Gamma Knife Surgery In Patients Research Articles

A 3-month survival model after Gamma Knife surgery in patients with brain metastasis from lung cancer with Karnofsky performance status ≤ 70

Gamma Knife surgery (GKS) for brain metastasis (BM) has been generally advocated for patients with a Karnofsky performance status (KPS) scale of ≥ 70. However, some patients with a poor KPS scale of < 70 are recoverable after GKS and show durable survival. A purpose of this study is to devise a 3-month survival prediction model to screen patients with BM with a KPS of ≤ 70 in whom GKS is needed. A retrospective analysis of 67 patients with a KPS scale of 60–70 undergoing GKS for BM of non-small cell lung cancer (NSCLC) from 2016 to 2020 in our institute was performed. Univariate and multivariate logistic regression analyses were performed to investigate factors related to survival for more than 3 months after GKS. The probability (P) prediction model was designed by giving a weight corresponding to the odds ratio of the variables. The overall survival was 9.9 ± 12.7 months (range 0.2–53.2), with a 3-month survival rate of 59.7% (n = 40). In multivariate logistic regression analysis, extracranial disease (ECD) control (p = .033), focal neurological deficit (FND) (p = .014), and cumulative tumor volume (∑ TV) (p = .005) were associated with 3-month survival. The prediction model of 3-month survival (Harrell’s C index = 0.767) was devised based on associated factors. In conclusion, GKS for BMs is recommended in selected patients, even if the KPS scale is ≤ 70.

RADI-21. Feasibility of Gamma Knife Surgery for patients with 20 or more brain metastases

BackgroundThe current standard-of-care treatment for brain metastases (BM)≥20 is Whole Brain Radiotherapy (WBRT), which can cause neurocognitive decline detrimental to patients’ quality of life, especially if their functional status is good on presentation. The benefits of Gamma Knife Surgery (GKS) have been shown for BM≤10, but there is no consensus on the upper limit where GKS is no longer beneficial. We hypothesize that selected patients with ≥20 BM may benefit by replacing WBRT with GKS to preserve neurocognition without compromising intracerebral tumor control and overall survival, with additional treatments as needed.MethodologyThis is retrospective analysis of 31 patients with ≥20 BM who underwent single-session GKS between 2016–2021. Twenty-two patients had ECOG of 0 at the time of GKS. Median number of BM at GKS was 30 (20–79) with median total tumour volume 4cm3 (2–28 cm3). Median marginal dose was 20Gy (10-25Gy).ResultsMedian overall survival following GKS was 14-months (95%CI 4-24months), justifying GKS in this population. 11/12 patients that died succumbed due to extracranial disease, while 1 patient, who was treated with WBRT before GKS, succumbed to intracranial tumor progression. Local tumor control achieved was achieved for 63% of patients at 2-years and distal tumor control in 24% of patients at 1.5-years without additional radiation treatment. Salvage GKS was given in seven patients and salvage WBRT in three. One local recurrence was surgically resected. Systemic treatment given to most patients probably contributed to intracranial tumor control. No patients developed significant neurocognitive deficits attributable to GKS during the follow-up period of median 7-months (Q1-Q3: 3-12months).ConclusionMost patients treated with GKS for ≥20 BM have sufficient survival time to benefit from the treatment. Local and distal recurrences can be managed with systemic treatment, salvage GKS, or WBRT, resulting in intracerebral tumor control in vast majority of cases.

Treatment Planning Factors Associated with Long-Term Outcomes of Gamma Knife Surgery in Patients with Trigeminal Neuralgia

Gamma Knife surgery (GKS) is an established treatment option for trigeminal neuralgia (TN). However, the long-term efficacy of GKS for patients with TN has not been well studied. The aim of the study is to evaluate the sequential course of pain control after GKS and analyze the factors associated with the long-term analgesic effect, focusing on radiation dosimetry and neurovascular conflict (NVC) factors. We analyzed 83 patients undergoing GKS for TN in our institution between 2005 and 2013 with a follow-up duration >7 years. Tolerable pain with increased medication, persistent-intractable pain, and recurrence were classified as poor outcomes, and any other outcome was classified as a favorable outcome. The dosimetry factors and locational relationship between NVC and the target were analyzed in terms of their correlation with a favorable outcome. Adequate pain relief was achieved in 93% of patients a month and a half after GKS, but the pain recurred in 41.5% of patients on average 36 months after treatment. A larger V40Gy (P= 0.002) and higher homogeneity index (P= 0.027) were significantly associated with the long-term favorable outcomes. About 40% of patients had multiple NVC sites, and insufficient inclusion of the NVC in the target was significantly correlated with long-term poor outcomes (P= 0.002). Targeting the center of the trigeminal nerve in the area of NVC with GKS is associated with favorable long-term pain control.

Gamma Knife Radiosurgery for Metastatic Brain Tumors with Exophytic Hemorrhage.

ObjectiveMetastatic brain tumors (MBTs) often present with intracerebral hemorrhage. Although Gamma Knife surgery (GKS) is a valid treatment option for hemorrhagic MBTs, its efficacy is unclear. To achieve oncologic control and reduce radiation toxicity, we used a radiosurgical targeting technique that confines the tumor core within the hematoma when performing GKS in patients with such tumors. We reviewed our experience in this endeavor, focusing on local tumor control and treatment-associated morbidities. MethodsFrom 2007 to 2014, 13 patients with hemorrhagic MBTs were treated via GKS using our targeting technique. The median marginal dose prescribed was 23 Gy (range, 20–25). GKS was performed approximately 2 weeks after tumor bleeding to allow the patient’s condition to stabilize. ResultsThe primary sites of the MBTs included the liver (n=7), lung (n=2), kidney (n=1), and stomach (n=1); in two cases, the primary tumor was a melanoma. The mean tumor volume was 4.00 cm3 (range, 0.74–11.0). The mean overall survival duration after GKS was 12.5 months (range, 3–29), and three patients are still alive at the time of the review. The local tumor control rate was 92% (tumor disappearance 23%, tumor regression 46%, and stable disease 23%). There was one (8%) instance of local recurrence, which occurred 11 months after GKS in the solid portion of the tumor. No GKS-related complications were observed. ConclusionOur experience shows that GKS performed in conjunction with our targeting technique safely and effectively treats hemorrhagic MBTs. The success of this technique may reflect the presence of scattered metastatic tumor cells in the hematoma that do not proliferate owing to the inadequate microenvironment of the hematoma. We suggest that GKS can be a useful treatment option for patients with hemorrhagic MBTs that are not amenable to surgery.

Gamma knife surgery with and without embolization for cerebral arteriovenous malformations: A systematic review and meta-analysis

The benefit and risk of gamma knife surgery (GKS) in the treatment of residual cerebral arteriovenous malformations (AVMs) after endovascular embolization remain controversial. The aim of this meta-analysis was to assess current evidence regarding the efficiency and safety of GKS for AVMs with and without prior embolization. To compare GKS in patients with and without embolization, the authors conducted a meta-analysis of studies by searching the literature via PubMed and EMBASE databases for the period between January 2006 and December 2017. Six retrospective studies were finally identified. Outcomes were the rate of AVM obliteration on a 3-year follow-up angiogram, hemorrhage at 3 years after GKS and permanent neurological deficits. Six studies eligible for analysis included 2069 patients: 637 had undergone embolization followed by GKS, and 1432 had undergone GKS alone. The obliteration rate was significantly lower in patients who had undergone embolization followed by GKS than in those who had undergone GKS alone (49.5% vs 70.4%, OR 2.29, 95% CI 1.55–3.38, p < 0.00001). Subgroup analysis also indicated high obliteration rates in ‘similar mean nidus volume’, ‘high quality’ and ‘sample size over 100 patients’ subgroups. However, the rates of rehemorrhage (8.9% vs 4.2%, OR 0.59, 95% CI 0.23–1.57, p = 0.29) and permanent neurological deficits rate (3.6% vs 4.6%, OR 0.51, 95% CI 0.57–3.12, p = 0.51) were not significantly different between the two groups and subgroups. Embolization prior to GKS significantly decreases the AVM obliteration rate and didn’t reduce the risk of hemorrhage and permanent neurological deficits. Further evaluation by well-designed prospective or randomized cohort studies is highly needed.

Long-term hearing outcomes after gamma knife surgery in patients with vestibular schwannoma with hearing preservation: evaluation in 92 patients with serial audiograms.

The treatment strategy for patients with vestibular schwannoma (VS) is controversial, and data concerning the long-term hearing outcomes > 5years after gamma knife surgery (GKS) are limited. The long-term hearing outcomes after GKS were evaluated in VS patients with hearing preservation. Ninety-two VS patients with a pure tone average (PTA) ≤ 50 dB were evaluated. The median age was 54 years; the median tumor volume was 1.5cm3. The tumors were treated with a median margin dose of 12Gy and a median mean cochlear dose of 4.0Gy. At the time of GKS, 65 patients retained a PTA of 0-30 dB, and 27 had a PTA of 31-50 dB. The median follow-up period was 106months. At the final follow-up, 2 (2%) developed tumor progression. During the median audiogram follow-up of 83 months, the PTA was ≤ 30 dB in 22 patients (24%) and 31-50 dB in 27 patients (29%); 43 patients (47%) worsened to a PTA > 50dB. Hearing preservation rates were 66, 57, and 44% at 3, 5, and 10 years, respectively. In multivariate analysis, the mean cochlear dose (P < 0.001) and pre-GKS PTA (P = 0.045) were significant for hearing preservation. GKS was an effective treatment option for VS patients with a PTA ≤ 50 dB. As a lower cochlear dose and better pre-GKS PTA contributed to long-term hearing preservation, prophylactic GKS before hearing deterioration or tumor growth would be a treatment of choice if patients provided informed consent.

Jaw Immobilization for Gamma Knife Surgery in Patients with Mandibular Lesions: A Newly, Innovative Approach

Background: The purpose of our report is to describe an innovative system used for mandibular immobilization during Gamma Knife surgery (GKS) procedures. It is based on an approach originally developed in Marseille in extracranial lesions, close to or involving the mandible, which may imply a certain degree of movement during the therapeutic image acquisitions and/or GKS treatment. Methods: The maxillofacial surgeon applied bone titanium self-tapping monocortical screws (4; 2 mm diameter, 10 mm length) between roots of the teeth in the fixed gingiva (upper and lower maxillae) the day before GKS (local anesthesia, 5-10 min time). Two rubber bands were sufficient for the desired tension required to undergo GKS. We further proceeded with application of the Leksell stereotactic G frame and carried out the usual GKS procedure. Results: The mean follow-up period was 2.3 years (range 0.6-3). Three patients have been treated with this approach: 2 cases with extracranial trigeminal schwannomas involving the mandibular branch, with decrease in tumor size on MR follow-up; 1 case with residual paracondylian mandibular arteriovenous malformation following partial embolization, completely obliterated at 7 months (digital subtraction angiography programmed 1 year after treatment). Conclusions: Jaw immobilization appears to be a quick, minimally invasive, safe and accurate adjunctive technique to enhance GKS targeting precision.

Gamma Knife surgery for patients with facial nerve schwannomas: a multiinstitutional retrospective study in Japan

The aim of this study was to explore the efficacy and safety of stereotactic radiosurgery for patients with facial nerve schwannomas (FNSs). This study was a multiinstitutional retrospective analysis of 42 patients with FNSs treated with Gamma Knife surgery (GKS) at 1 of 10 medical centers of the Japan Leksell Gamma Knife Society (JLGK1301). The median age of the patients was 50 years. Twenty-nine patients underwent GKS as the initial treatment, and 13 patients had previously undergone surgery. At the time of the GKS, 33 (79%) patients had some degree of facial palsy, and 21 (50%) did not retain serviceable hearing. Thirty-five (83%) tumors were solid, and 7 (17%) had cystic components. The median tumor volume was 2.5 cm(3), and the median prescription dose to the tumor margin was 12 Gy. The median follow-up period was 48 months. The last follow-up images showed partial remission in 23 patients and stable tumors in 19 patients. Only 1 patient experienced tumor progression at 60 months, but repeat GKS led to tumor shrinkage. The actuarial 3- and 5-year progression-free survival rates were 100% and 92%, respectively. During the follow-up period, 8 patients presented with newly developed or worsened preexisting facial palsy. The condition was transient in 3 of these patients. At the last clinical follow-up, facial nerve function improved in 8 (19%) patients, remained stable in 29 (69%), and worsened in 5 (12%; House-Brackmann Grade III in 4 patients, Grade IV in 1 patient). With respect to hearing function, 18 (90%) of 20 evaluated patients with a pure tone average of ≤ 50 dB before treatment retained serviceable hearing. GKS is a safe and effective treatment option for patients with either primary or residual FNSs. All patients, including 1 patient who required repeat GKS, achieved good tumor control at the last follow-up. The incidence of newly developed or worsened preexisting facial palsy was 12% at the last clinical follow-up. In addition, the risk of hearing deterioration as an adverse effect of radiation was low. These results suggest that GKS is a safe alternative to resection.

Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2.

The aim of this study was to evaluate long-term clinical outcomes after Gamma Knife surgery (GKS) for patients with neurofibromatosis Type 2 (NF2) and the role of GKS in the management of NF2. From December 1994 through December 2008, a total of 46 patients (21 male, 25 female) with NF2 underwent GKS and follow-up evaluation for at least 5 years at the Gamma Knife Center of the Beijing Neurosurgical Institute. GKS was performed using the Leksell Gamma Knife Models B and C. The mean age of the patients was 30 years (range 13-59 years). A family history of NF2 was found for 9 (20%) patients. The NF2 phenotype was thought to be Wishart for 20 (44%) and Feiling-Gardner for 26 (56%) patients. Among these 46 patients, GKS was performed to treat 195 tumors (73 vestibular schwannomas and 122 other tumors including other schwannomas and meningiomas). For vestibular schwannomas, the mean volume was 5.1 cm(3) (median 3.6 cm(3), range 0.3-27.3 cm(3)), the mean margin dose was 12.9 Gy (range 10-14 Gy), and the mean maximum dose was 27.3 Gy (range 16.2-40 Gy). For other tumors, the mean volume was 1.7 cm(3) (range 0.3-5.5 cm(3)), the mean margin dose was 13.3 Gy (range 11-14 Gy), and the mean maximum dose was 26.0 Gy (range 18.0-30.4 Gy). The median duration of follow-up was 109 months (range 8-195 months). For the 73 vestibular schwannomas that underwent GKS, the latest follow-up MR images demonstrated regression of 30 (41%) tumors, stable size for 31 (43%) tumors, and enlargement of 12 (16%) tumors. The total rate of tumor control for bilateral vestibular schwannomas in patients with NF2 was 84%. Of the 122 other types of tumors that underwent GKS, 103 (85%) showed no tumor enlargement. The rate of serviceable hearing preservation after GKS was 31.9% (15/47). The actuarial rates for hearing preservation at 3 years, 5 years, 10 years, and 15 years were 98%, 93%, 44%, and 17%, respectively. Of the 46 patients, 22 (48%) became completely bilaterally deaf, 17 (37%) retained unilateral serviceable hearing, and 7 (15%) retained bilateral serviceable hearing. The mean history of the disease course was 12 years (range 5-38 years). GKS was confirmed to provide long-term local tumor control for small- to medium-sized vestibular schwannomas and other types of tumors, although vestibular schwannomas in patients with NF2 responded less well than did unilateral sporadic vestibular schwannomas. Phenotype is the most strongly predictive factor of final outcome after GKS for patients with NF2. The risk for loss of hearing is high, whereas the risk for other cranial nerve complications is low.

Large intracranial metastatic tumors treated by Gamma Knife surgery: outcomes and prognostic factors

The use of radiosurgery has been well accepted for treating small to medium-size metastatic brain tumors (MBTs). However, its utility in treating large MBTs remains uncertain due to potentially unfavorable effects such as progressive perifocal brain edema and neurological deterioration. In this retrospective study the authors evaluated the local tumor control rate and analyzed possible factors affecting tumor and brain edema response. The authors defined a large brain metastasis as one with a measurement of 3 cm or more in at least one of the 3 cardinal planes (coronal, axial, or sagittal). A consecutive series of 109 patients with 119 large intracranial metastatic lesions were treated with Gamma Knife surgery (GKS) between October 2000 and December 2012; the median tumor volume was 16.8 cm(3) (range 6.0-74.8 cm(3)). The pre-GKS Karnofsky Performance Status (KPS) score for these patients ranged from 70 to 100. The most common tumors of origin were non-small cell lung cancers (29.4% of cases in this series). Thirty-six patients (33.0%) had previously undergone a craniotomy (1-3 times) for tumor resection. Forty-three patients (39.4%) underwent whole-brain radiotherapy (WBRT) before GKS. Patients were treated with GKS and followed clinically and radiographically at 2- to 3-month intervals thereafter. The median duration of imaging follow-up after GKS for patients with large MBTs in this series was 6.3 months. In the first follow-up MRI studies (performed within 3 months after GKS), 77 lesions (64.7%) had regressed, 24 (20.2%) were stable, and 18 (15.1%) were found to have grown. Peritumoral brain edema as defined on T2-weighted MRI sequences had decreased in 79 lesions (66.4%), was stable in 21 (17.6%), but had progressed in 19 (16.0%). In the group of patients who survived longer than 6 months (76 patients with 77 MBTs), 88.3% of the MBTs (68 of 77 lesions) had regressed or remained stable at the most recent imaging follow-up, and 89.6% (69 of 77 lesions) showed regression of perifocal brain edema volume or stable condition. The median duration of survival after GKS was 8.3 months for patients with large MBTs. Patients with small cell lung cancer and no previous WBRT had a significantly higher tumor control rate as well as better brain edema relief. Patients with a single metastasis, better KPS scores, and no previous radiosurgery or WBRT were more likely to decrease corticosteroid use after GKS. On the other hand, higher pre-GKS KPS score was the only factor that showed a statistically significant association with longer survival. Treating large MBTs using either microsurgery or radiosurgery is a challenge for neurosurgeons. In selected patients with large brain metastases, radiosurgery offered a reasonable local tumor control rate and favorable functional preservation. Exacerbation of underlying edema was rare in this case series. Far more commonly, edema and steroid use were lessened after radiosurgery. Radiosurgery appears to be a reasonable option for some patients with large MBTs.

Gamma knife surgery for patients with volumetric classification of nonfunctioning pituitary adenomas: a systematic review and meta-analysis

The aim of this study was to scrutinize the literature to determine the efficacy and safety of gamma knife surgery (GKS) for the treatment of nonfunctioning pituitary adenomas (NFPAs) with volumetric classification. Electronic databases including MedLine, PubMed, and Cochrane Central were searched. The literature related to patients with NFPAs treated with GKS was collected. Eligible studies reported on the rate of tumor control (RTC), the rate of radiosurgery-induced optic neuropathy injury (RRIONI), the rate of radiosurgery-induced endocrinological deficits (RRIED), and other parameters. A total of 17 studies met the criteria. based on the tumor volume, nfpas were divided into three groups: the RTC of group I (93 patients) with tumor volumes <2 ml was 99% (95% CI 96-100%), the RRIONI was 1% (95% CI 0-4%), and the RRIED was 1% (95% CI 0-4%). The RTC of group II (301 patients) with volumes from 2 to 4 ml was 96% (95% CI 92-99%), the RRIONI was 0 (95% CI 0-2%), and RRIED was 7% (95% CI 2-14%). The RTC of group III (531 patients) with volumes larger than 4 ml was 91% (95% CI 89-94%), the RRIONI was 2% (95% CI 0-5%), and the RRIED was 22% (95% CI 14-31%). There were significant differences in the RTC and in the RRIED among the three groups (P<0.001), indicating that there were higher RRIED and lower RTC with the increase of tumor volume. NFPAs, according to tumor volume classification, need stratification for GKS treatment. GKS is the optimal choice for the treatment of group II NFPAs. Patients with residual tumor volumes of <4 ml will benefit most from GKS treatment.

Gamma Knife surgery for the treatment of 5 to 15 metastases to the brain

It has been generally accepted that Gamma Knife surgery (GKS) is an effective primary or adjunct treatment for patients with 1-4 metastases to the brain. The number of studies detailing the use of GKS for 5 or more brain metastases, however, remains minimal. The aim of the current retrospective study was to elucidate the utility of GKS in patients with 5-15 brain metastases. Patients were chosen for GKS based on prior MRI of these metastatic lesions and a known primary cancer diagnosis. Magnetic resonance imaging was used post-GKS to assess tumor control; patients were also followed up clinically. Overall survival (OS) from the date of GKS was used as the primary end point. Statistical analysis was performed to identify prognostic factors related to OS. Between 2003 and 2012, 96 patients were treated for a total of 704 metastatic brain lesions. The histology of these lesions varied among non-small cell lung cancer (NSCLC), breast cancer, melanoma, renal cancer, and other more rare carcinomas. At the initial treatment, 18 of the patients (18.8%) were categorized in Recursive Partitioning Analysis (RPA) Class 1 and 77 (80.2%) in RPA Class 2; none were in RPA Class 3. The median number of treated lesions was 7 (mean 7.13), and the median planned treatment volume was 6.12 cm(3) (range 0.42-57.83 cm(3)) per patient. The median clinical follow-up was 4.1 months (range 0.1-40.70 months). Actuarial tumor control was calculated to be 92.4% at 6 months, 84.8% at 12 months, and 74.9% at 24 months post-GKS. The median OS was found to be 4.73 months (range 0.4-41.8 months). Multivariate analysis demonstrated that RPA class was a significant predictor of death (HR = 2.263, p = 0.038). Number of lesions, tumor histology, Graded Prognostic Assessment score, prior whole-brain radiation therapy, prior resection, prior chemotherapy, patient age, patient sex, controlled primary tumor, extracranial metastases, and planned treatment volume were not significant predictors of OS. In patients with 5-15 brain metastases at presentation, the number of lesions did not predict survival after GKS; however, the RPA class was predictive of OS in this group of patients. Gamma Knife surgery for such patients offers an excellent rate of local tumor control.

Role of Gamma Knife surgery in patients with 5 or more brain metastases

The authors evaluated overall survival and factors predicting outcome in patients with ≥ 5 brain metastases who were treated with Gamma Knife surgery (GKS). Medical records from patients with ≥ 5 brain metastases treated with GKS between 1997 and 2010 at the Cleveland Clinic Gamma Knife Center were retrospectively reviewed. Patient demographics, tumor characteristics, treatment-related factors, and outcome data were evaluated. One hundred seventy patients were identified, with a median age of 58 years. The female/male ratio was 1.2:1. Gamma Knife surgery was used as an upfront treatment in 35% of patients and as salvage treatment in 65% of patients with multiple brain metastases. The median overall survival after GKS was 6.7 months (95% CI 5.5-8.1). At the time of GKS, 128 patients (75%) had concurrent extracranial metastases, and in 69 patients (41%) multiple extracranial sites were involved. Ninety-two patients (54%) had a history of whole-brain radiation therapy, and 158 patients (93%) had a Karnofsky Performance Scale (KPS) score ≥ 70. The median total intracranial disease volume was 3.2 cm(3) (range 0.2-37.2 cm(3)). A total intracranial tumor volume ≥ 10 cm(3) was observed in 32 patients (19%). Lower KPS score at the time of treatment (p < 0.0001), patient age > 60 years (p = 0.004), multiple extracranial metastases (p = 0.0001), and greater intracranial burden of disease (p = 0.03) were prognostic factors for poor outcome in the univariate and multivariate analyses. In this study, GKS was safe and effective for upfront and salvage treatment in patients with ≥ 5 brain metastases. Gamma Knife surgery should be considered as an additional treatment modality for these patients, especially in the subset of patients with favorable prognostic factors.

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 patients with brainstem metastases

Because brainstem metastases are not deemed resectable, stereotactic radiosurgery (SRS) is the only treatment modality expected to achieve a radical cure. The authors describe their treatment results, focusing particularly on how long patients can survive without neurological deterioration following SRS for brainstem metastases. This was an institutional review board-approved, retrospective cohort study in which the authors pulled from their database information on 2553 consecutive patients with brain metastases who underwent Gamma Knife surgery (GKS) at the Mito GammaHouse between July 1998 and July 2011. Among the 2553 patients, excluding cases in which there was meningeal dissemination, 200 cases of brainstem metastases (78 women and 122 men with a mean age of 64 years [range 36-86 years]) were identified and analyzed. The most common primary site was the lung (137 patients) followed by the gastrointestinal tract (24 patients), breast (17 patients), kidney (12 patients), and others (10 patients). Among the 200 patients, 15 patients (7.5%) harbored at least 2 tumors in the brainstem: 11 patients had 2 tumors, 2 patients had 3 tumors, and 1 patient each had 4 or 5 tumors. Therefore, a total of 222 tumors were irradiated. These 222 tumors were located in the pons (121 lesions), the midbrain (65 lesions), and the medulla oblongata (36 lesions). The mean and median tumor volumes were 1.3 and 0.2 cm(3) (range 0.005-10.7 cm(3)), and the median peripheral radiation dose was 18.0 Gy (range 12.0-25.0 Gy). The overall median survival time (MST) was 6.0 months. Distribution of MSTs across Recursive Partitioning Analysis (RPA) classes showed that the MSTs were 9.4 months in Class I (20 patients), 6.0 months in Class II (171 patients), and 1.9 months in Class III (9 patients). Better Karnofsky Performance Scale score, single metastasis, and well-controlled primary tumor were significant predictive factors for longer survival. The neurological and qualitative survival rates were 90.8% and 89.2%, respectively, at 24 months post-GKS. Better KPS score and smaller tumor volume tended to be associated with prolonged qualitative survival. Follow-up imaging studies were available for 129 patients (64.5%). The tumor control rate was 81.8% at 24 months post-GKS. Smaller tumor volume tended to contribute to tumor control. The present results indicate that GKS is effective in the treatment of brainstem metastases, particularly from the viewpoint of maintaining a good neurological condition in the patient.

Gamma Knife surgery for patients with nonfunctioning pituitary macroadenomas: predictors of tumor control, neurological deficits, and hypopituitarism

Nonfunctioning pituitary macroadenomas often recur after microsurgery and thereby require further treatment. Gamma Knife surgery (GKS) has been used to treat recurrent adenomas. In this study, the authors evaluated outcomes following GKS of nonfunctioning pituitary macroadenomas and assessed predictors of tumor control, neurological deficits, and delayed hypopituitarism. Between June 1989 and March 2010, 140 consecutive patients with nonfunctioning pituitary macroadenomas were treated using GKS at the University of Virginia. The median patient age was 51 years (range 21-82 years), and 56% of patients were male. Mean tumor volume was 5.6 cm3 (range 0.6-35 cm3). Thirteen patients were treated with GKS as primary therapy, and 127 had undergone at least 1 open resection prior to GKS. Ninety-three patients had a history of hormone therapy prior to GKS. The mean maximal dose of GKS was 38.6 Gy (range 10-70 Gy), the mean marginal dose was 18 Gy (range 5-25 Gy), and the mean number of isocenters was 9.8 (range 1-26). Follow-up evaluations were performed in all 140 patients, ranging from 0.5 to 17 years (mean 5 years, median 4.2 years). Tumor volume remained stable or decreased in 113 (90%) of 125 patients with available follow-up imaging. Kaplan-Meier analysis demonstrated radiographic progression free survival at 2, 5, 8, and 10 years to be 98%, 97%, 91%, and 87%, respectively. In multivariate analysis, a tumor volume greater than 5 cm3 (hazard ratio=5.0, 95% CI 1.5-17.2; p=0.023) was the only factor predictive of tumor growth. The median time to tumor progression was 14.5 years. Delayed hypopituitarism occurred in 30.3% of patients. No factor was predictive of post-GKS hypopituitarism. A new or worsening cranial nerve deficit occurred in 16 (13.7%) of 117 patients. Visual decline was the most common neurological deficit (12.8%), and all patients experiencing visual decline had evidence of tumor progression. In multivariate analysis, a tumor volume greater than 5 cm3 (OR=3.7, 95% CI 1.2-11.7; p=0.025) and pre-GKS hypopituitarism (OR=7.5, 95% CI 1.1-60.8; p=0.05) were predictive of a new or worsened neurological deficit. In patients with nonfunctioning pituitary macroadenomas, GKS confers a high rate of tumor control and a low rate of neurological deficits. The most common complication following GKS is delayed hypopituitarism, and this occurs in a minority of patients.

Hearing Preservation after Gamma Knife Surgery in Patients with Vestibular Schwannoma

Introduction: The aim of this work was to evaluate the hearing preservation rate after treatment by gamma knife surgery.

Outcomes of Gamma Knife surgery for trigeminal neuralgia secondary to vertebrobasilar ectasia

Vertebrobasilar ectasia (VBE) is an unusual cause of trigeminal neuralgia (TN). The surgical options for patients with medically refractory pain include percutaneous or microsurgical rhizotomy and microvascular decompression (MVD). All such procedures can be technically challenging. This report evaluates the response to a minimally invasive procedure, Gamma Knife surgery (GKS), in patients with TN associated with severe vascular compression caused by VBE. Twenty patients underwent GKS for medically refractory TN associated with VBE. The median patient age was 74 years (range 48-95 years). Prior surgical procedures had failed in 11 patients (55%). In 9 patients (45%), GKS was the first procedure they had undergone. The median target dose for GKS was 80 Gy (range 75-85 Gy). The median follow-up was 29 months (range 8-123 months) after GKS. The treatment outcomes were compared with 80 case-matched controls who underwent GKS for TN not associated with VBE. Intraoperative MR imaging or CT scanning revealed VBE that deformed the brainstem in 50% of patients. The trigeminal nerve was displaced in cephalad or lateral planes in 60%. In 4 patients (20%), the authors could identify only the distal cisternal component of the trigeminal nerve as it entered into the Meckel cave. After GKS, 15 patients (75%) achieved initial pain relief that was adequate or better, with or without medication (Barrow Neurological Institute [BNI] pain scale, Grades I-IIIb). The median time until pain relief was 5 weeks (range 1 day-6 months). Twelve patients (60%) with initial pain relief reported recurrent pain between 3 and 43 months after GKS (median 12 months). Pain relief was maintained in 53% at 1 year, 38% at 2 years, and 10% at 5 years. Some degree of facial sensory dysfunction occurred in 10% of patients. Eventually, 14 (70%) of the 20 patients underwent an additional surgical procedure including repeat GKS, percutaneous procedure, or MVD at a median of 14 months (range 5-50 months) after the initial GKS. At the last follow-up, 15 patients (75%) had satisfactory pain control (BNI Grades I-IIIb), but 5 patients (25%) continued to have unsatisfactory pain control (BNI Grade IV or V). Compared with patients without VBE, patients with VBE were much less likely to have initial (p = 0.025) or lasting (p = 0.006) pain relief. Pain control rates of GKS in patients with TN associated with VBE were inferior to those of patients without VBE. Multimodality surgical or medical management strategies were required in most patients with VBE.

Pituitary insufficiency as a side effect after radiosurgery for pituitary adenomas: the role of the hypothalamus

Object Causes of pituitary insufficiencies as a side effect of Gamma Knife surgery (GKS) following irradiation of the hypothalamopituitary axis are still under debate. In an investigation of pituitary insufficiencies after GKS, the authors' main focus is on what role can be attributed to the hypothalamus with regard to endocrinological changes in hypothalamopituitary function following GKS. Methods A total of 108 patients consecutively treated between April 1992 and July 2003 were included in this retrospective study. All patients had undergone either transsphenoidal or transcranial surgery prior to GKS. The spot dosimetry method was used to determine doses delivered to structures of the hypothalamopituitary axis. For statistical analyses, endocrine insufficiency and deterioration in pituitary function were defined as a decrease in hormonal blood levels below the normal range for 1 or more anterior pituitary lobe hormones. Additionally, an analysis of the rate of patients requiring hormone replacement therapy after GKS due to new endocrinopathies was performed. Results Complete patient records of 61 male and 47 female patients with a mean age of 51.9 years (range 9.1–81.2 years) were available for our investigation. The overall tumor control rate was 97% and the endocrinological cure rate was 61.2%. Mean treatment doses in patients with and without new endocrine insufficiencies (shown as with/without insufficiencies and followed by probability values) were as follows: 1.3/0.8 Gy to the hypothalamus (p = 0.2); 2.2/1.6 Gy to the median eminence (p = 0.1); 6.5/4.1 Gy to the pituitary stalk (p = 0.004); and 12.4/9.5 Gy to the pituitary gland (p = 0.05). The median overall duration of follow-up after GKS was 6.7 years, with 84 patients (77.7%) whose follow-up was longer than 12 months. The median follow-up time after GKS in patients who developed a new pituitary dysfunction was 79.5 months (6.6 years, SD 3.8 years), and the median follow-up time in patients with no new insufficiencies was 78.4 months (6.5 years, SD 4 years). Conclusions Gamma Knife surgery is a safe and effective treatment for patients with residual and recurrent pituitary adenomas. The rate of pituitary insufficiencies after GKS is still lower than that after conventional radiotherapy. Very low radiation doses are directed to the hypothalamus, and thus this structure does not play a major role in the development of pituitary insufficiencies after GKS. The results of this study show that patients in whom the pituitary stalk and pituitary gland receive a high mean point dose are more likely to develop pituitary insufficiencies after GKS than those who receive a lower dose.

Wait-and-see strategy compared with proactive Gamma Knife surgery in patients with intracanalicular vestibular schwannomas

Object The roles of the wait-and-see strategy and proactive Gamma Knife surgery (GKS) in the treatment paradigm for small intracanalicular vestibular schwannomas (VSs) is still a matter of debate, especially when patients present with functional hearing. The authors compare these 2 methods. Methods Forty-seven patients (22 men and 25 women) harboring an intracanalicular VS were followed prospectively. The mean age of the patients at the time of inclusion was 54.4 years (range 20–71 years). The mean follow-up period was 43.8 ± 40 months (range 9–222 months). Failure was defined as significant tumor growth and/or hearing deterioration that required microsurgical or radiosurgical treatment. This population was compared with a control group of 34 patients harboring a unilateral intracanalicular VS who were consecutively treated by GKS and had functional hearing at the time of radiosurgery. Results Of the 47 patients in the wait-and-see group, treatment failure (tumor growth requiring treatment) was observed in 35 patients (74%), although conservative treatment is still ongoing for 12 patients. Treatment failure in the control (GKS) group occurred in only 1 (3%) of 34 patients. In the wait-and-see group, there was no change in tumor size in 10 patients (21%), tumor growth in 36 patients (77%), and a mild decrease in tumor size in 1 patient (2%). Forty patients in the wait-and-see group were available for a hearing level study, which demonstrated no change in Gardner-Robertson hearing class for 24 patients (60%). Fifteen patients (38%) experienced more than 10 db of hearing loss and 2 of them became deaf. At 3, 4, and 5 years, the useful hearing preservation rates were 75%, 52%, and 41% in the wait-and-see group and 77%, 70%, and 64% in the control group, respectively. Thus, the chances of maintaining functional hearing and avoiding further intervention were much higher in cases treated by GKS (79% and 60% at 2 and 5 years, respectively) than in cases managed by the wait-and-see strategy (43% and 14% at 2 and 5 years, respectively). Conclusions These data indicate that the wait-and-see policy exposes the patient to elevated risks of tumor growth and degradation of hearing. Both events may occur independently in the mid-term period. This information must be presented to the patient. A careful sequential follow-up may be adopted when the wait-and-see strategy is chosen, but proactive GKS is recommended when hearing is still useful at the time of diagnosis. This recommendation may be a main paradigm shift in the practice of treating intracanalicular VSs.