Search PubMed⌕ Search

Biomedical subjects

C Ohye

Publications and source records attributed to C Ohye.

At least 19 recordsLinked to original sources
PubMed2001

Lesioning the thalamus for dyskinesia.

Recent advances on understanding the pallidothalamic relation lead us to perform Vim-Vo thalamotomy (combined thalamic lesion in ventralis intermedius nucleus and ventralis oralis nucleus) for cases with dyskinesia. In our recent series of thalamotomies, there are 12 cases of dyskinesia caused by various etiologies. Therefore the clinical manifestation of the involuntary movement was different in each case, including, more or less, some elements of irregular involuntary hyperkinetic movement. Stereotactic operation was performed using Leksell's apparatus aided by Surgiplan and MRI. The Vim nucleus was identified by physiological study using microelectrodes. High background activity and kinesthetic neurons are reliable indicators of Vim nucleus (but only for the lateral part). Then, selective coagulation was made by dual coagulation needles. Since the Vo nucleus is located just rostral to the Vim nucleus, the coagulation needle was turned toward the anterior part to partly cover the Vo nucleus. Thus, selective Vim-Vo thalamotomy was shown to be quite successful for the treatment of dyskinesia.

Antiparkinson Agents↗
PubMed2000

Use of selective thalamotomy for various kinds of movement disorder, based on basic studies.

Methods of selective thalamotomy with microrecording for several kinds of movement disorder are described. Precise thalamotomy (Vim, VO or Vim+VO) depends on the understanding of the functional organization of the human thalamus on the one hand, and the patient's specific feature of movement disorders on the other. To realize selective thalamotomy, microrecording and a computerized planning system are essential. Thus, a properly selected thalamotomy for movement disorders is quite useful.

Antiparkinson Agents↗
PubMed2000

The idea of stereotaxy toward minimally invasive neurosurgery.

The idea of stereotaxy in modern neurosurgery is reviewed. Stereotactic surgery has been one of the particular neurosurgical techniques mainly used for functional disorders. Nowadays, it is widely used in the field of general neurosurgery owing to the rapid development of computer-assisted 3D brain images. Functional neurosurgery itself is also changing in the sense that many alternative surgical procedures are now available due to the progress in neuroscience. The original premise of stereotaxy is exactly the same as that of minimally invasive neurosurgery today.

Cerebral Hemorrhage↗
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed2000

[Prospect of neurosurgical approach to Parkinson's disease in the 21st century].

After a brief review of the past and present status of stereotactic surgery, prospect of neurosurgical approach to Parkinson's disease in the 21st century was considered. The stereotactic surgery has progressed markedly in its technical and theoretical aspects due to the rapid development of the basic neuroscience and computerized imaging technique. Although there are some points to be clarified and estimated in the future, these new tendencies will stand to the next century, and further progress will be achieved if it contains some truth in the light of the modern neuroscience. Also it should be clinically effective, safety and smart. The idea of stereotaxy since the beginning, namely the maximum effect with minimal damage of the human brain always holds true.

Brain↗
PubMed1999

Pituitary adenomas treated by microsurgery with or without Gamma Knife surgery: experience in 122 cases.

The clinical outcome of 122 patients with pituitary adenomas treated by microsurgery and/or Gamma Knife radiosurgery (GKRS) was analyzed to evaluate patient selection criteria and the role of GKRS. Sixty-six resections were performed in 59 patients. All tumors were macroadenomas, except for 5 ACTH-producing adenomas. Twenty-four of the 31 hypersecreting adenomas showed normal serum hormone values after treatment. Postoperative complications were rhinorrhea, cranial nerve palsies, and a small thalamic infarct. GKRS was performed on 18 of the operated patients because of residual tumors, mostly in the cavernous sinus. Thirty-five of the 63 patients treated by GKRS were followed for more than 2 years. All adenomas except 2 were stable or had decreased in size. Eleven of 17 functioning adenomas showed normal serum hormone values after treatment. It is concluded that tumors that compress the optic pathway should be removed and that residual tumors in the cavernous sinus are good indications for radiosurgery.

Adenoma↗
PubMed1998

In vitro neuronal and glial production and differentiation of human central neurocytoma cells.

Human central neurocytoma cells were cultured and characterized immunophenotypically and electrophysiologically to clarify their developmental potential. We conducted systematic in vitro studies utilizing fresh tissues from three patients. Initially small homogeneous cell clusters settled down onto the bottom of the culture flasks, and, after 2 weeks from plating, mature neuron-like cells developed from these clusters and expressed neurofilament proteins (NF: specific neuronal markers). On the other hand, approximately 80% of small round cell clusters and flat glial-like cells from which these clusters developed were positively stained for glial fibrillary acidic protein (GFAP: a specific glial marker). Furthermore these neuronal and glial cells showed distinct morphology, and dual-label, indirect immunohistochemistry for GFAP and NF-200 kD disclosed that the two antigens were not found co-localized in the same cells. In single-cell clonal analysis, neuronal, glial, and mixed neuronal and glial clones were generated. Electrophysiologically, the cells of neuronal morphology possessed sodium channels, and also L-type calcium channels in whole-cell voltage clamp. The sodium channels were of a characteristic neuronal phenotype which appears in neurons. These findings suggest that small round human central neurocytoma cells exhibit both neuronal and glial differentiations and have the properties reminiscent of precursor cells derived from subventricular matrix; thus, these cultured cells may be a potential source for investigations of human CNS neuronal and glial development and differentiation.

Adult↗
PubMed1998

Effect of electrical stimulation of the thalamic Vim nucleus on hand tremor during stereotactic thalamotomy.

OBJECTIVE: The aim of this study was to analyze the correlation between neuronal responses in the thalamic ventralis intermedius (Vim) nucleus to peripheral, natural stimulation and the modulation of tremor by electrical stimulation during stereotactic thalamotomy. DESIGN AND METHODS: The authors studied 36 patients with hand tremor using a microelectrode. The responses of tremor to electrical stimulation were analysed electromyographically. Sixty stimulation sites were divided into three groups. RESULTS: Group A (20 sites) where responses to stretching of the contralateral forearm muscles were recorded. Group B (26 sites) where responses to stretching of the other muscles of the upper extremity were recorded. Electrical stimulation at sites in groups A and B temporarily suppressed the contralateral tremor, but the minimum current intensity to suppress tremor at sites in group A was less than that in group B. Electrical stimulation in group C (14 sites), where kinesthetic responses of contralateral lower extremity were recorded, resulted in increased amplitude of hand tremor. Selective coagulation including the area of tremor suppression resulted in abolition of the tremor in all patients. CONCLUSIONS: These results suggest that the most effective site for thalamotomy may also be suitable for chronic stimulation in the Vim nucleus.

Electric Stimulation↗
PubMed1998

Stereotactic treatment of central pain.

In the present study, the effect of stereotactic treatment on central pain is briefly reviewed. Studies have shown that the spinothalamic tract projects to the shell zone of the principal sensory nucleus (Vc) and its rostral part (Vim), where it forms clusters. Recent anatomophysiological studies have revealed specific nociceptive neurons in the thalamic submedius and VMpo nucleus, from which fibers project to the insular and cingulate cortex. In the abnormal state of central pain, these structures may be subjected to excess excitation. Thalamic recording during the course of stereotactic thalamotomy strongly supports this hypothesis. Thus, Vim-Vcpc thalamotomy ameliorates the so-called deep pain after stroke.

Central Nervous System Diseases↗
PubMed1997

Basal interhemispheric supra- and/or infrachiasmal approaches via superomedial orbitotomy for hypothalamic lesions: preservation of hypothalamo-pituitary functions in combination treatment with radiosurgery.

Although several approaches to the hypothalamus have been used, none is able to give full views of the hypothalamus. The risk of permanent morbidity for hypothalamo-pituitary functions is still high, especially in patients with craniopharyngioma. Basal interhemispheric supra-chiasmal or infra-chiasmal approaches via superomedial orbitotomy were developed for better visualization of the hypothalamus. Operative techniques and results, including combination treatment with radiosurgery, are reported. Twelve patients with tumors compressing the hypothalamus upward or extending into the III ventricle, or both, were operated on: 3 tumors were removed totally, 6 tumors subtotally and 3 tumors partially. Six patients received radiosurgery for residual tumor. Four patients with hypopituitarism preoperatively required oral corticosteroids and thyroid hormones postoperatively. The basal interhemispheric approach via superomedial orbitotomy is useful for better visualization of the hypothalamus and preservation of hypothalamo-pituitary functions.

Adenoma↗
PubMed1997

Single-unit activity in the primate nucleus tegmenti pedunculopontinus related to voluntary arm movement.

In the pedunculopontine tegmental nucleus (PPN), single-unit activity was recorded in two monkeys trained to manipulate an on-off lever with a hand. Among 280 neurons recorded, a change in the firing rate related to the lever-off movement was observed in 125 neurons for the contralateral limb movement (53%) and in 96 neurons for the ipsilateral limb movement (48%). The changes were an increase in the firing rate in 122 neurons and a decrease in 99 neurons. These changes in the firing rate related to the task often occurred for both the contralateral and ipsilateral limb movements. The change of activity preceded the movement onset for both contralateral and ipsilateral arm movements. These findings suggest that in primates the PPN contributes to coordination of upper limb movements on both sides.

Animals↗
PubMed1997

Study on the function of the basal ganglia and frontal cortex using depth microrecording and PET scan in relation to the outcome of pallidotomy for the treatment of rigid-akinesia-type Parkinson's disease.

Stereotactic posteroventral pallidotomy was carried out in 13 cases with rigid-akinesia-type Parkinson's disease with the aid of depth microrecording. The outcome of the pallidotomy was classified into four groups: excellent (6 cases), good (3 cases), moderate (3 cases) and fair (1 case). Electrophysiological study during the operation showed continuous high-frequency and high-amplitude spike discharges in the globus pallidus (GPi) in the excellent-response group. Before the operation, a PET study had revealed low regional cerebral glucose metabolism in the prefrontal area in all the patients. Unilateral sequential opposite finger movement induced less increase of regional cerebral blood flow both in the supplementary and primary motor area in the less effective-response groups. The indications of pallidotomy for the treatment of rigid-akinesia-type Parkinson's disease are discussed.

Adult↗
PubMed1996

Gamma knife for glioma: selection factors and survival.

PURPOSE: To determine factors associated with survival differences in patients treated with radiosurgery for glioma. METHODS AND MATERIALS: We analyzed 189 patients treated with Gamma Knife radiosurgery for primary or recurrent glioma World Health Organization (WHO) Grades 1-4. RESULTS CONCLUSION: The median minimum tumor dose was 16 Gy (8-30 Gy) and the median tumor volume was 5.9 cc (1.3-52 cc). Brachytherapy selection criteria were satisfied in 65% of patients. Median follow-up of all surviving patients was 65 weeks after radiosurgery. For primary glioblastoma patients, median survival from the date of pathologic diagnosis was 86 weeks if brachytherapy criteria were satisfied and 40 weeks if they were not (p = 0.01), indicating that selection factors strongly influence survival. Multivariate analysis showed that increased survival was associated with five variables: lower pathologic grade, younger age, increased Karnofsky performance status (KPS), smaller tumor volume, and unifocal tumor. Survival was not found to be significantly related to radiosurgical technical parameters (dose, number of isocenters, prescription isodose percent, inhomogeneity) or extent of preradiosurgery surgery. We developed a hazard ratio model that is independent of the technical details of radiosurgery and applied it to reported radiosurgery and brachytherapy series, demonstrating a significant correlation between survival and hazard ratio. CONCLUSIONS: Survival after radiosurgery for glioma is strongly related to five selection variables. Much of the variation in survival reported in previous series can be attributed to differences in distributions of these variables. These variables should be considered in selecting patients for radiosurgery and in the design of future studies.

Adolescent↗
PubMed1996

Radiobiological effects of gamma knife radiosurgery on brain tumors studied in autopsy and surgical specimens.

To elucidate the radiobiological effect of Gamma Knife radiosurgery on brain tumors, we performed a histological study on nine cases. In two, the material was obtained at autopsy and in seven following surgery. In the central region of the radiation field, destructive changes occurred both in tumor cells and in vessels. In the peripheral area, destructive and proliferative vascular changes were intermingled with residual tumor tissue. Immunohistochemical staining of surgical specimens showed that the vascular proliferative changes consisted of pericytic proliferation with or without endothelial proliferation. These characteristic changes might suppress tumor growth, at least in the short-term.

Adolescent↗
PubMed1996

Lesion size following Gamma Knife treatment for functional disorders.

In this study we investigated the reproducibility and consistency of the size of radiosurgical lesions produced for functional disorders. The T1 gadolinium-enhanced magnetic resonance (MR) images of 56 patients treated for parkinsonism, pain, or other functional diseases were used to measure 140 lesion sizes at various times after radiosurgical treatment (1-26 months, mean: 11.3 months). Only the 4-mm collimator was used to create the lesions. The maximum dose ranged from 110 to 180 Gy (mean: 145 Gy). In 42 cases (78%), one isocenter was used to create the lesion. Thirteen lesions (20%) were created with two isocenters and in 1 case, three isocenters were used. Lesions were detectable on MR images as early as 30 days after treatment. The maximum lesion volume was reached after 6-12 months and ranged from nondetectable to more than 4,000 mm3. Larger lesion volumes were strongly associated with the use of more than one isocenter. In addition, maximum doses of 160 Gy or more increased the likelihood of producing lesions larger than expected. It is therefore concluded that the use of the Gamma Knife for the treatment of functional disorders is safest when single-isocenter shots with the 4-mm collimator and a maximum dose of less than 160 Gy are used.

Adult↗
PubMed1996

Gamma thalamotomy for parkinsonian and other kinds of tremor.

On the basis of our experiences with selective ventralis intermedius thalamotomy with microrecording, certain cases of tremor with Parkinson's disease (PD, six cases), intentional tremor (one case) and essential tremor (one case) were treated by Gamma Knife. In all cases, 140-150 Gy were irradiated using 4-mm collimators. Three different strategies were used. (1) Gamma thalamotomy as the primary surgical treatment. (2) As a secondary treatment, irradiation of the symmetric point of the contralateral selective thalamotomy. (3) Extension of the previous thalamotomy. For the first three cases (all PD), a special plug pattern (100 plugs) was used, but was not employed for the later cases. No acute untoward effects were noted, and overall there appeared to be a reduction in tremor. The time course of tremor reduction varied from case to case, from about 5-6 months to 1 year.

Adult↗