bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thalamic lesions produced by gamma thalamotomy for movement disorders
Authors: Ohye Chihiro , Shibazaki Tohru , Zhang Jie , Andou Yoshitaka 
Published: November 2018

Object. The treatment of Parkinson disease and other kinds of involuntary movement by gamma knife radiosurgery (GKS) is presented. This is an extension of previous work. The clinical course and thalamic lesions were the main factors examined.
Methods. Seventeen new cases were added to the previously reported 36 cases. The course and results for the whole series of 53 patients were examined. Treatment was undertaken using a single 4-mm collimator shot to deliver 130 Gy to the target. The target was determined in the previously treated patients by using classic methods involved in conventional stereotactic thalamotomy with microrecording. More recently, target localization has been performed by relating the target point to the total length of the thalamus. Points may then be defined as percentages of that length measured from the anterior pole. Targets can then be determined in relationship to the appropriate percentage.
Thirty-five patients have been followed for more than 2 years and the longest follow up was 8 years. Two kinds of thalamic lesion were seen after GKS. Volumetric analysis on MR imaging revealed that the larger lesion was 400 to 500 mm3 at the beginning and gradually decreased in size. The smaller lesion occupied approximately 200 mm3 and also shrank over several months. Eighty percent of the treated cases showed good results and no significant complications, with the tremor subsiding at 1 year (Type 1). Several cases deviated from this standard course in four different ways (Types 2–5). If tremor persisted, conventional stereotactic thalamotomy with microrecording was performed. During such operations, normal neuronal activity was recorded from the region adjacent to the GKS thalamotomy target. This was the region showing a high signal on MR imaging. The activity patterns included the rhythmical grouped discharge of tremor rhythm.
Conclusions. Gamma thalamotomy for functional disorders is still under development, but because the results with careful target planning are satisfactory, there are grounds for increasing optimism.
Leksell gamma knife treatment of uveal melanoma
Authors: s˘imonová Gabriela , Novotný Josef , Lis˘c˘ák Roman , Pilbauer Jir˘í 
Published: November 2018

Object. The purpose of this study was to analyze treatment results, radiation-induced side effects, and prognostic survival factors for patients with uveal melanoma.
Methods. Eighty-one patients with uveal melanoma were treated using the Leksell gamma knife during a period of 6 years (1996–2001). There were 45 men and 36 women with a median age of 59 years (range 22–85 years). Seventyfive of these patients underwent minimal follow up 10 months after treatment. After patient eye immobilization, magnetic resonance (MR) imaging was performed to enable stereotactic localization. A scoring system was used to measure radiation side effects. The median target volume was 640 mm3, and the median applied minimal dose was 31.4 Gy. All patients were examined by an ophthalmologist and with MR imaging at regular intervals. Factors influencing posttreatment survival and side effects were statistically analyzed.
Conclusions. Local tumor control in the 75 patients who underwent minimal follow up after 10 months was achieved in 63 patients (84%), whereas progression was observed in 12 patients (16%). The most frequent side effect was secondary glaucoma, which was detected in 18 patients (25%). The incidence of this side effect was significantly higher when the total volume of peripheral isodose was greater than 1000 mm3 (p = 0.015). Toxicity in the optic nerve here was also significantly higher when the maximum dose to this structure was higher than 9 Gy (p = 0.011), in the cornea when the maximum dose was higher than 15 Gy (p = 0.010), and in the lens when the maximum dose was higher than 10 Gy (p = 0.035). Altogether three pretreatment variables (patient age, tumor location, and dissemination of the disease) and one treatment variable (the minimum dose applied) were identified as having a significant influence on a patient's survival.
Evaluation of gamma knife radiosurgery in the treatment of oligodendrogliomas and mixed oligodendroastrocytomas
Authors: Sarkar Atom , Pollock Bruce E. , Brown Paul D. , Gorman Deborah A. 
Published: November 2018

Object. Radiosurgery is commonly used for the treatment of patients with glioma. The goal of this study was to evaluate the safety and efficacy of radiosurgery in the management of patients with oligodendrogliomas (ODGs) or mixed oligoastrocytomas (OGAs).
Methods. A retrospective chart review of patients treated between May 1990 and January 2000 identified 18 patients (21 tumors) with either an ODG (10) or a mixed OGA (11) who had undergone radiosurgery. The median patient age was 43 years (range 23–67 years). Sixteen patients had undergone one or more tumor resections before radiosurgery; in two patients biopsy sampling alone had been performed. Tumor grades at the most recent operation were Grade 1 (one), Grade 2 (one), Grade 3 (12), and Grade 4 (seven patients). Seventeen patients had undergone prior radiotherapy; 11 were treated with chemotherapy before radiosurgery, and one had undergone a prior linear accelerator—based radiosurgery treatment. The median tumor volume was 8.2 cm3 (range 1.9–47.7 cm3); the median margin dose was 15 Gy (range 12–20 Gy); and the median maximum dose was 32 Gy (range 24–50 Gy).
In this heterogeneous group, 12 patients died whereas six remain alive. Survival after radiosurgery was 78%, 61%, and 44% at 12, 24, and 48 months, respectively. Factors associated with an improved survival rate included younger age and smaller tumors.
Conclusions. For patients with oligoastroglial tumors that have failed to respond to conventional therapies, radiosurgery may provide some survival benefit. Further study is needed to determine which subpopulation of these patients will have the best chances of enhanced survival from this treatment.
Gamma Knife surgery for metastatic brain tumors
Authors: Serizawa Toru , Yamamoto Masaaki , Nagano Osamu , Higuchi Yoshinori , Matsuda Shinji , Ono Junichi , Iwadate Yasuo , Saeki Naokatsu 
Published: November 2018

Object
The authors compared results of Gamma Knife surgery (GKS) for brain metastases obtained at 2 institutions in Japan.

Methods
They analyzed a consecutive series of 2390 patients with brain metastases who underwent GKS from 1998 through 2005 in 2 institutes (1181 patients in Chiba; 1209 in Mito). In the 2 facilities, 1 neurosurgeon each was responsible for diagnosis, patient selection, GKS procedures, and follow-up (T.S. in Chiba, M.Y. in Mito). Even if tumor numbers exceeded 4, all visible lesions were irradiated with a total skull integral dose (TSID) of ≤ 10–12 J. No prophylactic whole-brain radiotherapy (WBRT) was applied. If new distant lesions were detected, salvage GKS was appropriately performed.

Results
The distributions of patient and treatment factors did not differ between institutes. The most common primary tumors were lung cancer (1572 patients), followed by gastrointestinal tract (316), breast (211), kidney (113), and other cancers (159). The median survival periods were 7.7 months in Chiba and 7.0 months in Mito (p = 0.0635). The significant poor prognostic factors for overall survival were active extracranial disease status, male sex, and low initial Karnofsky Performance Scale score on multivariate analysis (all p < 0.0001). The neurological survival rates at 1 year were 86.6% in Chiba and 84.2% in Mito (p = 0.3310).

Conclusions
This 2-institute study demonstrated no significant institutional differences in any of the treatment result items. Gamma Knife surgery for brain metastases without prophylactic WBRT prevents neurological death and allows a patient to maintain good brain condition. However, there is 1 important patient selection criterion: regardless of how many tumors there are, all lesions can be irradiated with a TSID of ≤12 J.
Complications of Gamma Knife surgery: an early report from 2 Canadian centers
Authors: Vachhrajani Shobhan , Fawaz Charbel , Mathieu David , Ménard Cynthia , Cusimano Michael D. , Gentili Fred , Hodaie Mojgan , Kenny Brendan , Kulkarni Abhaya V. , Laperriere Normand , Schwartz Michael , Tsao May , Bernstein Mark 
Published: November 2018

Object
Gamma Knife surgery (GKS) is used to treat benign and malignant brain tumors, arteriovenous malformations, trigeminal neuralgia, and other conditions. Patients experience reduced neurological morbidity from GKS compared with open microneurosurgery, but risks of radiation injury and technical limitations persist. The authors report treatment complications from the early experience of 2 Canadian GKS programs in Toronto and Sherbrooke.

Methods
In Toronto, a prospective administrative database was searched for adverse events and incomplete treatment administrations. In Sherbrooke, data were acquired by chart review. Patients were accrued until August 1, 2007, and a total of 973 patients were included in this report.

Results
During the radiosurgical procedure, 19 patients (2%) suffered anxiety or syncopal episodes, and 2 patients suffered acute coronary events. Treatments were incompletely administered in 12 patients (1.2%). Severe pain was a delayed complication: 8 patients suffered unexpected headaches, and 9 patients developed severe facial pain. New motor deficits developed in 11 patients, including edema-induced ataxia in 4 and one case of facial weakness after treatment of a vestibular schwannoma. Four patients required shunt placement for symptomatic hydrocephalus, and 16 patients suffered delayed seizures.

Conclusions
Gamma Knife surgery is a minimally invasive treatment modality for many intracranial diseases. Treatment is not risk free, and some patients will develop complications; these are likely to decrease as institutional experience matures. Expanding availability and indications necessitate discussion of these risks with patients considering treatment.
Dosimetric comparison of the Leksell Gamma Knife Perfexion and 4C
Authors: Novotny Josef , Bhatnagar Jagdish P. , Niranjan Ajay , Quader Mubina A. , Huq M. Saiful , Bednarz Greg , Flickinger John C. , Kondziolka Douglas , Lunsford L. Dade 
Published: November 2018

Object
The recently introduced Leksell Gamma Knife (LGK) Perfexion is an entirely new system with a different beam geometry compared with the LGK 4C. The new Perfexion system has 192 cobalt-60 sources that are fixed on 8 sectors (each sector has 24 sources). Each sector can be moved independently of the others and can be set to 1 of 5 different positions: 3 positions defining collimator sizes of 4, 8, and 16 mm; an off position (sources are blocked); and a home position. The purpose of this study is to compare the dosimetric characteristics of the GK 4C and the Perfexion models. This comparison is important especially for the treatment of functional disorders when only a single shot with the 4- or 8-mm collimator is used.

Methods
A 160-mm-diameter spherical polystyrene phantom was used for all measurements and calculations. The irradiation geometry consisted of the placement of a single shot at the center of this phantom. Comparisons were made among different dosimetric parameters obtained from calculations performed using Leksell GammaPlan v. 8.0 and measurements performed using film dosimetry. The dosimetric parameters investigated were dose profiles for all collimators in all 3 stereotactic planes (x, y, and z) including the full width at half maximum and the penumbra for each profile, cumulative dose–volume histograms, the volume encompassed by the 50% isodose surface, the mean doses delivered to a defined matrix volume, and relative output factors for all collimator sizes.

Results
There was excellent agreement between the dosimetric parameters of GK 4C and Perfexion for the 4- and 8-mm collimators.

Conclusions
The results of this study suggest that consistent treatments of functional disorders will be delivered using either GK 4C or Perfexion.
Treatment of essential trigeminal neuralgia with gamma knife surgery
Authors: Urgosik Dusan , Liscak Roman , Novotny Josef , Vymazal Josef , Vladyka Vilibald 
Published: November 2018

Object. The authors present the long-term follow-up results (minimum 5 years) of patients with essential trigeminal neuralgia (TN) who were treated with gamma knife surgery (GKS).
Methods. One hundred seven patients (61 females and 46 males) underwent GKS. The median follow up was time was 60 months (range 12–96 months). The target was the trigeminal root, and the maximum dose was 70 to 80 Gy. Repeated GKS was performed in 19 patients for recurrent pain, and the same dose was used.
Initial successful results were achieved in 96% of patients, with complete pain relief in 80.4%. Relief was achieved after a median latency of 3 months (range 1 day–13 months). Gamma knife surgery failed in 4% of patients. Pain recurred in 25% of patients after a median latent interval of 36 months (6–94 months). The initial success rate after a second GKS was 89% and 58% of patients were pain free. Pain relapse occurred in only one patient in this group. Hypesthesia was observed in 20% of patients after the first GKS and in 32% after the second GKS. The median interval to hypaesthesia was 35 months (range 3–94 months) after one treatment and 21 months (range 1–72 months) after a second treatment.
Conclusions. The initial success rate of pain relief was high and comparable to that reported in other studies. A higher than usual incidence of sensory impairment after GKS could be the long duration of follow-up study and due to the detailed neurological examination.
Gamma knife surgery of the pituitary: new treatment for thalamic pain syndrome
Authors: Hayashi Motohiro , Taira Takaomi , Ochiai Taku , Chernov Mikhail , Takasu Yuichi , Izawa Masahiro , Kouyama Nobuo , Tomida Mihoko , Tokumaru Osamu , Katayama Yoko , Kawakami Yoriko , Hori Tomokatsu , Takakura Kintomo 
Published: November 2018

Object. Although reports in the literature indicate that thalamic pain syndrome can be controlled with chemical hypophysectomy, this procedure is associated with transient diabetes insipidus. It was considered reasonable to attempt gamma knife surgery (GKS) to the pituitary gland to control thalamic pain.
Methods. Inclusion criteria in this study were poststroke thalamic pain, failure of all other treatments, intolerance to general anesthetic, and the main complaint of pain and not numbness. Seventeen patients met these criteria and were treated with GKS to the pituitary. The target was the pituitary gland together with the border between the pituitary stalk and the gland. The maximum dose was 140 to 180 Gy. All patients were followed for more than 3 months.
Conclusions. An initial significant pain reduction was observed in 13 (76.5%) of 17 patients. Some patients experienced pain reduction within 48 hours of treatment. Persistent pain relief for more than 1 year was observed in five (38.5%) of 13 patients. Rapid recurrence of pain in fewer than 3 months was observed in four (30.8%) of 13 patients. The only complication was transient diabetes insipidus in one patient. It would seem that GKS of the pituitary might have a role to play in thalamic pain arising after a stroke.
The effect of gamma knife irradiation on functions of striatum in rats
Authors: Tokumaru Osamu , Tomida Mihoko , Katayama Yoko , Hayashi Mootohiro , Kawakami Yoriko , Kouyama Nobuo 
Published: November 2018

Object. An animal model has been developed to study the effect of gamma knife surgery(GKS) on cerebral function.
Methods. A rat was fixed in a newly developed Régis—Valliccioni frame that enables the target region to be planned directly on the magnetic resonance images. The left striatum was irradiated with 150 Gy via a 4-mm collimator of the Leksell gamma knife. Apomorphine (dopamine agonist) was administered to elicit a circling behavior (apomorphine test) after the GKS so as to examine the time course of the changes in dopaminergic functions of irradiated striatum. After a series of behavioral analyses, irradiated brains were subjected to histological examination.
Necrosis was observed in the irradiated area surrounded by hemorrhage and gliosis. The distance between the histologically estimated and planned centers of the irradiation areas was 1.0 ± 0.5 mm. The extent of the distance was due to errors along dorsoventral axis. The distribution of the irradiation areas influenced the activity and the circling behaviors in apomorphine test, which was suggestive of involvement of the nigrostriatal pathway.
Conclusions. Targeting by using the Régis—Valliccioni frame was very accurate compared with targeting with coordinates based on brain maps used hitherto. Although targeting improved the accuracy, further effort will still be necessary to reduce errors along dorsoventral axis. The apomorphine test indicated a reduced dopaminergic function of the irradiated area including striatum, which accompanied histological changes after a high dose of irradiation (150 Gy).
Analysis of long-term outcomes and prognostic factors in patients with non—small cell lung cancer brain metastases treated by gamma knife radiosurgery
Authors: Gerosa Massimo , Nicolato Antonio , Foroni Roberto , Tomazzoli Laura , Bricolo Albino 
Published: November 2018

Object. The authors conducted a study to evaluate the long-term outcomes and prognostic factors for survival in a large series of patients treated by gamma knife surgery (GKS) for non—small cell lung cancer (NSCLC) brain metastases.
Methods. The study is based on the retrospective analysis of clinical and radiological records obtained during a 10-year period (1993–2003), concerning 836 lesions in 504 patients. The lesions were primary in 86% and recurrent 14% of the cases; they were solitary in 31%, single in 29%, and multiple in 40%. The mean follow-up period was 16 months (range 4–113 months). The most common histological types were adenocarcinoma (51%) and squamous cell carcinoma (27%). Dose planning parameters were as follows: mean target volume 6.2 cm3 (range 0.06–22.5 cm3); mean prescription dose 21.4 Gy (range 15.5–28 Gy); and mean number of isocenters 6.7 (range one–18). Progression-free and actuarial survival curves were calculated using the Kaplan—Meier method. The main factors affecting survival were determined by unimultivariate analysis (log-rank test and Cox proportional hazard models).
Analysis of long-term outcomes seemed to confirm that GKS is a primary therapeutic option in these patients. The 1-year local tumor control rate was 94%. The overall median survival was 14.5 months, with extremely rewarding quality of life indices. The recursive partitioning analysis classification was the dominant prognostic factor.
Conclusions. Gamma knife surgery is a useful treatment for brain metastases from NSCLC.
Low-dose radiosurgery for large vestibular schwannomas: long-term results of functional preservation
Authors: Inoue Hiroshi K. 
Published: November 2018

Object. The author conducted a study to assess the long-term results obtained in patients who underwent GKS for large vestibular schwannomas (> cochlear nerve functions were evaluated.
Methods. Twenty consecutive large tumors in 18 patients (including two cases of neurofibromatosus Type 2 [NF2]) were followed for more than 6 years. There were eight tumors that were more than 4 cm in maximum diameter. Microsurgery had already been performed prior to GKS in 11 patients (nine recurrent and two residual tumors).
Four patients (including one with NF2) died during the follow-up period of other diseases or by accident. Fourteen of 15 tumors were stable or decreased in size. Microsurgery was performed in one patient 2 years after radiosurgery. Facial nerve function was preserved in all patients and hearing preserved in four of five patients with cochlear nerve function prior to radiosurgery. No adverse effects of radiosurgery have been observed to date.
Conclusions. Gamma knife surgery seems to have a place in the low-dose treatment of selected large vestibular schwannoma in patients with a reasonable chance of retaining facial function and pretreatment hearing level. Patients with severe brainstem compression should first be undergo microsurgery.
Volume reduction in meningiomas after gamma knife surgery
Authors: Feigl Guenther C. , Bundschuh Otto , Gharabaghi Alireza , Samii Madjid , Horstmann Gerhard A. 
Published: November 2018

Object. The purpose of this study was to evaluate the volume-reducing effects of gamma knife surgery (GKS) of meningiomas with and without previous surgical treatment.
Methods. A group of 127 patients with a mean age of 57.1 years (range 9–81 years) with 142 meningiomas (128 World Health Organization Grade I and 14 Grade II) were included in this study. The management strategy reduces tumor volume with surgery when necessary (81 patients). Stereotactic GKS with a Gamma Knife model C was performed in all tumors of suitable size. Magnetic resonance imaging follow-up examinations with volumetric tumor analysis was performed 6 months after treatment and annually thereafter.
The mean tumor volume was 5.9 cm3 (range < 5 to > 40 cm3). The mean follow-up time after GKS was 29.3 months (range 11–61 months). The mean prescription dose was 13.8 Gy (range 10–18 Gy). A reduction in volume occurred in 117 (82.4%) of all tumors, and in 20 tumors (14.1%) growth ceased. The overall tumor control rate of 96.4%. The mean volume reduction achieved with GKS was more than 46.1%. Only five tumors (3.5%) showed a volume increase.
Conclusions. Gamma knife surgery was effective in reducing meningioma volume at short-term follow up. Further studies are needed to examine the development of these findings over a longer period.
The long-term results of gamma knife radiosurgery for hemangioblastomas of the brain
Authors: Wang En-Min , Pan Li , Wang Bing-Jiang , Zhang Nan , Zhou Liang-Fu , Dong Ya-Fei , Dai Jia-Zhong , Cai Pei-Wu , Chen Hong 
Published: November 2018

Object. The authors assessed the long-term result of gamma knife surgery (GKS) for hemangioblastomas of the brain (HABs) and show histopathological findings after GKS.
Methods. Thirty-five patients, 28 men and seven women, with a mean age of 36 years underwent GKS. Eighteen patients presented with multiple tumors and 17 with a solitary tumor. Twenty-one patients had von Hippel—Lindau (VHL) disease. The mean tumor diameter was 13 mm (range 5–55 mm). The mean follow up after GKS was 66 months (range 24–114 months). The mean prescription dose was 17.2 Gy (range 12–24 Gy) at the tumor margin. For tumors close to or within the brainstem a prescription dose of 12 to 13 Gy was used.
At the most recent follow up, 29 patients were alive, six were dead, and satisfactory tumor control had been achieved in 29. A stable or improved neurological status was obtained in 21 patients. Eight patients underwent open surgery because of tumor-associated cyst enlargement or the development of new tumors after GKS. Seven patients developed new tumors and five of them required a second GKS. The 1-year tumor control rate was 94%; 2 years, 85%; 3 years, 82%; 4 years, 79%; and 5 years, 71%. Histopathology showed that no tumor cells were found and there was degeneration and necrosis in a tumor nodule 48 months after GKS with a prescription dose of 18 Gy.
Conclusions. Gamma knife surgery was a useful choice for small- or medium-sized, solid HAB in the long term, especially when the tumor margin dose was 18 Gy. Although GKS can treat multiple tumors in a single session, for HABs associated with VHL disease, GKS faces the dual problems of tumor recurrence or development of a new tumor.