Radiosurgical Decompression of Trigeminal Nerve and Its Correlation with Functional Outcome in Tumor-Related Trigeminal Neuralgia

BACKGROUND

Target selection during Gamma Knife radiosurgery (GKRS) in cases of tumor-related trigeminal neuralgia is always debatable. We analyzed the correlation of regression of tumor size and degree of release of the nerve with long-term pain control.

METHODS

Between March 2012 and March 2023, 50 cases of tumor-related trigeminal neuralgia were treated with GKRS (tumor was targeted). Radiological findings after GKRS were categorized into 3 types: 1) tumor volume remained same or decreased, additional segment of nerve not seen; 2) tumor volume decreased, additional segment of trigeminal nerve seen, but tumor still adherent to the nerve; 3) tumor volume decreased, adjacent nerve seen completely separated from tumor. Pain score before and after GKRS (Barrow Neurological Institute I-III: good; Barrow Neurological Institute IV and V: poor) was correlated with these subgroups.

RESULTS

At median follow-up of 46.5 months, 18 cases showed type 1 radiological response, 23 showed type 2 response, and 9 showed type 3 response. Good pain control was achieved in 10 (55.5%) patients with type 1, 15 (65.21%) with type 2, and 7 (77.8%) with type 3 responses. The outcome differences among these 3 groups were not statistically significant (P = 0.519). Five patients with type 3 radiological response were off medication, which was statistically better than type 1 and type 2 radiological responses, with 3 patients (P = 0.012) and 2 patients (P = 0.002), respectively, still receiving medication.

CONCLUSIONS

Tumor volume reduction after GKRS may be associated with good pain control in tumor-related trigeminal neuralgia. Further, this allows visualization of additional segment of nerve that can be targeted in a second session for treating recurrent or failed cases.

Efficacy and Challenges: Minimally Invasive Procedures for Trigeminal Neuralgia Treatment in Multiple Sclerosis - A Systematic Review and Meta-Analysis

INTRODUCTION

Trigeminal neuralgia (TGN) poses a therapeutic challenge, particularly within the context of multiple sclerosis (MS). This study aimed to conduct a comprehensive meta-analysis and systematic review of four less-invasive treatment modalities for TGN in MS patients, namely, gamma knife radiosurgery (GKRS), glycerol rhizotomy (GR), balloon compression (BC), and radiofrequency ablation (RFA).

METHODS

Single-armed meta-analyses were employed to assess the overall efficacy of each treatment, while double-armed analyses compared the efficacy between different treatment options in double-armed studies. Outcome evaluations included acute pain relief (within 1 month post-procedure), recurrence rates throughout 18 months of follow-up, and reported complication rates.

RESULTS

The meta-analysis revealed diverse outcomes for each intervention. GKRS demonstrated favorable outcomes, achieving a 77% success rate in alleviating pain among a pooled cohort of 863 patients, reinforcing its status as a viable therapeutic option. Additionally, GR, BC, and RFA exhibited efficacy, with success rates of 77%, 71%, and 80%, respectively, based on outcomes observed in 611, 385, and 203 patients. Double-armed analyses highlighted distinctions between the treatments, providing nuanced insights for clinical decision-making.

CONCLUSION

This meta-analysis provides a comprehensive overview of less-invasive treatments for TGN in MS patients. GKRS emerges as a leading option with comparable efficacy and fewer complications. However, the study underscores the nuanced efficacy and considerations associated with GR, BC, and RFA. The findings offer valuable insights for clinicians navigating treatment choices in this challenging patient population, considering acute pain relief, recurrence rates, and complication profiles.

Factors Influencing Long-Term Outcomes of Single-Session Gamma Knife Radiosurgery in Large-Volume Meningiomas >10 cc

INTRODUCTION

Meningiomas are the most common primary intracranial tumour. Gamma knife radiosurgery (GKRS) is a frequently employed non-invasive method of treatment, with good remission rates and low morbidity in literature. However, the role of GKRS in the management of "large" meningiomas is unclear, with reported outcomes that vary by centre. We aimed to assess the factors that influence long-term outcomes following GKRS in meningiomas >10 cc in volume.

METHODS

A retrospectively analysed all patients with meningiomas exceeding 10 cc in volume who underwent GKRS between January 2006 and December 2021 at the National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru. Demographic, clinical, radiological, and follow-up data were acquired, and factors associated with progression following GKRS were assessed.

RESULTS

The cohort comprised 76 patients 29 males (38.2%) and 47 females (61.8%) with a mean age of 46.3 ± 11.02 years. Thirty-nine patients had been previously operated (51.3%). Meningiomas were most frequently located in the parasagittal region (26 tumours, 34.2%) and sphenopetroclival region (23 tumours, 30.3%), with mean lesion volume of 12.55 ± 5.22 cc, ranging 10.3 cc-25 cc. The mean dose administered to the tumour margin was 12.5 Gy ± 1.2 Gy (range 6-15 Gy). The median duration of clinical follow-up was 48 months, over which period radiological progression occurred in 14 cases (20%), with unchanged tumour volume in 20 cases (28.6%) and reduction in size of the tumour in 36 cases (51.4%). Progression-free survival after GKRS was 72% at 5 years, was significantly poorer among meningiomas with tumour volume >14 cc (log-rank test p = 0.045), tumours presenting with limb motor deficits (log-rank test p = 0.012), and tumours that underwent prior Simpson grade 3 or 4 excision (log-rank test p = 0.032).

CONCLUSIONS

Meningiomas >10 cc in volume appear to display a high rate of progression and subsequent need for surgery following GKRS. Primary surgical resection, when not contraindicated, may be considered with GKRS serving an adjuvant role, especially in tumours exceeding 14 cc in volume, and presenting with limb motor deficits. Long-term clinical and radiological follow-up is essential following GKRS as the response of large meningiomas may be unpredictable.

Is two-staged gamma knife surgery a reasonable management option for very large cerebellar metastases? A case series of three patients

OBJECTIVE

Two-staged gamma knife surgery (GKS) is a method that may extend the upper tumor volume limit for using GKS in the management of brain metastases. However, the safety of treating very large posterior fossa lesions with this technique has not been well demonstrated. Therefore, we analyzed our experience in treating cerebellar metastases larger than 12 cm3 with two-staged GKS.

METHODS

Four consecutive patients harboring 12 to 30 cm3 cerebellar metastases scheduled two-staged GKS were included in the study, and all but one patient completed the treatment. The treatment doses were 10-13 Gy. All patients were followed with regular MR imaging and clinical assessments, and the tumor volumes were measured on all treatment and follow-up images.

RESULTS

Tumor progression was not demonstrated in any of the patients. Tumor volumes decreased by, on average, more than half between the two stages. The median survival was 22 months, and no patient died due to intracranial tumor progression. Peritumoral edema at the first GKS resolved in all patients, replaced by asymptomatic mild T2 changes in two of them not requiring any treatment. No radiation-induced complication has developed thus far.

CONCLUSION

Staged GKS seems to be a feasible management option for very large cerebellar metastases.

Gamma Knife radiosurgery for central neurocytoma: a quantitative systematic review and metanalysis

Central neurocytomas (CN) are rare tumors within the central nervous system. Originating from the septum pellucidum and subependymal cells, they are typically found in the third and lateral ventricles. For this reason, they may lead to hydrocephalus and increased intracranial pressure. CNs are generally benign lesions that exhibit locally aggressive behavior and a high recurrence rate. Complete surgical resection is the preferred treatment; however, due to their anatomical location, this is often not feasible. Based on these findings, Gamma Knife radiosurgery (GKRS) has been introduced for managing both residual and recurrent tumors and as an initial therapy in selected cases. This study aimed to systematically review the available knowledge regarding GKRS for CN. A systematic investigation of the scientific literature was undertaken through an exhaustive search across prominent databases, including PubMed, Web of Science, and Google Scholar, by employing precise MeSH terms such as "Central neurocytoma," "Radiosurgery," "Gamma Knife," and "Stereotactic Radiosurgery." A comprehensive quantitative systematic review and meta-analysis were meticulously conducted, focusing on cases of CN treated with GKRS for a thorough evaluation of outcomes and efficacy. Seventeen articles, including 289 patients, met the inclusion criteria. Random effects meta-analysis estimates for disease control and local tumor control were 90% (95% CI 87-93%; I2 = 0%, p < 0.74) and 94% (95% CI 92-97%; I2 = 0%, p < 0.98), respectively. When considering only studies with at least 5 years of follow-up, progression-free survival was 89% (95% CI 85-94%; I2 = 0.03%, p < 0.74). The mean clinical control rate was 96%. This systematic review and meta-analysis confirmed the safety and efficacy of GKRS in managing CN.

Efficacy and indications of gamma knife radiosurgery for recurrent low-and high-grade glioma

PURPOSE

To investigate the indications and efficacy of gamma knife radiosurgery (GKRS) as a salvage treatment for recurrent low-and high-grade glioma.

METHODS

This retrospective study of 107 patients with recurrent glioma treated with GKRS between 2009 and 2022, including 68 high-grade glioma (HGG) and 39 low-grade glioma (LGG) cases. The Kaplan-Meier method was used to calculate the overall survival (OS) and progression-free survival (PFS). The log-rank test was used to analyze the multivariate prognosis of the Cox proportional hazards model. Adverse reactions were evaluated according to the Common Terminology Criteria for Adverse Events version 4.03. The prognostic value of main clinical features was estimated, including histopathology, Karnofsky performance status (KPS), recurrence time interval, target location, two or more GKRS, surgery for recurrence, site of recurrence, left or right side of the brain and so on.

RESULTS

The median follow-up time was 74.5 months. The median OS and PFS were 17.0 months and 5.5 months for all patients. The median OS and PFS were 11.0 months and 5.0 months for HGG, respectively. The median OS and PFS were 49.0 months and 12.0 months for LGG, respectively. Multivariate analysis showed that two or more GKRS, left or right side of the brain and brainstem significantly affected PFS. Meanwhile, the KPS index, two or more GKRS, pathological grade, and brainstem significantly affected OS. Stratified analysis showed that surgery for recurrence significantly affected OS and PFS for LGG. KPS significantly affected OS and PFS for HGG. No serious adverse events were noted post-GKRS.

CONCLUSION

GKRS is a safe and effective salvage treatment for recurrent glioma. Moreover, it can be applied after multiple recurrences with tolerable adverse effects.

Effectiveness of gamma knife radiosurgery in the management of trigeminal neuralgia associated with multiple sclerosis: a systematic review and meta-analysis

BACKGROUND

Trigeminal neuralgia (TN) is a chronic condition characterized by intense facial pain akin to electric shocks, often associated with the trigeminal nerve. It can be either idiopathic or secondary, with multiple sclerosis (Ms) being a significant contributing factor. Non-responsive patients may opt for minimally invasive procedures, such as gamma knife radiosurgery (GKRS), which offers precise, non-invasive treatment and is frequently chosen as a primary approach. This meta-analysis evaluates the long-term efficacy of GKRS in TN management in Ms patients.

METHODS

We conducted a focused search across various databases. Inclusion criteria encompassed studies with ≥ 30 patients using GKRS for TN in Ms, reporting pertinent clinical outcomes. Primary outcomes assessed GKRS efficacy through Barrow Neurological Institute Pain scores. Secondary outcomes encompassed bothersome numbness, facial numbness, and recurrence. Data analysis employed OpenMeta, random effect models, and odds ratios with 95% confidence intervals. Heterogeneity was assessed using I2 statistics.

RESULTS

Fourteen studies with 752 cases of GKRS for TN were included. Regarding the outcomes, 83% of patients experienced a positive initial pain response, while the overall treatment success rate was 51%. Additionally, 19.6% of patients reported facial numbness, 4.1% experienced bothersome numbness, and 40% faced recurrence. The odds ratio for positive initial pain response was 0.83 (95% CI, 0.76-0.89), while for treatment success, it was 0.51 (95% CI, 0.379-0.639). Facial numbness had an odds ratio of 0.196 (95% CI, 0.130-0.262), bothersome numbness had an odds ratio of 0.041 (95% CI, 0.013-0.069), and recurrence had an odds ratio of 0.403 (95% CI, 0.254-0.551).

CONCLUSIONS

In conclusion, treating trigeminal neuralgia in multiple sclerosis patients remains challenging. GKRS shows promise, but customized treatment approaches tailored to individual patient characteristics are urgently needed to address the unique challenges of this condition.

Predicting peritumoral edema development after gamma knife radiosurgery of meningiomas using machine learning methods: a multicenter study

OBJECTIVES

Edema is a complication of gamma knife radiosurgery (GKS) in meningioma patients that leads to a variety of consequences. The aim of this study is to construct radiomics-based machine learning models to predict post-GKS edema development.

METHODS

In total, 445 meningioma patients who underwent GKS in our institution were enrolled and partitioned into training and internal validation datasets (8:2). A total of 150 cases from multicenter data were included as the external validation dataset. In each case, 1132 radiomics features were extracted from each pre-treatment MRI sequence (contrast-enhanced T1WI, T2WI, and ADC maps). Nine clinical features and eight semantic features were also generated. Nineteen random survival forest (RSF) and nineteen neural network (DeepSurv) models with different combinations of radiomics, clinical, and semantic features were developed with the training dataset, and evaluated with internal and external validation. A nomogram was derived from the model achieving the highest C-index in external validation.

RESULTS

All the models were successfully validated on both validation datasets. The RSF model incorporating clinical, semantic, and ADC radiomics features achieved the best performance with a C-index of 0.861 (95% CI: 0.748-0.975) in internal validation, and 0.780 (95% CI: 0.673-0.887) in external validation. It stratifies high-risk and low-risk cases effectively. The nomogram based on the predicted risks provided personalized prediction with a C-index of 0.962 (95%CI: 0.951-0.973) and satisfactory calibration.

CONCLUSION

This RSF model with a nomogram could represent a non-invasive and cost-effective tool to predict post-GKS edema risk, thus facilitating personalized decision-making in meningioma treatment.

CLINICAL RELEVANCE STATEMENT

The RSF model with a nomogram built in this study represents a handy, non-invasive, and cost-effective tool for meningioma patients to assist in better counselling on the risks, appropriate individual treatment decisions, and customized follow-up plans.

KEY POINTS

• Machine learning models were built to predict post-GKS edema in meningioma. The random survival forest model with clinical, semantic, and ADC radiomics features achieved excellent performance. • The nomogram based on the predicted risks provides personalized prediction with a C-index of 0.962 (95%CI: 0.951-0.973) and satisfactory calibration and shows the potential to assist in better counselling, appropriate treatment decisions, and customized follow-up plans. • Given the excellent performance and convenient acquisition of the conventional sequence, we envision that this non-invasive and cost-effective tool will facilitate personalized medicine in meningioma treatment.

Successful MRI-Guided Focused Ultrasound Thalamotomy after Ipsilateral Gamma Knife Radiosurgery for Essential Tremor: A Case Report with Video

We report the case of a 67-year-old left-handed female patient with disabling medically refractory essential tremor who underwent successful right-sided magnetic resonance-guided focused ultrasound (MRgFUS) of the ventral intermediate nucleus after ipsilateral gamma knife radiosurgery (GKRS) thalamotomy performed 3 years earlier. The GKRS had a partial effect on her postural tremor without side effects, but there was no reduction of her kinetic tremor or improvement in her quality of life (QoL). The patient subsequently underwent a MRgFUS thalamotomy, which induced an immediate and marked reduction in both the postural and kinetic tremor components, with minor complications (left upper lip hypesthesia, dysmetria in her left hand, and slight gait ataxia). The MRgFUS-induced lesion was centered more medially than the GKRS-induced lesion and extended more posteriorly and inferiorly. The MRgFUS-induced lesion interrupted remaining fibers of the dentatorubrothalamic tract (DRTT). The functional improvement 1-year post-MRgFUS was significant due to a marked reduction of the patient's kinetic tremor. The QoL score (Quality of Life in Essential Tremor) improved by 88% and her Clinical Rating Scale for Tremor left hand score by 62%. The side effects persisted but were minor, with no impact on her QoL. The explanation for the superior efficacy of MRgFUS compared to GKRS in our patient could be due to either a poor response to the GKRS or to a better localization of the MRgFUS lesion with a more extensive interruption of DRTT fibers. In conclusion, MRgFUS can be a valuable therapeutic option after unsatisfactory GKRS, especially because MRgFUS has immediate clinical effectiveness, allowing intra-procedural test lesions and possible readjustment of the target if necessary.

Morphology of intra tumoral cystic vestibular schwannoma and their response to gammaknife radiosurgery

BACKGROUND

Cystic vestibular schwannoma (CVS) traditionally considered as poor responder to gammaknife radiosurgery (GKRS). Their longterm radiobiological behavior is less known. Here we discuss 38 cases with intra tumoral cyst CVS primarily treated with GKRS. Tumor morphology was assessed to understand their response to GKRS.

METHODS

Total 38 patients(21 male and 17 female with median age of 41.7 years) of CVS treated with GKRS were retrospectively analysed. Tumors were divided as predominantly (greater than50% of total tumor volume) cystic or solid. They were subclassified as type 1 (predominantly cystic CVS, single cyst), type 2 (predominantly solid CVS, single cysts), type 3 (multicystic CVS). The entire cyst was incorporated for radiosurgery. The results were compared with volume matched control of 58 solid tumors(SVS).

RESULT

The median tumor volume of CVS was 5.8 cc. The median tumor volume reduction was 44.5 % at a median follow-up of 68.5 months (30-110 months). Median tumor volume reduction was 68.5 %, 34.0%, 11.0.%, 30.5% at a median follow up of 52.5months, 66 months, 78.6 months, 96.5 months for type 1 CVS, type 2 CVS, type 3 CVS and SVS respectively. One patient with multicystic CVS showed increased tumor volume and expired after 9 months of surgery.The tumor volume reduction in type 1CVS was statistically significant as compared to type 3 CVS and SVS. However the tumor volume reduction among other groups did not differ significantly.

CONCLUSION

Intra tumoral cystic components respond better to gammaknife radiosurgery in CVS. Tumor with single cyst respond better than multicystic vestibular schwannoma.

Formation of internal carotid artery aneurysms following gamma knife radiosurgery for pituitary adenomas: a case series and literature review

Only two aneurysm formations in the internal carotid artery after gamma knife radiosurgery (GKRS) for pituitary adenomas are reported so far. Here, out of the 482 patients who underwent GKRS for pituitary adenomas at our institute, at least five developed aneurysms within the area of high single-dose irradiation. Three patients presented with epistaxis due to aneurysmal rupture and one presented with abducens paralysis due to nerve compression, while one was asymptomatic. The interval between irradiation and aneurysmal detection ranged from 14 to 21 years. Aneurysm formation in those conditions may be higher than previously thought.

Gamma Knife radiosurgery for Spetzler-Martin grade III brain arteriovenous malformations

BACKGROUND

Spetzler-Martin (SM) grade III AVMs exhibit angioarchitecture heterogeneity and lack a clearly defined treatment strategy. This study aims to evaluate outcomes following treatment of SM grade III AVMs with Gamma Knife Radiosurgery (GKRS).

METHODS

A single-institution retrospective analysis was conducted of 307 patients with SM grade III AVMs undergoing GKRS between October 2006 to December 2020 with follow-up times of at least 24 months. SM grade III AVMs were classified into four subtypes: IIIA (S1E1V1), IIIB (S2E0V1), subtype IIIC (S2E1V0), and IIID (S3E0V0).

RESULTS

Over a median follow-up time of 50.3 months, complete AVM obliteration was achieved in 211 patients (68.7%). Complete obliteration rates in subtypes IIIA, IIIB, IIIC, and IIID were 80.8%, 55.4%, 53.4%, and 25.0%, respectively. Annual post-GKRS hemorrhage risk was 0.8%. Significant radiosurgery-induced imaging changes occurred in 7 patients (2.3%). Three variables were identified as predictors of obliteration in final forward stepwise regression models, including volume of AVM (B= -0.011, p <0.001), age (B= -0.004, p =0.024) and prior AVM hemorrhage (B= 0.187, p = 0.077).

CONCLUSIONS

GKRS is a safe and effective treatment for SM grade III AVMs, particularly subtype IIIA (S1E1V1). AVM volume is the key predictor of post-GKRS obliteration.

Safety and Efficacy of Gamma Knife Radiosurgery for the Management of Trigeminal Neuralgia: A Retrospective and Cross-Sectional Study

Background

Medical management is the first line of care for patients with trigeminal neuralgia (TN), and carbamazepine is the drug of choice used alone or in combination with other drugs. Gamma knife radiosurgery (GKRS) has been an established option in the management of refractory TN based on its noninvasiveness and robust safety profile. Our study aims to confirm the safety and assess the efficacy of GKRS in the management of TN.

Material and Methods

A retrospective review of the patients with refractory TN treated with GKRS from 1997 to March 2019 by the senior author was carried out. Out of 194 eligible patients, detailed clinical information was not available in 41 patients. The remaining 153 patients' case files (post-GKRS cohort) were reviewed, and data obtained were collated, computed, and analyzed. An additional cross-sectional analysis was carried out telephonically in the post-GKRS cohort in January 2021 using Barrow Neurological Institute (BNI) pain scoring, to obtain the long-term efficacy of GKRS in TN.

Results

The majority of the patients (96.1%) received a radiation dose of 80 Gy. At 6 months, 94.8% of patients had satisfactory response to GKRS. Follow-up ranged between 1 and 7.5 years. The recurrence rate was 9.2% and the complication rate was 4.6%. Facial numbness was the commonest complication. No mortality was reported. The cross-sectional arm of the study had a response rate of 39.2% (60 patients). Adequate pain relief (BNI I/II/IIIa/IIIb) was reported in 85% of patients.

Conclusion

GKRS is a safe and effective modality of treatment for TN without any major complications. Both short-term and long-term efficacies are excellent.

Role of novel policy implementation for Gamma Knife (GK) procedures in improving access to neurosurgical care in lower middle income countries (LMICs) GK in LMICs

Background

The high cost of GK machines with resultant scarcity of GK centers, coupled to additional cost of contrast MRI brain makes it nearly impossible for the vast majority of the population without health insurance in LMICs to have access to this advancement in management.

Methods

AIIMS, Delhi is the premier public funded hospital in India with the largest Neurosurgical department in the country. We implemented a single payment policy which would cover the treatment and all subsequent GK treatments as well as Follow-up MRIs of the patient. The program was named 'Gamma Knife for life' and implemented in 2015. To check the efficacy, we conducted a retrospective analysis of the Neurosurgery cases managed before and after the implementation of this scheme in the last 12 years.

Results

Prior to implementation of the 'Gamma Knife for life' program, a total of 24,703 patients underwent Neurosurgical procedures in the years 2009-2015. Of these, only 2017 (8.16%) were GK procedures. In the years following the introduction of the program, the total number of neurosurgical procedures was 23,030 with 2947 (12.8%) being the GK procedures This difference in the number of GK procedures before and after the application of 'Gamma Knife for Life' was statistically significant (p = 0.026). The highest number of GK procedures (n = 789) reported so far were in 2020-21.

Conclusions

Ensuring holistic care by providing for not only the initial GK procedure but all subsequent procedures, as well as follow-up MRI's can improve the quality and consistency of care, especially in LMICs.

Leukoencephalopathy in patients with brain metastases who received radiosurgery with or without whole brain radiotherapy

BACKGROUND

Whole brain radiation therapy (WBRT) for brain metastases (BMs) is a common cause of radiation-induced leukoencephalopathy; however the safety of alternative stereotactic radiosurgery (SRS) remains unclear. This study examined the incidence of leukoencephalopathy in patients treated with SRS alone versus WBRT plus SRS for BMs with a focus on the relationship between prognostic factors and leukoencephalopathy.

METHODS

Analysis was performed between 2002 and 2021. The total enrollment was 993 patients with the distribution: WBRT plus SRS (n = 291) and SRS only (n = 702). Leukoencephalopathy was graded from 0 to 3 for changes in white matter indicated by the MRI after WBRT or SRS. Patient characteristics and SRS dosimetric parameters were reviewed to identify factors that contributed to the incidence of leukoencephalopathy or overall survival.

RESULTS

The incidence of leukoencephalopathy was consistently higher in WBRT plus SRS group than in SRS alone group (p < 0.001). Leukoencephalopathy was also associated with a larger total tumor volume (≧28cm³; p = 0.028) and age (> 77 years; p = 0.025). Nonetheless, the SRS integral dose to skull in the subgroup of WBRT plus SRS treatment was not demonstrated significance in development of leukoencephalopathy (p = 0.986 for integral dose 1-2 J, p = 0.776 for integral dose > 2 J).

CONCLUSIONS

This study revealed that SRS is safe for oligo-BMs in terms of leukoencephalopathy development. Patient age and total tumor volume were identified as important factors in assessing the development of leukoencephalopathy. The additional of SRS (even at an integral dose > 2 J) did not increase the incidence of leukoencephalopathy.

MRI Changes in Failed Radiosurgery for Vestibular Schwannomas

INTRODUCTION

Radiosurgery is now a recognized treatment of vestibular schwannoma (VS); however, radiosurgical irradiation sometimes fails to stop tumor growth in the long term. Some changes in MR imaging after radiosurgery that are supposed to be related to permanent tumor control may be observed in patients with failed treatment. The objective of the present study was to evaluate the MRI changes observed early after radiosurgery in a cohort of patients with failed radiosurgery for VS.

METHODS

From a large series of VS treated radiosurgically for 15 years, we reviewed the follow-up MRI data in a subgroup of VS that presented obvious treatment failure. T1-weighted MR imaging with standard timing of gadolinium injection was applied for image acquisition during the radiosurgical procedure and all follow-up MR imaging. Evolution of tumor volume and contrast enhancement were assessed on 3D-co-registered MRI.

RESULTS

Twenty-nine of 728 patients (4%) were retreated for the same VS after >2 years (median 3.14 years, range 2.04-9.47) following initial radiosurgical treatment. The median tumor volume was 0.94 cc at first radiosurgical treatment and 2.19 cc at retreatment. Fourteen patients (48.3%) had continuous increase in tumor volume. For 10 patients (34.5%), the tumor volume reduced significantly after irradiation before it increased again. Four patients (13.8%) showed a transient increase in tumor volume after irradiation, followed by significant volume reduction, then a very significant tumor regrowth. A significant loss of contrast enhancement at the center of the tumor was observed for 25 patients (86.2%); full recovery of contrast enhancement of the tumor was observed for 23 patients.

DISCUSSION/CONCLUSION

Tumor volume reduction and central loss of contrast enhancement of the tumor are MRI changes frequently observed during follow-up of VS treated radiosurgically even in patients with failed long-term tumor control and may therefore not be considered as signs of successful response of the tumor to the radiosurgical treatment.

Can Trigeminal Schwannoma-Related Symptoms be Controlled With Gamma Knife Radiosurgery?

OBJECTIVE

The effectiveness of gamma knife radiosurgery (GKRS) for the management of trigeminal schwannomas (TS) has been established. Although GKRS has been shown to inhibit tumor growth, the effect of GKRS on the symptoms caused by TS has not been sufficiently studied. In this study, symptomatic changes following GKRS for the management of symptomatic TS were investigated using long-term follow-up results.

METHODS

A retrospective analysis was performed on 32 patients with TS who underwent GKRS between May 1994 and December 2016. Clinical charts, radiographic results, and surgical records were reviewed. To evaluate whether symptoms improved after GKRS, patient demographics, GKRS profile, radiological tumor size change, and tumor location were analyzed.

RESULTS

Tumor control after GKRS for symptomatic TS was 87%. The improvement rates for facial pain at 6, 12, and 24 months after GKRS were 46%, 72%, and 86%, respectively. For the same time intervals, facial hypesthesia improved by 12%, 46%, and 52%, respectively. Of the patients with diplopia, 17% had improved symptoms 12 months after GKRS, and 50% of the patients improved after 24 months.

CONCLUSIONS

GKRS can be an effective treatment modality for TS tumor control and shows favorable results in improving TS-related symptom, especially facial pain.

Assessment of gamma knife radiosurgery for unruptured cerebral arterioveneus malformations based on multi-parameter radiomics of MRI

OBJECTIVE

The treatment of Gamma knife radiosurgery (GKS) for unruptured Arteriovenous Malformations (AVM) remains controversial. A safe, effective and non-invasive method to predict outcome seems attractive for GKS. The purpose of this study was to develop and validate a MRI based multi-parameter radiomics model predicting the outcome of GKS for unruptured AVM.

METHODS

Eighty-eight unruptured AVM patients who initial underwent GKS between January 2011 and December 2016 in our hospital were included in this retrospective study. Patients were divided into two groups named as favourable and unfavourable outcome, according to the clinical outcome. Favourable outcome was defined as obliteration without post-SRS hemorrhage or permanent radiation-induced changes (RIC). Multivariate logistic regression analysis was used to select appropriate clinical features and construct a clinical predicting model. In terms of radiomic model, manually segmentation and radiomics extracted were performed on each AVM lesions. Finally, 1684 radiomics features were extracted and Recursive Feature Elimination (RFE) method combined with Random forest classifier were used for feature selection and model construction. The performance of the radiomics model was evaluated by the area under the curve (AUC), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). In addition, the favourable group was further divided into early and late respond subgroup according to the time of obliteration evaluated by 2 years. The selected features were further compared according the respond time.

RESULTS

The median duration of neuroimaging follow-up was 65 months, 56 patients showed favourable outcome and 17 patients were observed obliteration within 2 years. The radiomics model constructed by 12 selected features achieved significant higher AUC of 0.88 (95% confidence interval 0.87-0.90) than traditional scoring system for predicting AVM outcome. Two selected radiomics features named "Dependence Variance" and "firstorder-Skewness" were found significant difference between the patients with early or late-respond.

CONCLUSIONS

The results suggest that the radiomics features could be successfully used for the pretreatment prediction of outcome for GKS in unruptured AVMs, which is helpful for decision-making process on unruptured AVM patients.

Gamma Knife Radiosurgery for Trigeminal Neuralgia : Review and Update

Accurate diagnosis of trigeminal neuralgia (TN) is the starting point for optimal treatment. Gamma knife radiosurgery (GKRS) is currently regarded as one of the first-line treatment options for medically refractory TN. GKRS is a less invasive treatment with a low risk of complications than other surgical procedures that provides a favorable pain control (BNI I–IIIb) rate of >75% at short-term follow-up. Drawbacks of GKRS include the latency period before pain relief and higher recurrence rate compared with microvascular decompression. Therefore, repeat treatment is necessary if the initial GKRS was effective but followed by recurrence. The concept of dose rate and the biologically effective dose of radiation has been actively studied in radiation oncology and is also applied in GKRS for TN to achieve high safety and efficacy by prescribing the optimal dose. Recent progress in functional imaging, such as diffusion tensor imaging, enables us to understand the pathophysiology of TN and predict the clinical outcome after GKRS. Here, we review TN, GKRS, and recent updates, especially in the concepts of radiation dose, diffusion tensor imaging studies, and repeat treatment in GKRS for TN.

Gamma knife radiosurgery versus transcatheter arterial chemoembolization for hepatocellular carcinoma with portal vein tumor thrombus: a propensity score matching study

BACKGROUND

The optimal locoregional treatment for hepatocellular carcinoma (HCC) patients with portal vein tumor thrombus (PVTT) is unclear. This study aimed to investigate the efficacy of Gamma knife radiosurgery (GKR) versus transcatheter arterial chemoembolization (TACE) in HCC patients with PVTT.

METHODS

This retrospective study included 544 HCC patients with PVTT (GKR, 202; TACE, 342). Propensity score matching (PSM) analysis identified 171 matched pairs of patients. The primary endpoint was overall survival (OS).

RESULTS

Before PSM, the GKR group exhibited longer median OS (mOS) than the TACE group (17.2 vs. 8.0 months, p < 0.001). We followed the Cheng's classification for PVTT. In the subgroup analysis, GKR was associated with significantly longer mOS for patients with PVTT II-IV (17.5 vs. 8.7 months, p < 0.001; 17.2 vs. 7.8 months, p = 0.001; 14.5 vs. 6.5 months, p = 0.001, respectively) and comparable OS for patients with PVTT I. After PSM, the GKR group had also a longer mOS than the TACE group (15.8 vs. 10.4 months, p < 0.001). In the subgroup analysis, the GKR group demonstrated superior mOS for patients with PVTT II-IV (all p < 0.05) and comparable OS for patients with PVTT I.

CONCLUSIONS

GKR was associated better OS than TACE in HCC patients with PVTT, especially for patients with PVTT II-IV.

CLINICAL TRIALS REGISTRATION

The study was registered in the Chinese Clinical Trials Registry under the registration number ChiCTR2100051057.

Gamma knife radiosurgery for trigeminal schwannomas: A systematic review and meta-analysis

BACKGROUND

Gamma knife radiosurgery (GKRS) has been deemed as the gold standard stereotactic radiosurgery (SRS) mode for the treatment of intracranial tumors, cerebrovascular diseases and brain functional diseases. Our study was aimed to systematically evaluate the efficacy, safety, and complications of gamma knife radiosurgery for trigeminal schwannomas.

METHOD

We performed a systematic review and meta-analysis to analyze the clinical outcomes of patients with trigeminal schwannomas treated primarily or adjunctly with GKRS. We searched two databases, Pubmed and Embase, for studies published before January 1, 2021, using GKRS for trigeminal schwannomas. Studies reporting treatment of other schwannomas, or other forms of SRS such as linear accelerator and Cyberknife were excluded to reduce its heterogeneity.

RESULTS

Our search achieved 351 studies, of which 35 were assessed for full-text eligibility. 19 studies were included in the meta-analysis. 456 of 504 patients (0.94, 95% CI 0.91-0.96, I² = 3.02%, p < 0.01) from 18 studies had local control, and 278 of 489 patients (0.63, 95%CI 0.48-0.78, I² = 88.75%, p < 0.01) from 16 studies experienced tumor regression or disappearance. 231 of 499 patients (0.50, 95% CI 0.37-0.62; I² = 83.89%, P < 0.01) from 17 studies had clinical symptoms improved. There was no significant difference in tumor control between those treated with GKRS as either primary treatment or adjuvant to surgery(p = 0.390).

CONCLUSION

GKRS is an efficacious primary and adjuvant method of treating trigeminal schwannomas, with reliable tumor control rates. Randomized controlled trials are needed to further and comprehensively evaluate the benefit-to-risk ratio of gamma knife radiosurgery.

Long-term outcomes of stereotactic radiosurgery for skull base tumors involving the cavernous sinus

PURPOSE

Stereotactic radiosurgery (SRS) is an effective and less invasive therapeutic option for cavernous sinus (CS) tumors. However, its long-term effectiveness and neurological outcomes have yet to be fully elucidated. We aimed to examine the long-term outcomes of SRS for CS tumors.

METHODS

Overall, a cohort of 113 patients with benign CS tumors, including 91 with meningioma, 14 with trigeminal schwannoma (TS), and eight with cavernous hemangioma, treated with SRS at our institution from 1990 to 2018, was included. Tumor control and functional preservation/recovery were evaluated in detail.

RESULTS

The median post-SRS follow-up period was 77 months (interquartile range, 39-177). Progression-free survival (PFS) was 97% at 5 years, 89% at 10 years, and 87% at 15 years for the entire cohort; 96% at 5 years and 87% at 10 years for meningiomas; and 100% at 10 years for the other tumors. No significant difference was observed between meningiomas and non-meningiomas (log-rank test, p = 0.107). Improvement in cranial nerve (CN) function was observed in 35 (27%) patients. TSs tended to show CN improvements more often than meningiomas did (total improvements, 62% vs. 23%; p = 0.004; eye movement function, 100% vs. 20%; p = 0.002). CN deterioration or development of new CN deficits was observed in 11 (10%) patients.

CONCLUSION

SRS provides good tumor control and acceptable long-term outcome with sufficient preservation of CN function in patients with benign CS tumors.

Multimodality MRI-based radiomics approach to predict the posttreatment response of lung cancer brain metastases to gamma knife radiosurgery

OBJECTIVES

To develop and validate a multimodality MRI-based radiomics approach to predicting the posttreatment response of lung cancer brain metastases (LCBM) to gamma knife radiosurgery (GKRS).

METHODS

We retrospectively analyzed 213 lesions from 137 patients with LCBM who received GKRS between January 2017 and November 2020. The data were divided into a primary cohort (102 patients with 173 lesions) and an independent validation cohort (35 patients with 40 lesions) according to the time of treatment. Benefit result was defined using pretreatment and 3-month follow-up MRI images based on the Response Assessment in Neuro-Oncology Brain Metastases criteria. Valuable radiomics features were extracted from pretreatment multimodality MRI images using random forests. Prediction performance among the radiomics features of tumor core (RFTC) and radiomics features of peritumoral edema (RFPE) together was evaluated separately. Then, the random forest radiomics score and nomogram were developed through the primary cohort and evaluated through an independent validation cohort. Prediction performance was evaluated by ROC curve, calibration curve, and decision curve.

RESULTS

Gender (p = 0.018), histological subtype (p = 0.009), epidermal growth factor receptor mutation (p = 0.034), and targeted drug treatment (p = 0.021) were significantly associated with posttreatment response. Adding RFPE to RFTC showed improved prediction performance than RFTC alone in primary cohort (AUC = 0.848 versus AUC = 0.750; p < 0.001). Finally, the radiomics nomogram had an AUC of 0.930, a C-index of 0.930 (specificity of 83.1%, sensitivity of 87.3%) in primary cohort, and an AUC of 0.852, a C-index of 0.848 (specificity of 84.2%, sensitivity of 76.2%) in validation cohort.

CONCLUSIONS

Multimodality MRI-based radiomics models can predict the posttreatment response of LCBM to GKRS.

KEY POINTS

• Among the selected radiomics features, texture features basically contributed the dominant force in prediction tasks (80%), especially gray-level co-occurrence matrix features (40%). • Adding RFPE to RFTC showed improved prediction performance than RFTC alone in primary cohort (AUC = 0.848 versus AUC = 0.750; p < 0.001). • The multimodality MRI-based radiomics nomogram showed high accuracy for distinguishing the posttreatment response of LCBM to GKRS (AUC = 0.930, in primary cohort; AUC = 0.852, in validation cohort).

Gamma Knife Radiosurgery in the Management of Hypothalamic Glioma: A Case Report with Long-Term Follow-Up

BACKGROUND

Optic pathway/hypothalamic gliomas are rare pediatric brain tumors. The management paradigm for these challenging tumors includes chemotherapy, radiotherapy, or surgical resection, but the optimal management strategy remains elusive. Gamma knife radiosurgery (GKRS) has emerged as a promising treatment for such lesions as documented by a small number of cases in the literature.

CASE PRESENTATION

We present a rare case of hypothalamic glioma in a 13-year-old girl who was referred to our service due to growth of an incidentally diagnosed hypothalamic lesion following head injury at the age of 8 years. The lesion demonstrated hypointensity on T1- and hyperintensity on T2-weighted imaging without contrast enhancement. Given the growth of the lesion on serial imaging, a stereotactic biopsy was performed demonstrating low-grade glioma. The patient underwent GKRS treatment with a marginal dose of 15 Gy at 50% isodose line for a tumor volume of 2.2 mL. Annual radiological surveillance over the next 17 years demonstrated a gradual shrinkage of the lesion until it completely disappeared. The patient is currently a healthy 31-year-old female without any visual, endocrine, or neurocognitive deficits.

CONCLUSION

The outcome obtained after extended follow-up in our patient highlights the safety and efficacy of GKRS in the management of hypothalamic gliomas in pediatrics, which in turn can avoid potentially serious complications of surgery in this vulnerable patient population, especially in this sensitive location.

The Impact of Volume Factor on the Long-Term Outcome of Gamma Knife Radiosurgery for Sporadic Cerebral Cavernous Malformations

OBJECTIVE

We aimed to evaluate the long-term outcome of gamma knife radiosurgery (GKRS) for the treatment of sporadic cerebral cavernous malformation (CCM), especially the influence of lesion volume on annual hemorrhage rate (AHR) of patients with CCM after GKRS.

METHODS

Fifty-one single-lesion patients with a history of hemorrhage who underwent radiosurgery at our institution were included and divided into 2 groups (A and B), based on their lesion volume. Group A included 25 patients with lesion volumes >1 cm³, whereas group B included 26 patients with lesion volumes ≤1 cm³. The clinical data of the patients were retrospectively analyzed.

RESULTS

All patients were followed up for more than 4 years after GKRS. The calculated AHR before GKRS was 18.49% in group A and 10.16% in group B. The calculated AHR after GKRS was 5.43% and 0.99% for groups A and B, respectively. Significant differences in AHR after GKRS were identified between group A and group B (P = 0.011). Thirty-seven patients with sporadic CCM (14 in group A, 23 in group B) experienced symptom improvement, and significant differences in symptom improvement were observed between group A and group B (P = 0.009).

CONCLUSIONS

GKRS decreased the risk of hemorrhage and was beneficial for symptomatic improvement in patients with sporadic CCM with a history of hemorrhage. The long-term clinical outcomes for patients with sporadic CCM with small lesion volumes (≤1 cm³) were better than those of patients with sporadic CCM with large lesion volumes (>1 cm³).

Use of GammaPlan convolution algorithm for dose calculation on CT and cone-beam CT images

Purpose

The aim of this study was to assess the suitability of using cone-beam computed tomography images (CBCTs) produced in a Leksell Gamma Knife (LGK) Icon system to generate electron density information for the convolution algorithm in Leksell GammaPlan (LGP) Treatment Planning System (TPS).

Materials and Methods

A retrospective set of 30 LGK treatment plans generated for patients with multiple metastases was selected in this study. Both CBCTs and fan-beam CTs were used to provide electron density data for the convolution algorithm. Plan quality metrics such as coverage, selectivity, gradient index, and beam-on time were used to assess the changes introduced by convolution using CBCT (convCBCT) and planning CT (convCT) data compared to the homogeneous TMR10 algorithm.

Results

The mean beam-on time for TMR10 and convCBCT was found to be 18.9 ± 5.8 minutes and 21.7 ± 6.6 minutes, respectively. The absolute mean difference between TMR10 and convCBCT for coverage, selectivity, and gradient index were 0.001, 0.02, and 0.0002, respectively. The calculated beam-on times for convCBCT were higher than the time calculated for convCT treatment plans. This is attributed to the considerable variation in Hounsfield values (HU) dependent on the position within the field of view.

Conclusion

The artifacts from the CBCT’s limited field-of-view and considerable HU variation need to be taken into account before considering the use of convolution algorithm for dose calculation on CBCT image datasets, and electron data derived from the onboard CBCT should be used with caution.

Importance of Pre-treatment Fractional Anisotropy Value in Predicting Volumetric Response in Patients with Meningioma Treated with Gamma Knife Radiosurgery

Background

The importance of pre-treatment Diffusion Tensor Imaging (DTI) parameters in determining the response to treatment after radiosurgery in patients with meningioma has not yet been clearly revealed.

Objective

This study was conducted to determine tumor volume changes in terms of radiological response in patients with meningioma treated with Gamma Knife Radiosurgery (GKR) and to analyze the relationship between Total Tumor Volume (TTV) and Diffusion Tensor Imaging (DTI) parameters. In addition, we investigated whether the response to treatment can be predicted by pre-radiosurgery DTI findings.

Methods

Fifty-four patients were assessed using MRI and DTI before and after GKR. Mean Diffusivity (MD), Fractional Anisotropy (FA), Radial Diffusivity (RD), and TTV of tumour were determined. Patients with 10% or more decrease in TTV after GKR were classified as group 1 and those with less than 10% decrease in volume or increase in volume were considered group 2. The relationships between MD, RD, and FA values and TTV were investigated.

Results

A decrease of 46.34% in TTV was detected in group 1 after GKR, while TTV increased by 42.91% in group 2. The lowest pre-treatment FA value was detected in group 1. In addition, after GKR, FA values showed a significant increase in group 1. MD and RD values increased in both groups after radiosurgery. There was a negative correlation between pre-treatment FA, RD, and MD values after radiosurgery.

Conclusion

Detection of low FA values due to the poor fiber content in meningioma before radiosurgery may be a guide in predicting the response to treatment. Further studies are required to have a better understanding of the relationship between pre- and post-treatment follow-up FA values and tumor volume in determining the efficacy of GKR in patients with meningioma.

Microvascular decompression as a second step treatment for trigeminal neuralgia in patients with failed two-isocentre gamma knife radiosurgery

OBJECTIVE

Subsequent microvascular decompression (MVD) might be affected by the previous two-isocentre gamma knife radiosurgery (GKS) due to the tissue changes caused by its higher dose radiation and larger treatment volume. This study aimed to evaluate the safety and efficacy of MVD as a second step treatment after two-isocentre GKS.

METHODS

Between December 2016 and May 2019, data from 19 consecutive trigeminal neuralgia (TN) patients who experienced MVD after failed two-isocentre GKS were collected. The clinical characteristics, intraoperative findings, surgical outcomes and complications were reviewed and compared with 158 patients who underwent MVD as an initial treatment.

RESULTS

Fifteen patients (78.9%) achieved complete pain relief (Barrow Neurological Institute, BNI class I) immediately after surgery and nine patients (47.4%) maintained complete pain relief at the last follow-up, which was similar to patients who underwent initial MVD. The median follow-up period was 36 months. The incidence of new or worsened facial numbness showed no statistical significance between the groups. During surgery, trigeminal nerve atrophy was noted in 9 patients (47.4%), thickened arachnoid in 3 patients (15.8%), atherosclerotic plaque in 3 patients (15.8%) and neurovascular adhesion in 1 patient (5.3%).

CONCLUSIONS

MVD remains an effective and safe rescue therapy for patients who elect the minimally invasive treatment with two-isocentre GKS for the first time, without an increased risk of facial numbness.

Stereotactic Radiosurgery for Atypical (World Health Organization II) and Anaplastic (World Health Organization III) Meningiomas: Results From a Multicenter, International Cohort Study

BACKGROUND

Atypical and anaplastic meningiomas have reduced progression-free/overall survival (PFS/OS) compared to benign meningiomas. Stereotactic radiosurgery (SRS) for atypical meningiomas (AMs) and anaplastic meningiomas (malignant meningiomas, MMs) has not been adequately described.

OBJECTIVE

To define clinical/radiographic outcomes for patients undergoing SRS for AM/MMs.

METHODS

An international, multicenter, retrospective cohort study was performed to define clinical/imaging outcomes for patients receiving SRS for AM/MMs. Tumor progression was assessed with response assessment in neuro-oncology (RANO) criteria. Factors associated with PFS/OS were assessed using Kaplan-Meier analysis and a Cox proportional hazards model.

RESULTS

A total of 271 patients received SRS for AMs (n = 233, 85.9%) or MMs (n = 38, 14.0%). Single-fraction SRS was most commonly employed (n = 264, 97.4%) with a mean target dose of 14.8 Gy. SRS was used as adjuvant treatment (n = 85, 31.4%), salvage therapy (n = 182, 67.2%), or primary therapy (1.5%). The 5-yr PFS/OS rate was 33.6% and 77.0%, respectively. Increasing age (hazard ratio (HR) = 1.01, P < .05) and a Ki-67 index > 15% (HR = 1.66, P < .03) negatively correlated with PFS. MMs (HR = 3.21, P < .05), increased age (HR = 1.04, P = .04), and reduced KPS (HR = 0.95, P = .04) were associated with shortened OS. Adjuvant versus salvage SRS did not impact PFS/OS. A shortened interval between surgery and SRS improved PFS for AMs (HR = 0.99, P = .02) on subgroup analysis. Radiation necrosis occurred in 34 (12.5%) patients. Five-year rates of repeat surgery/radiation were 33.8% and 60.4%, respectively.

CONCLUSION

AM/MMs remain challenging tumors to treat. Elevated proliferative indices are associated with tumor recurrence, while MMs have worse survival. SRS can control AM/MMs in the short term, but the 5-yr PFS rates are low, underscoring the need for improved treatment options for these patients.

Validation of the updated renal graded prognostic assessment (GPA) for patients with renal cancer brain metastases treated with gamma knife radiosurgery

INTRODUCTION

Prognosis of patients with brain metastasis (BM) from renal cell carcinoma (RCC) is relevant for treatment decisions and can be estimated with the Renal Graded Prognostic Assessment (GPA). The aim of this study is to validate the updated version of this instrument in a cohort treated with Gamma Knife radiosurgery (GKRS) without prior local intracerebral therapy.

METHODS

Between 2007 and 2018, 106 RCC patients with BM were treated with GKRS. They were categorized according to the updated Renal GPA. Overall survival (OS), distant intracranial failure and local failure were estimated using the Kaplan-Meier method and risk factors were identified with Cox proportional hazard regressions.

RESULTS

Median OS was 8.6 months. Median OS for GPA categories 0.0-1.0 (15%), 1.5-2.0 (12%), 2.5-3.0 (35%) and 3.5-4.0 (29%) was 2.9, 5.5, 8.1 and 20.4 months, respectively. Karnofsky performance status < 90, serum hemoglobin ≤ 12.5 g/dL, age > 65 years and time from primary diagnosis to brain metastasis < 1 year were significantly related with shorter survival, while presence of extracranial disease, the volume and total number of BM had no significant impact on OS. A total count of > 4 BM was the only predictive factor for distant intracranial failure, while none of the investigated factors predicted local failure.

CONCLUSIONS

This study confirms the updated Renal GPA in an independent cohort as a valuable instrument to estimate survival in patients with BM from RCC treated with GKRS.

Prognostic Factors for Patients With Brain Metastases Treated With Single-fraction Gamma Knife Radiosurgery

BACKGROUND/AIM

The aim of this study was to identify prognostic factors for brain metastases treated with Gamma knife radiosurgery.

PATIENTS AND METHODS

Multivariate Cox proportional hazards regression analyses were conducted for patients who received treatment between June 2013 and March 2018.

RESULTS

A total of 131 consecutive patients were included. The median follow-up period was 16.0 months (range=1.5-61.5 months). Brain metastases [hazard ratio (HR)=0.42, 95%CI=0.27-0.67, p<0.001], history of systemic therapy (HR=2.23, 95%CI=1.28-3.89, p=0.005), and active extracranial disease (HR=2.49, 95%CI=1.30-4.76, p=0.006) were independent predictors of overall survival. Number of brain metastases (HR=0.39, 95%CI=0.26-0.59, p<0.001) and history of systemic therapy (HR=1.90, 95%CI=1.17-3.08, p=0.005) were independent predictors of intracranial progression-free survival.

CONCLUSION

The number of brain metastases and the history of systemic therapy are associated with patient overall survival and intracranial progression-free survival.

India's March towards Development of Treatment for Pituitary Tumors

Background

Although low-and middle-income countries (LMIC) bear the burden of the pituitary adenomas, most research is conducted in developed countries. However, there has been significant growth in research on pituitary adenomas in India from 1995 to 2020. The cost of patient treatment, management, and surgery of pituitary lesions are comparatively lower in India in comparison to high income countries.

Objective

The intended goal is to highlight the current scenario of pituitary research in India with regards to prevalence/incidence, tumor size, treatment modalities, cost of pituitary surgery, and potential strategies for tackling pituitary adenoma disease burden in the country.

Methodology

In addition to the literature review, recommendations were included from neurosurgeons, endocrinologists, and radiologists from various centers in India.

Results

There is an increasing evidence of pituitary adenoma heterogeneity compared to western populations. Although there has been significant increase in research on pituitary tumors from India, it is considerably less as compared to the data from the rest of the world. The major challenges for the treatment of this benign disease in India are lack of imaging facility in rural areas, poor patient follow up, and financial constraints for periodic imaging and biochemical assessment.

Conclusion

A computerized pituitary registry and genetic screening and testing will significantly boost research and lead to better patient outcome in the country. Special emphasis should be laid on multimodal management to ascertain optimal long-term tumor control with best hormonal outcome.

Gamma Knife Radiosurgery for Cavernous Malformations of Basal Ganglia and Thalamus: A Retrospective Study of 53 Patients

INTRODUCTION

Gamma Knife radiosurgery (GKRS) has been used to treat cavernous malformations (CMs) located in basal ganglia and thalamus. However, previous reports are limited by small patient population.

METHODS

We retrospectively reviewed the clinical and radiological data of 53 patients with CMs of basal ganglia and thalamus who underwent GKRS at West China Hospital between May 2009 and July 2018. All patients suffered at least once bleeding before GKRS. The mean volume of these lesions was 1.77 cm3, and the mean marginal dose was 13.2 Gy. After treatment, patients were followed to determine the change in symptom and hemorrhage event.

RESULTS

The mean follow-up period was 52.1 months (6.2-104.3 months). The calculated annual hemorrhage rate (AHR) was 48.5% prior to GKRS and 3.0% after treatment (p < 0.001). The Kaplan-Meier analysis revealed that 2-, 3-, and 5-year hemorrhage-free survival were 88, 80.9, and 80.9%, respectively. Preexisting symptoms were resolved in 11 patients, improved in 14, and stable in 5. Only 2 patients (3.8%) developed new neurological deficit.

CONCLUSION

Our study suggests that AHR after GKRS was comparable to the recorded AHR of natural history (3.1-4.1%) in previous studies. GKRS is a safe and effective treatment modality for CMs of basal ganglia and thalamus. Considering the relative insufficient understanding of natural history of CMs, future study warrants longer follow-up.

Long-term outcome in meningiomas involving the major dural sinuses with combined therapy of subtotal resection and early postoperative gamma knife radiosurgery

INTRODUCTION

Total resection of meningiomas involving the major dural sinuses (MIMDS) is still challenging for neurosurgeons. Gamma knife radiosurgery (GKRS) was shown to have a high probability of tumor control. The current study evaluated the clinical outcomes of patients who underwent subtotal resection alone or in combination with postoperative GKRS for the treatment of WHO grade I MIMDS.

METHODS

From January 2006 to December 2016, 204 patients with MIMDS underwent Simpson IV subtotal resection in Wuhan Union Hospital. In 151 patients, no additional treatment was performed, while the tumor remnant was treated with GKRS in 53 patients. All patients were monitored with regular MR follow-ups. We retrospectively reviewed the clinical data, radiological characteristics, and outcomes of these 204 patients. Progression-free survival (PFS) was determined by Kaplan-Meier analysis. Related factors were determined by univariate Cox regression analyses.

RESULTS

The mean follow-up period was 75.5 months. The tumor recurrence/progression rates were 13.9% in the microsurgery group and 3.8% in the combined therapy group (p = 0.045). The 5- and 10- year progression-free survival (PFS) rates were 92.3 and 80.7%, respectively, in the microsurgery group and 100.0 and 88.5% in the combined therapy group. Treatment approach was found to be an independent prognostic factor for tumor recurrence/progression in the univariable analyses (p=0.04).

CONCLUSIONS

Compared with microsurgery alone, targeted Simpson grade IV resection combined with early gamma knife treatment resulted in longer progression-free survival without increased complications for WHO grade I MIMDS.

Midterm prognosis and surgical implication for clival chordomas after extended transsphenoidal tumor removal and gamma knife radiosurgery

Background

Treating chordoma through surgery alone is often ineffective. Thus, surgery often performed with irradiation, with a reported 5-year survival rate of 60–75%. The clinical course varies, and disease rarity prevents larger number of clinical investigations.

Methods

In total, 19 patients with clival chordomas were retrospectively extracted from our institutional database. They were initially treated with maximal tumor removal using the extended transsphenoidal approach between March 2006 and January 2021. When total tumor removal was achieved, prophylactic irradiation was not performed. If tumor remnants or recurrence were confirmed, Gamma Knife (GK) radiosurgery was performed. The mean follow-up period was 106.7 months (ranged 27–224 months). The clinical course and prognostic factors were investigated.

Results

Total removal was achieved in 10 patients, whereas 4 patients suffered recurrence and required GK. GK was applied to 11 patients with a 50% isodose of 13–18 Gy (mean: 15.4 Gy), and eight patients remained progression free, whereas three patients suffered repeated local recurrence and died of tumor-related complications. The mean overall progression-free interval was 57.2 months (range: 6–169 months). One male patient died of tumor un-related lung cancer 36 months after the initial treatment, and other patients survived throughout the observational periods. The mean overall survival was 106.7 months (range: 27–224 months). Thus, the 5-year survival rate was 94.7%. Statistical analysis indicated that sex (men), > 15 Gy of 50% isodose by GK, and screening brain examinations as prophylactic medicine were significant favorable prognostic factors.

Conclusions

The favorable outcomes in this investigation suggest the importance of early detection and treatment. Surgery may enable better conditions for sufficient GK doses.

Gamma Knife Radiosurgery for Incidental, Symptomatic Unruptured, and Ruptured Brain Arteriovenous Malformations

BACKGROUND

This study was performed to investigate clinical characteristics and outcome after gamma knife radiosurgery (GKS) in patients with incidental, symptomatic unruptured, or ruptured arteriovenous malformations (AVMs).

METHODS

A total of 491 patients with brain AVMs treated with GKS from June 2002 to September 2017 were retrospectively reviewed. All patients were classified into the incidental (n = 105), symptomatic unruptured (n = 216), or ruptured AVM (n = 170) groups.

RESULTS

The mean age at diagnosis of incidental, symptomatic unruptured, and ruptured AVMs was 40.3, 36.7, and 27.6 years, respectively. The mean nidus volume was 3.9, 5.7, and 2.4 cm3, respectively. Deep venous drainage was identified in 34, 54, and 76% patients, respectively. There were no significant differences in obliteration rates after GKS between the 3 groups (64.8, 61.1, and 65.9%, respectively) after a mean follow-up period of 60.5 months; however, patients with incidental AVM had a significantly lower post-GKS hemorrhage rate than patients with symptomatic unruptured or ruptured AVMs (annual hemorrhage rate of 1.07, 2.87, and 2.69%; p = 0.028 and p = 0.049, respectively).

CONCLUSIONS

There is a significant difference in clinical and anatomical characteristics between incidental, symptomatic unruptured, and ruptured AVMs. The obliteration rate after GKS is not significantly different between the 3 groups. Meanwhile, an older age at diagnosis and lower hemorrhage rate after GKS in incidental AVMs suggest that they have a more indolent natural course with a lower life-long risk of hemorrhage.

Frame-Based and Mask-Based Stereotactic Radiosurgery: The Patient Experience, Compared

INTRODUCTION

Noninvasive frameless modalities have become increasingly utilized for stereotactic radiosurgery (SRS) for benign and malignant pathologies. There is minimal comparison in the literature of frame-based (FB) and mask-based (MB) SRS. With the dual capabilities of the Elekta Gamma Knife® Icon™, we sought to compare patient perceptions of FB and MB SRS with respect to comfort and pain and to examine effects of lesion type on the patient experience of SRS.

METHODS

Over a 1-year period, patients who underwent single fraction, fractionated or hypofractionated FB or MB Gamma Knife SRS at our institution were given an 8-question survey about their experience with the procedure immediately after treatment was completed. Descriptive statistics were applied.

RESULTS

A total of 117 patients completed the survey with 65 FB and 52 MB SRS treatments. Mean pain for FB SRS (5.64 ± 2.55) was significantly greater than mean pain for MB SRS (0.92 ± 2.24; t114 = 10.46, p < 0.001). Patient comfort during the procedure was also higher for those having MB SRS (p < 0.001). Mixed results were obtained when investigating if benign versus malignant diagnosis affected patient experience of SRS. For the purposes of this study, malignant diagnoses were almost entirely metastatic lesions. Diagnosis played no role on pain levels when all patients were analyzed together. The treatment technique had no effect on patient comfort in patients with benign diagnoses, while patients with malignant diagnoses treated with MB SRS were more likely to be comfortable (p < 0.001). Among patient's receiving FB treatments, diagnosis played no role on patient comfort. When only MB treatments were analyzed, patients were more likely to be comfortable if they had a malignant lesion (p < 0.01).

CONCLUSIONS

Patients treated with MB SRS experience the procedure as more comfortable and less painful compared to those treated using a FB modality. Overall, this difference was not affected by a benign versus a malignant diagnosis and the treatment type is more indicative of the patient experience during SRS. A more homogenous sample between modalities and diagnoses and further follow-up with the patient's input on their experience would be beneficial.

Gamma knife radiosurgery for high-risk lactotroph adenomas: Long-term results

Gamma Knife radiosurgery (GKRS) for lactotroph adenomas (LAs) or prolactinomas is limited due to the effectiveness of medical treatments and surgery. Cases who are refractory to medical treatment and/or surgery may be managed with GKRS. We aimed to describe the effectiveness of GKRS for high-risk lactotroph adenomas (HRLAs) and LAs that were medically and surgically refractory. We analyzed our series of patients with HRLAs and LAs who were managed with GKRS following failed medical treatment and surgery and who had at least three years of follow-up. A total of 52 patients (22 HRLAs and 30 LAs) were included in the analysis of radiological, endocrine, and clinical outcomes. Radiological control was achieved in 68.2% of subjects in the HRLA group and 96.7% of subjects in the LA group. Hormonal control was achieved in 68.2% of patients in the HRLA group and 80% of patients in the LA group. On univariate analysis, hormonal control was significantly associated with pre-treatment volume (p = 0.007), higher margin dose (p = 0.002) and Ki-67 proliferative index (p = 0.007). Complications involved new pituitary hormone deficiencies in 19.2% of patients and asymptomatic peripheral visual field defect in 1.9% of patients. To the best of our knowledge, this is the first study to examine the effectiveness of GKRS in LAs and HRLAs, with the highest median follow-up in the literature. High hormonal control rate, even in HRLAs, and lower complication rates suggest that GKRS should be part of the techniques for managing treatment refractory LAs.

Effects of Ozone on Injury after Gamma Knife Radiosurgery

BACKGROUND

At present, gamma knife radiosurgery plays an important role in neurosurgical procedures. Gamma knife radiosurgery has been used to treat many types of brain tumors and as a functional intervention. However, gamma knife treatment has a devastating effect on the normal brain parenchyma surrounding the target point. It causes increased vascular permeability, vasodilation, and swelling in endothelial cells. Ozone has antioxidant, antiapoptotic, and anti-inflammatory effects in the body. Thus, we evaluated the radioprotective effects of ozone in rats undergoing gamma knife radiation.

METHODS

In the present study, 24 Sprague-Dawley male rats weighing 250-300 g in 3 groups of 8 rats each were used. The rats were selected randomly. The control group did not receive any gamma knife radiation. The other 2 groups received 50 Gy of radiation, with 1 group given ozone treatment and the other group not given ozone treatment after gamma knife radiosurgery. At 12 weeks after gamma knife radiation, the rats were sacrificed with high-dose anesthetic agents and the tissues prepared for evaluation. The slides were evaluated for necrosis, vacuolization, glial proliferation, and vascular proliferation using hematoxylin-eosin staining. Vascular endothelial growth factor (VEGF) and extracellular matrix metalloproteinase inducer (also known as CD147) were evaluated using immunohistochemical staining.

RESULTS

VEGF expression in glial tissue was significantly less in the group receiving ozone (χ² = 15.00; df = 4; P = 0.005) compared with the group that had not received ozone and was similar to the expression in the control group.

CONCLUSIONS

The lower expression of VEGF in the group receiving ozone might cause less edema in the surrounding tissue owing to less degradation of vascular permeability in the rat brain tissue.

Hypofractionated frameless gamma knife radiosurgery for large metastatic brain tumors

Hypofractionated stereotactic radiosurgery has become an alternative for metastatic brain tumors (METs). We aimed to analyze the efficacy and safety of frameless hypofractionated Gamma Knife radiosurgery (hfGKRS) in the management of unresected, large METs. All patients who were managed with hfGKRS for unresected, large METs (> 4 cm³) between June 2017 and June 2020 at a single center were reviewed in this retrospective study. Local control (LC), progression-free survival (PFS), overall survival (OS), and toxicities were investigated. A total of 58 patients and 76 METs with regular follow-up were analyzed. LC rate was 98.5% at six months, 96.0% at one year, and 90.6% at 2 years during a median follow-up of 12 months (range, 2-37). The log-rank test indicated no difference in the distribution of LC for any clinical or treatment variable. PFS was 86.7% at 6 months, 66.6% at 1 year, and 58.5% at 2 years. OS was 81% at 6 months, 63.6% at one year, and 50.7% at 2 years. On the log-rank test, clinical parameters such as control status of primary cancer, presence of extracranial metastases, RTOG-RPA class, GPA group, and ds-GPA group were significantly associated with PFS and OS. Patients presented with grade 1 (19.0%), grade 2 (3.5%) and grade 3 (5.2%) side effects. Radiation necrosis was not observed in any patients. Our current results suggest that frameless hfGKRS for unresected, large METs is a rational alternative in selected patients with promising results.

Please spare my teeth! Dental procedures and trigeminal neuralgia

Background:

The correct diagnosis of trigeminal neuralgia (TN) is still a far cry and the patients suffer from unnecessary dental procedures before getting the definite treatment. In this study, we evaluated, if the patients have undergone dental procedures for their misdiagnosed TN before receiving definite treatment for the same.

Methods:

A total of 187 patients received GKRS for their TN (excluding secondary TN) in two institutes from 2010 to 2019. We did a retrospective analysis of these patients’ primary complaints on a standard questionnaire.

Results:

One hundred and seventeen of the 187 patients responded. About 55.5% of patients had a toothache and 65.8% did visit a dentist for the pain. About 41.8% of patients underwent one dental procedure; 18.8% suffered from worsening of the pain while 8.5% received some partial improvement. About 19.6% also underwent root canal treatment while 6.8% had a nerve block. Mean of 1.6 teeth was extracted per person. About 71% of patients were satisfied with their Gamma Knife radiosurgery for TN at a median follow-up of 49 months.

Conclusion:

There is a need for a better understanding of the disease among the dentists and the patients for the timely and correct treatment, without losing their teeth. The onus lies on neurosurgeons/neurologists disseminate knowledge regarding proper diagnosis and treatment modalities.

Assessment of single isocenter linear accelerator radiosurgery for metastases and base of skull lesions

BACKGROUND

Newer technology for stereotactic radiosurgery (SRS) should be assessed for different multi-leaf collimators (MLC).

OBJECTIVE

Assess plan quality of an automated, frameless, linear accelerator based (linac) planning and delivery system (HyperArc) for SRS using both standard MLC (SMLC) and high definition MLC (HDMLC) compared to a cobalt-60 based SRS system (Gamma Knife, GK).

METHODS

We re-planned twenty GK Perfexion-treated SRS patients (27 lesions) for HyperArc using SMLC and HDMLC. We assessed plan quality using the following metrics: gradient index (GI), Paddick and RTOG conformity indices (CI_Paddick, CI_RTOG), volume receiving half of prescription isodose (PIV_half) and maximum dose to 0.03 cc for brainstem, optic chiasm and optic nerves, and V12Gy for brain-GTV.

RESULTS

Linac plans had better conformity with HDMLC being most conformal. GK exhibited better GI. PIV_half demonstrated no statistically significant difference between HDMLC and GK, and SMLC was nominally worse than GK. Mean PIV_half was generally 0.85 cc larger for SMLC than HDMLC. For TV > 1.0 cc, the relative differences in CI_RTOG, GI, and PIV_half for SMLC vs. HDMLC were less than 21%. For TV less than < 1.0 cc, there were more obvious relative differences for SMLC vs. HDMLC in CI_RTOG (mean 146%, max 700%), GI (mean 49%, max 162%), and PIV_half (mean 77%, max 522%). Organ at risk doses were met in all plans.

CONCLUSIONS

New linac-based plans positively compare to GK plans overall. HDMLC should be strongly considered for treatment of lesions < 1.0 cc given the significant improvements in conformity and PIV_half over SMLC.

Treatment of sellar metastases with gamma knife radiosurgery in patients with advanced cancer

PURPOSE

Metastases should be considered in a patient with a cancer history and a sellar/suprasellar lesion, as this diagnosis can change the management strategy in such patients. Once the diagnosis is established, stereotactic radiosurgery (SRS) can be a safe and effective approach for these patients.

METHODS

This case series describes five patients with pituitary metastases managed with GKRS at a single institution, taken from our prospective registry. All patients had SRS using the Gamma Knife Perfexion or Icon (Elekta), according to our standard institutional protocol. The optic nerves and chiasm were contoured, and the plan was adjusted to restrict dose to the optic apparatus as necessary. The tumor margin doses delivered were 11 Gy, 12 Gy, 14 Gy, 18 Gy (3 sessions of 6 Gy), and 12 Gy at the 50% isodose line.

RESULTS

In this series, all sellar metastases were treated successfully with good radiographic and clinical response. The histology of the tumors included endometrial, gastrointestinal, and lung adenocarcinomas. Typically, histology is taken into consideration when choosing the treatment dose, along with size and location. In these patients, however, the dose used for the sellar metastases was chosen primarily for visual safety. This was typically lower than the dose for brain metastases in other locations.

CONCLUSION

SRS provides an alternative treatment approach for sellar/suprasellar metastases with excellent local control, symptom improvement and maintenance of systemic therapy as desired. As such, CNS failure is rarely the proximate cause of demise in pituitary metastases provided that endocrinopathies are recognized and managed appropriately.

Long-term endocrinological outcomes of gamma knife radiosurgery in acromegaly patients

Gamma knife radiosurgery (GKS) is a treatment option for recurrent or persistent disease in patients with acromegaly.

OBJECTIVE

We aimed to retrospectively evaluate acromegaly patients who had undergone GKS in terms of pituitary hormone status, efficacy of GKS, and prognostic factors.

METHOD

One-hundred and ten acromegaly patients who underwent GKS, and who were referred to our outpatient endocrinology clinic between 2007 and 2017, were included in the study. Anterior pituitary hormones and radiology imaging during follow-up were recorded. Remission for acromegaly was defined as a normal insulin-like growth factor 1 (IGF-1) level adjusted for age and gender, and a random growth hormone (GH) level < 1 ng/ml. Endocrine control was defined as normal GH and IGF-1 levels under medication.

RESULTS

After a mean follow-up of 6.5 ± 4.7 years; remission, endocrine control, and uncontrolled status was observed in 16.4%, 60%, and 23.6% of patients; respectively. Adenoma volume was decreased after GKS (P < .0001). Remnant adenoma diameter was higher in the uncontrolled group compared to the remission and endocrine control group. The presence of tumor extension was associated with disease status (P = .03) and higher initial GH and IGF-1 levels. The mean time after GKS to remission was 26.5 months. Six (5.4%) patients had new-onset pituitary deficiency after GKS. In the multivariate analysis, pre-GKS IGF-1 levels and patient's age were associated with disease status.

CONCLUSION

GKS is an effective adjuvant treatment with minimal side effects to control GH and IGF-1 levels, increase remission rates, endocrine control, and reduce tumor diameter in persistent acromegaly patients after surgery.

Comparing primary gamma knife radiosurgery and postoperative gamma knife radiosurgery for acromegaly: A monocenter retrospective study

OBJECTIVE

To compare the efficacy and safety between primary GKS and postoperative GKS for acromegaly, and to elucidate predictors associated with endocrine remission, we performed a monocenter, retrospective study.

METHOD

Seventy-five patients with acromegaly who had received GKS in West China Hospital between March 2010 and December 2018 were included in this study. Endocrine remission was defined as age-sex matched IGF-I normalization and either nadir level of GH <1 ng/mL after OGTT or the random GH < 2.0 ng/mL.

RESULTS

We didn't find significant differences in endocrine remission, biochemical recurrence, imaging regression, imaging progression, radiation-induced complications between the primary GKS group and the postoperative GKS group(P > 0.05). Actuarial rates of durable endocrine remission at 3, 5, 8 year were 10.60 %, 33.80 % and 70.60 % in the primary GKS group and 6.70 %, 43.40 % and 78.80 % in the postoperative GKS group(P = 0.800). Only base nadir GH after OGTT (HR = 0.637,95 % CI:0.416-0.977; P = 0.039) was found to be a predictor of duration endocrine remission.

CONCLUSION

We find comparable efficacy and safety between primary GKS and postoperative GKS. Lower base nadir GH after OGTT was a positive predictor associated with endocrine remission. GKS should be considered for residual or recurrent tumor after surgery. For those who couldn't sustain surgery, GKS is an alternative treatment. Further studies are required to elucidate the efficacy and safety of GKS in acromegaly.

Pre-radiosurgery leucocyte ratios and modified glasgow prognostic score predict survival in non-small cell lung cancer brain metastases patients

INTRODUCTION

The predictive value of the pre-radiosurgery Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), Lymphocyte-to-Monocyte Ratio (LMR) and the modified Glasgow Prognostic Score (mGPS) was assessed for the first time in a homogenous group of NSCLC brain metastaes (BM) patients.

METHODS

We retrospectively evaluated 185 NSCLC-BM patients, who were treated with Gamma Knife Radiosurgery (GKRS). Patients with immunotherapy or targeted therapy were excluded. Routine laboratory parameters were reviewed within 14 days before GKRS1.

RESULTS

Median survival after GKRS1 was significantly longer in patients with NLR < 5 (p < 0.001), PLR < 180 (p = 0.003) and LMR ≥ 4 (p = 0.023). The Cox regression model for the continuous metric values revealed that each increase in the NLR of 1 equaled an increase of 4.3% in risk of death (HR: 1.043; 95%CI = 1.020-1.067, p < 0.001); each increase in the PLR of 10 caused an increase of 1.3% in risk of death (HR: 1.013; 95%CI = 1.004-1.021; p = 0.003) and each increase in the LMR of 1 equaled a decrease of 20.5% in risk of death (HR: 0.795; 95%CI = 0.697-0.907; p = 0.001). Moreover, the mGPS group was a highly significant predictor for survival after GKRS1 (p < 0.001) with a HR of 2.501 (95%CI = 1.582-3.954; p < 0.001). NLR, PLR, LMR values and mGPS groups were validated as independent prognostic factors for risk of death after adjusting for sex, KPS, age and presence of extracranial metastases.

CONCLUSION

NLR, PLR, LMR and mGPS represent effective and simple tools to predict survival in NSCLC patients prior to radiosurgery for brain metastases.

Radiosurgery for Glioblastoma

Glioblastoma (GBM) is infiltrative neoplasm with limited treatment options and poor overall survival. Stereotactic radiosurgery (SRS) allows spatially precise and conformal delivery of high doses of radiation. Salvage SRS for locally recurrent GBM was shown to improve patient survival and have more favorable safety profile than repeated surgical resection. Boost SRS after fractionated radiation therapy is sometimes attempted; however, Radiation Therapy Oncology Group 93-05 randomized clinical trial did not demonstrate benefits of upfront SRS that was administered before fractionated radiation. Administration of bevacizumab with SRS is associated with improved survival and can allow SRS dose escalation.

Treatment Outcome of Gamma Knife Radiosurgery for Petroclival Meningiomas: Retrospective Analysis of a Single Institution Experience

Background

Although Gamma Knife radiosurgery (GKRS) has been widely used for intracranial meningiomas as an alternative or adjuvant treatment, guidelines have not been established for the selection of patients with petroclival meningioma (PCM) for GKRS. In this study, we reported the factors related to tumor progression and postoperative complications in PCM patients treated by GKRS, with a review of the literatures.

Methods

Between 2004 and 2019, 64 patients (52 patients for alternative and 12 patients for adjuvant treatment) with PCM underwent GKRS in our institution. The clinical and radiological factors were retrospectively analyzed. The mean radiologic follow-up duration was 58.4 months (range, 6–164 months). The mean tumor volume and diameter before GKRS were 13.4 cm³ and 2.9 cm, respectively. The median marginal dose was 12 Gy (range, 10–14 Gy) with a 50% median isodose line. Fractionation was used in 19 cases (29%, two fractionations in 5 cases & three fractionations in 14 cases).

Results

Progression was noted in 7 cases (10.9%) and the progression-free survival rates were 91.1% at 5 years and 69.6% at 10 years. Although large in volume, moderate to severe peritumoral edema and male gender were somewhat related to progression, they did not reach statistical significance. Ten patients (15.6%) developed complications after GKRS. The most common complication was cranial nerve deficit (n=8), followed by hemiparesis, cognitive dysfunction, and hydrocephalus. Large size (maximal diameter ≥5 cm) [hazard ratio (HR) 0.091, 95% confidence interval (CI) 0.014–0.608; p=0.013] and multiplicity (HR 0.102, 95% CI 0.018–0.573; p=0.009) were independent factors for developing complications after GKRS.

Conclusion

GKRS can be considered an effective and safe treatment for large-volume PCM. However, for patients with large size or multiple masses, the treatment method should be determined with caution because the probability of complications after GKRS may increase.