Measuring biting behavior induced by acute stress in the rat.

Previous reports have indicated that biting behavior is enhanced in rats that are subject to acute stress. Several methods have been proposed for studying this phenomenon, one of which is the electromyography (EMG) of the jaw muscles. In this study, we compared total EMG activity with the EMG activity related to biting behavior, as determined by video monitoring, before and after restraint stress. Wistar albino rats (150 g) were subject to surgery for electrode placement 48 h before measurements. The EMG activity of the masseter muscle on one side was recorded for 10 min before and immediately after 30 min of restraint stress. Restraint stress increased jaw muscle EMG activity, although some of the activity was related to behaviors other than biting. Recording the EMG activity of jaw muscles is useful for measuring the stress response in rats, but careful video monitoring is needed if biting behavior is to be studied in particular.

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.

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.

Evaluation of gamma thalamotomy for parkinsonian and other tremors: survival of neurons adjacent to the thalamic lesion after gamma thalamotomy.

OBJECT: The effects of gamma thalamotomy for parkinsonian and other kinds of tremor were evaluated. METHODS: Thirty-six thalamotomies were performed in 31 patients by using a 4-mm collimator. The maximum dose was 150 Gy in the initial six cases, which was reduced to 130 Gy thereafter. The longest follow-up period was 6 years. The target was determined on T2-weighted and proton magnetic resonance (MR) images. The point chosen was in the lateral-most part of the thalamic ventralis intermedius nucleus. This is in keeping with open thalamotomy as practiced at the authors' institution. In 15 cases, gamma thalamotomy was the first surgical procedure. In other cases, previous therapeutic or vascular lesions were visible to facilitate targeting. Two types of tissue reaction were onserved on MR imaging: a simple oval shape and a complex irregular shape. Neither of these changes affected the clinical course. In the majority of cases, the tremor subsided after a latent interval of approximately 1 year after irradiation. The earliest response was demonstrated at 3 months. In five cases the tremor remained. In four of these cases, a second radiation session was administered. One of these four patients as well as another patient with an unsatisfactory result underwent open thalamotomy with microrecording. In both cases, depth recording adjacent to the necrotic area revealed normal neuronal activity, including the rhythmic discharge of tremor. Minor coagulation was performed and resulted in immediate and complete arrest of the remaining tremor. CONCLUSIONS: Gamma thalamotomy for Parkinson's disease seems to be an alternative useful method in selected cases.

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. 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.

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: 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.

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 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.

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.

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.

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.

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.