bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

OBJECTIVEPseudarthrosis 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.METHODSA 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.RESULTSA 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.CONCLUSIONSA 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

OBJECTIVEThere 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.METHODSThe 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.RESULTSA 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.CONCLUSIONSA 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.