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Objective: A retrospective comparative analysis of the outcomes of gamma knife radiosurgery (GKRS) for brain metastases from uterine cervical carcinoma (CC) and endometrial carcinoma (EC), investigated the efficacy and prognostic factors for survival and local tumor control. Histopathological analysis was also performed., Methods: The authors retrospectively reviewed 61 patients with 260 tumors of CC and 73 patients with 302 tumors of EC who had undergone GKRS., Results: The survival times after GKRS had no difference between CC and EC. Uncontrolled primary cancer was significant unfavorable factor. CC resulted in significantly higher neurological death and post-GKRS neurological deterioration. New lesions appeared intracranially after GKRS, with no significant difference between CC and EC. Local tumor control rates at 6, 12, and 24 months after GKRS were 90.0%, 86.6%, and 78.0% for CC and 92.2%, 87.9%, and 86.4% for EC. Primary cancer of CC, more than 7 cm 3 volume, and prescription dose less than 20 Gy were significantly correlated in control failure. Local tumor control rates were significantly lower for squamous cell carcinoma in CC. No significant differences were found between histopathological subtypes of EC., Conclusions: This study established a relationship between the efficacy of GKRS for CC and EC brain metastases and the histopathological. Though, survival time after GKRS has no difference between CC and EC, CC was significantly higher neurogenic death and neurological deterioration after GKRS. Squamous cell carcinoma had a significantly lower rate of local tumor control among all CC, thereby resulting in CC having lower local tumor control than EC., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: The present study evaluated outcomes after preplanned partial surgical removal of a large vestibular schwannoma (VS) followed by low-dose Gamma Knife surgery (GKS)., Methods: Between January 2000 and May 2015, 47 patients with a unilateral VS (median maximum diameter 32 mm) underwent preplanned partial tumor removal at our clinic. GKS for a residual lesion was done within a median time interval of 3 months. The median prescription dose was 12 Gy. The median length of subsequent follow-up was 74 months., Results: The actuarial tumor growth control rates without a need for additional management at 3, 5, and 15 years after GKS were 92%, 86%, and 86%, respectively. At the time of the last follow-up, the function of the ipsilateral facial nerve corresponded to House-Brackmann grade I in 92% of patients. Significant improvement of ipsilateral hearing was noted in two patients after partial tumor removal and in one after GKS. Among 16 patients who presented with ipsilateral serviceable hearing, it was preserved immediately after surgery in 81% of cases and at the time of the last follow-up in 44%. Salvage surgical treatment was required in 9% of patients., Conclusion: Preplanned partial surgical removal followed by low-dose GKS provides a high level of functional preservation in patients with a large VS.

Introduction: Brain metastasis (BM) is one of the most important issues in the management of breast cancer (BC), since BMs are associated with neurological deficits. However, the importance of BC subtypes remains unclear for BM treated with Gamma Knife radiosurgery (GKS). Thus, we conducted a multicenter retrospective study to compare clinical outcomes based on BC subtypes, with the aim of developing an optimal treatment strategy., Methods: We studied 439 patients with breast cancer and 1-10 BM from 16 GKS facilities in Japan. Overall survival (OS) was analyzed by the Kaplan-Meier method, and cumulative incidences of systemic death (SD), neurologic death (ND), and tumor progression were estimated by competing risk analysis., Results: OS differed among subtypes. The median OS time (months) after GKS was 10.4 in triple-negative (TN), 13.7 in Luminal, 31.4 in HER2, and 35.8 in Luminal-HER2 subtype BC (p < 0.0001). On multivariate analysis, poor control of the primary disease (hazard ratio [HR] = 1.84, p < 0.0001), active extracranial disease (HR = 2.76, p < 0.0001), neurological symptoms (HR 1.44, p = 0.01), and HER2 negativity (HR = 2.66, p < 0.0001) were significantly associated with worse OS. HER2 positivity was an independent risk factor for local recurrence (p = 0.03) but associated with lower rates of ND (p = 0.03). TN histology was associated with higher rates of distant brain failure (p = 0.03)., Conclusions: HER2 positivity is related to the longer OS after SRS; however, we should pay attention to preventing recurrence in Luminal-HER2 patients. Also, TN patients require meticulous follow-up observation to detect distant metastases and/or LMD.

Purpose: Stereotactic radiosurgery (SRS) has been increasingly used for elderly patients with brain metastases (BMs). However, no studies based on a large sample size have been reported. To compare SRS treatment results between elderly and non-elderly patients, we performed a subset study of elderly patients using our prospectively-accumulated multi-institution study database (JLGK0901 Study, Lancet Oncol 15:387-395, 2014)., Methods: During the 2009-2011 period, 1194 eligible patients undergoing gamma knife SRS alone for newly diagnosed BMs were enrolled in this study from 23 gamma knife facilities in Japan. Observation was discontinued at the end of 2013. The 1194 patients were divided into the two age groups, 693 elderly ( ≥ 65 years) and 501 non-elderly ( < 65 years) patients. Our study protocol neither set an upper age limit nor required dose de-escalation., Results: Median post-SRS survival time was significantly shorter in the elderly than in the non-elderly patient group (10.3 vs 14.3 months, HR 1.380, 95% CI 1.218-1.563, p < 0.0001). However, regarding all secondary endpoints including neurological death, neurological deterioration, SRS-related complications, leukoencephalopathy, local recurrence, newly-developed tumors, meningeal dissemination, salvage SRS, whole brain radiotherapy and surgery and decreased mini-mental state examination scores, the elderly patient group was not inferior to the non-elderly patient group. In the 693 elderly patients, there was no post-SRS median survival time difference between those with 5-10 versus 2-4 tumors (10.8 vs 8.9 months, HR 0.936, 95% CI 0.744-1.167, p = 0.5601)., Conclusions: We conclude that elderly BM patients are not unfavorable candidates for SRS alone treatment.

OBJECTIVEPrevious Japanese Leksell Gamma Knife Society studies (JLGK0901) demonstrated the noninferiority of stereotactic radiosurgery (SRS) alone as the initial treatment for patients with 5-10 brain metastases (BMs) compared with those with 2-4 BMs in terms of overall survival and most secondary endpoints. The authors studied the aforementioned treatment outcomes in a subset of patients with BMs from non-small cell lung cancer (NSCLC).METHODSPatients with initially diagnosed BMs treated with SRS alone were enrolled in this prospective observational study. Major inclusion criteria were the existence of up to 10 tumors with a maximum diameter of less than 3 cm each, a cumulative tumor volume of less than 15 cm3, and no leptomeningeal dissemination in patients with a Karnofsky Performance Scale score of 70% or better.RESULTSAmong 1194 eligible patients, 784 with NSCLC were categorized into 3 groups: group A (1 tumor, n = 299), group B (2-4 tumors, n = 342), and group C (5-10 tumors, n = 143). The median survival times were 13.9 months in group A, 12.3 months in group B, and 12.8 months in group C. The survival curves of groups B and C were very similar (hazard ratio [HR] 1.037; 95% CI 0.842-1.277; p < 0.0001, noninferiority test). The crude and cumulative incidence rates of neurological death, deterioration of neurological function, newly appearing lesions, and leptomeningeal dissemination did not differ significantly between groups B and C. SRS-induced complications occurred in 145 (12.1%) patients during the median post-SRS period of 9.3 months (IQR 4.1-17.4 months), including 46, 54, 29, 11, and 5 patients with a Common Terminology Criteria for Adverse Events v3.0 grade 1, 2, 3, 4, or 5 complication, respectively. The cumulative incidence rates of adverse effects in groups A, B, and C 60 months after SRS were 13.5%, 10.0%, and 12.6%, respectively (group B vs C: HR 1.344; 95% CI 0.768-2.352; p = 0.299). The 60-month post-SRS rates of neurocognitive function preservation were 85.7% or higher, and no significant differences among the 3 groups were found.CONCLUSIONSIn this subset analysis of patients with NSCLC, the noninferiority of SRS alone for the treatment of 5-10 versus 2-4 BMs was confirmed again in terms of overall survival and secondary endpoints. In particular, the incidence of neither post-SRS complications nor neurocognitive function preservation differed significantly between groups B and C. These findings further strengthen the already-reported noninferiority hypothesis of SRS alone for the treatment of patients with 5-10 BMs.

Background: Trigeminal neuralgia is a rare feature of basilar impression, a complication of osteochondrodysplasic disorders. Microvascular decompression is difficult in medically refractory cases. Gamma knife radiosurgery (GKS) is effective for classical trigeminal neuralgia, and we first applied this GKS for a patient suffering from trigeminal neuralgia with basilar impression complicated by osteogenesis imperfecta., Case Description: An 18-year-old man with type I osteogenesis imperfecta presented with a 2-year history of typical left trigeminal neuralgia affecting the ophthalmic, maxillary, and mandibular nerves. His condition was poorly controlled by carbamazepine and pregabalin. Magnetic resonance imaging confirmed severe basilar impression and an elongated cisternal portion of the left trigeminal nerve. GKS was performed under local anesthesia. The middle part of the cisternal portion of the left trigeminal nerve was chosen as the radiosurgical target, despite the lack of neurovascular compression. The maximum radiosurgical dose was 85 Gy, using a single 4-mm collimator. The patient's trigeminal neuralgia improved by 1 month after GKS, and at 21 months after GKS he remained free of pain and medications., Conclusions: We report a case of trigeminal neuralgia resulting from severe basilar impression. Conventional microvascular decompression would not have been an appropriate treatment for this patient, so GKS was used. GKS is a simple and effective option even in cases with severe cranial deformity., (Copyright © 2018. Published by Elsevier Inc.)

Purpose: The JLGK0901 study showed the noninferiority of stereotactic radiosurgery (SRS) alone as initial treatment of 5 to 10 brain metastases (BMs) compared with 2 to 4 BMs in terms of overall survival and most secondary endpoints (Lancet Oncol 2014;15:387-95). However, observation periods were not long enough to allow confirmation of the long-term safety of SRS alone in patients with 5 to 10 BMs., Methods and Materials: This was a prospective observational study of Gamma Knife SRS-treated patients with 1 to 10 newly diagnosed BMs enrolled at 23 facilities between March 1, 2009, and February 15, 2012., Results: The 1194 eligible patients were categorized into the following groups: group A, 1 tumor (n=455); group B, 2 to 4 tumors (n=531); and group C, 5 to 10 tumors (n=208). Cumulative rates of Mini-Mental State Examination (MMSE) score maintenance (MMSE score decrease <3 from baseline) determined with a competing risk analysis of groups A, B, and C were 93%, 91%, and 92%, respectively, at the 12th month after SRS; 91%, 89%, and 91%, respectively, at the 24th month; 89%, 88%, and 89%, respectively, at the 36th month; and 87%, 86%, and 89%, respectively, at the 48th month (hazard ratio [HR] of group A vs group B, 0.719; 95% confidence interval [CI], 0.437-1.172; P=.18; HR of group B vs group C, 1.280; 95% CI, 0.696-2.508; P=.43). During observations ranging from 0.3 to 67.5 months (median, 12.0 months; interquartile range, 5.8-26.5 months), as of December 2014, 145 patients (12.1%) had SRS-induced complications. Cumulative complication incidences by competing risk analysis for groups A, B, and C were 7%, 8%, and 6%, respectively, at the 12th month after SRS; 10%, 11%, and 11%, respectively, at the 24th month; 11%, 11%, and 12%, respectively, at the 36th month; and 12%, 12%, and 13%, respectively, at the 48th month (HR of group A vs group B, 0.850; 95% CI, 0.592-1.220; P=.38; HR of group B vs group C, 1.052; 95% CI, 0.666-1.662, P=.83). Leukoencephalopathy occurred in 12 of the 1074 patients (1.1%) with follow-up magnetic resonance imaging and was detected after salvage whole-brain radiation therapy in 11 of these 12 patients. In these 11 patients, leukoencephalopathy was detected by magnetic resonance imaging 5.2 to 21.2 months (median, 11.0 months; interquartile range, 7.0-14.4 months) after whole-brain radiation therapy., Conclusions: Neither MMSE score maintenance nor post-SRS complication incidence differed among groups A, B, and C. This longer-term follow-up study further supports the already-reported noninferiority hypothesis of SRS alone for patients with 5 to 10 BMs versus 2 to 4 BMs., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The authors retrospectively analyzed cyst formations and expanding haematomas (EHs) that developed after Gamma Knife surgery (GKS) for arteriovenous malformations (AVMs), and evaluated the treatment results of these lesions. Cyst formations and/or EHs which developed after GKS for AVMs were identified in 20 patients (5.0%) out of 404 patients who underwent this procedure. There were nine patients with cyst formations, two with EHs and nine with cyst formations with EHs. These lesions developed between 36 and 192months (median 99months) after GKS. The median nidus volume was 4.7ml (range, 1.8-14.2ml) and the median prescribed margin dose was 20Gy (range, 15-23Gy). The multivariate analysis showed no correlation between the appearance of cyst formations and/or EHs and the patients' age, sex, nidus volume, margin dose, repeated GKS, nidus obliteration, pre-GKS embolization and prior hemorrhage. Surgical treatment was required in nine patients. Eight patients had total removal of the angiomatous lesions (EHs or nodular lesions that were detected as enhancement part on MRI) via a craniotomy and one had a cyst aspiration. There was no recurrence of the lesions in all the patients that underwent a craniotomy. In the patient treated with a cyst aspiration, regrowth of the cyst formation occurred. Surgical treatment should be considered for symptomatic lesions and we recommend total removal of the angiomatous lesions to achieve a complete cure., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: Central neurocytoma (CN) is a rare benign neuronal tumor, and a limited number of reports have described the usefulness of radiosurgery for a relatively large group of patients. We evaluated the effectiveness and outcomes of Gamma Knife radiosurgery (GKS) for CN in a Japanese multi-institutional study., Methods: We performed retrospective analysis of 36 patients with CN who were treated with GKS in 12 institutes in Japan. All patients underwent surgery before GKS. The median tumor volume at GKS was 4.9 mL (range, 0.07-23.4 mL), and the median radiation dose prescribed to the tumor margin was 15 Gy (range, 10-20 Gy). The median follow-up period was 54.5 months (range, 3-180 months)., Results: The local tumor progression-free survival rates at 5 and 10 years were 94% and 86%, respectively. Three patients developed distant dissemination 16-90 months later. Overall progression-free survival was unrelated to the prescribed dose (<15 Gy vs. ≥15 Gy, P = 0.62), tumor size (<6 mL vs. ≥6 mL, P = 0.46), gender (P = 0.36), age (<30 vs. ≥30 years, P = 0.37), target of GKS (residual vs. recurrence, P = 0.90), and type of enhancement (homogeneous vs. inhomogeneous, P = 0.19). Two permanent complications occurred with 1 intratumoral hemorrhage and 1 radiation injury., Conclusions: GKS is effective for CN because of its high rate of long-term local tumor control. GKS may have a potential role as a primary treatment for asymptomatic, relatively small tumors in the absence of hydrocephalus without surgical resection., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: The treatment goal for vestibular schwannomas (VS) has been changed from total removal of the tumor to functional preservation with long-term tumor growth control. The small- to medium-sized VS can be treated by stereotactic radiosurgery, but large VS require surgical decompression for the relief of cerebellar dysfunction and increased intracranial pressure. We have been performing planned partial surgical resections followed by gamma knife radiosurgery (GKS) for large VS. Here, we evaluate a recent series of such cases from the standpoint of functional outcomes., Methods: From January 2000 to May 2013, we treated 40 patients with large unilateral VS (maximum tumor diameter at least 25 mm) with planned partial tumor removal followed by GKS for functional preservation. The median maximum diameter of the tumors was 32.5 mm (range 25-52 mm). All patients underwent surgery via the retrosigmoid approach, and tumors situated on the ventral and in the internal auditory canal intentionally were not removed, thus preserving cranial nerve functions. GKS was performed 1-12 months after surgical resection (median interval 3 months). The median tumor volume at GKS was 3.3 cm(3) (range 0.4-10.4 cm(3)) and the median prescribed dose was 12 Gy (range 10-12 Gy). The median follow-up period after GKS was 65 months (18-156 months)., Results: At the final follow-up, facial nerve preservation (House-Brackmann grade I-II) was achieved in 38 patients (95%; House-Brackmann grade I: 92.5%, II: 2.5%). Among the 14 patients with preoperative pure tone average (PTA) less than 50 dB, 6 of them (42.9%) maintained PTA less than 50 dB at the last follow-up. Two patients improved from severe hearing loss to PTA less than 50 dB (1 patient after surgery and 1 patient one and half years after GKS). Five- and 10-year tumor growth control occurred in 86% of patients. Four patients (10%) required salvage surgery; the predictive factor was tumor volume greater than 6 cm(3) at GKS (P = 0.01)., Conclusions: Planned partial removal of large VS followed by GKS achieved a high rate of facial nerve and hearing preservation. To achieve long-term tumor growth control, the tumor volume at GKS after planned partial surgical resection should be smaller than 6 cm(3). Our results revealed that patients with hearing preservation postoperatively have a chance of maintaining hearing function, even though the possibility exists of deterioration by long-term follow-up after surgical intervention and GKS. Furthermore, some patients with severe hearing loss before treatment have the chance of hearing improvement, even those with large VS., (Copyright © 2015 Elsevier Inc. All rights reserved.)

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 (largest 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 (HR) of 1·30, and all data were analysed by intention to treat. The study was finalised on 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 five to ten tumours. Overall survival did not differ between the patients with two to four tumours and those with five to ten (HR 0·97, 95% CI 0·81-1·18 [less than non-inferiority margin], p=0·78; pnon-inferiority<0·0001). 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 five to ten tumours. The proportion of patients who had one or more treatment-related adverse event of any grade did not differ significantly between the two groups of patients with multiple tumours (50 [9%] patients with two to four tumours vs 18 [9%] with five 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., Funding: Japan Brain Foundation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

We evaluated the endocrinological outcomes of gamma knife radiosurgery (GKS) for the treatment of growth hormone (GH)-producing pituitary adenomas. Twenty-six patients treated with GKS (median treatment [tumour] volume: 0.8 mL; median marginal radiation dose: 20Gy) were followed for a median of 84 months. "Disease remission" was defined as either nadir levels of GH <1 microg/L during an oral glucose load, or random GH levels <2 microg/L and normal age-adjusted and sex-adjusted levels of insulin-like growth factor without pituitary suppressive medications. The remission rate was 38% (10/26) and the 5-year and 10-year actuarial remission rates were 16.9% and 47.4%, respectively. Two patients (8%) suffered hypopituitarism requiring medication, but no other serious deficits were observed. Although GKS requires a relatively long time to achieve hormonal remission, it is a very useful, long-term treatment for GH-producing adenomas. We propose that compared to continuing life-long medication, GKS is less invasive and more cost effective., (Copyright 2009 Elsevier Ltd. All rights reserved.)

We report the usefulness of gamma knife radiosurgery for hemangioblastomas, hemangiopericytomas, germ cell tumors and pineal parenchymal tumors, and primary central nervous system lymphoma (PCNSL). In hemangioblastomas, small solid tumors can be treated very effectively. Hemangiopericytomas are still difficult to control due to their aggressiveness and metastasis to other organs. However, radiosurgery is a useful alternative to repeat craniotomy for recurrence. Radiosurgery is a reasonable option to control residual and recurrent germ cell tumors and pineoblastomas. Although the prognosis is poor for PCNSL patients, gamma knife radiosurgery, even with a relatively low tumor margin dose, is an effective treatment for controlling PCNSL.

Object: In this study, the authors evaluate the long-term results after Gamma Knife radiosurgery of cranial base meningiomas. This study is a follow-up to their previously published report on the early results., Methods: Between January 1994 and December 2001, the authors treated benign cranial base meningiomas in 108 patients using low-dose Gamma Knife radiosurgery. The tumor volumes ranged from 1.7 to 55.3 cm3 (median 8.1 cm3), and the radiosurgery doses ranged from 8 to 12 Gy (median 12 Gy) to the tumor margin., Results: The mean duration of follow-up was 86.1 months (range 20-144 months). Tumor volume decreased in 50 patients (46%), remained stable in 51 patients (47%), and increased (local failure) in 7 patients (6%). Eleven patients experienced tumor recurrence outside the treatment field. Among these patients, marginal failure was seen in 5 and distant recurrence was seen in 6. Seven patients were thought to have malignant transformation based on histological or radiological characteristics of the lesion. The actuarial progression-free survival rate, including malignant transformation and outside recurrence, was 93% at 5 years and 83% at 10 years. Neurological status improved in 16 patients (15%). Permanent radiation injury occurred in 7 patients (6%)., Conclusions: Gamma Knife radiosurgery is a safe and effective treatment for cranial base meningiomas as demonstrated with a long-term follow-up period of > 7 years. Surgeons must be aware of the possibility of treatment failure, defined as local failure, marginal failure, and malignant transformation; however, this may be the natural course of meningiomas and not related to radiosurgery.

In the present study we reviewed our long-term experience with radiosurgery for intracanalicular acoustic neuromas. The study involved 25 patients with unilateral intracanalicular acoustic neuromas. The treatment volume was 0.07 to 0.8 cm(3) (median: 0.27 cm(3)). The marginal radiation dose used for treatment was 12 Gy for all patients. The follow-up period ranged from 36 to 132 months (mean: 89 months). The actuarial rate of tumour growth control at 5 and 10 years after radiosurgery was 96%. Hearing preservation was achieved in 16 patients (64%) and improvement (>20 dB relative to presurgical values) was noted in one patient (4%). No patients experienced post-radiosurgery facial palsy or other cranial nerve deficits. Based on our study and long-term follow-up, radiosurgery can produce high rates of tumour growth control and hearing preservation for intracanalicular acoustic neuromas, and is an alternative to surgical resection given its low level of invasiveness. When determining treatment for intracanalicular acoustic neuromas, the condition's benign natural course and the likelihood of hearing preservation must be taken into account.

Background: We evaluated results of resection surgery followed by boost radiosurgery for the treatment of brain metastases., Methods: We treated 21 patients (13 male, 8 female) with surgical resection (subtotal or total) followed by boost radiosurgery. The mean patient age was 61 years (range, 41-80 years); supratentorial lesions were treated in 12 patients, and posterior fossa lesions were treated in 9 patients. The most common primary cancers were lung (24%) and colon (24%). Fifty-three percent of patients had brain metastases only, whereas 47% had extracranial metastases. The radiosurgery dose plan was designed to radiate the operative cavity; the mean treatment volume (50% isodose) was 10.7 mL (range, 3.4-23.3 mL), and the mean marginal dose was 17 Gy (range, 13-20 Gy)., Results: Local control was achieved in 16 (76%) patients. However, new intracranial lesions developed in 10 patients, and meningeal carcinomatosis occurred in 5 patients. Local tumor recurrence occurred more often for patients treated with lower radiotherapy doses (<18 vs > or =18 Gy, P = .03), and meningeal carcinomatosis occurred more often in patients with posterior fossa lesions (P = 0.05). Gamma knife radiosurgery was performed in 13 patients, and whole-brain radiation was performed in 2 patients. No patients experienced symptomatic radiation injury, and the median survival time was 20 months., Conclusions: Although boost radiosurgery is less invasive and reduces morbidity, the radiosurgical dose must be higher than 18 Gy for the treatment to be most effective. Treatment of lesions of the posterior fossa must be considered carefully because of the higher frequency of meningeal carcinomatosis. Also, we recommend that the surgeons who operate on the metastatic tumors must try to decrease the resected cavity volume and to prevent cerebrospinal fluid dissemination at the operation for posterior fossa lesions.

A 37-year-old man was treated for lung cancer by chemo-radiation therapy. Subsequently, magnetic resonance (MR) imaging identified a ring-enhanced lesion in the left temporal lobe. Gamma knife radiosurgery was performed under a diagnosis of brain metastasis. Nevertheless, MR imaging showed regrowth of the tumor 1 year later, so radiosurgery was repeated on the same lesion. Two years after the first radiosurgery, MR imaging revealed an irregularly enhanced lesion with increasing perifocal edema in the left temporal lobe. Emergency surgery was performed under a diagnosis of impending uncal herniation. The histological diagnosis was cavernous malformation. This case demonstrates that gamma knife radiosurgery can cause radiation-induced cavernous malformation.

Objective: To retrospectively review the authors' experience with surgical resections after failed radiosurgery for acoustic neuromas., Methods: The study group consisted of six patients with acoustic neuromas. The median age was 61 years (range, 18-72 yr). The median marginal radiation dose was 11 Gy (range, 10-12.5 Gy). The median interval between radiosurgery and surgical resection was 28 months (range, 4-74 mo). The operative indications were cerebellar ataxia and symptoms associated with increased intracranial pressure. The median follow-up period was 36 months (range, 11-72 mo) after surgical resection., Results: The tumors were subtotally removed (> or = 80%) in four patients and partially removed (< 80%) in the other two patients. Three patients had intratumoral bleeding. Preexisting facial nerve palsy improved in two patients and deteriorated in one patient, and one patient experienced new facial palsy. No other new neurological deficits emerged after surgery. Histological features were typical of acoustic schwannoma, and some tumors were associated with foamy macrophages, myxoid degeneration, and necrosis attributed to radiation effects. At follow-up, the residual tumor was decreased in five patients and increased in one patient with an expanding intratumoral hematoma., Conclusion: Surgical resection after radiosurgery is indicated in the presence of such symptoms as cerebellar ataxia and increased intracranial pressure. It must be carefully considered because of the natural regression of transient tumor swelling over time. Surgical resection should be limited to subtotal removal for functional preservation. In patients with tumor enlargement several years after radiosurgery, the possibility of chronic intratumoral bleeding resulting from delayed radiation injury must be considered.

Background: We evaluated the efficacy of gamma knife radiosurgery for cavernous sinus metastases and invasion., Method: We treated and followed up 21 patients with cavernous sinus metastases and invasion using gamma knife radiosurgery. Nine of these patients had nasopharyngeal cancer, and 12 had distant metastases from other cancers. The volume of tumors ranged from 2.9 to 50.0 (median 9.9) mL. and the radiation dose to the tumor margin was 10 to 21 (median 14) Gy., Results: The median follow-up period was 9 months. Clinical symptoms were improved in 48% of the patients after treatment, and tumor growth control was obtained in 67% of the patients at their final follow-up. The actual 1- and 2-year tumor growth control rates were 68% and 43%, respectively. The mean survival time was 13 months. No patient had radiation injury., Conclusion: Gamma knife radiosurgery is a very useful therapeutic option for the treatment of cavernous sinus metastases and invasion, either as initial treatment or as an adjunct treatment for recurrences even in preirradiated patients.

We evaluated the treatment results of nonfunctioning pituitary adenomas in the era of radiosurgery. Between January 1994 and December 2003, we operated on 44 patients with nonfunctioning pituitary adenomas. 43 patients were operated on by transsphenoidal surgery and one patient was operated on by the transcranial approach. Total removal was able to be achieved in 13 patients (30%). Gamma knife radiosurgery was performed for residual tumor in 26 patients and for recurrence in 2 patients. The mean tumor diameter at the gamma knife radiosurgery was 18.2 mm (7.9 to 26.3 mm). The treatment dose was a mean of 12.3 Gy (8 to 16 Gy) to the tumor margin. The mean follow-up period after radiosurgery was 36.4 months. Tumor growth control was able to be achieved in 26 patients (93%). Two patients (7%) required adrenal and thyroid hormonal replacement during the follow-up period after radiosurgery due to radiation-induced endocrinopathy. None of the patients suffered from new cranial nerve deficits. This included optic neuropathy. Surgical resection using transsphenoidal surgery and subsequent gamma knife radiosurgery for residual and recurrent tumor proved to have a highly effective tumor growth control rate, and maintained the quality of life in patients with nonfunctioning pituitary adenomas.

Objective: We evaluated the effectiveness of gamma knife radiosurgery in the treatment of nonfunctioning pituitary adenomas., Methods: Between January 1994 and December 1999, we treated 34 patients with nonfunctioning pituitary adenomas. Thirty-one of these patients were followed for more than 30 months. Their mean age was 52.9 years. All patients underwent resection before radiosurgery. In four patients, treatment was performed with staged radiosurgery. The treatment volume was 0.7 to 36.2 cm3 (median, 2.5 cm3). The treatment dose ranged from 8 to 20 Gy (median, 14.0 Gy) to the tumor margin. In 15 patients (48.4%), the tumor either compressed or was attached to the optic apparatus. The maximum dose to the optic apparatus was from 2 to 11 Gy (median, 8 Gy)., Results: Patients were followed for 30 to 108 months (median, 59.8 mo). The tumor size decreased in 18 patients (58.1%), remained unchanged in 9 patients (29.0%), and increased in four patients (12.9%). The 5-year actual tumor growth control rate was 93%. Among patients with tumor growth, two cases were secondary to cyst formation. Two patients (6.5%) required adrenal and thyroid hormonal replacement during the follow-up period after radiosurgery because of radiation-induced endocrinopathy. None of the patients sustained new cranial nerve deficits, which included optic neuropathy., Conclusion: In this series, radiosurgery had a high tumor growth control rate during the long-term follow-up period. Furthermore, we observed a low morbidity rate, with endocrinopathies and optic neuropathies. This low rate included even patients in whom the tumor compressed or was attached to the optic apparatus. We emphasize the necessity of long-term follow-up to evaluate late complications.

We evaluated the usefulness of adjuvant treatment with gamma knife radiosurgery following meningioma surgery. During the past 8 years, we operated on 78 patients with meningiomas. Among these, 28 patients (36%) received gamma knife radiosurgery postoperatively. The indications for radiosurgery were as follows: residual tumour after surgery in 13 patients (46.4%), regrowth of residual tumour during the follow-up period in 7 patients (25%), recurrence after total removal (Simpson grade 1 or 2) in 7 patients (25%), and another intracranial meningioma in one patient (3.6%). The tumour diameter at the time of radiosurgery ranged from 5.2 to 48.1 mm (median 21.6 mm). Larger tumours with a mean diameter above 40 mm in two patients were treated with two-staged radiosurgery. The tumor marginal dose ranged from 8 to 23 Gy (median 12 Gy). The follow-up period was 3-84 months (median 30 months) after radiosurgery. The tumour size decreased in 17 patients (60.7%), remained unchanged in 9 patients (32.1%), and increased in 2 patients (7.2%). No radiation injury was experienced. Adjuvant therapy using gamma knife radiosurgery for meningiomas can achieve control of tumour growth and may improve patient outcomes. Careful surgical planning and follow-up are required to understand the usefulness and limitations of radiosurgery in this setting.

Object: Following stereotactic radiosurgery (SRS), we examined how to differentiate radiation necrosis from recurrent malignant glioma using positron emission tomography (PET) with 11C-methionine (Met)., Methods: Met-PET scans were obtained from 11 adult cases of recurrent malignant glioma or radiation injury, suspected on the basis of magnetic resonance images (MRI). Patients had previously been treated with SRS after primary treatment. PET images were obtained as a static scan of 10 minutes performed 20 minutes after injection of Met. We defined two visual grades (e.g., positive or negative Met accumulation). On Met-PET scans, the portion of the tumor with the highest accumulation was selected as the region of interest (ROI), tumor-versus-normal ratio (TN) was defined as the ratio of average radioisotope counts per pixel in the tumor (T), divided by average counts per pixel in normal gray matter (N). The standardized uptake value (SUV) was calculated over the same tumor ROI. Met-PET scan accuracy was evaluated by correlating findings with subsequent histological analysis (8 cases) or, in cases without surgery or biopsy, by the subsequent clinical course and MR findings (3 cases)., Results: Histological examinations in 8 cases showed viable glioma cells with necrosis in 6 cases, and necrosis without viable tumor cells in 2 cases. Three other cases were considered to have radiation necrosis because they exhibited stable neurological symptoms with no sign of massive enlargement of the lesion on follow-up MR after 5 months. Mean TN was 1.31 in the radiation necrosis group (5 cases) and 1.87 in the tumor recurrence group (6 cases). Mean SUV was 1.81 in the necrosis group and 2.44 in the recurrence group. There were no statistically significant differences between the recurrence and necrosis groups in TN or SUV. Furthermore, we made a 2 x 2 factorial cross table (accumulation or no accumulation, recurrence or necrosis). From this result, the Met-PET sensitivity, specificity, and accuracy in detecting tumor recurrence were determined to be 100%, 60%, and 82% respectively. In a false positive-case, glial fibrillary acidic protein (GFAP) immunostaining showed a positive finding., Conclusion: There were no significant differences between recurrent malignant glioma and radiation necrosis following SRS in Met-PET. However, this study shows Met-PET has a sensitivity and accuracy for differentiating between recurrent glioma and necrosis, and presents important information for developing treatment strategies against post radiation reactions.

We report a case of a growth hormone secreting microadenoma associated with empty sella treated by gamma knife radiosurgery and we evaluate the effectiveness of radiosurgery for this lesion. A 58-year-old female complained of an acromegalic appearance for 10 years. Magnetic resonance imaging revealed an enlarged sella floor with a compressed, but slightly enlarged pituitary gland. Serum GH values were 8.52 ng/ml. From these results, we diagnosed the presence of a GH-secreting pituitary microadenoma with empty sella. Stereotactic gamma knife radiosurgery was performed to treat the adenoma. The treatment dose was 30 Gy for the tumour margin (50% isodose). The patient was monitored for 5 years without any reported problem. Serum GH values were gradually decreased to 4.1 and 3.5 ng/ml at 1.6 and 3 years. Serum GH values at 5 years after radiosurgery were 1.8 ng/ml within 2 h after glucose load and serum IGF-1 was normalized. We conclude that gamma knife radiosurgery can be an useful alternative treatment modality for GH-secreting adenoma with empty sella in the selected patients when surgery is contraindicated as the primary treatment.

Gamma knife radiosurgery (GKS) was used to treat seven patients with pituitary metastases between November 1994 and February 2003. The diagnoses were based on magnetic resonance imaging and clinical symptoms in six patients and by previous surgery in one patient. The cancer originated in the lung in five patients, and in the breast in two patients. The tumor volume was 0.2 to 9.6 cm3 (mean 4.0 cm3). The marginal dose was 10 to 14 Gy (mean 11.9 Gy) because of the close proximity to the optic apparatus. The maximum radiation dose to the optic apparatus was 8 to 10 Gy (mean 9.5 Gy). The survival period after GKS was 0.3 to 42 months (mean 11.5 months). Five patients died of systemic disease, and one patient died of unknown causes 10 days after GKS. Tumor growth was controlled in five of the six patients (83%) followed up after GKS. Tumor regrowth was seen 18 months after GKS in one patient. The clinical symptoms improved in five of the six patients (83%) followed up. GKS is effective and useful for the primary treatment of pituitary metastases with limited survival and less invasiveness compared to conventional radiation therapy.

Objective: The results of radiosurgical treatment of acoustic neuromas have improved by reducing the tumor marginal doses. We report relatively long-term follow-up results (>5 yr) for patients who underwent low-dose radiosurgery., Methods: We treated and followed 51 consecutive patients with unilateral acoustic neuromas who were treated from January 1994 to December 1996 by gamma knife radiosurgery at low doses (20 dB of improvement) were noted in 9% of the patients with any hearing. Hearing was preserved at a useful level (Gardner-Robertson Classes 1 and 2) in 56% of patients. Although preexisting trigeminal neuropathy worsened in 4% of the patients, our patients did not experience new facial palsies or trigeminal neuropathies after radiosurgery. Facial spasm occurred in 6% of the patients, and intratumoral bleeding occurred in 4% of patients., Conclusion: Low-dose radiosurgery (

We evaluated the treatment results in asymptomatic meningiomas in the era of radiosurgery. We encountered 56 patients with asymptomatic meningiomas from January, 1994 to December, 2001. There were 16 male patients and 40 female patients. The most common location was the cerebral convexity. We performed gamma knife radiosurgery for three patients after diagnosis of cavernous sinus meningiomas. The other patients were followed-up after diagnosis for a mean follow-up period of 30.8 months (5 months to 8 years). Tumor growth was verified in 25 patients (43%) and two patients (3.7%) suffered neurological deficits. Among the tumor growth patients, operative resection was performed in six patients (11%) and gamma knife radiosurgery was performed in four patients (7.5%). The other patients were placed under observation. We decided the treatment strategy paying attention to the tumor location, tumor growth speed, tumor size and operative difficulty. The tumor growth rate was 0.1 cm/year among the patients with tumor growth. It was 0.72 cm/year (0.02 to 1.54 cm/year) in the operative group, 0.3 cm/year (0.04 to 0.76 cm/year) in the gamma knife radiosurgery group and 0.08 cm/year (0.01 to 0.76 cm/year) in the observed group. One patient suffered procedure-related deterioration of paresis after operation. The treatment of asymptomatic meningiomas must be decided depending on their natural history and locations. We recommend early radiosurgery for cavernous sinus meningiomas.

We evaluated the surgical treatment results of parasellar meningiomas in the era of radiosurgery. We treated 24 patients of parasellar meningiomas surgically. The median age was 60 yrs (ranging from 29 to 82 yrs). The most common tumor location was the sphenoid ridge in 12 patients and the tuberculum sellae in 7 patients. The pterional approach using fronto-temporal craniotomy was performed for all patients. The residual or recurrent tumors were treated by gamma knife radiosurgery (GKS). We are able to follow up these cases for a median of 3.8 yrs (ranging from 1 to 8 yrs) after the operations. The radicality of tumor resection was Simpson grade II in 13 patients (54%), grade III in 3 patients (13%) and grade IV in 7 patients (33%). Clinical improvement was achieved in 81% of the patients. Of the patients who had visual disturbance preoperatively, 8 patients (73%) showed improvement, but 3 patients suffered deterioration postoperatively. None of the patients died. One patient suffered transient memory disturbance and one patient suffered mild facial numbness postoperatively. Boost radiosurgery for the residual tumors was performed for six patients and tumor growth control was able to be achieved in all patients, with a median of 3.1 years follow-up period (ranging from 0.5 to 6 yrs). Five patients with tumor regrowth or recurrence were treated by GKS. We recommend fronto-temporal craniotomy with nonradical resection for parasellar meningiomas and radiosurgery for residual and recurrent tumors. This strategy will achieve good functional outcome with long-term tumor growth control.

Object: In this study the authors examined how to differentiate radiation necrosis from recurrent metastatic brain tumor following stereotactic radiosurgery by using positron emission tomography (PET) with L-[methyl-11C]methionine (MET)., Methods: In 21 adult patients with suspected recurrent metastatic brain tumor or radiation injury, MET-PET scans were obtained. These patients had previously undergone stereotactic radiosurgery and subsequent contrast-enhanced magnetic resonance (MR) examinations before nuclear medicine imaging. Positron emission tomography images were obtained as a static scan of 10 minutes performed 20 minutes after injection of 370 MBq of MET. On MET-PET scans, the portion of the tumor with the highest accumulation of MET was selected as the region of interest (ROI), and the ratio of tumor tissue to normal tissue (T/N) was defined as the mean counts of radioisotope per pixel in the tumor divided by the mean counts per pixel in normal gray matter. The standardized uptake value (SUV) was calculated using the same ROI in the tumor. The accuracy of the MET-PET scan was evaluated by correlating findings with results of subsequent histological analysis (11 cases) or, in cases in which surgery or biopsy was not performed, with subsequent clinical course and MR imaging findings (10 cases). Histological examinations performed in 11 cases showed viable tumor cells with necrosis in nine and necrosis with no viable tumor cells in two. Another 10 cases were characterized as radiation necrosis because the patients exhibited stable neurological symptoms with no sign of massive enlargement of the lesion on follow-up MR images after 5 months. The mean T/N was 1.15 in the radiation necrosis group (12 cases) and 1.62 in the tumor recurrence group (nine cases). The mean SUV was 1.78 in the necrosis group and 2.5 in the recurrence group. There were statistically significant differences between the recurrence and necrosis groups in T/N and SUV. Furthermore, the borderline T/N value was 1,42 according to a 2 x 2 factorial table (high T/N or low T/N, recurrence or necrosis). From this result, the sensitivity and specificity of MET-PET scanning in detecting tumor recurrence were determined to be 77.8 and 100%, respectively., Conclusions: The use of MET-PET scanning is a sensitive and accurate technique for differentiating between metastatic brain tumor recurrence and radiation necrosis following stereotactic radiosurgery. This study reveals important information for creating strategies to treat postradiation reactions.

Unlabelled: The treatment of acoustic neuromas has been improved by advancements in microsurgical techniques and in radiosurgery. To further elucidate the degree of clinical improvement, we evaluated the treatment results of a combination of surgery and radiosurgery for large acoustic neuromas., Methods: From January 1994 through December 2000, we treated 14 patients with large acoustic neuromas using a combination of surgery and radiosurgery. Of these, 8 were male and 6 were female patients, with an average age of 47 years (range, 18-64). The average maximum diameter of the tumor was 42 mm (range, 30-58 mm). All patients underwent operations using the retrosigmoid approach, and one patient was retreated using the transpetrosal transtentorial approach. The tumors were removed subtotally in thirteen patients and partially in one who had a very large hypervascular acoustic neuroma. There were no mortality and no surgical complications, such as hemorrhage or CSF leakage. Postoperative facial palsy was avoided in 10 patients (71%). Radiosurgery was performed 1 to 6 months (mean, 2.9 months) after surgery. At the time of radiosurgery, the treatment size (mean diameter) became 19.2 mm (range, 9.8-36.1 mm). The average tumor marginal dose was 12.1Gy (range, from 10-14 Gy). The mean follow-up period was 32 months after radiosurgery., Results: The tumor size decreased in 6 patients, unchanged in 5 patients, and increased in 3 patients. Only 1 patient (7%) with extra large tumor needed surgical resection 1 year after radiosurgery. Excellent facial nerve function (House & Brackmann Grade I or II) was preserved in 12 patients (85.7%) in the final follow-up., Conclusions: In the case of large acoustic neuromas, subtotal removal and subsequent radiosurgery is one option for maintaining cranial nerve function and long-term tumor growth control.

Objective: We report on the efficacy of gamma knife radiosurgery for cavernous sinus meningiomas., Methods: Between January 1994 and December 1999, we used gamma knife radiosurgery for the treatment of 43 patients with cavernous sinus meningiomas. Forty-two patients were followed up for a mean of 49.4 months (range, 18-84 mo). The patients' average age was 55 years (range, 18-81 yr). Twenty-two patients (52%) underwent operations before radiosurgery, and 20 patients (48%) underwent radiosurgery after the diagnosis was made by magnetic resonance imaging. The tumor volumes ranged from 1.2 to 101.5 cm(3) (mean, 14.7 cm(3)). The tumors either compressed or were attached to the optic apparatus in 17 patients (40.5%). The marginal radiation dose was 8 to 15 Gy (mean, 11 Gy), and the optic apparatus was irradiated with 2 to 12 Gy (mean, 6.2 Gy). Three patients with a mean tumor diameter greater than 4 cm were treated by two-stage radiosurgery., Results: Thirty-eight patients (90.5%) demonstrated tumor growth control during the follow-up period after radiosurgery. Tumor regression was observed in 25 patients (59.5%), and growth was unchanged in 13 patients (31%). Regrowth or recurrence occurred in four patients (9.5%). The actual tumor growth control rate at 5 years was 92%. Only one patient (2.4%) experienced regrowth within the treatment field; in other patients, regrowth occurred at sites peripheral to or outside the treatment field. Twelve patients (28.6%) had improved clinically by the time of the follow-up examination. None of the patients experienced optic neuropathy caused by radiation injury or any new neurological deficits after radiosurgery., Conclusion: Gamma knife radiosurgery may be a useful option for the treatment of cavernous sinus meningiomas not only as an adjuvant to surgery but also as an alternative to surgical removal. We have shown it to be safe and effective even in tumors that adhere to or are in close proximity to the optic apparatus.

Background: In this study, we report on the effectiveness and usefulness of two-staged gamma knife radiosurgery (GKS) for large petroclival and cavernous sinus meningiomas that have a high rate of surgical morbidity., Methods: We have treated 7 patients suffering from large petroclival and cavernous sinus meningiomas using two-staged radiosurgery since March 1995. The tumors were located in the petroclival region in 4 patients, the cavernous sinus region in 2 patients, and in the petrocavernous region in the remaining patient. Three of the patients had been surgically treated and 4 patients (57%) were only followed with MR imaging. The volume of the tumors ranged between 34.5 to 101 cm(3) (mean 53.5 cm(3)). The treatment volume was between 6.8 to 29.6 cm(3) (mean 18.6 cm(3)). The treatment interval between the first GKS and second GKS was 6 months. The marginal doses for the tumors were 8 to 12 Gy (mean, 9 Gy)., Results: Six patients demonstrated tumor growth control during the follow-up period after the first radiosurgery (mean 39 months). Tumor regression was observed in 3 patients (43%). Three patients (43%) had improved clinically by the time of the follow-up examinations. No patient suffered from symptomatic radiation injury., Conclusion: Although we have treated only 7 patients using two-staged GKS, we believe this treatment may be a very useful option for large petroclival and cavernous sinus meningiomas in selected patients.

Objective: The treatment for brain metastasis has undergone remarkable changes since the development of radiosurgery. We investigated the results of treatment for brain metastasis from lung cancer since the initiation of gamma knife radiosurgery (GKRS) and we discuss the usefulness of GKRS combined with other treatments in cases with recurrence., Methods: We treated 142 patients with brain metastasis from lung cancer. Sixteen patients were treated surgically, 11 patients were treated with whole brain radiation therapy (WBRT), and 115 patients were treated with GKRS. Our treatment plan is to use GKRS in cases with less than 5 lesions and lesions less than 3 cm in mean diameter. We use WBRT in cases with 5 or more lesions, and surgery in cases with lesions 3 cm or larger. If new lesions or tumor regrowth appeared after the initial treatment, we retreated them with one of the methods mentioned above., Results: Twice or three-time treatments were performed in 30 patients. Median survival including all cases was 10 months and the number of deaths due to local treatment failure was only 5 (6.5%) out of the total 77 deaths which occurred., Conclusion: We were able to carry out less invasive treatment for brain metastasis from lung cancer by utilizing GKRS. Though we have to consider the indications for other treatments, we can say that radiosurgery is usually the treatment of first choice for brain metastasis from lung cancer. When new lesions appear in cases where a particular initial treatment was used, it is possible to maintain or improve the quality of life by retreatment, using a combination of GKRS, surgery or WBRT, to prolong the patient's life.

Skull base meningiomas can be treated by radiosurgery with low morbidity. We evaluated the effectiveness of gamma knife radiosurgery for skull base meningiomas. We also evaluated patient satisfaction through answers to a questionnaire. We treated 77 patients of skull base meningiomas using gamma knife radiosurgery from January 1994 to June 1998. Among these patients, 73 patients were able to be followed up from 6 to 60 months (average 25 months). The diagnosis was made by operations on 39 patients (53%), and on magnetic resonance imagings in 34 patients (47%). 21 patients (28.7%) had residual tumors after operations and 18 patients (24.3%) had recurrence after operations. 40% of neurological deficits occurred after previous operations and 20% of the patients were asymptomatic. The locations of the tumors were mainly the cavernous sinus region in 35 patients and the petroclival region in 20 patients. The tumor sizes were 8.6 to 58.3 mm (average 24.7 mm) and five cases of tumors with a mean diameter above 40 mm were treated by two-staged radiosurgery. Treatment volume was 0.3 to 31 ml (average 9.8 ml). The treatment dose was 8 to 16 Gy (average 11.2 Gy) at the tumor margin. The tumor decreased in size in 50 patients (68%) and was unchanged in 20 patients (28%) and we were able to achieve 96% tumor growth control. The clinical symptoms improved in 22 patients (30.1%) and were unchanged in 47 patients (64.4%) and only 4 patients (5.5%) showed deterioration. 50 patients (68%) felt clinical improvement and only 3 patients (4%) sensed deterioration. 58 patients (79%) were able to continue their previous work. Gamma knife radiosurgery has a very low morbidity rate and enables good tumor control, and patients with skull base meningiomas express satisfaction with the treatment results.

Background: The surgical removal of skull base meningiomas has a high morbidity rate, even by modern microsurgical standards. We evaluated the results of gamma knife surgery for skull base meningiomas using a relatively low radiation dose for the tumor margins., Methods: We reviewed 24 cases of skull base meningiomas during a 30-month period. The locations of the tumors were the petroclival region in 11 cases, the cavernous sinus region in 9 cases, and the cerebellopontine angle region in 4 cases. Eight patients (33%) had been operated on previously and fourteen patients (67%) had been treated by neuroimaging. The marginal doses for the tumors were 8 Gy to 15 Gy (median, 10.6 Gy). A large petroclival tumor 58 mm in diameter was treated with a staged treatment protocol with a 6-month interval between treatments., Results: Tumor regression was observed in 46% of the patients imaged during the follow-up period (median, 17.1 months). No patients revealed tumor growth in the follow-up period (100% tumor control rate). Eleven patients (46%) had improved clinically by the time of the follow-up examinations. Preexisting cranial nerve deficit in one patient worsened because of radiation injury., Conclusion: Although a longer follow-up period is required, the relatively low minimum tumor radiation dose treatment for skull base meningiomas using a gamma knife seems to be an effective treatment with low morbidity.

To determine the factors related to optimal treatment of brain metastasis from lung cancer by gamma knife radiosurgery, we investigated those influencing survival and local tumor control. We observed 156 patients with 315 such lesions treated by gamma knife radiosurgery (GKS). The factor that most affected survival was whether extracranial disease was controlled at the time of treatment. Patients with a high Karnofsky Performance Score (KPS) tended to survive longer. The local tumor control rate was higher with tumors less than 20 mm in diameter than larger lesions. Tumors treated with a high marginal dose (23 Gy < or =) were better controlled than those treated with a lower marginal dose. Control of extranial lesions, high KPS, small (< 20 mm) lesions, and high marginal dose (23 Gy < or =) were important factors in obtaining good results with GKS for brain metastasis from lung cancer.

A 40-year-old female presented with cavernous sinus cavernous hemangioma manifesting as left abducens and trigeminal nerve pareses. Magnetic resonance imaging revealed a left cavernous sinus tumor. The tumor was partially removed. Histological examination of the specimen confirmed cavernous hemangioma. Radiosurgery was performed using the gamma knife. The tumor markedly decreased in size after radiosurgery and morbidity was avoided. Cavernous sinus cavernous hemangiomas may be difficult to treat surgically due to intraoperative bleeding and cranial nerve injury. Stereotactic radiosurgery can be used either as an adjunct treatment to craniotomy, or as the primary treatment for small cavernous sinus cavernous hemangioma.

Forty-one patients with a total of 193 metastatic brain tumors were treated because of new lesions or in a few cases because of tumor regrowth. The management involved two to four treatments with Gamma Knife radiosurgery (GKRS). The overall median survival was 15 months. The local control rate of tumors was 89% for the first treatment and 93% for repeated treatments. Symptomatic radiation-induced edema appeared in only two cases (4.9%). Patients with metastatic brain tumors who developed new lesions after GKRS were treated with GKRS alone for subsequent lesions. It was possible to control tumors for a long period with minimal side effects. As a result, we were able to maintain the quality of life of these patients, but, the effect of GKRS in controlling tumor regrowth seemed temporary.

We treated 18 patients with skull base metastasis or invasion using Gamma Knife radiosurgery. Seven of these patients had invasive nasopharyngeal cancer and 11 had distant metastasis from other cancers. The mean diameter of tumors was 22-46 mm (median 32.1 mm) and the radiation dose to the tumor margin was 12-23 Gy (median 16.2 Gy). The median follow-up period was 10.5 months. Clinical symptoms were improved in 61% of the patients after treatment and tumor control was obtained in 67% of cases at their final followup. Radiation injury occurred in only one patient (6%) who had received previous radiotherapy to the same region. Gamma Knife radiosurgery is a useful therapeutic option for the treatment of skull base metastasis and invasion, either as a secondary treatment for recurrence after previous radiotherapy or as a primary treatment.