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Biomedical subjects

C Ohye

Publications and source records attributed to C Ohye.

At least 91 records · Page 5Linked to original sources
PubMed1985

Plastic change of thalamic organization in patients with tremor after stroke.

Thirteen patients with tremor after stroke were treated by stereotactic thalamotomy. Prior to making therapeutic lesions, microrecordings were tried and the findings were compared with our own results obtained in Parkinson's disease. Several characteristic features were revealed in terms of changes in electrical activity in and around the thalamic Vim nucleus. These findings support the idea that reorganization of the thalamic sensory nuclei might take place.

Adult↗
PubMed1985

Cell sparse zones in the ventrolateral thalamic mass in humans, monkeys and cats: their special reference to kinesthetic neurons.

The Vim nucleus of the human thalamus is the cell sparse zone. The neurons in this zone respond to peripheral stimuli of kinesthetic modality with a short latency. In the cytometrical study, the cell sparse zone is identifiable in both the monkey and cat thalamus. The cell dimension and density in a 1 mm2 area in the cell sparse zone of each species are as follows: humans--large neuron 500-900 microns2, medium neuron 200-400 microns2, cell density 60-90/mm2/50 microns thickness; monkeys--large neuron 400-800 microns2, medium neuron 200-400 microns2, cell density 120-250/mm2/50 microns thickness; cats--large neuron 400-800 microns2, medium neuron 200-400 microns2, cell density 120-250/mm2/50 microns thickness. In this zone, there are large and medium thalamocortical relay neurons defined by the Golgi impregnated and HRP studies. It is still obscure which neurons respond to kinesthetic stimulation and which neurons or afferent fibers play important roles in the tremor mechanism.

Animals↗
PubMed1985

[Long-term follow-up study of selective VIM-thalamotomy].

To evaluate the effect of the physiologically defined selective Vim-thalamotomy on tremor type Parkinson's disease (PA, 26 cases) and essential tremor (ESS-T, 16 cases), a long-term follow-up study was conducted. The follow-up time extended from 4 months to 7 years (mean: 3.6 years). On 42 cases a total of 49 operations (4 bilateral surgery and 3 reoperations) were carried out. After identifying kinesthetic neuron, the coagulative lesion was made by using Leksell's apparatus between two needles of 4 mm effective tip length located with 3 mm interval including the recording point. One coagulation (unit lesion) destroyed about 20 mm3 brain tissue taking account of the mechanical damage by the needles themselves. The unit lesion was added around an imaginary cylinder of 3 mm radius, until the tremor was abolished completely. On the basis of number of unit lesion and its extent within an imaginary cylinder, these 49 operations were divided into the following group. Group I (minimal lesion group): coagulative lesion of 1 to 3 units within a quadrant of the imaginary cylinder. Group II: 3 to 5 units within 1/2 to one cylinder. The early (14 days after operation) and the late results on the tremor were evaluated clinically and electromyographically by 4 different categories: complete abolition, slight residual, residual, and recurrence in a strict sense. The late results in 13 PA cases of group I (similar to the early results) were: 10 complete abolition, 2 slight residual and one recurred, this case was reoperated 3 months after first operation and therefore categolized in group II. The late results in 11 ESS-T cases of group I were: 6 complete arrest, 4 slight residual, and one recurred case, which had been reoperated 2 years after operation. Therefore in a total of 24 minimal lesioned cases with PA and ESS-T complete abolition in 16, slight residual in 6, and 2 reoperated cases. In these successful 22 cases with minimal lesion, the tremor was abolished without noticeable long-lasting side effect. In other 20 cases with PA and ESS-T of group II, the tremor was almost completely relieved and maintained. In conclusion, by radiographically and physiologically controlled selective Vim thalamotomy for Parkinsonian and essential tremor, it was shown that the effect of minimal lesion was valid and well maintained on the long-term follow-up base.

Adult↗
PubMed1984

Clinical pathology of malignant meningiomas.

Nineteen cases of malignant meningiomas-seven haemangiopericytic, two papillary and ten of the anaplastic type-were examined clinicopathologically. These were ten male and nine female patients and eleven of these received reoperation for recurrence. Tumours of the hemangiopericytic type had similar angiographic and macrooscopic features and malignant characteristics were found microscopically in some tumours. There were intratumoral cysts in both cases of the papillary type and these tumours had a high cellularity, an increased number of mitosis, haemorrhage and partially haemangiopericytic patterns. Six cases of the anaplastic type had changed from a benign type at recurrence and those tumours had variable features radiographically and macroscopically. Lack of typical arrangement, a large number of mitoses, increased cellularity, focal necrosis, brain infiltration, pleomorphism and anaplasia were found histologically. Four cases of the anaplastic type were diagnosed at the first operation and these tumours had apparently similar angiographic and macroscopic features, but with variable organoid structures and malignant forms, microscopically. Electron microscopic features are also described. In malignant meningiomas, the recurrence rate was high even in cases of total removal. The outcome for these patients was good in the papillary type, relatively good in the haemangiopericytic type and poor in the anaplastic type. From these results therapeutic indications are also suggested.

Adult↗
PubMed1984

Stereotactic CT scan applied to stereotactic thalamotomy and biopsy.

A stereotactic method to visualize deep subcortical structures through which the electrode would pass intraoperatively is described in detail. The procedures are: Approximation of the tentative target point in the lateral craniogram according to some craniometric data. Determination of the invading route and its transfer to the patient's scalp. CT scanning by a new generation scanner to distinguish between gray and white matter along the predetermined plane. Intraoperative adjustment of the electrode to the predetermined CT image and error correction. Verification by recording electrical activities in subcortical tissue. This simple method would be of great benefit for the accurate and safe performance of stereotactic thalamotomy and biopsy.

Biopsy↗
PubMed1983

The correlation between tremor characteristics and the predicted volume of effective lesions in stereotaxic nucleus ventralis intermedius thalamotomy.

In 51 cases (6 cases with bilateral operations) with various kinds of tremor, stereotaxic ventralis intermedius (Vim) thalamotomies were performed using Leksell's apparatus and the results of operation evaluated. Several characteristics of the tremor, including clinical features and EMG, were correlated with the assumed location and volume of the coagulative lesion. In 54 of the 57 operations, the thalamic Vim nucleus was identified physiologically and a therapeutic lesion placed at a site that included the Vim neurons. In all these cases, except one in which the lesion was estimated to be too small, tremor was immediately abolished by a relatively small lesion. The estimated volume of the lesion was about 40 to 200 mm3 and the effect persisted over a long follow-up period (maximum ten years). The size of the lesion that was necessary apparently depended on several features of the tremor. A larger lesion was required in cases of movement type tremor, tremor with a low rate (less than 4 Hz), tremor of high amplitude (more than 600 microV), and tremor involving proximal muscles or with a wide distribution. Tremor following a cerebrovascular lesion and post-traumatic tremor were characterized by coarse oscillation (high amplitude and low frequency) involving proximal muscles. A relatively larger coagulative lesion was therefore necessary to relieve this type of tremor. In contrast, parkinsonian and essential tremor were usually of low amplitude and distal in distribution. For the relief of such tremor, the lesion could be very small: if aided by electrophysiological methods to identify Vim neurons, the minimal effective volume of the lesion was estimated as about 40 mm3 and restricted to the Vim nucleus. Based on these results, the importance of the Vim nucleus in tremor mechanisms is discussed.

Adult↗
PubMed1983

Stereotactic selective thalamotomy for the treatment of tremor type cerebral palsy in adolescence.

6 cases with tremor-athetotic type cerebral palsy and 2 cases with moderate dystonia-tremor type cerebral palsy were treated by selective stereotactic thalamotomy. In the former group, postural-movement type tremor in the upper limb gradually progressed with age while athetosis remained unchanged. In the latter group, dystonia in the truncal muscles predominated over the irregular tremulous movement of the upper limbs. In all cases, the intelligence was almost normal. Stereotactic selective thalamotomy (Vim for tremor athetosis, VL-Vim for dystonia tremor) was performed under local anesthesia with the aid of radiological and neurophysiological control methods. The results of the operations were satisfactory in regard to the tremor relief and concomitant improvement of motor performances in most of the cases. Stereotactic treatment might be an effective way to make possible a one-step progress in these handicapped cases. The importance of postoperative physical therapy is also emphasized.

Adolescent↗
PubMed1982

Primary writing tremor treated by stereotactic selective thalamotomy.

Three cases with primary writing tremor were treated successfully by stereotactic selective thalamotomy centred mainly on the ventralis intermedius nucleus. They exhibited progressive coarse tremor of 5-7 Hz during writing, and Westphal's phenomenon on stretch, as the only neurological manifestations. Within the thalamus, a very high incidence of irregular burst discharges was recorded. These findings suggest that the writing tremor is an organic disorder.

Dominance, Cerebral↗
PubMed1980

Stereotactic CT scan and its correlation with the neural activity of deep structures.

An attempt has been made to visualize beforehand a brain section through which an electrode would pass to reach the target point in stereotactic thalamotomy for the treatment of tremor. On the basis of several craniometric measurements of a plain craniogram (lateral view), the level of the intercommissural line could be approximately estimated and a tentative target point set on the craniogram. Then, a line is drawn to connect this target point and the bregma. Extrapolating this line, an angle between the Reid baseline and this line could be measured in order to transfer the line to the scalp. With the aid of a GE scanner (GE-CT/T-X2), several 5-mm thick sections are made parallel to this line including the tentative target point. Among these images of CT scan thus made, referring to the foramen of Monro and the aqueduct (either of which might be visualized) one of the sections would be chosen as a tentative plane through which the electrode would pass. On the operation day, a burr hole should be made on or near the line used for CT scanning and drawn on the scalp, so the electrode tract will coincide with the CT scan image. GE scan images are clear enough to estimate the range of gray matter, white matter, caudate nucleus and thalamus. The neural activities of the deep structures recorded during the operation by stepping displacement of the electrode are correlated with this CT scan image. So far, the coincidence of both findings are satisfactory and of great value in this kind of blind operation.

Brain↗
PubMed1980

Importance of microstereoencephalotomy for tremor alleviation.

Application of the microelectrode technique in human stereotactic surgery, which is especially important for tremor control, is now routine for the procedure in our surgical theater. Neurons responsible for tremor generation can very delicately and exactly be identified within the ventralis intermedius nucleus (Vim) of the thalamus, which automatically determines the location of the minimum required thermocoagulation lesion to abolish tremor. Neurons with rhythmic burst discharges, which are synchronus in phase to the peripheral tremor, are organized in delicate somatotopic fashion within the Vim. Electrical stimulation of the neuron area through this microelectrode usually inhibits tremor of the corresponding area and a small thermocoagulation lesion, usually 3 mm in diameter, permanently abolishes tremor. These three findings, i.e., existence of rhythmic bursts, effect of the stimulation and surgical lesion, are the same in parkinsonian tremor, postural tremor and intention tremor. Physiological interpretation of different types of tremor will be proposed. In the cases of idiopathic neck tremor, a single Vim neuron corresponded to four neck muscles, i.e., bilateral sternocleidomastoid muscle (SCM) and bilateral posterior neck muscles, and most markedly to the controlateral posterior neck muscle and the ipsilateral SCM. Instrumentation of microstereoencephalotomy is also explained.

Aged↗