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.

Stress analysis in the TMJ during jaw opening by use of a three-dimensional finite element model based on magnetic resonance images

This study was designed to investigate temporomandibular joint (TMJ) stress distribution during mouth opening using a finite element (FE) model of an individual TMJ based on magnetic resonance (MR) images. A dry skull with a silicon disk was used to test the three-dimensional reconstruction procedure, and showed enough accuracy and reproducibility in linear dimensions and disk volume for the following FE modelling for stress analysis in the TMJ. From an individual FE analysis of a normal subject, relatively high stresses were observed in the anterior and posterior regions of the disk during mouth opening, and furthermore, the superior boundary contacting with the glenoid fossa exhibited lower stresses than those on the inferior boundary facing the condyle. During transmission of stress through the disk, mechanical stress may be reduced by the stress redistribution function of the disk.

Parenchymal perianeurysmal cystic changes in the brain: report of five cases

PURPOSE

To describe parenchymal perianeurysmal cystic changes in the brain.

MATERIALS AND METHODS

Among 247 patients with cerebral aneurysms described in the medical or radiologic records in three institutions, five had perianeurysmal cystic changes. These were evaluated with computed tomography or magnetic resonance (MR) imaging and were categorized according to size, appearance, and the presence of hemosiderin deposit. Confirmation at stereotactic needle biopsy was available in one case.

RESULTS

Perianeurysmal cysts comprised multiple clustered cysts in three cases and a unilocular cyst in two, and diameters were 1.5-3.5 cm. Hemosiderin was depicted at MR imaging in one unilocular cyst. Associated aneurysms had diameters of 0.7-4.0 cm, and prominent aneurysmal thrombosis and calcifications were seen in two cases. Findings at stereotactic needle biopsy were of mild reactive gliosis. At long-term follow-up in two patients, the cystic regions were stable.

CONCLUSION

Parenchymal perianeurysmal cysts are rare and may display various morphologic characteristics from unilocular to multilocular. Since there may or may not be evidence of previous hemorrhage, other mechanisms such as abnormal angiogenesis factors may play a role.

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.

The role of intravascular embolization prior to radiosurgery of cerebral arteriovenous malformations. from the standpoint of hemorrhage and early obliteration after gamma knife radiosurgery

The role of intravascular embolization prior to radiosurgery of cerebral arteriovenous malformations was evaluated based on the basis of the results of gamma knife radiosurgery in relation to hemorrhage and early obliteration after treatment. Nine of 213 patients experienced hemorrhage 4 to 42 months after radiosurgery. All AVMs in these patients had dilated feeding arteries, and the flow of the AVM was rapid and/or high. An intranidal aneurysm was seen in one patient. Drainage of all AVMs consisted of a single and/or deep draining veins, and venous obstruction was found in six. Sixty-three of 87 patients followed for more than four years after radiosurgery were examined angiographically, and total obliteration of AVM was observed in 52 of them (82.5%). Early obliteration was found in 19 of the 34 patients examined within 12 months. The obliteration rate was significantly higher in slow- and low-flow AVMs (73.9%) than in rapid- and/or high-flow AVMs (18.2%). It is concluded that the role of intravascular embolization prior to radiosurgery is not only decreasing the size of the AVM but decreasing the risk of hemorrhage and shortening the latency period by decreasing their flow rate and flow volume.

Acute lymphoblastic leukemia with isolated adrenocorticotropic hormone deficiency

A 57-year-old female was admitted to our hospital because of Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). On admission, disturbance of consciousness and hyponatremia were recognized. The patient's endocrinological data showed low levels of adrenocorticotropic hormone (ACTH) (less than 5 pg/ml) and cortisol (5.9 microg/dl). Other anterior pituitary hormones were normal. Plasma ACTH and cortisol did not respond to the corticotropin releasing factor (CRF) test. A diagnosis of isolated ACTH deficiency was made. This is a rare case of isolated ACTH deficiency complicated with hematological malignancies.

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.

Relevance of the arginine transport activity to the nitric oxide synthesis in mouse peritoneal macrophages stimulated with bacterial lipopolysaccharide

Transport of arginine and production of nitrite have been investigated in mouse peritoneal macrophages stimulated with bacterial lipopolysaccharide (LPS). The arginine transport activity was induced by LPS at very low concentration (maximally induced at 1 ng/ml), whereas much higher concentration of LPS was required for the induction of nitrite production. Arginine was more concentrated in the cells when its transport activity was induced. Lysine, which is a competitive inhibitor of the transport of arginine, neutralized the concentrative effect of the induced transport activity and thus inhibited the nitrite production. Induction of the arginine transport activity seems to be prerequisite to the enhanced synthesis of nitric oxide in activated macrophages.

Grade II astrocytoma visualized by technetium-99m-ECD SPECT

We present a case of primary brain tumor demonstrating increased uptake of 99mTc-ECD. Astrocytoma (Grade II) showed significantly increased cerebral blood perfusion on dynamic images and homogeneously increased uptake on static images with 99mTc-ECD brain SPECT. There seems to be some difference in perfusion and mechanism of tumor uptake among the cerebral blood flow imaging agents (99mTc-ECD, 99mTc-HMPAO and [123I]-IMP) and 201TI-chloride.

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.

Pathobiology of cerebral gliomas in children and the role of radiosurgery

Twenty-five gliomas of the cerebral hemisphere in children were examined. Most hemispheric gliomas in children have relatively clear margins and less infiltrative potential. Radiosurgery has a role in the treatment of these tumors in addition to reducing the risk of radiation injuries developing later. Fifteen patients were alive 1-27 years (mean 8.4) following treatment and 10 patients died. Histologic examination demonstrated 10 differentiated gliomas, 10 poorly differentiated gliomas and 5 other gliomas. Most tumors had relatively clear margins on computed tomography and/or magnetic resonance images, and peritumoral edema was slight. In 9 autopsy cases, tumor dissemination and/or metastasis were seen in 7. However, tumor infiltration was not extensive, and clear tumor margins were found in some cases. Thus, cerebral gliomas in children have relatively clear margins and low infiltrative potential. Radiosurgery has a role in the treatment of these tumors.

Gamma Knife radiosurgery for acoustic schwannoma: effects of low radiation dose and functional prognosis

The effects of relatively low dose Gamma Knife irradiation on acoustic schwannoma were evaluated in 29 patients followed over 2 years after treatment. The mean dose delivered to the tumor periphery was 12.1 Gy. Lowering of the magnetic resonance signal intensity in the tumor center appeared in 69% and signs of tumor shrinkage appeared in 59% of cases. The cyst in the tumor enlarged in 3 cases, and 2 cases developed hydrocephalus. The percentage of pure-tone hearing preservation was 82% at 3 months, 73% at 6 months, 68% at 12 months. 64% at 18 months and 59% at 24 months in 22 out of 29 cases. Relatively low dose Gamma Knife radiosurgery was effective in suppressing tumor growth, with preservation of hearing.

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.

Gamma knife radiosurgery for acoustic schwannoma: early effects and preservation of hearing

The effects of relatively low dose gamma knife irradiation on acoustic schwannoma were evaluated. The signal intensity change and tumor shrinkage on magnetic resonance (MR) images, change in hearing, and complications in 28 patients (mean age 47.0 +/- 13.6 yrs) were studied. Three patients had bilateral tumors. Six were already deaf when treated. The maximum tumor diameter was 35 mm. The mean dose delivered to the tumor was 12.1 +/- 1.6 Gy at the periphery, and 25.2 +/- 4.3 Gy at the center. The mean follow-up time was 16 months and the longest 24 months. Lowering of the MR signal intensity in the tumor center appeared after 3 months at earliest but generally after 6 months. Signs of tumor shrinkage appeared within 12 months on average. Cyst in the tumor enlarged rapidly after treatment in two patients. The percentage of hearing preservation was 85% (17/20) at 3 months, 80% (16/20) at 6 months, 72% (13/18) at 9 months, 75% (12/16) at 12 months, 67% (8/12) at 15 months, 60% (6/10) at 18 months, and 50% (2/4) at 24 months. Subtle changes in hearing were detected by speech tone audiometry. Temporary facial numbness and weakness was seen in one patient each. No patient had lower cranial nerve paresis. Relatively low dose gamma knife radiosurgery is effective in suppressing growth of acoustic schwannoma with preservation of hearing.

Gamma Knife radiosurgery for the treatment of brainstem tumors

Ten patients with brainstem tumors (BST) underwent Gamma Knife radiosurgery. In 5 cases, there were definitive histological diagnoses; ependymoma (n = 3) and CNS lymphoma (n = 2). The others were diagnosed as ependymoma (n = 1), CNS lymphoma (n = 2) and glioma (n = 2) on clinical grounds. Of 4 cases with ependymoma, the tumor showed a marked response in 3 cases. Of 4 cases with CNS lymphoma, all responded rapidly and the clinical symptoms improved markedly. However, in the 2 cases with glioma, the tumor remained unchanged or continued to grow. Gamma Knife radiosurgery was effective in local growth control of BST without adverse effects. An alternative treatment design will be required in glioma cases.

Gamma Knife thalamotomy for the treatment of functional disorders

Gamma Knife thalamotomy was performed with a 4-mm collimator in 2 cases with thalamic pain following a stroke and in 1 case of Parkinson's disease with tremor. In both cases with pain the maximum dose of 130 Gy was focused at the mediocaudal region of the previous thalamic lesion. In the case with tremor in Parkinson's disease, the maximum dose was 150 Gy. Longer follow-up is now proceeding, but the short-term results are encouraging. Based on data obtained from selective thalamotomy with depth microrecording, Gamma Knife thalamotomy could be a safe and effective technique for the treatment of these functional disorders.

Fractionated Gamma Knife radiosurgery for malignant gliomas: neurobiological effects and FDG-PET studies

Experimental single-dose neural irradiation was performed in rats and monkeys. Acute and 'early' late damage was observed following single high-dose treatments. By contrast, following a single low-dose treatment, neither 'early' nor 'delayed' late damage was noted. Based on these experiments, a clinical trial of fractionated Gamma Knife surgery for malignant gliomas was begun, and patients were followed by FDG-PET studies. An acute response of the tumor was obtained without damage to the surrounding brain. Fractionated Gamma Knife surgery is a potential alternative treatment for malignant gliomas.

Classification of arteriovenous malformations for radiosurgery. Neuroimaging, histopathology and radiobiologic effects

Arteriovenous malformations (AVMs) were classified based on morphologic and hemodynamic factors. They were categorized as Moya type, shunt type or mixed type on the basis of hemodynamic factors, and as homogeneous or heterogeneous types on the basis of morphology. Histopathologic and radiobiologic characteristics were evaluated with respect to these AVM types. Classification depending on the type as well as the size of an AVM is important for modern treatment modalities, especially radiosurgery.

Parkinsonian rigidity, dopa-induced dyskinesia and chorea--dynamic studies on the basal ganglia-thalamocortical motor circuit using PET scan and depth microrecording

Regional cerebral glucose metabolism (rCMRGlu-18FDG) was measured in 6 cases with rigid type Parkinson's disease (PD) (2 cases with dopa-induced dyskinesia = DID), 6 cases with chorea (Ch), 5 cases with essential tremor (EssT) and 2 cases with normal subjects (N). The effects of L-Dopa on rCMRGlu was studied in 3 cases with PD. With the aid of depth microrecording study, stereotactic pallidotomy was performed in all cases with PD. Thalamotomy was performed in 3 cases with Ch. In the EssT and N group, the metabolic pattern was high in the frontal cortex (FCx) but low in the lenticular nucleus (LN). In contrast, all cases with a rigid type PD showed lower rCMRGlu in FCx (premotor, prefrontal area). However, 4 out of 6 cases were higher in LN than the control group. Administration of L-Dopa shifted rCMRGlu toward the normal pattern in this group. Five out of 6 cases with Ch represented higher rCMRGlu in FCx (3 focal, 2 diffuse) but lower in LN. Moreover, when DID occurred, it showed almost the same pattern as in Ch. Electrophysiological studies showed high background neuronal activity (BNA) in the medial segment of the globus pallidus (GP) but low BNA in the lateral segment of the GP in the rigid type of PD. In cases with Ch, irregular burst discharges were often encountered in ventro-oral thalamus. From these results, the on-going changes of basal ganglia-thalamocortical motor circuit in cases with a rigid type PD, DID and Ch are discussed. The underlying mechanisms of Parkinsonian rigidity was considered to contrast with those of DID and Ch within the same motor circuit.

[Neuronal behavior of the striatum in man]

Units of the caudate and putamen were studied during stereotactic operations in 11 patients with movement disorders. Responses of these units to different visual stimuli were found for cells of the caudate nucleus head. These units were activated mainly during the presentation of nutritional stimuli. The responses appeared when a slide was shown presenting an image of drink or food or the corresponding word. Frequently the same unit was activated by slides of the image and the word presented in succession. Responses to similar stimulations were not observed in the putamen. Among the parkinsonian patients, only those with tremor had responsive cells while the rigid patients had not. This discrepancy was correlated with the lowering of cortical metabolism demonstrated by PET scan in the rigid group of patients. These results are in agreement with those obtained in monkeys during food presentation. They present, moreover, the advantage of showing that these responses could be provoked in man by more abstract stimuli, not only the image but the name of the object. These observations do not imply a long testing period; 2 or 3 cells only are studied in each patient. They have the advantage for the patient of ascertaining the position of the trajectory in the striate structure, in the same way as thalamic nuclei are delineated using other types of stimuli. Moreover, it is of interest to have a better knowledge of the behavioral role played by different striatal regions at a time when lesions or stimulations at this level are proposed to cure abnormal movements in human.

Radiosensitive craniopharyngiomas: the role of radiosurgery

Clinical characteristics of radiosensitive craniopharyngiomas and histologically identical tumours were re-evaluated from among 53 patients. There were 9 squamous cell type and 3 mixed type tumours. Early effects of radiosurgery for two recent cases are reported. Radiosurgery may have an important role to play in the treatment of craniopharyngiomas, especially of the squamous cell type.

Long-term follow-up study of conventional irradiation for brain tumours in children: a role for radiosurgery

21 younger patients (less than 10 years of age) with brain tumours, treated by conventional irradiation, were followed 5 to 20 years (mean 12), using CT scan and/or MR imaging, in order to evaluate adverse effects on the developing brain. Pathological changes such as brain atrophy, lesions in the white matter, calcifications in the brain, and angiopathy were observed in 13 (62%) out of 21 cases. The incidence of abnormalities was related to the age at treatment and the follow-up period. All six cases treated at or under 5 years old and followed more than 10 years showed pathological changes in the brain. In order to minimize the radiation damage, 5 patients with brain tumours less than 5 years old were treated by gamma knife surgery. The early results encourage further trials. Radiosurgery may play a role as an alternative treatment or as a component of future multidisciplinary treatment for brain tumours is children.

Clinical evaluation of thallium-201 SPECT in supratentorial gliomas: relationship to histologic grade, prognosis and proliferative activities

We performed 201Tl SPECT and cell kinetic studies on 28 presurgical patients with supratentorial gliomas by administering bromodeoxyuridine (BUdR). All patients had surgery and had follow-up for more than 25 mo. In patients with grade IV glioma (198.1% +/- 32.8%, n = 10), the 201Tl index, expressed as the count rate of the tumor site to the count rate over the contralateral normal region, was significantly higher than that in patients with grade III glioma (140.5% +/- 15.1%, n = 4, p < 0.01) or low-grade glioma (104.1% +/- 22.6%, n = 14, p < 0.001). A significant correlation was observed between the 201Tl index and BUdR-positive cells in excised tumor specimens (r = 0.67, p < 0.001). The 201Tl index of the 12 patients who died was higher than those who survived (173.2% versus 122.4%, p < 0.01). These results show the clinical utility of 201Tl brain SPECT in imaging supratentorial glioma and that the 201Tl index is representative of proliferative activity of the tumor.

[Effect of tranilast ophthalmic solution on allergic conjunctivitis in guinea pigs]

The effect of the ophthalmic solution of tranilast, an anti-allergic agent, on allergic conjunctivitis was studied in passively sensitized guinea pigs. We determined the content of uranine dye and histamine in tears and histopathologically examined palpebral conjunctiva. After instillation of antigen into the conjunctival sac, inflammation of the palpebral conjunctiva, an increase in leaked dye and the release of histamine were found. In the histopathological study, tranilast (1.0%) suppressed the appearance of edema and infiltration of inflammatory cells. Tranilast suppressed the leakage of uranine in a dose-dependent manner. A 0.5% solution of diphenhydramine also showed the inhibitory effect on the leakage of uranine. The inhibitory effect of 0.5% tranilast on antigen-induced dye leakage and histamine release lasted for 6 hr. These results suggest that topically applied tranilast is effective for allergic conjunctivitis.

Tremor-mediating thalamic zone studied in humans and in monkeys

The thalamic zone mediating the rhythmic burst activity related to the contralateral tremor was studied by microelectrodes in clinical cases with tremor and in monkeys with experimental tremor. The rhythmic burst time-locked with the tremor was found in a restricted area of the ventrointermedius nucleus (Vim) in humans and also in VPLo nucleus in monkeys. In both cases, only the lateral and ventrocaudal part of each nucleus, which was defined as the kinesthetic zone, was involved. A possible tremor-mediating neural circuit is postulated.

[Evaluation of 201Tl SPECT in patients with glioma: a comparative study with histological diagnosis, clinical feature and proliferative activity]

The purpose of this study is to clarify the usefulness of 201Tl brain SPECT in the prediction of clinical degree of malignancy. Quantitative evaluation of 201Tl uptake in the tumor was expressed as count ratio of tumor site over contralateral normal region (D/C ratio) on 201Tl SPECT image. Fourteen patients with gliomas received an intravenous administration of bromodeoxyuridine (BUdR) at surgery to label tumor cells in the DNA synthesis phase. BUdR-positive cells in excised tumor specimen were stained with anti-BUdR monoclonal antibody by indirect immunoperoxidase staining. Percentage of labeled cells in relation to the total number of tumor cells in microscopic fields was defined as labeling index (BUdR-LI). D/C ratio in patients with grade IV glioma (198.7 +/- 31.7) was higher than that in patients with grade III glioma (138.3 +/- 33.9) or more low-grade gliomas (94.2 +/- 11.9, p less than 0.001). BUdR-LI in patients with high-grade glioma was also higher than that in patients with low-grade glioma. D/C ratio correlated well (r = 0.753) with BUdR-LI, which is considered to represent proliferative activity of the tumor. D/C ratio does not only correlate well with histological grade of glioma, but with clinical course or prognosis of individual patient with glioma. In conclusion, degree of 201Tl uptake in the tumor may provide non-invasive prediction of malignancy grade of gliomas and accurate estimation of efficacy of the therapy and early detection of recurrence or malignant transformation of the tumors, by delineating viable tumor tissue in patients with gliomas.

Pathophysiology of central (thalamic) pain: a possible role of the intralaminar nuclei in superficial pain

In 15 patients with central pain (thalamic pain) after stroke, CT, PET scan and intraoperative thalamic microrecordings were performed. The results are considered together to evaluate a possible role of thalamic intralaminar nuclei in the genesis of central pain, especially of superficial pain. In the non-thalamic lesion group (deep pain dominant), thalamic background neural activity (BNA) was relatively high in Vim but low in CL. Conversely, in the thalamic lesion group (superficial pain dominant), thalamic BNA was higher in CL than in Vim, and markedly decreased in VC. In this group, regional cerebral oxygen consumption (rCMRO2) was relatively maintained, and regional oxygen extraction ratio (raOEF) and the relative value of regional cerebral glucose utilization (CMRGL), compared to rCMRO2, was increased in the cerebral cortex around the central sulcus. The genesis of superficial pain is discussed.

Strategy of selective VIM thalamotomy guided by microrecording

Our routine procedure for stereotactic selective Vim thalamotomy is described briefly. Preoperative steps identify the tremor qualitatively and quantitatively. The highlight of the procedure is the use of intraoperative microrecording to determine tremor time-locked rhythmic discharge in the presumed Vim nucleus. Results of the operation are also estimated quantitatively.

[Analysis of relative cerebral perfusion in ischemic cerebral diseases by single photon emission computed tomography using N-isopropyl-p-[123I]iodoamphetamine]

Semiquantitative analysis of 123I-IMP SPECT enabled to evaluate relative regional cerebral perfusion and redistribution rates. Two parameters were calculated; the relative perfusion rate (RPR) is the ratio of radioactivity on a localized lesion divided by radioactivity on the visual cortex, the redistribution rate (RR) is the ratio of RPR in late images at 3 hrs divided by that in early images at 15 min postinjection. Total of 45 patients with ischemic cerebral diseases were studied. There were 29 males and 16 females with the age ranging from 37 yr to 80 yr. The RPRs were 81.3 +/- 5.1% in TIA (14 cases), 63.6 +/- 10.6% in RIND (8 cases), 64.6 +/- 8.5% in mild infarction (9 cases) and 40.2 +/- 13.8% in severe infarction (14 cases). RPR on the lesion of the severe infarction was extremely low compared to that of TIA, RIND and mild infarction. RPRs of lesions in the mild and severe infarction were reversely correlated to the size of LDA on X-ray CT (p less than 0.01). RPR was well correlated to clinical status of ischemic diseases. The RRs were 1.18 +/- 0.08 in TIA, 1.41 +/- 0.20 in RIND, 1.28 +/- 0.15 in mild infarction and 1.21 +/- 0.31 in severe infarction. The RR of RIND was significantly higher than those of other categorized groups (p less than 0.01). The RR may prove useful as a parameter reflecting tissue viability in cerebral ischemic diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Further physiological observations on the ventralis intermedius neurons in the human thalamus

1. During the course of stereotaxic thalamotomy for 56 cases with tremor mainly due to Parkinson's disease and essential tremor, extracellular recordings were made from the thalamic ventralis intermedius (Vim) nucleus under local anesthesia. These procedures have been justified as an essential technique to achieve the best therapeutic results by a selective coagulation. These physiological observations provide important information about the functional organization of the ventrolateral thalamic mass in humans. 2. Using Leksell's stereotaxic apparatus, a pair of semimicroelectrodes was introduced simultaneously to the thalamic ventral lateral region from the prefrontal area. The Vim nucleus was identified tentatively by characteristic high background activity which contrasted to that found in its rostral part and by superimposed large amplitude spontaneously active units. 3. In this high activity zone, 135 units (approximately 1/5 of the recorded units) responded to natural stimulation applied to contralateral body parts. Among them, approximately 90% responded to a passive or active movement of a joint. Several lines of evidence suggested that probably muscle receptors were responsible. 4. The rest of units (approximately 10%) responded to light touch applied to contralateral skin surface. Convergent responses between kinesthetic and tactile units were never encountered. Also, kinesthetic and tactile neurons were geographically separated. The latter were found always at the end of our oblique trajectory, following the kinesthetic neurons. 5. Neurons with sensory responses were clustered mostly within the confines of the Vim nucleus, probably extending caudally to the ventrocaudalis externus anterior of Hassler. Evidence for a somatotopic representation in the Vim nucleus was obtained. 6. Electrical stimulation of the appropriate peripheral nerve produced responses of the same thalamic unit(s) that responded to natural stimulation. The latency to upper limb nerve stimulation was between approximately 10 and 20 ms. It was almost fixed in a given case. 7. It is concluded that the Vim nucleus receives kinesthetic afferent input from the contralateral body parts (mainly from the muscle receptor) and may be concerned with muscle sense. This may explain why a small, selective coagulation of the physiologically identified Vim has such a constant effect on several different kinds of tremor.

Microrecording for the study of thalamic organization, for tumor biopsy and removal

Use of microrecording technique in stereotactic selective thalamotomy, and in stereotactic biopsy for deep-seated lesions and in tumor removal was briefly described. For selective thalamotomy, the microrecording gives ample information to delineate thalamic subnuclei. Thus, the ventrointermedius (Vim) nucleus is identified by high-amplitude background activity and large-spike discharge, some of which responds solely to contralateral natural stimuli of kinesthetic modality. A small coagulation including this thalamic Vim point resulted in permanent arrest of the various kinds of tremor. As the normal brain tissue, whether the gray or white matter, is electrically active, the microrecording is useful to delineate the brain tumor from its surroundings. Stereotactic diagnostic biopsy and removal of the brain tumor were facilitated by this adjuvant method.

A special role of the parvocellular red nucleus in lesion-induced spontaneous tremor in monkeys

The neural mechanisms underlying spontaneous tremor were investigated in monkeys. Tremor-producing ventromedial tegmental (VMT) lesions involve at least three major neural elements. (1) Parvocellular division of the red nucleus (RNpc); (2) cerebellothalamic fibers passing through the red nucleus, and, (3) nigrostriatal fibers. These three elements were destroyed stereotaxically in areas remote from the VMT area separately and/or in various combinations, and correlation between the site of lesions and tremor was made. Lesion-induced tremor appeared only when the three elements were destroyed. A possible, particular role of the RNpc in the production of the spontaneous tremor is discussed.

Long-term follow-up results of selective VIM-thalamotomy

The authors report the results of a long-term follow-up study of the effects of the physiologically defined selective VIM (nucleus ventralis intermedius)-thalamotomy on tremor of Parkinson's disease in 27 patients and essential tremor in 16 patients. The follow-up period ranged from 3.25 to 10 years (mean 6.58 years). In 43 patients a total of 50 operations (including four bilateral operations and three reoperations) were carried out. The early (2 to 4 weeks after surgery) and late effects on the tremors were determined clinically and electromyographically. Fourteen parkinsonian cases were treated with minimal lesions (about 40 cu mm). Their late results were very similar to the early results: in 10, the tremors were completely abolished, three had a slight residual tremor, and one underwent reoperation 3 months after the first surgery. Eleven essential tremor cases were treated with minimal lesions. Six of these tremors were completely abolished, four patients had slight residual tremors, and one patient with a recurrence underwent reoperation 2 years after the initial surgery. In these 23 successful operations with minimal lesions (excluding two cases with reoperation), the tremor was abolished without discernible long-lasting side effects. The other 23 operations on 16 patients with Parkinson's disease (including one reoperation) and on seven with essential tremor (one of whom also had a minimal lesion on the other side) involved relatively large lesions. In this group, the surgery was successful in almost every case. It was concluded that radiographically and physiologically monitored selective VIM-thalamotomy for parkinsonian and essential tremor is effective even when lesioning is minimal. Moreover, the beneficial effect is maintained over a long period of time.

[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.