functional Brain Mapping Using H2 15O Positron Emission Tomography ( I ): Statistical Parametric Mapping Method / 대한핵의학회잡지

PURPOSE: We investigated the statistical methods to compose the functional brain map of human working memory and the principal factors that have an effect on the methods for localization. MATERIALS AND METHODS: Repeated PET scans with successive four tasks, which consist of one control and three different activation tasks, were performed on six right-handed normal volunteers for 2 minutes after bolus injections of 925 MBq H0 at the intervals of 30 minutes. Irnage data were analyzed using SPM96 (Statistical Parametric Mapping) imple-mented with Matlab (Mathworks Inc., U.S.A.). Images from the same subject were spatially registered and were normalized using linear and nonlinear transformation methods. Significant difference between control and each activation state was estimated at every voxel based on the general linear model. Differences of global counts were removed using analysis of covariance (ANCOVA) with global activity as covariate. Using the mean and variance for each condition which was adjusted using ANCOVA, t-statistics was performed on every voxel To interpret the results more easily, t-values were transformed to the standard (saussian distri-bution (Z-score). RESULTS: All the subjects carried out the activation and control tests successfully. Average rate of correct answers was 95%. The numbers of activated blobs were 4 for verbal memory I, 9 for verbal memory II, 9 for visual memory, and 6 for canjunctive activation of these three tasks. The verbal working memory activates predominantly left-sided slruetures, and the visual memory activates the right hernisphere. CONCLUSION: We conclude that rCBF PET imaging and statistical parametric mapping method were useful in the localization of the brain regions for verbal and visual working memory.

Functional Brain Mapping Using H2 15O Positron Emission Tomography ( II ): Mapping of Human Working Memory / 대한핵의학회잡지

PURPOSE: To localize and compare the neural basis of verbal and visual human working memory, we erforrned functional activation study using H2O PET. MATERIALS AND METHODS: Repeated H213O PET scans with one control and three different activation tasks were performed on six right-handed narmal volunteers. Each activation task was composed of 13 matching trials. On each trial, four targets, a fixation dot and a probe were presented sequentially and subjects task was to press a response button to indicate whether or nat the probe was one of the previous targets. Short meaningful Korean words, simple drawings and monochromic pictures of human faces were used as matching objects for verbal or visual memory. All the images were spatially normalized and the differences between control and activation states were statistically analyzed using SPM96. RESULTS: Statistical analysis of verbal memory activation with short words showed activation in the left Broca's area, premotor cortex, cerebellum and right cingulate gyrus. In verbal memory with simple drawings, activation was shown in the larger regions including where activated with short words and left superior temporal cortex, basal ganglia, thalamus, prefrontal cortex, anterior portion of right superior temporal gyrus and right infero-lateral frontal cortex. On the other hand, the visual memory task activated predominantly right-sided structures, especially inferior frontal cortex, supplementary motor cortex and superior parietal cortex. CONCLUSION: The results are :consistent with the hypothesis of the laterality and dissociation of the verbal and visual workmg memory from the invasive electrophysiological studies and emphasize the pivotal role of frontal cortex and cingulate gyrus in working memory system.

Intravenous Propofol Anesthesia in Epilepsy Surgery: A Comparative Clinical Study on the Usefulness of Pofol(R) and Diprivan(R) / 대한마취과학회지

BACKGROUND: Propofol is a new, short-acting intravenous sedative-hypnotic anesthetics for induction and maintenance. Awakening craniotomy for resection of seizure focus is performed when the area to be excited is too close to an eloquent area to be mapping accurately. This study was performed to evaluate the efficacy and the hemodynamic effects of Pofol(R) in comparison with Diprivan(R) for the maintenance of total intravenous anesthesia (TIVA) in epilepsy surgery. METHODS: This procedure is carried out under what has been euphemistically called local anesthesia or monitored anesthesia care (MAC). For induction, 2 mg/kg in bolus was administered in both groups, and the usual maintaining dose was 100 mcg/kg/min. Surgical procedures are divided in 6 stage (I: Craniotomy, II: Electrocorticography (ECoG), III: Functional mapping, IV: Cortical resection, V: Post-resection EEG, VI: Craniotomy closure). RESULTS: Arterial blood gases and vital signs of Pofol(R) group and Diprivan(R) group were analysed. But, awakening time was slightly rapid in Pofol(R) group (8.9+/-2.64 min.) compared with Diprivan(R) group (10.6+/-3.22 min.). And there were no statistically significant differences between the two groups. CONCLUSIONS: We concluded that both Pofol(R) and Diprivan(R) are the ideal total intravenous anesthetics for long time epilepsy surgery. However, Pofol(R) group is more helpful in intraoperative ECoG and functional brain mapping because of its slightly rapid awakening time.

Presurgical Invasive Study in Intractable Epilepsy: Intracranial Electrode and Brain Mapping

Improved diagnostic tools, patient selections, and operative techniques have brought a resurgence of the surgical management of intractable epilepsy recently. And the most remarkable developments of epilepsy surgery are various kinds of intensive presurgical evaluation. The aims of presurgical evaluation for intractable epilepsy are : 1) The diagnosis of exact types of epilepsy for appropriate medical treatment as well as for surgical intervention. 2) The exact localization of epileptogenic region responsible for the patient's habitual seizures and testing for functional safety of the focal resection of epileptogenic region. Theoretically the presurgical evaluations can be classified as noninvasive and invasive studies. The noninvasive presurgical studies include various kinds of EEG investigations, neuroimaging, neuropsychological studies and other laboratory studies. The invasive presurgical evaluations include various kinds of intracranial electrode recording and functional brain mapping, The authors analysed the invasive presurgical evaluation of Yonsei epilepsy program since Oct. 1989 and review the literatures.

Surgery for seizure-related structural lesions of the brain with intraoperative acute recording(ECoG) and functional mapping

Epilepsy surgery has been demonstrated to be an effective alternative treatment for intractable partial or localization related epilepsy. Primary intracranial neoplasms and other structural lesions of the brain are important etiological factors in patients with partial seizure disorders. A neuroimaging identified lesion in patients with seizures, not necessarily medically refractory, may also be an indication for surgery in selected patients. Twelve patients operated on under local or general anesthesia for resection surgery underwent intraoperative recording(electrocorticogram) and/or functional mapping by electrical stimulation or somatosensory evoked potentials-(SSEPs) for identification of the secondary epileptogenic area and/or functional area; 2 meningiomas, 5 astrocytomas, 1 gangliocytoma, 1 abscess, 1 small AVM, 1 cysticercosis and one gliosis by previous intracerebral hemorrhage with middle cerebral artery(MCA) aneurysm. Among these, additional corticectomy or anterior temporal lobectomy was performed in eleven patients. All the patients did well after surgery with good outcomes as seizure free in nine(75%) out of 12 patients with 11.9 months of follow-up period, without any neurological deficits. Intraoperative recording and functional mapping of adjacent areas of the structural lesions of the brain are useful in surgery and can guide the extent of further resection.