Biomedical subjects

S Chitoku

Publications and source records attributed to S Chitoku.

14 recordsLinked to original sources

PubMed2001

Malignant rolandic-sylvian epilepsy in children: diagnosis, treatment, and outcomes.

OBJECTIVE: To describe the diagnosis, treatment, and outcomes in children with malignant rolandic-sylvian epilepsy (MRSE), defined as a form of epilepsy characterized by sensorimotor seizures, medical refractoriness, normal MRI, frontocentrotemporal EEG spikes, rolandic-sylvian spike sources on magnetoencephalography (MEG), and cognitive problems. METHODS: A retrospective chart analysis of seven patients who had shown these characteristics and undergone extensive diagnostic testing, including MEG and intracranial video-EEG was performed. RESULTS: Interictal scalp EEG spikes were seen over the frontocentrotemporal regions bilaterally (6) and unilaterally (1). MEG showed spike sources in the perisylvian region in two patients (both bilateral) and in the perirolandic fissure in five (two bilateral). Three patients required bilateral subdural strips to lateralize seizures before electrocorticography. Final electrocorticograms showed an ictal onset zone around the rolandic (four cases) and rolandic-sylvian regions (three cases). Six patients showed neuropsychological deficits. After cortical excision and multiple subpial transection, three were seizure free and four had seizures rarely (30 months' mean follow-up). No child had a permanent deficit in sensorimotor or cognitive functions, although two showed exacerbation of preexisting attentional deficits. Tissue analysis showed definite evidence of neuronal migration disorders (3) and gliosis (2). CONCLUSIONS: MEG was helpful for localizing both malignant rolandic-sylvian neuronal activities and functional cortex. Successive neuropsychological assessments are necessary to detect cognitive deterioration and indicate remedial programming. If, after careful observation over at least 5 years, surgery is considered to control refractory seizures, intracranial video-EEG is needed to localize the epileptogenic zone.

Adolescent↗

PubMed2001

Extraoperative cortical stimulation of motor function in children.

The purpose of the study was to investigate factors altering the amperage threshold needed to provoke functional responses in children with epilepsy. Twenty patients (4-18 years of age) who underwent epilepsy surgery at our institution from 1996-2000 after insertion of subdural grid electrodes were reviewed retrospectively. Extraoperative electrical cortical stimulation was performed with 50-Hz biphasic pulses of 0.2 ms in duration using a "distance reference" technique. Amperage thresholds of primary motor responses and afterdischarges were evaluated. The patients were grouped according to underlying pathology: eight with neuronal migration disorders (group A) and 12 with other disorders (group B). The motor cortex was defined successfully in all children because the afterdischarges threshold was higher than the motor cortical threshold. Amperage thresholds ranged from 2-20 mA (mean = 7.7) for primary motor function. An inverse relationship was found between amperage threshold and age: the younger the patient, the higher the threshold (P = 0.0005). Patients in group A required a higher amperage (2-20 mA, mean = 8.6) for motor cortical mapping than those in group B (2-14 mA, mean = 6.4). Younger children with neuronal migration disorders require a higher amperage threshold to achieve adequate motor functional mapping with careful observation of afterdischarges.

Adolescent↗

PubMed2001

Dipole localization for identification of neuronal generators in independent neighboring interictal EEG spike foci.

PURPOSE: We evaluated dipole localizations of independent neighboring interictal spike foci using scalp electroencephalogram (EEG) to identify neuronal generators of epileptic discharges. METHODS: Three pediatric patients with extratemporal lobe epilepsy who had two independent neighboring interictal spike foci on scalp EEG were studied. Prolonged video EEG was digitally recorded from 19 scalp electrodes, whose positions were registered using a three-dimensional digitizer. Interictal spikes were visually selected based on negative phase reversals on bipolar montages. We analyzed the dipole position and moment of each spike using a single moving dipole and three-shell spherical head model. The dipoles were overlaid onto magnetic resonance (MR) images and divided into two groups based on two spike foci. RESULTS: The dipoles of the two groups were oriented either tangentially or radially to the scalp in close proximity to each other. The dipoles oriented radially were located underneath the electrode with a negative peak; those oriented tangentially were between electrodes with a negative and positive peak. The positions of tangential dipoles were more concentrated than those of radial dipoles. The epileptogenic regions corresponded to the dipole localizations. Surgical excisions were performed based on the results of electrocorticography. After surgery, two patients were seizure free, and one had rare seizures (follow-up period, 13-31 months). CONCLUSIONS: We showed that dipoles in close proximity but with different orientations projected two negative maxima on scalp EEG in three patients with extratemporal localization-related epilepsy. Equivalent current dipole analysis of individual interictal spikes can provide useful information about the epileptogenic zone in these patients.

Adolescent↗

PubMed2001

Image-guided, frameless stereotactic sectioning of the corpus callosum in children with intractable epilepsy.

Corpus callosotomy is an effective neurosurgical procedure for children with intractable atonic or drop attack seizures. While this procedure has not changed significantly over the past three decades, some technical issues remain to be resolved. These include the intraoperative determination of the extent of the callosotomy, the need to stage the procedure, as well as side of approach of craniotomy. We report our 8-year experience with corpus callosotomy using a frameless stereotactic image-guided system (ISG Viewing Wand). Seventeen children with atonic seizures underwent sectioning of the corpus callosum. The mean patient age was 10.5 years. Six children underwent complete callosotomy while 11 underwent resection of the anterior two-thirds. MRI 3D reconstruction of the sagittal sinus and draining cerebral veins was undertaken in all cases. The side of the craniotomy was determined on the basis of favorability of the draining veins with respect to the extent of the callosotomy. The extent of the callosotomy was determined by intraoperative feedback using the ISG Viewing Wand((R)). Nine of 11 patients in the partial callosotomy group and 4 of 6 patients in the complete callosotomy group showed significant improvement in atonic seizures. We conclude that the use of frameless stereotaxy can function as an important adjunct in the planning and conduction of successful sectioning of the corpus callosum in children with intractable seizures.

Adolescent↗

PubMed2001

Computerized brain-surface voltage topographic mapping for localization of intracranial spikes from electrocorticography. Technical note.

The purpose of this paper is to describe the use of computerized brain-surface voltage topographic mapping to localize and identify epileptic discharges recorded on electrocorticographic (ECoG) studies in which a subdural grid was used during intracranial video electroencephalographic (IVEEG) monitoring. The authors studied 12 children who underwent surgery for intractable extrahippocampal epilepsy. Cortical surfaces and subdural grid electrodes were photographed during the initial surgery to create an electrode map that could be superimposed onto a picture of the brain surface. Spikes were selected from ictal discharges recorded at the beginning of clinically confirmed seizures and from interictal discharges seen on ECoG studies during IVEEG recording. A computer program was used to calculate the sequential amplitude of the spikes by using squared interpolation, and they were then superimposed onto the electrode map. Interictal discharges and high-amplitude spike complexes at seizure onset were plotted on the map. This mapping procedure depicted the ictal zone in nine patients and the interictal zone in 12, and proved to be an accurate and useful source of information for planning corrective surgery.

Action Potentials↗

PubMed2001

[Surgery for intractable epilepsy in children: pre- and perioperative evaluations with special reference to dipole tracing method estimated from interictal spike].

Methods of preoperative and perioperative evaluation methods for surgical treatment of intractable epilepsy in children are described. Among non-invasive diagnostic methods, EEG-video monitoring is the most fundamental. Amygdalohippocampal volume measurement by MR was useful for the differential diagnosis of mesial temporal lobe epilepsy (TLE) from lateral TLE and generalized epilepsy. The dipole tracing method with a realistic head model was useful for identification of epileptic foci from the interictal spikes of scalp EEG, when an abnormal electric source was estimated as an equivalent current dipole (ECD) in the brain of patients with organic lesion and TLE. ECD concentration ratio ranged from 70 to 90% within 20 mm around the lesion. After lesionectomy seizures disappeared in every patient. The mean distance between the centers of the ECD and epileptic focus (identified by subdural electrode recording) was 14 mm (range: 8 to 18 mm). ECDs of mesial TLE were located in the temporal base rather than mesial temporal lobe, whereas those of lateral TLE in the lateral cortex precisely. In unilateral, intermediate and bilateral TLE, 76%, 52% and 36% of ECDs were localized in the ictal onset zone respectively (p = 0.007). Electrical cortical stimulation with chronically placed intracranial electrodes was used to accurately identify eloquent areas to avoid postsurgical complications. Immediately after operation, 10 to 20% of patients showed better or deteriorated results in neuropsychological examinations, which recovered in all patients after one year. Postoperative seizures were absent in three fourths of patients. Further efforts are needed to obtain better seizure control in future.

Adolescent↗

PubMed1999

Spinal intramedullary ependymal cyst: a case report.

BACKGROUND: Spinal intramedullary ependymal cysts are extremely rare. Only seven pathologically proven cases have been reported in the literature. METHOD: We present an 18-month-old female with thoracic spinal intramedullary ependymal cyst that was diagnosed pathologically. RESULTS: Histological diagnosis was made by light microscopy after immunostaining. After partially removing the cyst wall and establishing communication between the cyst and the subarachnoid space, the patient improved neurologically. CONCLUSIONS: For spinal intramedullary ependymal cyst we recommend diagnosis by MR imaging without myelography, then enucleation of the cyst, if possible. Otherwise, we remove the cyst wall as much as possible and create adequate communication between the cyst and the subarachnoid space.

Cysts↗

PubMed1999

Accuracy and availability of the computed assisted neurosurgery navigation system during epilepsy surgery.

The magnetic-force-based Computed Assisted Neurosurgery System was used for epilepsy surgery to localize targets accurately in the operative field. The correlation between X components of target coordinates in the axial plane and the coronal plane for the same target was strong in all cases. Concerning Y components, there were statistically significant differences in 2 cases. There was a case that showed statistically significant differences only in the Z dimension. The interdisk distance by data sets of coordinates obtained from neuronavigation was calculated to quantify localization error, and the measuring error ranged from -5 to 13.3 mm (1.3 +/- 3.2 mm). The magnitude of the application errors in this study tended to be large in the frontal and vertex regions.

Adolescent↗

PubMed1999

Usefulness of the dipole tracing method with a scalp-skull-brain head model: relationship between the epileptic focus and equivalent current dipole locations.

PURPOSE: We examined whether the dipole tracing (DT) method with a realistic three-shell head model and inhomogeneous electric conductivity is useful to estimate the epileptic focus from interictal spikes. METHOD: This study included 17 temporal lobe epilepsy (TLE) cases, classified into three types as type A (unilateral), type B (intermediate) and type C (bilateral) and 5 extratemporal epilepsy (XTLE) cases. The epileptic areas were determined by noninvasive and/or invasive examinations. Selected interictal spikes were analyzed and the calculated equivalent current dipoles (ECDs) of dipolarity greater than 0.98 were superimposed over the realistic head model in each patient. We evaluated the ECD concentration within and around the epileptic area. RESULTS: In TLE cases, types A showed better ECD concentration (87%) within the epileptic area than other types (type B: 68%; type C: 74%). XTLE exhibited variable ECD distribution within and around the epileptic area. CONCLUSION: The DT method with a realistic head model and inhomogeneous electric conductivity can be useful to estimate the epileptic area from interictal spikes, especially in unilateral TLE cases.

Action Potentials↗

PubMed1998

Intradural spinal hibernoma: case report.

BACKGROUND: Hibernoma is a rare, benign tumor arising from vestigial remnants of brown adipose tissue. It usually affects muscle and subcutaneous tissue and is asymptomatic and slow growing. METHODS: A review of the worldwide literature contains about 110 cases of hibernomas. However, only two cases (including our case) of hibernoma located in the intradural spine have been reported. We present an extremely rare case of intradural extramedullary spinal hibernoma and summarize the magnetic resonance imaging (MRI) findings of the lesion. CASE DESCRIPTION: A 35-year-old woman suffered from motor weakness and numbness of the left upper extremity. Cervical spinal MRI revealed an intradural extramedullary mass at C7. She underwent surgery via the posterior approach and the lesion was completely removed. Histopathologic examination showed multivacuolated cells with centrally placed nuclei, and the diagnosis of hibernoma was made. CONCLUSIONS: Because the CT and MRI findings of hibernoma are almost same as those of other lipomatous tumors, a surgical specimen of this tumor is necessary to establish the correct diagnosis. Early diagnosis and total resection are necessary as some cases showed malignant features or rapid growth. Etiologically, the tumor may have developed by the ectopic growth or migration of adipose tissue.

Adult↗

PubMed1998

[Superior sagittal sinus occlusion due to calvarial metastasis of renal cell carcinoma: 2 cases report].

We report two cases of superior sagittal sinus (SSS) occlusion due to calvarial metastasis of renal cell carcinoma. Both cases were presented with bulging of the skull. No stigmata of increased intracranial pressure was detected. Cerebral angiogram showed the occlusion of the SSS. Tumor cells did not penetrate into the dura mater nor the galea and the tumors were able to be removed easily in both cases. One case without collateral circulation showed recanalization of the SSS on the postoperative angiography. Another case with development of collateral circulation did not show recanalization of SSS on the postoperative magnetic resonance angiography. In the latter case, cortical veins flowed into the occluded portion. We consider that SSS should be preserved to prevent venous congestion in the cases where collateral circulation has not developed.

Aged↗

PubMed1997

Multiple intramedullary spinal sarcoidosis: case report.

BACKGROUND: According to past reported cases, spinal intramedullary sarcoidosis has the radiologic characteristics of a single enhanced lesion with cord swelling. However, it is difficult to make a diagnosis using only radiologic examinations. Including our case, 20 cases have been reported of intramedullary spinal sarcoidosis. Only six cases were diagnosed as primary spinal sarcoidosis. We present a rare case of multiple spinal intramedullary sarcoidosis without cord swelling. CASE DESCRIPTION: This 63 year-old man was afflicted with progressive paraparesis and numbness of the lower extremities. Magnetic resonance imaging showed intramedullary lesions without cord swelling. The patient underwent biopsy for diagnosis and the specimen showed a noncaseating granuloma mainly composed of epitheloid cells. Postoperative corticosteroid therapy was effective and the lesion disappeared 1 month after the operation. CONCLUSIONS: Biopsy is a less invasive method and is useful for early diagnosis. Early diagnosis is important for spinal sarcoidosis so that high-dose corticosteroid therapy can be commenced while the lesion still has a good chance of being successfully treated.

Humans↗

PubMed1996

Cervical ventral epithelial cyst treated by anterior corpectomy--case report.

A 15-year-old boy presented with a cervical ventral epithelial cyst manifesting as intractable cervical pain. Neurological examination revealed weakness of his left grasp and increased deep tendon reflexes. The anterior approach was selected because the lesion was located directly ventral to the spinal cord. He underwent C4-5 anterior corpectomy and subtotal resection of the cyst wall. He made a good recovery without additional deficits. Most previously reported cases have been treated using the posterior approach despite the ventral location of the lesion. The anterior approach offers a safer and more effective means of treating such lesions because it allows direct access to the lesion without manipulation of the spinal cord.

Adolescent↗

PubMed1992

[Germinoma with granulomatous reaction arising from the corona radiata; case report and review of articles].

We report a rare case of germinoma with granulomatous reaction arising from the corona radiata. This 20-year-old man was admitted to our hospital complaining of progressive motor weakness on the right side. CT demonstrated a poorly demarcated high density area in the left corona radiata, which was heterogeneously enhanced after administration of contrast medium. Moreover, the continuity of the mass to the ventricular wall was confirmed on MRI. At the first operation, subtotal removal of the tumor was performed through a fronto-parietal craniotomy. The diagnosis for the specific neoplasm was not established histologically, but granuloma caused by fungal infection was the most likely cause of the lesion. We tried amphotericin B (AmB), and remission of the tumor was obtained. However, during the following 3 months, the size of the tumor gradually enlarged again. AmB was repeatedly administered, but this time the treatment was ineffective. Six months later, on May 21, 1990, the second operation was performed and histological examination revealed typical germinoma consisting of two-cell pattern. Subsequently, the patient underwent focal irradiation of 33 Gy to the tumor site, and the tumor completely disappeared. As intracranial germinomas are observed to be successfully cured by radiotherapy and/or chemotherapy, choice of the therapeutic management must be carefully determined according to the histological diagnosis, especially in young people. A variety of locations of germinomas and the accompanying granulomatous reactions could create some diagnostic confusion, so great care must be taken in the treatment of much intracranial germinomas.

Adult↗