Biomedical subjects

Shigeki Sunaga

Publications and source records attributed to Shigeki Sunaga.

6 recordsLinked to original sources

PubMed2006

Efficacy of intraoperative electrocorticography for assessing seizure outcomes in intractable epilepsy patients with temporal-lobe-mass lesions.

PURPOSE: The findings of previous studies have been controversial regarding the optimal surgical procedures required for effective seizure control. In particular, there are varying views as to whether or not lesionectomy of a temporal-lobe-mass lesion is a satisfactory process or whether removal of additional seizure foci is necessary. In this study, we evaluated the efficacy of additional removal of electrically positive foci using intraoperative electrocorticography on mass lesions related to temporal lobe epilepsy. METHODS: Thirty-five medically intractable epilepsy patients with temporal-lobe benign mass lesions, who had been surgically treated, were assessed. The relationship between resection of the epilepsy focus using intraoperative electrocorticography and seizure outcome was analyzed. In addition, the sites of residual spikes after lesion removal were evaluated. RESULTS: In this study, the benign mass lesions consisted of 21 gangliogliomas, 8 cavernous angiomas and 6 dysembryoplastic neuroepithelial tumors. The number of 3-year postoperative seizure-free incidences for the group that underwent lesionectomy plus additional spike-positive site resection equated to 90.9%. In contrast, in the group that underwent a lesionectomy only, 76.9% were seizure-free for 3-years postoperatively. After complete removal of mass lesions, 86.4% of the residual spikes were detected over the hippocampus. CONCLUSION: Even after the complete removal of temporal-lobe-mass lesions, a high frequency of residual spikes was obtained from the hippocampus. Effective surgical seizure control was achieved by carrying out additional procedures on the affected hippocampus. To detect seizure foci surrounding the lesion, especially over the hippocampus, intraoperative electrocorticogram monitoring was shown to be an effective technique.

Adult↗

PubMed2006

Hippocampal transection for treatment of left temporal lobe epilepsy with preservation of verbal memory.

Despite good seizure outcome with temporal lobectomy, postoperative impairment of verbal memory remains unsolved. To address this problem we developed a new method, applying the rationale of multiple subpial transection (MST) to the hippocampus. The inferior ventricle is accessed without disrupting the neuronal pathways related to verbal memory. Intraoperative electrocorticography is recorded over the hippocampus and amygdala. After the extent of the epileptic area is determined, multiple transections of the pyramidal layer under the alveus is performed using specially designed ring transectors. After this procedure, epileptic discharges from the hippocampus can be completely abolished. Of 21 cases undergoing this operation, 12 left-sided and nine right-sided, 17 were followed up for more than one year. Fourteen (82%) are seizure free, two (12%) have rare seizures, and one (6%) has significantly improved. Of eight patients who underwent a battery of neuropsychometric tests both before and after left hippocampal transection, postoperative verbal memory was completely preserved in seven cases, and one transiently worsened patient recovered within 6 months. However, these results are still preliminary as the number of patients is small and the follow-up time short. The accumulation of cases and follow-up of greater duration will be necessary to precisely confirm the efficacy of this new technique.

Electroencephalography↗

PubMed2006

Temporal lobe epilepsy caused by dermoid cyst.

A 15-year-old boy presented with a dermoid cyst in the left temporal lobe manifesting as complex partial seizures. Magnetic resonance imaging demonstrated a tumor with mixed signal intensity in the left anterior temporal subdural area, but no evidence of rupture. Intraoperatively, the tumor was located mainly in the deep sylvian fissure, adjacent to the amygdala, and had compressed the hippocampus. Intraoperative electrocorticography (ECoG) showed sporadic interictal spikes in both the adjacent areas of the tumor and over the anterior segment of the hippocampus. Total removal of the tumor and gliotic area of the surrounding tissue including the amygdala was performed. The hippocampal epileptic region was treated by transection of the pyramidal layer to preserve verbal memory function. Histological examination showed the dermoid tumor was closely attached to the brain parenchyma. The complex partial seizures ceased completely after surgery. Intraoperative recording of ECoG from the hippocampus and other limbic structures was very important to determine the epileptogenic area even if the tumor did not directly invade the hippocampus.

Adolescent↗

PubMed2006

[A case of Sturge-Weber syndrome with severe temper tantrum].

We report a case of Sturge-Weber syndrome with intractable epilepsy presenting complex partial seizures(CPSs) and severe temper tantrum successfully treated with anterior temporal lobectomy. A 23-month-old girl without facial angioma presented with seizures from 8 months after birth. Neuroradiological examination demonstrated angioma in the left temporooccipital lobes and calcification in the left occipital lobe. Thus she was diagnosed as having Sturge-Weber syndrome. Her parents sought medical advice because of intractable and more frequent CPSs and a change in temperament manifesting as severe temper tantrums. Interictal electroencephalogram (EEG) showed relatively mild abnormal slow wave discharges in the left temporal region. The patient underwent left anterior temporal lobectomy based on intraoperative electrocorticography (ECoG) findings. Histopathological examination demonstrated gliotic change in the amygdala. After the surgery, she has remained seizure-free for 14 months while taking anticonvulsants and temper tantrums ultimately showed remission 10 months following surgery. This case may indicate that severe temper tantrum was associated with a change in amygdala structures.

Amygdala↗

PubMed2004

[Surgical treatment for temporal lobe epilepsy with preservation of postoperative memory function].

Temporal lobe epilepsy is frequently drug-resistant in adult epilepsy. However, its surgical treatment is very effective and about 70% of operated patients become seizure-free. As preoperative evaluation, analysis of seizure characteristics, scalp EEG with sphenoidal lead, and neuroimaging are most important. When these noninvasive examinations are concordant in focus localization, surgical treatment without prolonged recording by intracranial electrodes become feasible. In spite of good seizure outcome after temporal lobectomy, postoperative impairment of verbal memory has remained to be a long-standing problem. To cope with this ominous complication, we developed a new surgical method of hippocampal transection, based on the principle of multiple subpial transection (MST). Placing a small corticotomy on the anterior part of superior temporal gyrus, the inferior ventricle is opened through suctioning the temporal stem. Intraoperative electrocorticography (ECoG) is recorded over the hippocampus. After the extent of the epileptic area is determined, the alveus is cut with microscissors and the pyramidal layer is transected in parallel with neuronal fibers by a specially designed ring transector. With this procedure, epileptic discharges from the hippocampus can be completely abolished. In all 7 cases undergoing left hippocampal transection, postoperative verbal memory was preserved with excellent seizure outcome.

Adult↗

PubMedDate not supplied

Impulse response function based on multivariate AR model can differentiate focal hemisphere in temporal lobe epilepsy.

The purpose of this study is to propose and investigate a new approach for discriminating between focal and non-focal hemispheres in intractable temporal lobe epilepsy, based on applying multivariate time series analysis to the discharge-free background brain activity observed in nocturnal electrocorticogram (ECoG) time series. Five unilateral focal patients and one bilateral focal patient were studied. In order to detect the location of epileptic foci, linear multivariate autoregressive (MAR) models were fitted to the ECoG data; as a new approach for the purpose of summarizing these models in a single relevant parameter, the behavior of the corresponding impulse response functions was studied and described by an attenuation coefficient. In the majority of unilateral focal patients, the averaged attenuation coefficient was found to be almost always significantly larger in the focal hemisphere, as compared to the non-focal hemisphere. Also the amplitude of the fluctuations of the attenuation coefficient was significantly larger in the focal hemisphere. Moreover, in one patient showing a typical regular sleep cycle, the attenuation coefficient in the focal hemisphere tended to be larger during REM sleep and smaller during Non-REM sleep. In the bilateral focal patient, no statistically significant distinction between the hemispheres was found. This study provides encouraging results for new investigations of brain dynamics by multivariate parametric modeling. It opens up the possibility of relating diseases like epilepsy to the properties of inconspicuous background brain dynamics, without the need to record and analyze epileptic seizures or other evidently pathological waveforms.

Adult↗