樋口 佳則

The efficacy of stereotactic radiosurgery (SRS) instead of whole brain radiotherapy (WBRT) following high-dose methotrexate (HD-MTX) for primary central nervous system lymphoma (PCNSL) is unclear. To clarify whether SRS in combination with up-front HD-MTX supplements the effect of HD-MTX in remaining or refractory lesions after initial HD-MTX treatment. The authors conducted a retrospective review for newly diagnosed PCNSL patients who underwent SRS after HD-MTX as a first-line treatment. The local control (LC), the progression-free survival (PFS), the recurrence patterns, the salvage treatments, the overall survival (OS), the Karnofsky Performance Status (KPS), the activities of daily living (ADL) were analyzed as well as radiosurgical parameters. Twenty patients underwent SRS for 51 lesions with the median volume of 0.45 cm(3). The median age at SRS was 67 (range 37-82). The median KPS at SRS was 90. The LC rate at 2 years was 86.0 %, the median PFS after SRS was 17 months, necessitating additional SRS and chemotherapy. The median OS was 52 months. No significant side effects related to SRS were observed. During follow-up period, the good ADL preservation was achieved for 13 months from SRS. Patients with KPS ≥ 90 at SRS demonstrated longer ADL preservation (32 months from SRS). SRS following up-front HD-MTX without WBRT provided excellent LC, acceptable OS and the long ADL preservation period. These benefits may be more emphasized especially in patients with good KPS, but should be validated in a large patient population.

Functional radiosurgery has advanced steadily, since Leksell first utilized the gamma knife (GK) to treat intractable cancer pain (Acta Chir Scand. 1968 134(8):585–95). Worldwide, 5 % of GK surgery procedures are performed for the treatment of functional disorders, predominantly for trigeminal neuralgia. The ablation of deep brain structures using GK surgery is not widespread because visualization of functional targets is still difficult, in spite of the increased availability of advanced neuroimaging technology. However, much experience of intraoperative neurophysiological evaluation in radiofrequency thalamotomy and deep brain stimulation of the ventralis intermedius nucleus supports the use of GK thalamotomy (Stereotact Funct Neurosurg. 2005 83(2–3):108–12). GK thalamotomy is an effective alternative to radiofrequency and stimulation techniques for patients suffering from intractable tremor, who are at high surgical risk. The effectiveness of GK pallidotomy and subthalamotomy for treatment of Parkinson’s disease needs to be further clarified. This chapter includes a review of the literature on treatment, efficacy, and potential adverse events of GK surgery for patients with movement disorders.

OBJECTIVES: We tested the validity of 5 prognostic indices, Recursive Partitioning Analysis (RPA), Score Index for Radiosurgery (SIR), Basic Score for Brain Metastases (BSBM), Graded Prognostic Assessment (GPA), and Modified-RPA, for patients who underwent repeat stereotactic radiosurgery (re-SRS). METHODS: For this study, we used our database, which included 804 patients who underwent gamma knife re-SRS during the period 1998-2013. RESULTS: There were statistically significant survival differences among patients stratified into 3 or 4 groups based on the 5 systems (P < 0.001). With RPA, SIR, BSBM, and the Modified-RPA, there were statistically significant median survival time (MST) differences between any 2 pairs within the 3/4 groups. With the GPA system, however, the MST difference between the GPA 3.5-4.0 and GPA 3.0 groups did not reach statistical significance (P = 0.48). There were large patient number discrepanciesamong the 3/4 groups in the RPA, SIR, BSBM, and GPA whereas patient numbers were very similar among the 3 Modified-RPA system groups. Our present results show the RPA and BSBM systems to reflect changes less well, with 86%-95% of patients remaining in the same categories between the first and second SRS procedures. However, with SIR, GPA, and the Modified-RPA, 25%-31% of patients were categorized into different subclasses, either better or worse. With the modified-RPA system, such categorical change correlated well with post-re-SRS MSTs. CONCLUSIONS: Among the 5 systems, based on patient number proportions, MST separation among the 3/4 groups, and/or detailed reflection of status changes, the Modified-RPA system was shown to be most applicable to re-SRS patients.

Object. Although stereotactic radiosurgery (SRS) alone is not a standard treatment for patients with 4-5 tumors or more, a recent trend has been for patients with 5 or more, or even 10 of more, tumors to undergo SRS alone. The aim of this study was to reappraise whether the treatment results for SRS alone for patients with 10 or more tumors differ from those for patients with 2-9 tumors. Methods. This was an institutional review board approved, retrospective cohort study that gathered data from the Katsuta Hospital Mito GammaHouse prospectively accuniulated database. Data were collected for 2553 patients who consecutively had undergone Gamma Knife SRS alone, without whole-brain radiotherapy (WBRT), for newly diagnosed (mostly) or recurrent (uncommonly) brain metastases during 1998-2011. Of these 2553 patients, 739 (28.9%) with a single tumor were excluded, leaving 1814 with multiple metastases in the study. These 1814 patients were divided into 2 groups: those with 2-9 tumors (Group A, 1254 patients) and those with 10 or more tumors (Group B, 560 patients). Because of considerable bias in pre-SRS Clinical factors between groups A and B, a case-matched study, which used the propensity score matching method, was conducted for clinical factors (i.e., age, sex, primary tumor state, extracerebral metastases, Karnofsky Performance Status, neurological symptoms, prior procedures [surgery and WBRT], volume of the largest tumor, and peripheral doses). Ultimately, 720 patients (360 in each group) were selected. The standard Kaplan-Meier method was used to determine post-SRS survival times and post-SRS neurological death free survival times. Competing risk analysis was applied to estimate cumulative incidence for local recurrence, repeat SRS for new lesions, neurological deterioration, and SRS-induced complications. Results. Post-SRS median survival times did not differ significantly between the 2 groups (6.8 months for Group A vs 6.0 months for Group B; hazard ratio [HR] 1.133, 95% CI 0.974-1.319, p = 0.10). Furthermore, rates of neurological death were very similar: 10.0% for group A and 9.4% for group B (p = 0.89); neurological death free survival times did not differ significantly between the 2 groups (HR 1.073,95% CI 0.649-1.771, p = 0.78). The cumulative incidence of local recurrence (BR 0.425, 95% CI 0.0.181-0.990, p = 0.04) and repeat SRS for new lesions (HR 0.732, 95% CI 0.554-0.870, p = 0.03) were significantly lower for Group B than for Group A patients. No significant differences between the groups were found for cumulative incidence for neurological deterioration (HR 0.994,95% CI 0.607-1.469, p = 0.80) or SRS-related complications (HR 0.541,95% CI 0.138-2.112, p = 0.38). Conclusions. Post-SRS treatment results (i.e., median survival time; neurological death free survival times; and cumulative incidence for local recurrence, repeat SRS for new lesions, neurological deterioration, and SRS-related complications) were not inferior (neither less effective nor less safe) for patients in Group B than for those in Group A. We conclude that carefully selected patients with 10 or more tumors are not unfavorable candidates for SRS alone. A randomized controlled trial should be conducted to test this hypothesis.

Object. The Basic Score for Brain Metastases (BSBM) proposed by Lorenzoni and colleagues is one of the best grading systems for predicting survival periods after stereotactic radiosurgery (SRS) for brain metastases. However, it includes no brain factors and cannot predict neurological outcomes, such as preservation of neurological function and prevention of neurological death. Herein, the authors propose a modified BSBM, adding 4 brain factors to the original BSBM, enabling prediction of neurological outcomes, as well as of overall survival, in patients undergoing SRS. Methods. To serve as neurological prognostic scores (NPSs), the authors scored 4 significant brain factors for both preservation of neurological function (qualitative survival) and prevention of neurological death (neurological survival) as 0 or 1 as described in the following: > 10 brain tumors = 0 or <= 10 = 1, total tumor volume > 15 cm(3) = 0 or <= 15 cm(3) = 1, MRI findings of localized meningeal dissemination (yes =0 or no = 1), and neurological symptoms (yes = 0 or no = 1). According to the sum of NPSs, patients were classified into 2 subgroups: Subgroup A with a total NPS of 3 or 4 and Subgroup B with an NPS of 0, 1, or 2. The authors defined the modified BSBM according to the NPS subgroup classification applied to the original BSBM groups. The validity of this modified BSBM in 2838 consecutive patients with brain metastases treated with SRS was verified. Results. Patients included 1868 with cancer of the lung (including 1604 with non-small cell lung cancer), 355 of the gastrointestinal tract, 305 of the breast, 176 of the urogenital tract, and 134 with other cancers. Subgroup A had 2089 patients and Subgroup B 749. Median overall survival times were 2.6 months in BSBM 0 (382 patients), 5.7 in BSBM 1(1143), 11.4 in BSBM 2 (1011) and 21.7 in BSBM 3 (302), and pairwise differences between the BSBM groups were statistically significant (all p < 0.0001). One-year qualitative survival rates were 64.6% (modified BSBM OA, 204 patients), 45.0% (OB, 178), 82.5% (1A, 825), 63.3% (1B, 318), 86.4% (2A, 792), 73.7% (2B, 219), 91.4% (3A, 268), and 73.5% (3B, 34). One-year neurological survival rates were 82.6% (OA), 52.4% (OB), 90.5% (1A), 78.1% (1B), 91.1% (2A), 83.2% (2B), 93.9% (3A), and 76.3% (3B), where A and B identify the subgroup. Statistically significant differences in both qualitative and neurological survivals between Subgroups A and B were detected in all BSBM groups. Conclusions. The authors' new index, the modified BSBM, was found to be excellent for predicting neurological outcomes, independently of life expectancy, in SRS-treated patients with brain metastases.

Object. Recently, an increasing number of patients with brain metastases, even patients over 80 years of age, have been treated with stereotactic radiosurgery (SRS). However, there is little information on SRS treatment results for patients with brain metastases 80 years of age and older. The authors undertook this study to reappraise whether SRS treatment results for patients 80 years of age or older differ from those of patients who are 65-79 years old. Methods. This was an institutional review board approved, retrospective cohort study. Among 2552 consecutive brain metastasis patients who underwent SRS during the 1998-2011 period, we studied 165 who were 80 years of age or older (Group A) and 1181 who were age 65-79 years old (Group B). Because of the remarkable disproportion in patient numbers between the 2 groups and considerable differences in pre-SRS clinical factors, the authors conducted a case-matched study using the propensity score matching method. Ultimately, 330 patients (165 from each group, A and B) were selected. For time-to-event outcomes, the Kaplan-Meier method was used to estimate overall survival and competing risk analysis was used to estimate other study end points, as appropriate. Results. Although the case-matched study showed that post-SRS median survival time (MST, months) was shorter in Group A patients (5.3 months, 95% CI 3.9-7.0 months) than in Group B patients (6.9 months, 95% Cl 5.0-8.1 months), this difference was not statistically significant (HR 1.147, 95% CI 0.921-1.429, p = 0.22). Incidences of neurological death and deterioration were slightly lower in Group A than in Group B patients (6.3% vs 11.8% and 8.5% vs 13.9%), but these differences did not reach statistical significance (p = 0.11 and p = 0.16). Furthermore, competing risk analyses showed that the 2 groups did not differ significantly in cumulative incidence of local recurrence (HR 0.830,95% CI 0.268-2.573, p = 0.75), rates of repeat SRS (HR 0.738,95% Cl 0.438-1.242, p = 0.25), or incidence of SRS-related complications (HR 0.616,95% CI 0.152-2.495, p = 0.49). Among the Group A patients, post-SRS MSTs were 11.6 months (95% CI 7.8-19.6 months), 7.9 months (95% CI 5.2-10.9 months), and 2.8 months (95% CI; 2.4-4.6 months) in patients whose disease status was modified recursive partitioning analysis (RPA) Class(es) I+IIa, IIb, and IIc+III, respectively (p <0.001). Conclusions. Our results suggest that patients 80 years of age or older are not unfavorable candidates for SRS as compared with those 65-79 years old. Particularly, even among patients 80 years and older, those with modified-RPA Class I+IIa or lIb disease are considered to be favorable candidates for more aggressive treatment of brain metastases.

Here we report a case of moyamoya disease in which cortical veins reddened after superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis, following postoperative hyperperfusion. A 37-year-old man with moyamoya disease suffered cerebral infarction in his right hemisphere. Single photon emission computed tomography (SPECT) showed impaired cerebral blood flow (CBF) in both cerebral hemispheres. The patient underwent STA-MCA anastomosis in the right cerebral hemisphere. During operation, soon after declamping the STA, cortical veins near the anastomosis site changed its color from blue to red. This change was repeatable by clamping and declamping of the STA. Postoperative SPECT and computed tomography (CT) demonstrated increased CBF and subarachnoid hemorrhage at the anastomosis site, suggesting the occurrence of postoperative hyperperfusion. By strictly controlling the patient's blood pressure, the syndrome resolved 1 week after the operation. We propose that the venous reddening after STA-MCA anastomosis may be a sign of postoperative hyperperfusion.

Object. Management of small acoustic neuromas (ANs) consists of 3 options: observation with imaging follow-up, radiosurgery, and/or tumor removal. The authors report the long-term outcomes and preservation of function after retrosigmoid tumor removal in 44 patients and clarify the management paradigm for small ANs. Methods. A total of 44 consecutively enrolled patients with small ANs and preserved hearing underwent retrosigmoid tumor removal in an attempt to preserve hearing and facial function by use of intraoperative auditory monitoring of auditory brainstem responses (ABRs) and cochlear nerve compound action potentials (CNAPs). All patients were younger than 70 years of age, had a small AN (purely intracanalicular/cerebellopontine angle tumor <= 15 mm), and had serviceable hearing preoperatively. According to the guidelines of the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology Head and Neck Surgery Foundation, preoperative hearing levels of the 44 patients were as follows: Class A, 19 patients; Class B, 17; and Class C, 8. The surgical technique for curative tumor removal with preservation of hearing and facial function included sharp dissection and debullcing of the tumor, reconstruction of the internal auditory canal, and wide removal of internal auditory canal dura. Results. For all patients, tumors were totally removed without incidence of facial palsy, death, or other complications. Total tumor removal was confirmed by the first postoperative Gd-enhanced MRI performed 12 months after surgery. Postoperative hearing levels were Class A, 5 patients; Class B, 21; Class C, 11; and Class D, 7. Postoperatively, serviceable (Class A, B, or C) and useful (Class A or B) levels of hearing were preserved for 84% and 72% of patients, respectively. Better preoperative hearing resulted in higher rates of postoperative hearing preservation (p = 0.01); preservation rates were 95% among patients with preoperative Class A hearing, 88% among Class B, and 50% among Class C. Reliable monitoring was more frequently provided by CNAPs than by ABRs (66% vs 32%, p < 0.01), and consistently reliable auditory monitoring was significantly associated with better rates of preservation of useful hearing. Long-term follow-up by MRI with Gd administration (81 +/- 43 months [range 5-181 months]; median 7 years) showed no tumor recurrence, and although the preserved hearing declined minimally over the long-term postoperative follow-up period (from 39 +/- 15 dB to 45 +/- 11 dB in 5.1 +/- 3.1 years), 80% of useful hearing and 100% of serviceable hearing remained at the same level. Conclusions. As a result of a surgical technique that involved sharp dissection and internal auditory canal reconstruction with intraoperative auditory monitoring, retrosigmoid removal of small ANs can lead to successful curative tumor removal without long-term recurrence and with excellent functional outcome. Thus, the authors suggest that tumor removal should be the first-line management strategy for younger patients with small ANs and preserved hearing.

Background: Chronic subdural hematoma (CSDH) is known to have a substantial recurrence rate. Artificial cerebrospinal fluid (ACF) is an effective irrigation solution in general open craniotomy and endoneurosurgery, but no evidence of its use in burr-hole surgery exists. Objective: To identify the potential of ACF irrigation to prevent CSDH recurrence. More specifically, to investigate the perioperative and intraoperative prognostic factors, and to identify controllable ones. Methods: To examine various prognostic factors, 120 consecutive patients with unilateral CSDH treated with burr-hole drainage between September 2007 and March 2013 were analyzed. Intraoperative irrigation was performed with one of two irrigation solutions: normal saline (NS; n = 60) or ACF (n = 60). All patients were followed-up for at least 6 months postoperatively. We also examined the morphological alternations of the hematoma outer membranes after incubation with different solutions. Results: Eleven patients (9.2%) had recurrence. Nine patients (15%) required additional surgery in the NS group, whereas only 2 patients (3.3%) in the ACF group required additional surgery. Among preoperative and intraoperative data, age (, 80 years old, P =.044), thrombocyte (>22.0, P=.037), laterality (right, P=.03), and irrigation solution (ACF, P=.027) were related to smaller recurrence rates by log-rank tests. Only the type of irrigation solution used significantly correlated with recurrence in favor of ACF in both Cox proportional hazards (relative hazard: 0.20, 95% confidence interval (CI): 0.04-0.99; P=.049) and logistic regression models (odds ratio, 0.17, 95% CI: 0.03-0.92; P=.04) using these factors. Histological examinations of the hematoma membranes showed that the membranes incubated with NS were loose and infiltrated by inflammatory cells compared with those incubated with ACF. Conclusion: Irrigation with ACF decreased the rate of CSDH recurrence.

Objective: The present study tested the hypothesis of whether antiplatelet agents (APA) induce chronic subdural hematoma (CSDH) recurrence via a platelet aggregation inhibitory effect. Method: We examined risk factors for CSDH recurrence, focusing on APA, in 719 consecutive patients who admitted to three tertiary hospitals and underwent burr-hole craniostomy and irrigation for CSDH. This was a multicenter, retrospective, observational study. Results: Age, sex, history of diabetes mellitus, hypertension, chronic renal failure, alcohol consumption habits, consciousness disturbance on admission, or preoperative CT density was not associated with recurrence. Subdural drainage was significantly associated with less recurrence. Preoperative oral APA administration was significantly associated with more recurrence. The recurrence rate of CSDH in non-APA group was 11% if surgery was performed on admission. However, if surgery was performed immediately after discontinuation of oral APA administration, the recurrence rate in APA group significantly increased to 32% (p value < 0.0001; odds ratio, 3.77; 95% confidence interval, 1.72-8.28). The effect of APA on CSDH recurrence gradually diminished as the number of days until initial surgery, after stopping APA, increased. Conclusion: Antiplatelet therapy significantly influences the recurrence of CSDH. (C) 2014 Elsevier B.V. All rights reserved.

Intermittent monitoring of abnormal muscle response (iAMR) has been reported to be useful for improving the surgical outcome of microvascular decompression (MVD) for hemifacial spasm (HFS). However, iAMR has not elucidated the relationship between AMR change and the corresponding surgical procedure, or the pathogenesis of AMR and HFS. The purpose of this study is to clarify the usefulness of continuous AMR monitoring (cAMR) for improving the surgical results of MVD and for understanding the relationship between AMR change and corresponding surgical procedure, and the pathogenesis of AMR and HFS. Fifty consecutive patients with HFS treated by MVD under cAMR monitoring, which continuously records AMR every minute throughout the surgical period, were retrospectively analyzed. The patients were assessed for the presence of HFS 1 week after the surgery and at final follow-up. Forty-six patients showed the complete disappearance of HFS. In 32, AMR disappeared abruptly and simultaneously with decompression of an offending vessel. AMR showed dynamic and various changes including temporary disappearance, or sudden, gradual, or componential disappearance before and during the decompression procedure, and even during the dural and skin closure after the initial decompression procedure. Facial spasm remained in four patients despite permanent AMR disappearance. cAMR monitoring improves the outcome of MVD. Although the main cause of HFS and AMR is vascular compression at the facial nerve, hyperexcitability of the facial nucleus is also involved in the pathogenesis of HFS and AMR. The proportional involvement of these causes differs between patients.

Background We aimed to examine whether stereotactic radiosurgery without whole-brain radiotherapy (WBRT) as the initial treatment for patients with five to ten brain metastases is non-inferior to that for patients with two to four brain metastases in terms of overall survival. Methods This prospective observational study enrolled patients with one to ten newly diagnosed brain metastases Clargest tumour < 10 mL in volume and < 3 cm in longest diameter; total cumulative volume <= 15 mL) and a Karnofsky performance status score of 70 or higher from 23 facilities in Japan. Standard stereotactic radiosurgery procedures were used in all patients; tumour volumes smaller than 4 mL were irradiated with 22 Gy at the lesion periphery and those that were 4-10 mL with 20 Gy. The primary endpoint was overall survival, for which the non-inferiority margin for the comparison of outcomes in patients with two to four brain metastases with those of patients with five to ten brain metastases was set as the value of the upper 95% CI for a hazard ratio CHR) of 1. 30, and all data were analysed by intention to treat. The study was finalised Dec 31, 2012, for analysis of the primary endpoint; however, monitoring of stereotactic radiosurgery-induced complications and neurocognitive function assessment will continue for the censored subset until the end of 2014. This study is registered with the University Medical Information Network Clinical Trial Registry, number 000001812. Findings We enrolled 1194 eligible patients between March 1, 2009, and Feb 15, 2012. Median overall survival after stereotactic radiosurgery was 13 . 9 months [95% CI 12 .0- 15 . 6] in the 455 patients with one tumour, 10 . 8 months [9 . 4- 12 . 4] in the 531 patients with two to four tumours, and 10.8 months [9.1- 12.7] in the 208 patients with fi ve to ten tumours. Overall survival did not diff er between the patients with two to four tumours and those with fi ve to ten (HR 0 . 97, 95% CI 0.81- 1.18 [less than non- inferiority margin], p= 0.78; p non- inferiority < 0.001). Stereotactic radiosurgery- induced adverse events occurred in 101 (8%) patients; nine (2%) patients with one tumour had one or more grade 3- 4 event compared with 13 (2%) patients with two to four tumours and six (3%) patients with fi ve to ten tumours. The proportion of patients who had one or more treatment- related adverse event of any grade did not diff er signifi cantly between the two groups of patients with multiple tumours (50 [9%] patients with two to four tumours vs 18 [9%] with fi ve to ten; p= 0.89). Four patients died, mainly of complications relating to stereotactic radiosurgery (two with one tumour and one each in the other two groups). Interpretation Our results suggest that stereotactic radiosurgery without WBRT in patients with five to ten brain metastases is non-inferior to that in patients with two to four brain metastases. Considering the minimal invasiveness of stereotactic radiosurgery and the fewer side-effects than with WBRT, stereotactic radiosurgery might be a suitable alternative for patients with up to ten brain metastases.

The authors discuss the results of Gamma Knife (Elekta AB, Stockholm, Sweden) radiosurgery (GKS) for brain metastases based on their retrospective review of 2645 cases. All patients were treated according to the same protocol, with the tumors being irradiated with GKS without up-front whole-brain radiation therapy at the initial treatment. New distant lesions, detected by gadolinium-enhanced magnetic resonance imaging (MRI) performed every 2 to 3 months, were treated primarily with GKS. New distant lesions are generally well controlled with GKS salvage treatment. However, careful observation with enhanced MRI and appropriate salvage treatments are needed to prevent neurologic death and maintain activities of daily life.

We tested the validity of two prognostic indices for stereotactic radiosurgically (SRS)-treated patients with brain metastases (BMs) from five major original cancer categories. The two indices are Diagnosis-Specific Graded Prognostic Assessment (DS-GPA) and our Modified Recursive Partitioning Analysis (RPA). Forty-six hundred and eight BM patients underwent gamma knife SRS during the 1998-2011 period. Primary cancer categories were non-small cell lung cancer (NSCLC, 2827 patients), small cell lung cancer (SCLC, 460), gastro-intestinal cancer (GIC, 582), breast cancer (BC, 547) and renal cell cancer (RCC, 192). There were statistically significant survival differences among patients stratified into four groups based on the DS-GPA systems (p < 0.001) in all five original cancer categories. In the NSCLC category, there were statistically significant mean survival time (MST) differences (p < 0.001) among the four groups without overlapping of 95 % confidence intervals (CIs) between any two pairs of groups with the DS-GPA system. However, among the SCLC, GIC, BC and RCC categories, MST differences between some pairs of groups failed to reach statistical significance with this system. There were, however, statistically significant MST differences (p < 0.001) among the three groups without overlapping of 95 % CIs between any two pairs of groups with the Modified RPA system in all five categories. The DS-GPA system is applicable to our set of patients with NSCLC only. However, the Modified RPA system was shown to be applicable to patients with five primary cancer categories. This index should be considered when designing future clinical trials involving BM patients.

Objective: To study dynamic postural balance for Parkinson's disease patients, axial mobility and center of foot pressure (COP) were recorded simultaneously during movements of a head or chest. Materials and Methods: Fifteen patients with treated Parkinson's disease and age matched 15 volunteers with no neurological disease participated in this study. Head movements were monitored with a gyroscope on the head, and COP was monitored on a force platform. The subjects were standing upright on the platform and they were asked to rotate the head only alternatively repetitively, and then asked to rotate the chest and head synchronized alternatively repetitively. Both movements were asked to do at own pace for 20 sec, respectively, gazing at a cue synchronized to the head movements. Results: Head angular velocity showed significant differences for ratios of the peak power of the power spectra by the integrated power without the peak power between groups with PD and of volunteers (P &lt 0.0001), and between movements with the head only and with the head-thorax synchronized (P &lt 0.05). COP showed significant differences for the integrated power between groups with PD and of volunteers (P &lt 0.0001) and between movements with the head only and with the head-thorax synchronized (P &lt 0.0001). Conclusion: This simple and useful measurement might give numerical evaluation of axial rigidity for Parkinson's disease patients. © 2013 Japan International Cultural Exchange Foundation &amp Japan Health Sciences University.

The efficacy and limitations of salvage gamma knife surgery (GKS) have not been thoroughly described. This study evaluated the efficacy of GKS for treating brain metastases associated with small-cell lung cancer (SCLC) after whole-brain radiotherapy (WBRT) as the first-line radiation therapy. Forty-four patients with recurrent or new SCLC-associated brain metastases underwent GKS after receiving WBRT (median age, 62 years; median duration between WBRT and first GKS, 8.8 months). The median Karnofsky performance status (KPS) score was 100 (range, 40-100), and the median number of brain metastases at the first GKS was five. Ten patients who partially or completely responded to chemotherapy received prophylactic cranial irradiation (PCI) for limited disease. The median prescribed dose and number of lesions treated with the initial GKS were 20.0 Gy and 3.5, respectively, and the tumor control rate was 95.8 % (median follow-up period, 4.0 months). The 6-month new lesion-free survival, functional preservation rates, and overall survival were 50.0 %, 94.7 %, and 5.8 months, respectively. Neurological death occurred in 17.9 % of cases. The poor prognostic factors for new lesion-free survival time and functional preservation were > 5 brain metastases and carcinomatous meningitis, respectively. Poor prognostic factors for survival time were KPS < 70, > 10 brain metastases, diameter of the largest tumor > 20 mm, and carcinomatous meningitis. Median overall survival time from brain metastasis diagnosis was 16.9 months. GKS may be an effective option for controlling SCLC-associated brain metastases after WBRT and for preventing neurological death in patients without carcinomatous meningitis.

Purpose: We tested the validity of 3 recently proposed prognostic indexes for breast cancer patients with brain metastases (METs) treated radiosurgically. The 3 indexes are Diagnosis-Specific Graded Prognostic Assessment (DS-GPA), New Breast Cancer (NBC)-Recursive Partitioning Analysis (RPA), and our index, sub-classification of RPA class II patients into 3 sub-classes (RPA class II-a, II-b and II-c) based on Karnofsky performance status, tumor number, original tumor status, and non-brain METs. Methods and Materials: This was an institutional review board-approved, retrospective cohort study using our database of 269 consecutive female breast cancer patients (mean age, 55 years; range, 26-86 years) who underwent Gamma Knife radiosurgery (GKRS) alone, without whole-brain radiation therapy, for brain METs during the 15-year period between 1996 and 2011. The Kaplan-Meier method was used to estimate the absolute risk of each event. Results: Kaplan-Meier plots of our patient series showed statistically significant survival differences among patients stratified into 3, 4, or 5 groups based on the 3 systems (P<.001). However, the mean survival time (MST) differences between some pairs of groups failed to reach statistical significance with all 3 systems. Thus, we attempted to regrade our 269 breast cancer patients into 3 groups by modifying our aforementioned index along with the original RPA class I and III, (ie, RPA I+II-a, II-b, and II-c+III). There were statistically significant MST differences among these 3 groups without overlap of 95% confidence intervals (CIs) between any 2 pairs of groups: 18.4 (95% CI = 14.0-29.5) months in I+II-a, 9.2 in II-b (95% CI = 6.8-12.9, P<.001 vs I+II-a) and 5.0 in II-c+III (95% CI = 4.2-6.8, P<.001 vs II-b). Conclusions: As none of the new grading systems, DS-GPS, BC-RPA and our system, was applicable to our set of radiosurgically treated patients for comparing survivals after GKRS, we slightly modified our system for breast cancer patients. (C) 2012 Elsevier Inc.

Object. The authors conducted validity testing of the 5 major reported indices for radiosurgically treated brain metastases-the original Radiation Therapy Oncology Group's Recursive Partitioning Analysis (RPA), the Score Index for Radiosurgery in Brain Metastases (SIR), the Basic Score for Brain Metastases (BSBM), the Graded Prognostic Assessment (GPA), and the subclassification of RPA Class II proposed by Yamamoto-in nearly 2500 cases treated with Gamma Knife surgery (GKS), focusing on the preservation of neurological function as well as the traditional endpoint of overall survival. Methods. The authors analyzed data from 2445 cases treated with GKS by the first author (T.S.), the primary surgeon. The patient group consisted of 1716 patients treated between January 1998 and March 2008 (the Chiba series) and 729 patients treated between April 2008 and December 2011 (the Tokyo series). The interval from the date of GKS until the date of the patient's death (overall survival) and impaired activities of daily living (qualitative survival) were calculated using the Kaplan-Meier method, while the absolute risk for two adjacent classes of each grading system and both hazard ratios and 95% confidence intervals were estimated using the Cox proportional hazards model. Results. For overall survival, there were highly statistically significant differences between each. two adjacent patient groups characterized by class or score (all p values < 0.001), except for GPA Scores 3.5-4.0 and 3.0. The SIR showed the best statistical results for predicting preservation of neurological function. Although no other grading systems yielded statistically significant differences in qualitative survival, the BSBM and the modified RPA appeared lobe better than the original RPA and GPA. Conclusions. The modified RPA subclassification, proposed by Yamamoto, is well balanced in scoring simplicity with respect to case number distribution and statistical results for overall survival. However, a new or revised grading system is necessary for predicting qualitative survival and for selecting the optimal treatment for patients with brain metastasis treated by GKS. (http://thejns.org/doi/abs/10.3171/2012.8.GKS12710)

Long-term outcomes of the surgically treated unruptured intracranial aneurysms (UIA) are not well known. We conducted this study to clarify the surgical results and the long-term outcomes of the surgically treated UIA. <br> Seventy-three consecutive patients who were surgically treated and were followed over five years were enrolled in this study. Mean (median) age was 58.3 (59) years. The location of aneurysm was as follows: internal carotid in 32%, middle cerebral in 27%, multiple in 23% and so on. In the aneurysmal size, medium (4–11 mm) was most common (55%), followed by large or giant (12 mm or more) one (16%).<br> Results: 1) Permanent surgical morbidity was 5.5% and mortality was 1.4% (one case due to fulminant hepatitis). 2) Surgical treatment of the single aneurysm: craniotomy in 57 patients and intervention (GDC embolization) in four. 3) Mean (median) follow-up period was 8.6 (8) years. 4) Regrowth of the aneurysm was observed in one patient (1.4%), and de novo aneurysms were visualized in three (4.5%). 5) Long-term outcomes: modified Rankin scale 0–1 in 65 patients (89%), and six in five (7%). 6) Factors related to outcomes: cardiovascular events were seen in five patients; cerebrovascular in three patients and cardiac in two.<br> It is concluded that long-term outcomes of UIA were fairly favorable, and cardio- and cerebrovascular events were the main factor related to unfavorable outcome.<br>

Purpose: Although the recursive partitioning analysis (RPA) class is generally used for predicting survival periods of patients with brain metastases (METs), the majority of such patients are Class II and clinical factors vary quite widely within this category. This prompted us to divide RPA Class II patients into three subclasses. Methods and Materials: This was a two-institution, institutional review board-approved, retrospective cohort study using two databases: the Mito series (2,000 consecutive patients, comprising 787 women and 1,213 men; mean age, 65 years [range, 19-96 years]) and the Chiba series (1,753 patients, comprising 673 female and 1,080 male patients; mean age, 65 years [range, 7-94 years]). Both patient series underwent Gamma Knife radiosurgery alone, without whole-brain radiotherapy, for brain METs during the same 10-year period, July 1998 through June 2008. The Cox proportional hazard model with a step-wise selection procedure was used for multivariate analysis. Results: In the Mito series, four factors were identified as favoring longer survival: Karnofsky Performance Status (90% to 100% vs. 70% to 80%), tumor numbers (solitary vs. multiple), primary tumor status (controlled vs. not controlled), and non-brain METs (no vs. yes). This new index is the sum of scores (0 and 1) of these four factors: RPA Class II-a, score of 0 or 1; RPA Class II-b, score of 2; and RPA Class II-c, score of 3 or 4. Next, using the Chiba series, we tested whether our index is valid for a different patient group. This new system showed highly statistically significant differences among subclasses in both the Mito series and the Chiba series (p &lt; 0.001 for all subclasses). In addition, this new index was confirmed to be applicable to Class II patients with four major primary tumor sites, that is, lung, breast, alimentary tract, and urogenital organs. Conclusions: Our new grading system should be considered when designing future clinical trials involving brain MET patients. (C) 2012 Elsevier Inc.

It is established that deep brain stimulation of the subthalamic nucleus improves motor function in advanced Parkinson's disease, but its effects on autonomic function remain to be elucidated. The present study was undertaken to investigate the effects of subthalamic deep brain stimulation on gastric emptying. A total of 16 patients with Parkinson's disease who underwent bilateral subthalamic deep brain stimulation were enrolled. Gastric emptying was expressed as the peak time of (CO2)-C-13 excretion (T-max) in the C-13-acetate breath test and was assessed in patients with and without administration of 100-150 mg levodopa/decarboxylase inhibitor before surgery, and with and without subthalamic deep brain stimulation at 3 months post-surgery. The pattern of (CO2)-C-13 excretion curve was analysed. To evaluate potential factors related to the effect of subthalamic deep brain stimulation on gastric emptying, we also examined the association between gastric emptying, clinical characteristics, the equivalent dose of levodopa and serum ghrelin levels. The peak time of (CO2)-C-13 excretion (T-max) values for gastric emptying in patients without and with levodopa/decarboxylase inhibitor treatment were 45.6 +/- 22.7 min and 42.5 +/- 13.6 min, respectively (P = not significant), thus demonstrating levodopa resistance. The peak time of (CO2)-C-13 excretion (T-max) values without and with subthalamic deep brain stimulation after surgery were 44.0 +/- 17.5 min and 30.0 +/- 12.5 min (P &lt; 0.001), respectively, which showed that subthalamic deep brain stimulation was effective. Simultaneously, the pattern of the (CO2)-C-13 excretion curve was also significantly improved relative to surgery with no stimulation (P = 0.002), although the difference with and without levodopa/decarboxylase inhibitor was not significant. The difference in peak time of (CO2)-C-13 excretion (T-max) values without levodopa/decarboxylase inhibitor before surgery and without levodopa/decarboxylase inhibitor and subthalamic deep brain stimulation after surgery was not significant, although motor dysfunction improved and the levodopa equivalent dose decreased after surgery. There was little association between changes in ghrelin levels (delta ghrelin) and changes in T-max values (delta T-max) in the subthalamic deep brain stimulation trial after surgery (r = -0.20), and no association between changes in other characteristics and delta T-max post-surgery in the subthalamic deep brain stimulation trial. These results showed that levodopa/decarboxylase inhibitor did not influence gastric emptying and that subthalamic deep brain stimulation can improve the dysfunction in patients with Parkinson's disease possibly by altering the neural system that controls gastrointestinal function after subthalamic deep brain stimulation. This is the first report to show the effectiveness of subthalamic deep brain stimulation on gastrointestinal dysfunction as a non-motor symptom in Parkinson's disease.

BACKGROUND: No prospective study of gamma knife thalamotomy for intractable tremor has previously been reported. OBJECTIVE: To clarify the safety and optimally effective conditions for performing unilateral gamma knife (GK) thalamotomy for tremors of Parkinson disease (PD) and essential tremor (ET), a systematic postirradiation 24-month follow-up study was conducted at 6 institutions. We present the results of this multicenter collaborative trial. METHODS: In total, 72 patients (PD characterized by tremor, n = 59; ET, n = 13) were registered at 6 Japanese institutions. Following our selective thalamotomy procedure, the lateral part of the ventralis intermedius nucleus, 45% of the thalamic length from the anterior tip, was selected as the GK isocenter. A single 130-Gy shot was applied using a 4-mm collimator. Evaluation included neurological examination, magnetic resonance imaging and/or computerized tomography, the unified Parkinson's disease rating scale (UPDRS), electromyography, medication change, and video observations. RESULTS: Final clinical effects were favorable. Of 53 patients who completed 24 months of follow-up, 43 were evaluated as having excellent or good results (81.1%). UPDRS scores showed tremor improvement (parts II and III). Thalamic lesion size fluctuated but converged to either an almost spherical shape (65.6%), a sphere with streaking (23.4%), or an extended high-signal zone (10.9%). No permanent clinical complications were observed. CONCLUSION: GK thalamotomy is an alternative treatment for intractable tremors of PD as well as for ET. Less invasive intervention may be beneficial to patients.

A 58-year-old immunocompetent man gradually developed loss of appetite, cognitive decline, gait disturbances, and personality changes over 4 months. Brain magnetic resonance imaging (MRI) revealed bilateral diffuse leukoencephalopathy without mass formation on admission. His condition progressively deteriorated, and we treated him with intravenous high-dose steroids. His symptoms improved rapidly, but exacerbated when therapy was withdrawn. A brain biopsy was performed, and the diagnosis of primary central nervous system lymphoma (PCNSL) was confirmed. He was successfully treated with high-dose methotrexate therapy. Although it is difficult to diagnose PCNSL without mass formation in the early stages, steroid responsiveness is important and brain biopsy is essential for the correct diagnosis of PCNSL.

Background Urinary dysfunction is common in Parkinson's disease (PD); however, little is known about urinary dysfunction in early and untreated PD patients.Methods Fifty consecutive untreated PD patients (mean age, 66.7; mean disease duration, 23.6 months; and mean Hoehn & Yahr scale, 1.9) were recruited; those with other conditions that might have influenced urinary function were excluded. Patients were evaluated using a urinary questionnaire and urodynamic studies.Results Sixty-four per cent complained of urinary symptoms (storage, 64.0%; voiding, 28.0%). Urodynamic studies showed abnormal findings in the storage phase in 84%, with detrusor overactivity (DO) and increased bladder sensation without DO in 58.0% and 12.0% of patients, respectively. In the voiding phase, detrusor underactivity, impaired urethral relaxation such as detrusor sphincter dyssynergia, and bladder outlet obstruction were present in 50.0%, 8.0% and 16% of patients, respectively. In patients with both storage and voiding phase abnormalities, DO+detrusor underactivity was the most common finding. Few patients experienced urge incontinence and/or quality-of-life impairment owing to urinary dysfunction; none had low-compliance bladder or abnormal anal-sphincter motor unit potential. These urinary symptoms and urodynamic findings were not correlated with gender, disease severity or motor symptom type.Conclusion Urinary dysfunction, manifested primarily as storage disorders with subclinical voiding disorders and normal anal-sphincter electromyography, occurs in early and untreated PD patients. In cases with severe voiding disorder and/or abnormal anal-sphincter electromyography, other diagnoses should be considered.

Aggressive tumor removal is not always the best treatment for petroclival meningioma (PCM). However, radical removal actually provides the cure with minimal morbidity. We evaluated the relation of surgical results and tumor size in the PCM removal to clarify the treatment policy for PCM. This study comprised 32 consecutive patients with newly-diagnosed PCM who underwent tumor removal; tumor size was small (&lt; 3 cm) in 12 patients and large (a parts per thousand yen3 cm) in 20. Tumor removal was classified into radical (Simpson&apos;s grade I/II) and non-radical (Simpson&apos;s grade III/IV). Removal of small PCM was 11 radical and one non-radical; no surgical morbidity/mortality occurred and postoperative regular follow-up using magnetic resonance imaging showed no recurrence in the period of 66 +/- 45 months. Removal of large PCM was eight radical and 12 non-radical; despite no mortality, the incidence of permanent cranial nerve deficits and major neurological deficits newly developed postoperatively was 35% and 25%, respectively. Radical removal was significantly more frequent in small PCMs than in large PCMs. Permanent cranial nerve deficits newly developed postoperatively and poor outcome (Karnofsky score a parts per thousand currency sign80) were significantly more frequent in large PCMs than in small PCMs. Radical removal of small PCM is achieved with minimal morbidity and results in the cure. Notwithstanding high morbidity, aggressive removal of large PCM does not achieve a high rate of radical removal. To find and remove PCM radically while it is small is the only way to cure the disease with minimal morbidity.

Despite the accumulating evidences of high chemosensitivity especially in anaplastic oligodendrogliomas with loss of chromosomes 1p and 19q, the optimal management strategy for low-grade tumors using the 1p/19q information remains controversial. We have treated all low-grade oligodendrogliomas by a chemotherapy-preceding strategy without radiotherapy, and here we analyzed the survival outcomes of 36 consecutive patients in relation to 1p/19q status. The treatment protocol was as follows: (1) simple observation after gross total resection, and (2) modified PCV chemotherapy for postoperative residual tumors or recurrence after total resection. The 1p and 19q status were analyzed by fluorescence in situ hybridization. The median follow-up period was 7.5 years and no patient was lost during the follow-up periods. 1p/19q co-deletion was observed in 72% of the patients, and there was no significant association between 1p/19q co-deletion and chemotherapy response rate. The 5- and 10-year progression-free survival (PFS) rate was 75.1 and 46.9%, respectively, and the median PFS was 121 months for 1p/19q-deleted tumors and 101 months for non-deleted tumors (log-rank test: P = 0.894). Extent of surgery did not affect PFS (P = 0.685). In contrast, the elder patients (&gt; 50) had significantly shorter PFS (P = 0.0458). Recurrent tumors were well controlled by chemotherapy irrespective of 1p/19q status, and 35 out of 36 patients survived without receiving radiotherapy. The 5- and 10-year overall survival rates were 100 and 93.8%, respectively. Two of the patients in their sixties (29%) suffered from severe cognitive dysfunctions and marked brain atrophy following chemotherapy alone. These results show that low-grade oligodendrogliomas could be successfully treated by surgical resection and nitrosourea-based chemotherapy alone without radiotherapy irrespective of 1p/19q status.

The natural history of intracranial arterial dissection (ICAD) is not known precisely, so that treatment strategy is hard to determine in some cases. We examined the clinical features, treatment and long-term outcomes in the ICAD of ischemic onset.<br> Among 214 consecutive patients with ICAD [199 in the vertebrobasilar system (VBs) and 15 in the internal carotid system (ICs)], 76 presented with brain ischemia. Those were classified into 2 groups: 63 in the VBs and 13 in the ICs. We analyzed age, site of dissection, progression or recurrence of ischemia, medical and surgical treatment, and long-term outcomes. The outcomes were evaluated by modified Rankin disability scale (mRS). Good outcome was defined as mRS 0 to 2.<br> Results: 1) The patients were younger in the ICs (mean: 44.8 years) than in the VBs (mean: 53.0 years). 2) The vertebral artery was mostly affected in both arterial systems. 3) The acute stage progression or recurrence of ischemia was observed in 37% of the VBs and 54% of the ICs. The progression or recurrence is more frequent in the patients of the VBs with antithrombotic therapy (p=0.0224). 4) Treatment: Medical treatment was performed in 94% of the VBs and in all of the ICs. In addition, antithrombotic agents were prescribed in 38% of the VBs and in 85% of the ICs. Four patients (6%) of the VBs were surgically treated because of enlargement of the aneurysmal dilatation on follow-up study of MRI/MRA or 3D-CT angiography. 5) Long-term outcomes: In the medical group, good outcomes were achieved in 77% of the VBs and all of the ICs. In the VBs, the patients with antithrombotic therapy had poorer outcomes than those without the therapy (P=0.0399). All the patients in the surgical group had good outcomes in the VBs.<br> These results suggest that antithrombotic therapy might lead to the progression or recurrence of ICAD and a poorer outcome. This therapy should be selected prudently in the ICAD of ischemic onset, especially in the VBs.<br>

Object. The authors retrospectively reviewed the results of Gamma Knife surgery (GKS) used as the sole treatment for brain metastases in patients who met the eligibility criteria for the ongoing JLGK0901 multi-institutional prospective trial. They also discuss the anticipated results of the JLGK0901 study. Methods. Data from 1508 consecutive cases were analyzed. All of the patients were treated at the Gamma Knife House of Chiba Cardiovascular Center or the Mito Gamma House of Katsuta Hospital between 1998 and 2007 and met the following JLGK0901 inclusion criteria: 1) newly diagnosed brain metastases, 2) 1-10 brain lesions, 3) less than 10 cm(3) volume of the largest tumor, 4) no more than 15 cm(3) total tumor volume, 5) no findings of CSF dissemination, and 6) no impairment of activities of daily living (Karnofsky Performance Scale score &lt; 70) due to extracranial disease. At the initial treatment, all visible lesions were irradiated with GKS without upfront whole-brain radiation therapy. Thereafter, gadolinium-enhanced MR imaging was performed every 2-3 months, and new distant lesions were appropriately retreated with GKS. Patients were divided into groups according to numbers of tumors: Group A, single lesions (565 cases); Group B, 2-4 tumors (577 cases); and Group C, 5-10 tumors (366 cases). The differences in overall survival (OS) were compared between groups. Results. The median age of the patients was 66 years (range 19-96 years). There were 963 men and 545 women. The primary tumors were in the lung in 1114 patients, gastrointestinal tract in 179, breast in 105, urinary tract in 66, and other sites in 44. The overall mean survival time was 0.78 years (0.99 years for Group A, 0.68 years for Group B, and 0.62 years for Group C). The differences between Groups A and B (p &lt;0.0001) and between Groups B and C (p = 0.0312) were statistically significant. Multivariate analysis revealed significant prognostic factors for OS to be sex (poor prognostic factor: male, p &lt;0.0001), recursive partitioning analysis class (Class I vs Class II and Class II vs III, both p &lt;0.0001), primary site (lung vs breast, p = 0.0047), and number of tumors (Group A vs Group B, p &lt; 0.0001). However, no statistically difference was detected between Groups B and C (p = 0.1027, hazard ratio 1.124, 95% Cl 0.999-1.265). Conclusions. The results of this retrospective analysis revealed an upper CI of 1.265 for the hazard ratio, which was lower than the 1.3 initially set by the JLGK0901 study. The JLGK0901 study is anticipated to show noninferiority of GKS as sole treatment for patients with 5-10 brain metastases compared with those with 2-4 in terms of OS. (DOI: 10.3171/2010.8.GKS10838)

Object. Gamma Knife surgery (GKS) is an effective treatment option for intractable trigeminal neuralgia (TN). The incidence of trigeminal nerve dysfunction, such as facial numbness or dysesthesia, has been reported to be higher than previously published, and the degree and prognosis of trigeminal nerve dysfunction has not been well evaluated. The authors evaluated the incidence, timing, degree, and outcome of trigeminal nerve dysfunction after GKS for TN. Methods. One hundred four patients with medically refractory TN were treated by GKS. Thirty-nine patients were men and 65 were women; their median age at GKS was 74 years. Using a single isocenter and a 4-mm collimator, 80 or 90 Gy was directed to the trigeminal nerve root. Follow-up data were obtained at clinical examinations every 3-6 months after GKS. Each patient's pain-control status and degree of trigeminal nerve dysfunction were recorded. The incidence, timing, and degree of dysfunction (assessed using the Barrow Neurological Institute facial numbness scale [BNI-N]) and the prognosis and factors related to trigeminal nerve dysfunction were analyzed. Results. The median duration of follow-up in these patients was 37 months (range 6-121 months). At the final clinical visit, a pain-free status was still observed in 71 patients (68.3%). In 51 patients (49.0%), new or increased trigeminal nerve dysfunction developed at a median of 10.5 months (range 4-68 months) after GKS. In 24 patients (23.1%), this dysfunction was categorized as BNI-N Score II, in 20 patients (19.2%) as BNI-N Score III, and in 7 patients (6.7%) as BNI-N Score IV. Among those patients, 18 patients, including 3 patients with BNI-N Score IV, experienced improvement in nerve dysfunction between 24 and 108 months after GKS (median 52.5 months). At the final clinical visit, 43 patients (41.3%) reported having some trigeminal nerve dysfunction: in 26 patients (25.0%) this was categorized as BNI-N Score II, in 13 patients (12.5%) as BNI-N Score III, and in 4 patients (3.8%) as BNI-N Score IV. The only independent factor that was correlated to all trigeminal nerve dysfunction and also specifically to bothersome trigeminal nerve dysfunction was pain-free status at the final clinic visit. Conclusions. The incidence of trigeminal nerve dysfunction after GKS for TN was 49%. The severity of the dysfunction improved in one-third of the afflicted patients, even in those with severe dysesthesia at long-term follow-up. A strong relationship between TN and good pain control was identified. (DOI: 10.3171/2010.8.GKS10953)

Object. The authors prospectively analyzed volume changes in vestibular schwannomas (VSs) after Gamma Knife surgery (GKS). Methods. Among 104 VSs treated by GKS at the Chiba Cardiovascular Center between 1998 and 2004, 87 consecutively treated unilateral VSs observed on follow-up MR imaging for at least 5 years were analyzed. These lesions were harbored by 31 men and 56 women, with a mean age of 58.6 years (range 29-80 years). The Gd-enhanced volume of each lesion was measured serially every 3 months during the 1st year and every 6 months thereafter using GammaPlan or SurgiPlan. The frequency and degree of volume shrinkage were documented and possible prognostic factors were analyzed. Results. The mean tumor volume at GKS was 2.5 cm(3) (range 0.1-13.2 cm(3)). The lesions were irradiated by directing a mean dose of 12.0 Gy (range 10.5-13.0 Gy) to the tumor margin, which was located at the mean 52.2% isodose line (range 50%-67% isodose line). The mean follow-up period was 7.5 years (range 5.0-11.1 years). Peak tumor volume expansion was most frequently observed at 8.6 months after GKS and averaged 58% (range 0%-613%). Five years after GKS, the mean reduction in tumor volume was 31%, and 9 tumors still remained larger than their initial volumes. Tumors that homogeneously enhanced on MR images displayed less shrinkage than other tumors. Conclusions. Most VSs exhibit shrinkage 5 years after GKS. The mean volume reduction in this series was 31%. These results indicate that careful serial follow-up is necessary for patients who harbor tumors that display homogeneous enhancement on MR images and patients whose tumors continue to expand in size after GKS. (DOI: 10.3171/2010.8.GKS10960)