bluuebunny/crossref_metadata_2025 huggingface dataset:
Calvarial and skull base metastases: expanding the clinical utility of Gamma Knife surgery
Authors: Kotecha Rupesh , Angelov Lilyana , Barnett Gene H. , Reddy Chandana A. , Suh John H. , Murphy Erin S. , Neyman Gennady , Chao Samuel T.
Published: November 2018

Object

Traditionally, the treatment of choice for patients with metastases to the calvaria or skull base has been conventional radiation therapy. Because patients with systemic malignancies are also at risk for intracranial metastases, the utility of Gamma Knife surgery (GKS) for these patients has been explored to reduce excess radiation exposure to the perilesional brain parenchyma. The purpose of this study was to report the efficacy of GKS for the treatment of calvarial metastases and skull base lesions.

Methods

The authors performed a retrospective chart review of 21 patients with at least 1 calvarial or skull base metastatic lesion treated with GKS during 2001–2013. For 7 calvarial lesions, a novel technique, in which a bolus was placed over the treatment site, was used. For determination of local control or disease progression, radiation therapy data were examined and posttreatment MR images and oncology records were reviewed. Survival times from the date of procedure were estimated by using Kaplan-Meier analyses.

Results

The median patient age at treatment was 57 years (range 29–84 years). A total of 19 (90%) patients received treatment for single lesions, 1 patient received treatment for 3 lesions, and 1 patient received treatment for 4 lesions. The most common primary tumor was breast cancer (24% of patients). Per lesion, the median clinical and radiographic follow-up times were 10.3 months (range 0–71.9 months) and 7.1 months (range 0–61.3 months), respectively. Of the 26 lesions analyzed, 14 (54%) were located in calvarial bones and 12 (46%) were located in the skull base. The median lesion volume was 5.3 cm3 (range 0.3–55.6 cm3), and the median prescription margin dose was 15 Gy (range 13–24 Gy). The median overall survival time for all patients was 35.9 months, and the 1-year local control rate was 88.9% (95% CI 74.4%–100%). Local control rates did not differ between lesions treated with the bolus technique and those treated with traditional methods or between calvarial lesions and skull base lesions (p > 0.05). Of the 3 patients for whom local treatment failed, 1 patient received no further treatment and 2 patients responded to salvage chemotherapy. Subsequent brain parenchymal metastases developed in 2 patients, who then underwent GKS.

Conclusions

GKS is an effective treatment modality for patients with metastases to the calvarial bones or skull base. For patients with superficial calvarial lesions, a novel approach with bolus application resulted in excellent rates of local control. GKS provides an effective therapeutic alternative to conventional radiation therapy and should be considered for patients at risk for calvarial metastases and brain parenchymal metastases.
Hemorrhage during pregnancy in the latency interval after stereotactic radiosurgery for arteriovenous malformations
Authors: Tonetti Daniel , Kano Hideyuki , Bowden Gregory , Flickinger John C. , Lunsford L. Dade
Published: November 2018

Object

The presentation for patients with arteriovenous malformations (AVMs) is often intracranial hemorrhage; for women, this frequently occurs during the prime childbearing years. Although previous studies have addressed the risk for AVM hemorrhage during pregnancy, such studies have not assessed the risk for hemorrhage among women who become pregnant during the latency interval between stereotactic radiosurgery (SRS) and documented obliteration of the lesion. The authors sought to evaluate the risk for hemorrhage in patients who become pregnant during the latency interval after SRS.

Methods

This single-institution retrospective analysis reviewed the authors' experience with Gamma Knife SRS during 1987–2012. During this time, 253 women of childbearing age (median age 30 years, range 15–40 years) underwent SRS for intracranial AVM. The median target volume was 3.9 cm3 (range 0.1–27.1 cm3), and the median marginal dose was 20 Gy (range 14–38 Gy). For all patients, the date of AVM obliteration was recorded and the latency interval was calculated. Information about subsequent pregnancies and/or bleeding events during the latency interval was retrieved from the medical records and supplemented by telephone contact.

Results

AVM obliteration was confirmed by MRI or angiography at a median follow-up time of 39.3 months (range 10–174 months). There were 828.7 patient-years of follow-up within the latency interval between SRS and the date of confirmed AVM obliteration. Among nonpregnant women, 20 hemorrhages occurred before AVM obliteration, yielding an annual hemorrhage rate of 2.5% for nonpregnant women during the latency interval. Among women who became pregnant during the latency interval, 2 hemorrhages occurred over the course of 18 pregnancies, yielding an annual hemorrhage rate of 11.1% for women who become pregnant during the latency interval. For the 2 pregnant patients who experienced hemorrhage, the bleeding occurred during the first trimester of pregnancy.

Conclusions

The authors present the first series of data for women with intracranial AVMs who became pregnant during the latency interval after SRS. Hemorrhage during the latency interval occurred at an annual rate of 2.5% for nonpregnant women and 11.1% for pregnant women. The data suggest that pregnancy might be a risk factor for AVM hemorrhage during the interval between SRS and AVM obliteration. However, this suggestion is not statistically significant because only 18 patients in the study population became pregnant during the latency interval. To mitigate any increased risk for hemorrhage, patients should consider deferring pregnancy until treatment conclusion and AVM obliteration.
Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2
Authors: Sun Shibin , Liu Ali
Published: November 2018

Object

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.

Methods

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 cm3 (median 3.6 cm3, range 0.3–27.3 cm3), 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 cm3 (range 0.3–5.5 cm3), 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).

Results

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).

Conclusions

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.
Change in the cross-sectional area of the thecal sac following balloon kyphoplasty for pathological vertebral compression fractures prior to spine stereotactic radiosurgery
Authors: Lis Eric , Laufer Ilya , Barzilai Ori , Yamada Yoshiya , Karimi Sasan , McLaughlin Lily , Krol George , Bilsky Mark H.
Published: November 2018

OBJECTIVE

Percutaneous vertebral augmentation procedures such as vertebroplasty and kyphoplasty are often performed in cancer patients to relieve mechanical axial-load pain due to pathological collapse deformities. The collapsed vertebrae in these patients can be associated with varying degrees of spinal canal compromise that can be worsened by kyphoplasty. In this study the authors evaluated changes to the spinal canal, in particular the cross-sectional area of the thecal sac, following balloon kyphoplasty (BKP) prior to stereotactic radiosurgery (SRS).

METHODS

The authors retrospectively reviewed the records of all patients with symptomatic vertebral compression fractures caused by metastatic disease who underwent kyphoplasty prior to single-fraction SRS. The pre-BKP cross-sectional image, usually MRI, was compared to the post-BKP CT myelogram required for radiation treatment planning. The cross-sectional area of the thecal sac was calculated pre- and postkyphoplasty, and intraprocedural CT imaging was reviewed for epidural displacement of bone fragments, tumor, or polymethylmethacrylate (PMMA) extravasation. The postkyphoplasty imaging was also evaluated for evidence of fracture progression or fracture reduction.

RESULTS

Among 30 consecutive patients, 41 vertebral levels were treated with kyphoplasty, and 24% (10/41) of the augmented levels showed a decreased cross-sectional area of the thecal sac. All 10 of these vertebral levels had preexisting epidural disease and destruction of the posterior vertebral body cortex. No bone fragments were displaced posteriorly. Minor epidural PMMA extravasation occurred in 20% (8/41) of the augmented levels but was present in only 1 of the 10 vertebral segments that showed a decreased cross-sectional area of the thecal sac postkyphoplasty.

CONCLUSIONS

In patients with preexisting epidural disease and destruction of the posterior vertebral body cortex who are undergoing BKP for pathological fractures, there is an increased risk of further mass effect upon the thecal sac and the potential to alter the SRS treatment planning.
Development of a validated computer-based preoperative predictive model for pseudarthrosis with 91% accuracy in 336 adult spinal deformity patients
Authors: Scheer Justin K. , Oh Taemin , Smith Justin S. , Shaffrey Christopher I. , Daniels Alan H. , Sciubba Daniel M. , Hamilton D. Kojo , Protopsaltis Themistocles S. , Passias Peter G. , Hart Robert A. , Burton Douglas C. , Bess Shay , Lafage Renaud , Lafage Virginie , Schwab Frank , Klineberg Eric O. , Ames Christopher P. , _ _
Published: November 2018

OBJECTIVE

Pseudarthrosis can occur following adult spinal deformity (ASD) surgery and can lead to instrumentation failure, recurrent pain, and ultimately revision surgery. In addition, it is one of the most expensive complications of ASD surgery. Risk factors contributing to pseudarthrosis in ASD have been described; however, a preoperative model predicting the development of pseudarthrosis does not exist. The goal of this study was to create a preoperative predictive model for pseudarthrosis based on demographic, radiographic, and surgical factors.

METHODS

A retrospective review of a prospectively maintained, multicenter ASD database was conducted. Study inclusion criteria consisted of adult patients (age ≥ 18 years) with spinal deformity and surgery for the ASD. From among 82 variables assessed, 21 were used for model building after applying collinearity testing, redundancy, and univariable predictor importance ≥ 0.90. Variables included demographic data along with comorbidities, modifiable surgical variables, baseline coronal and sagittal radiographic parameters, and baseline scores for health-related quality of life measures. Patients groups were determined according to their Lenke radiographic fusion type at the 2-year follow-up: bilateral or unilateral fusion (union) or pseudarthrosis (nonunion). A decision tree was constructed, and internal validation was accomplished via bootstrapped training and testing data sets. Accuracy and the area under the receiver operating characteristic curve (AUC) were calculated to evaluate the model.

RESULTS

A total of 336 patients were included in the study (nonunion: 105, union: 231). The model was 91.3% accurate with an AUC of 0.94. From 82 initial variables, the top 21 covered a wide range of areas including preoperative alignment, comorbidities, patient demographics, and surgical use of graft material.

CONCLUSIONS

A model for predicting the development of pseudarthrosis at the 2-year follow-up was successfully created. This model is the first of its kind for complex predictive analytics in the development of pseudarthrosis for patients with ASD undergoing surgical correction and can aid in clinical decision-making for potential preventative strategies.
Variability in the utility of predictive models in predicting patient-reported outcomes following spine surgery for degenerative conditions: a systematic review
Authors: Dietz Nicholas , Sharma Mayur , Alhourani Ahmad , Ugiliweneza Beatrice , Wang Dengzhi , Nuño Miriam A. , Drazin Doniel , Boakye Maxwell
Published: November 2018

OBJECTIVE

There is increasing emphasis on patient-reported outcomes (PROs) to quantitatively evaluate quality outcomes from degenerative spine surgery. However, accurate prediction of PROs is challenging due to heterogeneity in outcome measures, patient characteristics, treatment characteristics, and methodological characteristics. The purpose of this study was to evaluate the current landscape of independently validated predictive models for PROs in elective degenerative spinal surgery with respect to study design and model generation, training, accuracy, reliability, variance, and utility.

METHODS

The authors analyzed the current predictive models in PROs by performing a search of the PubMed and Ovid databases using PRISMA guidelines and a PICOS (participants, intervention, comparison, outcomes, study design) model. They assessed the common outcomes and variables used across models as well as the study design and internal validation methods.

RESULTS

A total of 7 articles met the inclusion criteria, including a total of 17 validated predictive models of PROs after adult degenerative spine surgery. National registry databases were used in 4 of the studies. Validation cohorts were used in 2 studies for model verification and 5 studies used other methods, including random sample bootstrapping techniques. Reported c-index values ranged from 0.47 to 0.79. Two studies report the area under the curve (0.71–0.83) and one reports a misclassification rate (9.9%). Several positive predictors, including high baseline pain intensity and disability, demonstrated high likelihood of favorable PROs.

CONCLUSIONS

A limited but effective cohort of validated predictive models of spine surgical outcomes had proven good predictability for PROs. Instruments with predictive accuracy can enhance shared decision-making, improve rehabilitation, and inform best practices in the setting of heterogeneous patient characteristics and surgical factors.
Carcinomatous meningitis: are surgery or gamma knife radiosurgery treatment risk factors?
Authors: Mahajan Anita , Borden Jonathan , Tsai Jen-san
Published: November 2018

Object. The purpose of this study was to identify possible risk factors leading to carcinomatous meningitis in patients with a known brain metastasis and who were treated with gamma knife radiosurgery (GKS).

Methods. Two hundred eighty lesions in 101 patients were treated during 121 GKS procedures. The clinical and neuroimaging history, tumor histology, and follow-up studies were reviewed for all patients. Evidence as demonstrated by magnetic resonance imaging criteria and/or cerebrospinal fluid (CSF) cytology of carcinomatous meningitis was evaluated. The data were then analyzed to identify potential risk factors for the development of CSF dissemination.

Conclusions. It appears that carcinomatous meningitis is exclusively identified in patients with adenocarcinoma, in particular with primary lung cancer. Furthermore, the incidence is higher if surgery is performed and the interval to subsequent GKS is prolonged.
Gamma knife radiosurgery for jugular foramen schwannomas
Authors: Zhang Nan , Pan Li , Dai Jia Zhong , Wang Bin Jiang , Wang En Min , Cai Pei Wu
Published: November 2018

Object. The purpose of this study was to evaluate the effect on tumor growth and symptom relief in patients with jugular foramen schwannomas after undergoing gamma knife radiosurgery (GKS).

Methods. Between November 1993 and December 2000, 27 patients were treated for jugular foramen schwannomas. The results of GKS in these cases are reviewed. Twelve patients had undergone previous tumor resection and the others underwent GKS as their primary treatment. The mean tumor volume was 13.5 cm3 (range 4.7–35.7 cm3). The mean margin dose was 14.6 Gy (range 9.8–20 Gy). The mean maximum dose was 32.6 Gy (range 25.4–50 Gy). The prescription isodose was 35 to 55%. Twenty-five patients were followed for a mean period of 38.7 months (range 9–90 months). Tumors shrank in 11 patients, remained stable in 13, and enlarged in one patient who underwent a second GKS procedure. Sixteen patients improved and nine remained at their pre-GKS clinical status. No patient developed new cranial nerve deficits after GKS.

Conclusions. The follow-up results indicate that GKS is a safe and effective primary or adjuvant treatment method for the control of jugular foramen schwannomas.
Gamma knife radiosurgery for renal cell carcinoma brain metastases
Authors: Hernandez Laura , Zamorano Lucia , Sloan Andrew , Fontanesi James , Lo Simon , Levin Kenneth , Li Qinghang , Diaz Fernando
Published: November 2018

Object. The purpose of this study was to clarify the effectiveness of gamma knife radiosurgery (GKS) in achieving a partial or complete remission of so-called radioresistant metastases from renal cell carcinoma (RCC) and to propose guidelines for optimal treatment

Methods. During a 5-year period, 29 patients (19 male and 10 female) with 92 brain metastases from RCC underwent GKS. The median tumor volume was 4.7 cm3 (range 0.5–14.5 cm3). Fourteen patients (48%) also underwent whole-brain radiotherapy (WBRT) before GKS, and two patients (6.8%) after GKS. The mean GKS dose delivered to the 50% isodose at the tumor margin was 16.8 Gy (range 13–30 Gy). All cases were categorized according to the Recursive Partitioning Analysis (RPA) classification for brain metastases. Univariate analysis was performed to determine significant prognostic factors and survival.

The overall median survival was 7 months after GKS treatment. Age, sex, Karnofsky Performance Scale score, and controlled primary disease were not predictors of survival. Combined WBRT/GKS resulted in median survival of 18, 8.5, and 5.3 months for RPA Classes I, II, and III, respectively, compared with the median survival 7.1, 4.2, and 2.3 months for patients treated with WBRT alone.

Conclusions. These results suggest that WBRT combined with GKS may improve survival in patients with brain metastases from RCC. Furthermore, this improvement in survival was seen in all RPA classes.
Gamma knife radiosurgery and brain metastases: local control, survival, and quality of life
Authors: Vesagas Theodor S. , Aguilar Jose A. , Mercado Eduardo R. , Mariano Manuel M.
Published: November 2018

Object. The purpose of this paper was to describe the clinical outcome in patients with brain metastases who underwent gamma knife radiosurgery (GKS).

Methods. The authors retrospectively reviewed the clinical courses of 54 patients with brain metastases who underwent 62 GKS procedures. This series covered a 43-month period. A total of 174 lesions were treated: 38 patients harbored solitary whereas 24 patients harbored multiple metastases. The authors assessed outcome by examining local disease control, survival, and quality of life.

The overall local control rate was 85%; the mean time to failure of local control was 10.5 months; and median survival was 8.4 months. Median survival, evaluated by the log-rank test, was greater among patients with a single metastasis (p = 0.043), breast cancer (p = 0.021), and those who had undergone multiple GKS procedures for local failure (p = 0.009). The initial Karnofsky Performance Scale (KPS) score and whole-brain radiotherapy were not significantly related to median survival. The KPS scores tended to remain stable through the follow-up period. There were no morbidities or deaths attributable to the procedure.

Conclusions. Results in this series suggest that GKS can be an effective tool for the control of brain metastases. A prospective investigation should be performed to validate trends seen in this retrospective study.
A new magnetic resonance head coil and head immobilization device for gamma knife radiosurgery: an analysis of geometric distortion and signal/noise characteristics
Authors: Jursinic Paul , Prost Robert , Schultz Christopher
Published: November 2018

Object. The authors report on a new head coil into which the Leksell aluminum localization frame can be easily and securely mounted. Mechanically, the head coil interferes little with the patient.

Methods. The head coil, which is for magnetic resonance (MR) imaging, is a 12-element quadrature transmitand-receive high-pass birdcage coil with a nominal operation frequency (63.86 MHz). The coil was built into a plastic housing.

This new head coil minimizes patient motion and provides a 20% increase in signal/noise ratios compared with standard head coils. An MR image test phantom was mounted in the coil and this allowed quantification of image distortion due to inhomogeneities in the main magnetic field, nonlinearity in the gradient field, and paramagnetism of the aluminum headframe. There were no significant differences in geometric distortion between the new head coil and the standard coil.

Conclusions. The new head coil has advantages for reducing patient movement artifacts and has a better signal/noise ratio with no reduction in geometric accuracy.
The clinical application of plugging patterns for the Leksell gamma knife
Authors: Vaughan Paul , Hampshire Anna , Soanes Tracy , Kemeny Andras , Radatz Matthias , Rowe Jeremy , Walton Lee
Published: November 2018

Object. In this report the authors explore the use of standardized plugging templates in formulating stereotactic radiosurgery dose plans for the Leksell gamma knife.

Methods. Unplugged gamma knife dose plans previously used in the treatment of patients with trigeminal neuralgia (TN) and vestibular schwannoma (VS) were studied. Standardized plugging templates were then superimposed on these plans, and their effects on the conformity index of tumors and the transposition of the radiation field from the brainstem to the cerebrospinal fluid spaces for the trigeminal cases were examined.

Conclusions. The standardized plugging templates significantly increased the conformity indices in cases of VS plans and for TN. Plugging significantly reduced the brainstem exposure to radiation while at the same time not altering the length of the trigeminal nerve being treated. Standardized plugging templates may therefore be a useful tool in optimizing dose plans.
Three-dimensional dose verification using BANG gel: a clinical example
Authors: Scheib Stefan G. , Gianolini Stefano
Published: November 2018

Object. The authors sought to demonstrate the possible value of three-dimensional dose verification by using gel dosimetry.

Methods. In this study, commercially available BANG—25 Gy gel was used. This polymer gel is tissue equivalent and the relaxation rate (R2) measured using magnetic resonance (MR) imaging is proportional to the absorbed dose in the gel. A cylindrical container filled with BANG was mounted within an anthropomorphic head phantom and was handled using the same process as would be used for a patient undergoing gamma knife radiosurgery (GKS). An irregular target outline was constructed and a dose plan was created consisting of seven shots, three using the 8-mm and four using the 4-mm collimator helmet. The maximum dose specified was 25 Gy. A combination of several single spin-echo MR imaging sequences with different echo times was used to calculate the R2. The geometric resolution of the MR images was approximately 1 mm3. To compare the measured dose distribution with the calculated one, isodoses were overlaid in three orthogonal planes by using specially designed analysis software.

Conclusions. Comparisons of the measured and calculated relative dose distributions showed good overall agreement, with differences of less than 3 mm between measured and calculated isodoses.

High resolution BANG gel dosimetry for GKS can be useful for the verification of clinical treatment plans, especially when multiple shots are involved. Further verifications will be done using additional imaging parameters and absolute dose calibrations to improve the method.
Impact of the model C and Automatic Positioning System on gamma knife radiosurgery: an evaluation in vestibular schwannomas
Authors: Régis Jean , Hayashi Motohiro , Porcheron Denis , Delsanti Christine , Muracciole Xavier , Peragut Jean Claude
Published: November 2018

Object. The technical advances associated with the model C gamma knife include a robotized system enabling automatic positioning of the stereotactic coordinates. The purpose of this study was to analyze the clinical impact of this technical modification.

Methods. The authors studied a sample of patients with vestibular schwannoma (VS). This sample included three groups treated using gamma knife radiosurgery. Group I comprised 21 patients with VS treated just before the installation of the Automatic Positioning System (APS). Group II included patients in Group I with new dose plans created using the APS (in other words, simulated dose plans). Group III consisted of a control group of 20 patients matched for tumor grade with the previous group and treated recently with the APS. Treatment times were calculated after correcting the time for each shot according to the age of the sources after reloading. The treatment times, including total time, irradiation time, and duration of the neurosurgical procedure, were analyzed. In addition, dose planning including number of isocenters, number of different collimators, malfunctions, and the conformity and selectivity indices were recorded.

The trend was to reduce the mean number of collimator runs from 7.9 to 1.2 and to increase the mean number of shots from 7.9 to 15.6, mostly by using the 4-mm collimator exclusively. The APS-related conformity and selectivity were improved from 95 to 97% and from 78 to 84%, respectively. The total treatment time was reduced by 53%, and time required to interact with the patient in the room was considerably reduced (75%), giving the neurosurgeon greater freedom to perform other tasks during the treatment period. The reduction of the time spent by the neurosurgeon at work in the room was 84%. The total radiation time was increased by 54%.

Conclusions. The preliminary results of this study indicate that the robotization of the gamma knife is likely a major advance in radiosurgery.
High- compared with low-dose radiosurgery for uveal melanomas
Authors: Langmann Gerald , Pendl Gerhard , Müllner Klaus , Feichtinger K. H. , Papaefthymiouaf Georg
Published: November 2018

Object. The authors compared the results of gamma knife radiosurgery in patients with uveal melanoma who underwent high-dose (treated from 1992–1995) and low-dose irradiation (treated from 1996–2002).

Methods. Thirty-one patients with uveal melanomas were treated with a mean margin dose of 52.1 Gy (high dose) and 33 with a mean dose of 41.5 Gy (low dose), and results were compared between groups. The technical procedure was the same in each group except for radiation dose.

In the low-dose group, complete tumor regression (scar formation) occurred in 12% and in the high-dose group in 26%. Partial regression (reduction of the tumor prominence between 50 and 80%) occurred in 81% of the low-dose group and in 58% of the high-dose group.

Neovascular glaucoma as a severe complication developed in 9% of the low-dose group and in 48% of the high-dose group.

Conclusions. Reduction of the margin dose from 52.1 to 41.5 Gy appears to achieve the same rate of tumor regression but is associated with a lower rate of severe side effects such as neovascular glaucoma. The follow-up period in the lowdose group, however, was much shorter.
Intratumoral bleeding in meningioma after gamma knife radiosurgery
Authors: Kwon Yang , Ahn Jae Sung , Jeon Sang Ryong , Kim Jeong Hoon , Kim Chang Jin , Lee Jung Kyo , Kwun Byung Duk , Lee Do Hee , Kim Sun Young
Published: November 2018

Object. The authors evaluated whether gamma knife radiosurgery (GKS) could be a causative factor in intratumoral bleeding in meningiomas.

Methods. Gamma knife radiosurgery was used in the treatment of 173 meningiomas during a 10-year period. Four patients suffered post-GKS intratumoral hemorrhage. The course in these patients was reviewed.

Four of 173 patients suffered an intratumoral hemorrhage during a follow-up period of 1 to 8 years. The risk of intratumoral bleeding after GKS for meningioma was 2.3%. Intracystic hemorrhage occurred in two patients 1 and 5 years, respectively, after radiosurgery. In the other two cases intratumoral bleeding occurred 2 and 8 years, respectively, after radiosurgery. Histological examination in three cases found no specific findings related to the postradiosurgical changes.

Conclusions. Because the reported risk of spontaneous intratumoral bleeding in meningiomas is 1.3 to 2.7%, the incidence in this series was not unduly high. Radiosurgery itself could not be shown to be a significant factor in the development of the intratumoral bleeding.
Gamma knife radiosurgery for pilocytic astrocytomas
Authors: Boëthius Jörgen , Ulfarsson Elvar , Ráhn Tiit , Lippitz Bodo
Published: November 2018

Object. The authors report on the follow-up studies in patients treated at the Karolinska Hospital to evaluate the efficacy of gamma knife radiosurgery (GKS) for pilocytic astrocytoma.

Methods. Twelve male and seven female patients were treated (mean age 10.6 years [range 2–60 years]). Sixteen of these patients were children in whom GKS was performed to treat residual tumor after surgery. Most tumors were treated with a prescription dose of 10 to 12 Gy (range 9–20 Gy). The corresponding maximum dose varied between 22 and 30 Gy (range 10–50 Gy). The median clinical follow-up time was 7 years and mean clinical follow-up time 8.5 years. Median radiological follow-up time was 4.7 years and the mean radiological follow-up time was 5.9 years.

Tumor control was achieved in all patients. In 85% of the cases a moderate tumor volume reduction was observed after GKS. This result occurred despite the low prescription dose administered. The radiological follow-up studies showed adverse radiation effects in 25% of patients with increasing contrast enhancement and some edema. These effects generally appeared within 7 months and resolved later. Cyst development occurred in two patients, which may have been treatment related.

Conclusions. It appears that small pilocytic astrocytomas may be treated with low-prescription-dose GKS, resulting in satisfactory clinical outcomes and only minor side effects. There were a certain number of radiologically demonstrated side effects that appeared relatively early but subsequently resolved. This study should be regarded as a preliminary one because the number of patients is small and the follow-up period is short compared with the natural time course of the disease.
Gamma Knife surgery of vestibular schwannomas: longitudinal changes in vestibular function and measurement of the Dizziness Handicap Inventory
Authors: Wackym P. Ashley , Hannley Maureen T. , Runge-Samuelson Christina L. , Jensen Jamie , Zhu Yong-Ran
Published: November 2018

Object

Gamma Knife surgery (GKS) is one of the methods available to treat vestibular schwannomas (VSs), in addition to microsurgical resection; however, clear information regarding balance function outcomes and the impact of treatment on patients' quality of life over time remains an important clinical need. The purpose of this study was to assess the longitudinal balance outcomes and Dizziness Handicap Inventory (DHI) following GKS for VSs.

Methods

This was a prospective clinical study of balance outcomes in all patients with VSs treated in the Acoustic Neuroma and Skull Base Surgery Program at a tertiary referral center by the senior author and the Gamma Knife team between June 2000 and May 2008. The main outcome measures included preoperative vestibular testing and postoperative caloric testing performed at 6-month intervals to determine vestibular function. The DHI questionnaires were administered retrospectively to assess the impact of GKS on self-perceived disability.

Results

Between June 2000 and May 2008, 55 sporadic VSs were treated. There was a ≥ 60-month follow-up available in 27 of these patients, ≥ 48 months in 32, ≥ 36 months in 38, ≥ 24 months in 43, ≥ 12 months in 51, and ≥ 6 months in 54 (1 patient was excluded from the analysis because the follow-up was < 6 months). Various patterns of changes in vestibular function were observed in either positive or negative directions. A significant difference in total DHI score was seen only in the elderly (> 65 years old) patients pre-GKS compared with post-GKS (t = 1.34, p = 0.05).

Conclusions

Longitudinal changes in vestibular function occur over time, with the largest changes seen in the first 6 months after treatment. Potential for clinical intervention, such as vestibular rehabilitation therapy, exists during this interval; however, larger cohorts must be studied to determine the timing and efficacy of this intervention. The statistically significant improvement in the DHI score in the patient cohort > 65 years old treated with GKS suggests that this group may benefit from this option when considering the symptom of dizziness.
Gamma Knife surgery for trigeminal pain caused by benign brain tumors
Authors: Huang Chuan-Fu , Tu Hsien-Tang , Liu Wen-Shan , Lin Long-Yau
Published: November 2018

Object

The authors report the effects of Gamma Knife surgery (GKS) on benign tumor–related trigeminal pain in patients who underwent follow-up for a mean 57.8 months.

Methods

From 1999 to 2004, 21 patients with benign tumor–related trigeminal pain (12 meningiomas and 9 schwannomas) underwent GKS as a primary or repeated treatment. These patients harbored tumors within the radiosurgical target area. For meningiomas, the mean radiosurgical treatment volume was 8.2 ml (range 1.1–21 ml), and the mean radiosurgical tumor margin dose was 12.7 Gy (range 12–15 Gy); for schwannomas, the mean volume was 5.6 ml (range 2–9.2 ml), and the mean marginal dose was 13 Gy (range 11.5–16 Gy). Seven patients underwent retreatment for recurrent or persistent pain; the ipsilateral trigeminal nerve or ganglion was identified and a mean maximal dose of 60.7 Gy (range 40–70 Gy) was delivered to these targets. In 1 patient undergoing retreatment, the margin dose was 12 Gy. The mean age at the time of radiosurgery was 54.5 years (range 18–79 years).

Results

The mean follow-up period was 57.8 months (range 36–94 months). Overall, 12 (57%) of 21 patients experienced pain relief without medication after the first GKS and the mean time to drug discontinuation was 10.5 months (range 2–24 months). Initial pain improvement was noted in 17 patients (81%) with a mean time of 3.7 months (range 1 week–10 months) after GKS. Eight patients underwent repeated GKS for persistent and recurrent pain. Four patients (50%) had complete pain relief. The final results of the first and repeated GKS were excellent in 16 patients (76%), and in only 1 patient did GKS fail, and this patient later underwent open surgery. For all 21 patients (100%), control of tumor growth was documented at a mean of 46 months after GKS. Three of 6 patients with pre-GKS facial numbness reported improvement, but 4 suffered new facial numbness after repeated GKS.

Conclusions

Gamma Knife surgery appears to be an effective tool to treat benign tumor–related trigeminal pain and control tumor growth. Repeated GKS targeting the trigeminal root or ganglion can be considered a tool to enhance the efficacy of pain management if pain persists or recurs, but the optimum treatment dose needs further investigation.
Virtual framing: the feasibility of frameless radiosurgical planning for the Gamma Knife
Authors: Giller Cole A. , Fiedler Jeffrey A.
Published: November 2018

Object

Gamma Knife (GK) treatments are typically delivered in 1 day with little opportunity to test different planning strategies. The authors demonstrate 2 methods for imposing GK coordinate systems upon imaging datasets without frame attachment to allow leisurely preprocedural planning, and discuss potential applications.

Methods

A “virtual framing” is constructed by coregistering a CT scan of a Leksell frame with a patient dataset using the GammaPlan (Multiview) module. Equations for skull radii are derived by approximating the skull as an ellipsoid. No proprietary software other than that of the GK system is required. In a second method, images of fiducial markers are directly superimposed on the patient dataset. Validation of the first method was achieved by comparing the lengths of 75 line segments and 60 single shot diameters measured in the virtual coordinates with those measured in real coordinates. In addition to preplanning, 2 applications are discussed. The first is the use of GK software to aid radiosurgical planning for other devices. The second is the use of virtual framing to enhance automatic optimization algorithms.

Results

Mean (± standard deviation) and root-mean-square differences in lengths were 0.18 ± 0.32 and 0.37 mm. Mean and root-mean-square differences in diameters of single-shot plans were 0.01 ± 0.18 and 0.18 mm.

Conclusions

Virtual framing allows exploration of radiosurgical planning strategies prior to the day of treatment using only the GK software. Other applications include enhancement of radiosurgical planning for other systems and enhancement of optimization algorithms.
Neurosurgical data bases
Authors: Foulkes Mary A.
Published: November 2018

✓ Prospectively collected data bases are discussed with particular reference to neurosurgical data. The objectives, design, and collection of data bases are detailed. Statistical issues that relate to the analysis of these data bases are reviewed, with examples from the National Institute of Neurological Disorders and Stroke-supported Traumatic Coma Data Bank. The utility and limitations of data base inferences are considered.
Verbal learning deficits following severe head injury: heterogeneity in recovery over 1 year
Authors: Ruff Ronald M. , Young David , Gautille Theresa , Marshall Lawrence F. , Barth Jeff , Jane John A. , Kreutzer Jeff , Marmarou Anthony , Levin Harvey S. , Eisenberg Howard M. , Foulkes Mary A.
Published: November 2018

✓ A total of 40 severely head-injured patients were selected from the Traumatic Coma Data Bank, supported by the National Institute of Neurological Disorders and Stroke, to analyze the recovery of verbal learning across baseline and 6- and 12-month evaluations postinjury. During the initial 6 months, the group demonstrated marked recovery, followed by an absence of improvement over the latter part of the year. Analysis of this recovery curve on a case by case basis revealed three recovery subtypes: namely, a flat curve, a peak-drop curve, or an improvement curve. These three subtypes proved to have concurrent validity when compared with another memory test. Adding 19 new patients to the sample cross-validated the subtypes. However, the memory performance of the 59 patients was dissociated from other neuropsychological tests which showed recovery at more equivalent rates across the subtypes. Analysis of the demographic and neurological characteristics disclosed that the group with a peak-drop recovery curve was less well educated and the group with a flat curve demonstrated a trend toward higher levels of hypoxia. Moreover, the three subgroups were rated by their relatives to have equivalent levels of depression at baseline and at 6 months, but only the improved subgroup demonstrated reduced depression at 1 year. The clinical relevancy of these differential recovery curves is discussed.
Does new magnetic resonance imaging technology provide better geometrical accuracy during stereotactic imaging?
Authors: Novotny Josef , Vymazal Josef , Novotny Josef , Tlachacova Daniela , Schmitt Michal , Chuda Pavel , Urgosik Dusan , Liscak Roman
Published: November 2018

Object. The authors sought to compare the accuracy of stereotactic target imaging using the Siemens 1T EXPERT and 1.5T SYMPHONY magnetic resonance (MR) units.

Methods. A water-filled cylindrical Perspex phantom with axial and coronal inserts containing grids of glass rods was fixed in the Leksell stereotactic frame and subjected to MR imaging in Siemens 1T EXPERT and Siemens 1.5T SYMPHONY units. Identical sequences were used for each unit. The images were transferred to the GammaPlan treatment planning system. Deviations between stereotactic coordinates based on MR images and estimated real geometrical positions given by the construction of the phantom insert were evaluated for each study. The deviations were further investigated as a function of the MR unit used, MR sequence, the image orientation, and the spatial position of measured points in the investigated volume.

Conclusions. Larger distortions were observed when using the SYMPHONY 1.5T unit than those with the EXPERT 1T unit. Typical average distortion in EXPERT 1T was not more than 0.6 mm and 0.9 mm for axial and coronal images, respectively. Typical mean distortion for SYMPHONY 1.5T was not more than 1 mm and 1.3 mm for axial and coronal images, respectively. The image sequence affected the distortions in both units. Coronal T2-weighted spin-echo images performed in subthalamic imaging produced the largest distortions of 2.6 mm and 3 mm in the EXPERT 1T and SYMPHONY 1.5T, respectively. Larger distortions were observed in coronal slices than in axial slices in both units, and this effect was more pronounced in SYMPHONY 1.5T. Noncentrally located slice positions in the investigated volume of the phantom were associated with larger distortions.
Long-term complications after gamma knife surgery for arteriovenous malformations
Authors: Izawa Masahiro , Hayashi Motohiro , Chernov Mikhail , Nakaya Koutarou , Ochiai Taku , Murata Noriko , Takasu Yuichi , Kubo Osami , Hori Tomokatsu , Takakura Kintomo
Published: November 2018

Object. The authors analyzed of the long-term complications that occur 2 or more years after gamma knife surgery (GKS) for intracranial arteriovenous malformations (AVMs).

Methods. Patients with previously untreated intracranial AVMs that were managed by GKS and followed for at least 2 years after treatment were selected for analysis (237 cases). Complete AVM obliteration was attained in 130 cases (54.9%), and incomplete obliteration in 107 cases (45.1%). Long-term complications were observed in 22 patients (9.3%). These complications included hemorrhage (eight cases), delayed cyst formation (eight cases), increase of seizure frequency (four cases), and middle cerebral artery stenosis and increased white matter signal intensity on T2-weighted magnetic resonance imaging (one case of each). The long-term complications were associated with larger nidus volume (p < 0.001) and a lobar location of the AVM (p < 0.01). Delayed hemorrhage was associated only with incomplete obliteration of the nidus (p < 0.05). Partial obliteration conveyed no benefit. Delayed cyst formation was associated with a higher maximal GKS dose (p < 0.001), larger nidus volume (p < 0.001), complete nidus obliteration (p < 0.01), and a lobar location of the AVM (p < 0.05).

Conclusions. Incomplete obliteration of the nidus is the most important factor associated with delayed hemorrhagic complications. Partial obliteration does not seem to reduce the risk of hemorrhage. Complete obliteration can be complicated by delayed cyst formation, especially if high maximal treatment doses have been administered.
Gamma knife surgery for arteriovenous malformations involving the corpus callosum
Authors: Maruyama Keisuke , Shin Masahiro , Tago Masao , Kurita Hiroki , Kawamoto Shunsuke , Morita Akio , Kirino Takaaki
Published: November 2018

Object. The purpose of this study was to evaluate the safety and efficacy of gamma knife surgery (GKS) for the treatment of arteriovenous malformations (AVMs) involving the corpus callosum.

Methods. Thirty-two patients aged from 7 to 65 years (median 25 years) with AVMs of the corpus callosum underwent GKS between 1990 and 2002. The maximum AVM diameter was more than 3 cm in 11 patients (34%). The AVM volume ranged from 0.1 to 19.1 cm3 (median 1.6 cm3). The median dose to the AVM margin was 20 Gy (range 17–28 Gy). Patients were followed for 1 to 12 years (median 9 years). The angiographically confirmed actuarial obliteration rate was 64% and 74% at 4 and 6 years, respectively. Younger patient age (p < 0.05) and lower radiosurgery-based grading score (calculated from the patient age and AVM volume; p < 0.01) were the significant factors affecting successful AVM obliteration. No patient suffered a hemorrhage after GKS, although 28 patients (88%) had a history of hemorrhage from their AVMs. Radiation-induced neurological deficit was observed only in one patient (3%) who had undergone previous radiotherapy (50 Gy). No patient experienced complications of occlusion or stenosis of the normal vascular structures adjacent to the AVM.

Conclusions. Gamma knife surgery is a safe and effective treatment for selected patients with AVMs involving the corpus callosum, and it carries a low risk of damaging adjacent critical vascular structures. Even ruptured AVMs with relatively large diameter can be successfully treated, especially in younger patients, with minimal morbidity and a low risk of repeated hemorrhage.