Gamma Knife Surgery Group Research Articles

Surgical management of large cerebellopontine angle meningiomas: long-term results of a less aggressive resection strategy.

Cerebellopontine angle (CPA) meningiomas present many surgical challenges depending on their volume, site of dural attachment, and connection to surrounding neurovascular structures. Assuming that systematic radical resection of large CPA meningiomas carries a high risk of permanent morbidity, the authors adopted an alternative strategy of optimal resection followed by radiosurgery or careful observation of the residual tumor and assessed the efficiency and safety of this approach to meningioma treatment management. This single-center retrospective cohort study included 50 consecutive patients who underwent surgery for meningioma between January 2003 and February 2020. The most common main dural attachments of the meningiomas were posterior (42%) and superior (26%) to the internal auditory meatus. The suboccipital retrosigmoid route was the most routinely used (92%). At the last follow-up examination, 93% of the patients with normal preoperative facial nerve (FN) function retained good House-Brackmann (HB) grades of I and II, whereas 3 patients (7%) displayed intermediate HB grade III FN function. Hearing preservation was achieved in 86% of the patients who presented with preoperative serviceable hearing, and recovery after surgery was achieved in 19% of the patients experiencing preoperative hearing loss. In order to preserve all cranial nerve function, gross-total resection was obtained in 26% of patients. Of the 35 patients who had undergone subtotal resection, 20 (57%) had been allocated into a wait-and-rescan treatment approach and 15 (43%) underwent upfront Gamma Knife surgery (GKS). The mean postoperative tumor volume was 1.20 cm3 in the upfront GKS group and 0.73 cm3 in the wait-and-rescan group (p = 0.08). Tumor control was achieved in 87% and 55% of cases (p < 0.001), with a mean follow-up of 85 and 69 months in the GKS and wait-and-rescan groups, respectively. The 1-, 5-, and 7-year tumor progression-free survival rates were 100%, 100%, and 89% in the GKS group and 95%, 59%, and 47% in the wait-and-rescan group, respectively (p < 0.001). Optimal nonradical resection of large CPA meningiomas provides favorable long-term tumor control and functional preservation. Adjuvant GKS does not carry additional morbidity and appears to be an efficient adjuvant treatment.

Radiosurgery-Based AVM Scale Is Proposed for Combined Embolization and Gamma Knife Surgery for Brain Arteriovenous Malformations.

Background and purpose: To evaluate whether a radiosurgery-based arteriovenous malformation (AVM) scale (RBAS) could be used to predict obliteration of brain arteriovenous malformations (bAVMs) supposed for combined endovascular embolization (EMB) and gamma knife surgery (GKS) treatment.Methods: bAVM patients who underwent GKS with or without previous EMB from January 2011 to December 2016 at our institution were retrospectively reviewed. The patients were categorized into a combined treatment group and a GKS group. A 1:1 propensity score matching (PSM) was used to match the two groups. Pre-EMB and pre-GKS RBAS were assessed for every patient. Multivariate analysis was performed to find factors associated with complete obliteration in the combined treatment group. Survival analysis based on sub-groups according to RBAS was performed to compare obliteration rate and find cutoffs for appropriate treatment modalities.Results: A total of 96 patients were involved, and each group comprised 48 patients. There was no difference between the two groups in terms of obliteration rate (75.0 vs. 83.3%, p = 0.174). Pre-EMB RBAS (p = 0.010) and the number of feeding arteries (p = 0.014) were independent factors associated with obliteration rate in the combined treatment group. For the combined treatment patients, sub-group analysis according to pre-EMB RBAS (score <1.0, 1.0–1.5, and >1.5) showed statistical difference in obliteration rate (p = 0.002). Sub-group analysis according to RBAS between the two groups showed that the obliteration rate of the GKS group is significantly higher than the combined group when RBAS >1.5 (47.4 vs. 66.7%, p = 0.036).Conclusions: The RBAS is proposed to be efficient in predicting obliteration of bAVMs supposed to receive combined EMB and GKS treatment. Patients with RBAS >1.5 are inclined to be more suitable for GKS instead of the combined treatment.

Outcome and prognostic factors for atypical meningiomas after first recurrence

Atypical meningioma (AM) tends to be tumor with high rates of recurrence and mortality. In this retrospective study, 131 recurrent AM patients underwent AM surgery in Beijing Tiantan Hospital between January 2008 and December 2015. Of the 131 cases collected, 61 were male (46.6%), and 70 (53.4%) were female. 53 (40.5%) patients chose observation instead of therapy, 53 (40.5%) received repeat surgery and 25 patients (19.0%) received gamma knife surgery (GKS). The median overall survival (OS) was 34.6 months and actuarial OS of patients at 1, 3 and 5 years were 88.6%, 48.8%, 36.0%, respectively. In the treatment group including 78 patients with surgery and GKS group, a tumor progression happened to 35 patients (44.9%). The median duration of progression-free survival (PFS) was 34.5 months and the median OS was 61.7 months. Second PFS at 1, 3 and 5 years were 84.1%, 46.5% and 24.0%, respectively; the corresponding OS was 98.5%, 75.1%, 57.9%, respectively. Multivariate analysis revealed treatment strategy was the only independent factor (P < 0.001). In the treatment group, non-peritumoral edema (P = 0.002), preoperative KPS (per 10 scores increase) (P < 0.001) and GKS (P = 0.042) was related to better OS. Short interval (<24 months) from symptoms onset to intervention was related to better PFS (P = 0.004) in univariate analysis. This retrospective study presents the largest cohort of recurrent AM patients, surgical treatment is recommended in patients with tumor recurrence, and GKS is considered a promising therapeutic option of recurrence atypical meningioma.

Adjuvant gamma knife surgery and image-guided, intensity-modulated radiation therapy for the treatment of sacral chordomas.

The aim of this study was to confirm whether patients with sacral chordoma benefit from adjuvant radiotherapy and to determine the optimal photon radiotherapy module for comprehensive treatment. Chordoma is a rare slow-growing neoplasm arisen from cellular remnants of the notochord. About 50% occur in the sacrococcygeal region. Surgical resection and adjuvant radiation therapy are recommended treatment due to the improving local control rate. 118 patients treated by surgery and adjuvant radiotherapy from August 2003 to May 2015 were retrospectively analyzed. All patients received surgical resection after diagnosis. Among these patients, 44 were treated by exclusive surgery, and 48 were treated with adjuvant image-guided, intensity-modulated radiation therapy (IG-IMRT). In addition, 26 patients were treated with gamma knife surgery (GKS) after surgical resection. The median follow-up was 54 months for all patients. Kaplan-Meier analysis was used to calculate recurrence-free survival (RFS) overall survival (OS). Patients treated with adjuvant radiotherapy had better RFS (p=0.014) than those treated exclusively by surgery. The patients in the IG-IMRT group exhibited better recurrence-free survival (p=0.01) than the GKS group. Moreover, in the IG-IMRT group, patients treated by higher dose were associated with better RFS (p=0.04). No significant difference in OS was found. No grade 3 late toxicity was found. We confirmed that adjuvant radiotherapy improved RFS but not OS in sacral chordoma patients after surgery. Furthermore, favorable RFS and low adverse event rates were observed following IG-IMRT. Our results suggest that high dose IG-IMRT is an appropriate module of adjuvant radiotherapy for sacral chordoma patients.

Adjunctive Gamma Knife Surgery or Wait and Scan Policy After Optimal Resection of Large Vestibular Schwannomas: Clinical and Radiologic Outcomes

Patients with large vestibular schwannomas (VSs) will require surgical treatment owing to the potential consequences of long tract and cranial nerve compression. We assessed the long-term clinical and radiologic outcomes of patients harboring large VSs treated with a facial nerve (FN)-sparing technique. We performed a single-center retrospective cohort study of 169 consecutive large VSs treated surgically from January 2003 to May 2015. The postoperative volume of the tumor residue was assessed using thin-slice magnetic resonance imaging 6 months after surgery. Postoperatively, the patients were allocated to a wait and rescan (W&reS) or an upfront gamma knife surgery (GKS) policy. At the last follow-up examination, FN function was good (House-Brackmann grade I or II) in 84% of the patients. Of the 169 patients, 11% had undergone gross total resection, 59% near total, 21% subtotal, and 9% partial resection. In the 143 patients without gross total resection, the overall median tumor residue volume was 0.39 cm3. Of these 143 patients, 66 had been allocated to the W&reS policy and 77 to upfront GKS. Overall tumor control was achieved in 83% of cases, with a mean follow-up of 62 months. Of the 27 growing residues, 17 required salvage treatment (11% failure rate). The 1-, 5-, and 7-year progression-free survival rate was 95%, 82%, and 76% in the W&reS group and 99%, 81%, and 78% in the GKS group, respectively (P= 0.57). Functional nerve-sparing resection provides satisfactory FN preservation. The low probability of long-term regrowth of small remnants is an argument for a W&reS protocol. GKS is a legitimate option for salvage treatment.

Clinical and radiological outcomes of proactive Gamma Knife surgery for asymptomatic meningiomas compared with the natural course without intervention.

This study aimed to verify the effect of proactive Gamma Knife surgery (GKS) in the treatment of asymptomatic meningioma compared with the natural course without any therapeutic intervention. From January 2006 to May 2017, 354 patients newly diagnosed with asymptomatic meningioma were reviewed and categorized into GKS (n = 153) and observation (n = 201) groups. Clinical and radiological progression rates were examined, and changes in volume were analyzed. Clinical progression (i.e., clinician-judged progression), combining symptomatic progression (n = 43) and clinician-judged increase in size using images routinely acquired (n = 34), occurred in 4 patients (2.6%) and 73 patients (36.3%) in the GKS and observation groups, respectively (p < 0.001). The clinical progression-free survival (PFS) rates in the GKS and observation groups were 98.7% and 64.6%, respectively, at 5 years (p < 0.001), and 92.9% and 42.7%, respectively, at 10 years (p < 0.001). The radiological tumor control rate was 94.1% in the GKS group, and radiological progression was noted in 141 patients (70.1%) in the observation group. The radiological PFS rates in the GKS and observation groups were 94.4% and 38.5%, respectively, at 5 years (p < 0.001), and 88.5% and 7.9%, respectively, at 10 years (p < 0.001). Young age, absence of calcification, peritumoral edema, and high T2 signal intensity were correlated with clinical progression in the observation group. Volumetric analysis showed that untreated tumors gradually increased in size. However, GKS-treated tumors shrank gradually, although transient volume expansion was observed in the first 6 months. Adverse events developed in 26 of the 195 GKS-treated patients (13.3%), including 1 (0.5%) major event requiring microsurgery due to severe edema after GKS. Peritumoral edema was related to the development of adverse events (p = 0.004). Asymptomatic meningioma is a benign disease; however, nearly two-thirds of patients experience tumor growth and one-third of untreated patients eventually require neurosurgical interventions during watchful waiting. GKS can control tumors clinically and radiologically with high probability. Although the risk of transient adverse events exists, proactive GKS may be a reasonable treatment option when there are no comorbidities limiting life expectancy.

Efficacy and Safety of Microvascular Decompression and Gamma Knife Surgery Treatments for Patients with Primary Trigeminal Neuralgia: A Prospective Study

To compare efficacy and safety of microvascular decompression (MVD) and Gamma Knife surgery (GKS) treatments for trigeminal neuralgia. Patients with primary trigeminal neuralgia were randomly divided into 2 groups to undergo either MVD or GKS. All patients were followed for 2 years to evaluate efficacy, recurrence rates, and complications of treatment. Of 441 enrolled patients, 220 were in the MVD group, and 221 were in the GKS group. There were no deaths in either group. At the 2-year follow-up, 183 patients (83%) in the MVD group reported complete pain relief, 5 (2%) had obvious pain relief, and 20 (9%) had no relief. In the GKS group, 55 patients (25%) reported complete pain relief, 106 (48%) had obvious pain relief, and 37 (17%) had no relief. There was no significant difference in the recurrence rate (0.45% vs. 0.9%) between the 2 groups. The most common complications in the MVD group were chemical meningitis (6%), cerebrospinal fluid leakage (4%), and facial palsy (4%). Loss of corneal reflex (6%) and facial numbness (5%) were the most common complications in the GKS group. Both MVD and GKS are effective surgical treatments for trigeminal neuralgia. The rate of complete pain relief in the MVD group was significantly superior to the rate of complete pain relief in the GKS group. There was no significant difference in recurrence rates between the groups; however, there were more severe complications in the MVD group than in the GKS group.

World Health Organization Grade II Meningiomas: The Role of Adjuvant/Salvage Gamma Knife Surgery After Initial Surgery and Prognostic Factor Assessment.

This study was performed to evaluate the efficiency of Gamma Knife surgery (GKS) on reducing recurrence of World Health Organization (WHO) grade II meningiomas after surgery and to define the risk factors associated with tumor recurrence/progression and patient's death. This retrospective study included 75 patients who were diagnosed with WHO grade II meningiomas after initial surgery. The Kaplan-Meier method with a log-rank test was used to calculate the survival curves. Univariate and multivariate Cox proportional hazards model were used to identify the risk factors associated with tumor recurrence/progression and patient's death. The median follow-up period was 70 months. The overall survival (OS) was 97.2% at 2 years and 89.8% at 5 years. The progression-free survival (PFS) at 1, 3, and 5 years was 89.3%, 72.6%, and 59.3%, respectively. Comparing the effects on PFS and OS between different groups, there were no statistically significant differences between the surgery-alone group and the surgery with adjuvant/salvage GKS group (P= 0.512; P= 0.949). In multivariate Cox proportional hazards model analysis, extent of resection (P= 0.001) and tumor location (P= 0.015) were associated with tumor recurrence; only histologic subtypes (P= 0.005) were associated with patient's death. There was no significant PFS or OS benefit for patients with WHO grade II meningiomas treated with adjuvant/salvage GKS postoperatively. Convexity meningiomas with gross total resection tended to benefit PFS. We suggest trying to achieve maximum safe gross total resection for patients with WHO grade II meningiomas, then following up closely.

Multicentric randomized phase II trial of gamma knife surgery (GKS) versus image-guided, intensity-modulated radiation therapy (IG-IMRT) in patients with sacrococcygeal chordoma.

11033 Background: Chordoma is a rare slow-growing neoplasm arisen from cellular remnants of the notochord. About 30% occur in the sacrococcygeal region. Surgical resection is recommended treatment. Due to the high recurrence rate, adjuvant radiation therapy was suggested to receive as an effective method to improve local control rates. Methods: Thirty eight patients were pathologically diagnosed as non-metastatic sacrococcygeal chordoma from Aug. 2003 to May. 2015 were recruited retrospectively to analysis. All patients received surgical resection after diagnosed. Initial surgery included subtotal resection (24% of patients), and gross total resection (76% of patients). Among these patients, 25 patients treated with adjuvant IG-IMRT, while 13 patients treated GKS after surgical resection. The median follow-up was 40 months (range, 6–151 month) for all patients, The PTV of IG-IMRT group received total doses were 60 Gy (range, 56-74Gy), delivered with 2-2.2 Gy/fraction, while GKS group underwent a total of 6-8 sessions treatment. Results: For the IG-IMRT group and the GKS group, the 5-year overall survival and local control rates were 87.5% and 67.7%, respectively. And 5-year local control rates were 35% and 22.2%, respectively. In total, 18 patients progressed locally: 11 were in the IG-IMRT group and 7 in the GKS group. In comparison with GKS group, the IG-IMRT group has a better overall recurrence-free survival (p = 0.03), the significance remained after adjusted for surgery results, age and gender. Moreover, there is no significant difference of overall survival was found between these two groups. Conclusions: We report favorable local control and adverse event rates following IG-IMRT, and suggested IG-IMRT is the first choice of adjuvant radiation therapy for sacrococcygeal chordoma treatment.

Patient- versus physician-reported facial disability in vestibular schwannoma: an international cross-sectional study.

OBJECTIVE Patient-reported outcomes are increasingly used in studies of vestibular schwannoma (VS); however, few studies have examined self-evaluated facial nerve function and its relation to physician-reported outcomes. The primary objective of this study was to compare patient self-evaluations of facial disability with physician-evaluated facial nerve status and with self-evaluations of a healthy control group. The second objective was to provide insight into the controversial subject of the optimal initial management of small- and medium-sized VSs; consequently, the authors compared patient-reported facial nerve disability following treatment via observation (OBS), Gamma Knife surgery (GKS), or microsurgery (MS). Lastly, the authors sought to identify risk factors for facial nerve dysfunction following treatment for small- and medium-sized VSs. METHODS All patients with a VS 3 cm or smaller that was singly treated with OBS, GKS, or MS at either of 2 independent treatment centers between 1998 and 2008 were retrospectively identified. Longitudinal facial nerve measures and clinical data, including facial nerve evaluation according to the House-Brackmann (HB) grading system, were extracted from existing VS databases. Supplementing the objective data were Facial Disability Index (FDI) scores, which were obtained via survey of patients a mean of 7.7 years after initial treatment. RESULTS The response rate among the 682 eligible patients was 79%; thus, data from a total of 539 patients were analyzed. One hundred forty-eight patients had been managed by OBS, 247 with GKS, and 144 with MS. Patients who underwent microsurgery had larger tumors and were younger than those who underwent OBS or GKS. Overall, facial nerve outcomes were satisfactory following treatment, with more than 90% of patients having HB Grade I function at the last clinical follow-up. Treatment was the major risk factor for facial nerve dysfunction. Almost one-fifth of the patients treated with MS had an objective decline in facial nerve function, whereas only 2% in the GKS group and 0% in the OBS cohort had a decline. The physical subscale of the FDI in the VS patients was highly associated with HB grade; however, the social/well-being subscale of the FDI was not. Thus, any social disability caused by facial palsy was not detectable by use of this questionnaire. CONCLUSIONS The majority of patients with small- and medium-sized VSs attain excellent long-term facial nerve function and low facial nerve disability regardless of treatment modality. Tumor size and microsurgical treatment are risk factors for facial nerve dysfunction and self-reported disability. The FDI questionnaire is sensitive to the physical but not the social impairment associated with facial dysfunction.

Clinical outcome with gamma-knife surgery or surgery for brain metastases from colorectal cancer

The aim of this study was to investigate the clinical outcomes after gamma knife surgery (GKS) or surgery as the first treatment for brain metastases in colorectal cancer (CRC). Of the 4350 patients diagnosed with CRC at our institution identified from 1987 to 2009, 27 patients who underwent GKS (GKS group) and 11 who underwent surgery (surgery group) were included. The oncologic outcomes were compared between the two groups. Local control was significantly better in the surgery group than in the GKS group (90% versus [vs.] 71.4%, respectively; p=0.006). The rate of symptom relief after 3months was significantly higher in the surgery group than in the GKS group (72.7 vs.18.5%, respectively; p=0.005). The median survival after GKS was 5.6months and surgery was 16.2months. In multivariate analysis, controlled primary tumor (p=0.038) and solitary metastasis (p=0.028) were correlated with prolonged overall survival, whereas surgery (p=0.034) was associated with longer local control. Surgery for brain metastasis from CRC is more advantageous in local control and neurologic symptom palliation than GSK. In multivariate analysis, overall survival was associated with controlled primary tumor and solitary metastasis.

Comparative study of Gamma Knife surgery and percutaneous retrogasserian glycerol rhizotomy for trigeminal neuralgia in patients with multiple sclerosis

Among patients with multiple sclerosis (MS) there is a high incidence of trigeminal neuralgia (TN), and outcomes after treatment seem inferior to those in patients suffering from idiopathic TN. The goal of this study was to evaluate clinical outcomes in patients with MS-related TN after Gamma Knife surgery (GKS) and compare them with those obtained using percutaneous retrogasserian glycerol rhizotomy (PRGR). The authors retrospectively reviewed the charts of 45 patients with MS-related TN. The first procedure undertaken was GKS in 27 patients and PRGR in 18 patients. Pain had been present for a median of 60 months (range 12-276 months) in patients who underwent GKS and 48 months (range 12-240 months) in patients who underwent PRGR. The following outcome measures were assessed in both groups of patients: pain relief (using the Barrow Neurological Institute [BNI] Pain Scale), procedure-related morbidity, time to pain relief and recurrence, and subsequent procedures that were performed. The median duration of follow-up was 39 months (range 13-69 months) in the GKS group and 38 months (range 2-75 months) in the PRGR group. Reasonable pain control (BNI Pain Scale Scores I-IIIb) was noted in 22 patients (81.5%) who underwent GKS and in 18 patients (100%) who underwent PRGR. For patients who underwent GKS, the median time to pain relief was 6 months; for those who underwent PRGR, pain relief was immediate. In the GKS group 12 patients required subsequent procedures (3 patients for absence of response and 9 patients for pain recurrence), whereas in the PRGR group 6 patients required subsequent procedures (all for pain recurrence). As of the last follow-up, complete or reasonable pain control was finally achieved in 23 patients (85.2%) in the GKS group and in 16 patients (88.9%) in the PRGR group. The morbidity rate was 22.2% in the GKS group (all due to sensory loss and paresthesia) and 66.7% in the PRGR group (mostly hypalgesia, with 2 patients having corneal reflex loss and 1 patient suffering from meningitis). Both GKS and PRGR are satisfactory strategies for treating MS-related TN. Gamma Knife surgery has a lower rate of sensory and overall morbidity than PRGR, but requires a delay before pain relief occurs. The authors propose that patients with extreme pain in need of fast relief should undergo PRGR. For other patients, both management strategies can lead to satisfactory pain relief, and the choice should be made based on patient preference and expectations.

Intracapsular decompression or radical resection followed by Gamma Knife surgery for patients harboring a large vestibular schwannoma

Microsurgery is the primary treatment used for patients harboring a large vestibular schwannoma (VS). However, its outcome may lead to hearing impairment and facial nerve dysfunction particularly when resection is extended outside the tumor capsule. When surgery for a large VS consists of intracapsular resection and decompression, better preservation of facial and hearing function are obtained. In this study, the authors compared outcomes of intracapsular decompression followed by Gamma Knife surgery (GKS) with outcomes of standard microsurgery followed by radiosurgery. Between August 2003 and October 2008, 35 patients harboring large VSs (> 3 cm in diameter) were enrolled in this study. Eighteen patients underwent intracapsular decompression followed by GKS (Group I), and 17 patients underwent radical extracapsular resection followed by GKS (Group II). In all cases GKS was performed with a margin dose of 12 Gy. All patients were followed up for at least 3 years. All patients also underwent periodic audiography, electroneuronography (ENoG), MR imaging, and testing with the SF-36 form. The Student t-test and repeated ANOVA were used for statistical analysis. The mean ages of the patients (± SEM) in Groups I and II were 50 ± 3.0 and 49 ± 2.3 years, respectively. The female/male ratios were 8:10 in Group I and 7:10 in Group II. All patients had excellent facial function as measured according to the House-Brackmann Facial Grading System (Grade I or II) preoperatively. After the operation, 16 patients (89%) in Group I retained excellent facial function, whereas only 6 patients (35%) in Group II had excellent facial function (p < 0.01). In Group I, 11 patients had serviceable hearing, and all 11 (100%) retained hearing function after the operation. In Group II, 11 patients had serviceable hearing, but none retained hearing function postoperatively (p < 0.001). In Group I, the mean tumor volume (± SEM) was 17.5 ± 1.1 cm(3), and the postoperative volume was 9.35 ± 1.02 cm(3). In Group II, the mean tumor volume was 16.4 ± 0.95 cm(3), whereas the postoperative volume was 1.1 ± 0.14 cm(3) (p < 0.001). After GKS, the tumor volume was reduced to 5.12 ± 1.1 cm(3) and 0.9 ± 0.1 cm(3) in Groups I and II, respectively. No patients experienced adverse effects after GKS. The mean return-to-work times were 2.4 ± 0.16 and 33.4 ± 4.3 weeks in Groups I and II, respectively (p < 0.001). According to the results obtained using the 36-Item Short Form Health Survey (SF-36), patients in Group I enjoyed more significant improvements in quality of life than patients in Group II (p < 0.001). Intracapsular decompression followed by GKS afforded a better neurological outcome and quality of life than radical extracapsular resection followed by GKS. Further application of this approach in patients harboring large VSs seems warranted.

Gamma Knife surgery for recurrent or residual trigeminal neuralgia after a failed initial procedure

The purpose of this study was to assess outcomes of Gamma Knife surgery (GKS) as a second treatment for recurrent or residual trigeminal neuralgia (TN) after failure of 3 initial procedures: microvascular decompression (MVD), GKS, and percutaneous radiofrequency rhizotomy (PRR). Between 1999 and 2008, 65 patients (31 men [48%] and 34 women [52%]) with recurrent TN were treated with GKS. All 65 patients had undergone previous medical procedures that failed to achieve sufficient pain relief: 27 patients (42%) had undergone MVD, 8 (12%) had undergone PRR, and 30 (46%) had undergone GKS as the initial treatment. The entry zone of the trigeminal nerve was targeted using a 4-mm collimator and treated with 35-90 Gy. The isocenter was positioned so that the brainstem surface was usually irradiated at an isodose no greater than 20% (59 patients) to 30% (6 patients). The median duration of TN symptoms in these patients was 39 months (range 1-192 months). At the clinical evaluation, 42 patients (65%) with idiopathic TN reported successful pain control at a median follow-up point of 64 months (range 18-132 months). Of these patients, 33 (51%) were no longer using medication. At the 1-, 2-, and 3-year follow-up examinations, 74%, 71%, and 66% of patients experienced successful pain control, respectively. There was no significant difference in pain relief in the initial MVD group compared with the initial GKS and initial PRR groups (74% vs 59% and 50%, respectively; p = 0.342). Recurrence of pain was noted in 23 patients. Twelve of these 23 patients underwent another GKS, resulting in pain control in 8 patients (67%); 8 other patients underwent MVD, resulting in pain relief in 7 patients (87.5%). The median time from GKS to pain recurrence was 7 months (range 3-48 months). There was no significant difference in new facial numbness among the 3 groups (p = 0.24); however, in the initial GKS group, facial numbness was significantly associated with freedom from pain (p = 0.0012). There was a significant correlation between the total radiation dose and facial numbness. The cutoff value for facial numbness ranged from 115 to 120 Gy (p = 0.037). Gamma Knife surgery as a second treatment achieved acceptable levels of pain control in 65% of patients with residual or recurrent TN after long-term follow-up. Initial treatment was not a factor that affected pain control, but salvage surgery may be considered separately for each group.

Optimal timing for Gamma Knife surgery after hemorrhage from brain arteriovenous malformations

Optimal timing of Gamma Knife surgery (GKS) after hemorrhage from brain arteriovenous malformations (AVMs) is unclear and of concern to neurosurgeons because GKS is usually performed after absorption of the hematoma. The authors investigated whether waiting for hematoma absorption is beneficial and aimed to clarify the optimal treatment timing. The authors retrospectively studied 211 patients with AVMs who presented with hemorrhage and underwent GKS as the initial treatment. Patients were categorized into 3 groups according to the interval between the time of first hemorrhage and GKS, as follows: Group 1, 0-3 months (70 patients); Group 2, 3-6 months (62 patients); and Group 3, > 6 months (79 patients). The obliteration rates, number of hemorrhages before and after GKS, and complication rates were compared between these 3 groups. The authors also analyzed a subgroup of 127 patients who presented with intracerebral hemorrhage (ICH) to identify the influence of ICH on outcome. After a median follow-up of 6.3 years, the rates of obliteration, hemorrhage after treatment, and complication were not significantly different between the 3 groups even though the patients with a longer interval before GKS (Group 3) had more AVMs in eloquent areas and neurological deficits. However, the numbers of patients with preoperative hemorrhage in the interval before GKS was significantly higher in Group 3 (1, 3, and 20 patients in Group 1, 2, and 3, respectively). These results were similar in the analyses of 127 patients presenting with ICH. No benefit was detected in waiting for hematoma absorption until GKS after hemorrhage from AVM. Because of higher hemorrhagic risk until GKS > 6 months after hemorrhage, the authors recommend GKS within 6 months after hemorrhage.

Treatment of arteriovenous malformations with linear accelerator–based radiosurgery compared with Gamma Knife surgery

The authors sought to compare the outcomes of patients with arteriovenous malformations (AVMs) treated by Gamma Knife surgery (GKS) with those of patients treated by linear accelerator-based (LINAC) radiosurgery. One hundred and eighty-seven patients with AVMs were treated at our institution between 1992 and 2003. Ninety-one patients were treated with GKS and 96 patients were treated with LINAC radiosurgery. Patient and treatment characteristics in the two groups included the following. In the LINAC group, the median age was 33 years (range 9-66 years); the median dose was 16 Gy (70% isodose line); the median treated AVM volume was 5.5 cm3; and 46% of patients in this group were treated after hemorrhage. In the GKS group, the median age was 38 years (range 6-63 years); the median dose was 20 Gy (50% isodose line); the median treated AVM volume was 4.3 cm3; and 44% of patients in this group were treated after hemorrhage. Obliteration of AVMs was determined by performing computed tomography (CT) angiography and/or magnetic resonance (MR) angiography and angiography. Patient follow-up evaluation included obtaining an MR angiogram/MR image or CT angiogram at 6 months, at 1 year, and then annually thereafter. Angiography was performed to confirm obliteration when MR angiography and/or CT angiography no longer revealed evidence of an AVM. The 5-year estimated AVM obliteration rate was 66% in the entire patient group; the LINAC group was 60%; the GKS group was 72%; this difference was not statistically significant (p = 0.97). Twelve patients who underwent treatment with LINAC radiosurgery underwent retreatment with GKS and one was retreated with LINAC radiosurgery. The obliteration rate was 82%. Six patients treated with GKS were retreated with GKS, but the follow-up time is of short duration. Chronic toxicity occurred in 8% of both the GKS and the LINAC groups (p = 0.61). Posttreatment hemorrhage during the time of risk before AVM obliteration was 13% in the GKS group and 6.2% in the LINAC group (p = 0.05). Treatment of patients with AVMs by using LINAC radiosurgery and GKS treatment produces high obliteration rates with acceptable long-term radiation toxicity in the patients treated.

Preservation of quality of life by preradiotherapy stereotactic radiosurgery for unresectable glioblastoma multiforme

The authors conducted a retrospective study to evaluate the efficacy of Gamma Knife surgery (GKS) followed by radiotherapy for the treatment of unresectable glioblastomas multiforme (GBMs) on patient survival and quality of life. A total of 19 patients with unresectable GBMs located in eloquent areas of the brain were eligible for this study. Beginning in January 2002, 10 patients underwent GKS followed by fractionated radiotherapy. Nine patients who had undergone radiotherapy alone after biopsy-proven diagnosis served as the control group. The mean patient ages were 53 years and 56 years, respectively. Preoperative Karnofsky Performance Scale (KPS) scores were 80 (range 60-100) and 90 (range 50-100), respectively. The median margin dose for GKS was 12 Gy (9-16 Gy), and the total dose for radiotherapy was 60 Gy in 30 fractions. The mean follow-up duration was 7.2 months, the median patient survival time was 52 weeks (95% confidence interval [CI] 22-110.6 weeks) in the GKS group, and the median overall survival time was 28 weeks (95% CI 22.5-33.5 weeks) in the control group. The difference was not statistically significant (p = 0.0758). The estimated progression-free survival rate at 3 months was 75% in the GKS group and 45% in the control group (p = 0.082). The posttreatment KPS scores were either unchanged or improved in the GKS group, whereas it deteriorated by 20 or more points in six of nine patients of the control group (p = 0.004). Gamma Knife surgery prior to radiotherapy may be helpful in preserving patients' daily activities in the adjuvant management of unresectable GBM.