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Or Cohen-Inbar, Robert M. Starke, Gabriella Paisan, Hideyuki Kano, Paul P. Huang, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, David Mathieu, Danilo Silva, Mahmoud Abbassy, Symeon Missios, John Y. K. Lee, Gene H. Barnett, Douglas Kondziolka, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

The goal of stereotactic radiosurgery (SRS) for arteriovenous malformation (AVM) is complete nidus obliteration, thereby eliminating the risk of future hemorrhage. This outcome can be observed within the first 18 months, although documentation of AVM obliteration can extend to as much as 5 years after SRS is performed. A shorter time to obliteration may impact the frequency and effect of post-SRS complications and latency hemorrhage. The authors' goal in the present study was to determine predictors of early obliteration (18 months or less) following SRS for cerebral AVM.

METHODS

Eight centers participating in the International Gamma Knife Research Foundation (IGKRF) obtained institutional review board approval to supply de-identified patient data. From a cohort of 2231 patients, a total of 1398 patients had confirmed AVM obliteration. Patients were sorted into early responders (198 patients), defined as those with confirmed nidus obliteration at or prior to 18 months after SRS, and late responders (1200 patients), defined as those with confirmed nidus obliteration more than 18 months after SRS. The median clinical follow-up time was 63.7 months (range 7–324.7 months).

RESULTS

Outcome parameters including latency interval hemorrhage, mortality, and favorable outcome were not significantly different between the 2 groups. Radiologically demonstrated radiation-induced changes were noted more often in the late responder group (376 patients [31.3%] vs 39 patients [19.7%] for early responders, p = 0.005). Multivariate independent predictors of early obliteration included a margin dose > 24 Gy (p = 0.031), prior surgery (p = 0.002), no prior radiotherapy (p = 0.025), smaller AVM nidus (p = 0.002), deep venous drainage (p = 0.039), and nidus location (p < 0.0001). Basal ganglia, cerebellum, and frontal lobe nidus locations favored early obliteration (p = 0.009). The Virginia Radiosurgery AVM Scale (VRAS) score was significantly different between the 2 responder groups (p = 0.039). The VRAS score was also shown to be predictive of early obliteration on univariate analysis (p = 0.009). For early obliteration, such prognostic ability was not shown for other SRS- and AVM-related grading systems.

CONCLUSIONS

Early obliteration (≤ 18 months post-SRS) was more common in patients whose AVMs were smaller, located in the frontal lobe, basal ganglia, or cerebellum, had deep venous drainage, and had received a margin dose > 24 Gy.

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Or Cohen-Inbar, Robert M. Starke, Hideyuki Kano, Gregory Bowden, Paul Huang, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, David Mathieu, Danilo Silva, Mahmoud Abbassy, Symeon Missios, John Y. K. Lee, Gene H. Barnett, Douglas Kondziolka, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

Cerebellar arteriovenous malformations (AVMs) represent the majority of infratentorial AVMs and frequently have a hemorrhagic presentation. In this multicenter study, the authors review outcomes of cerebellar AVMs after stereotactic radiosurgery (SRS).

METHODS

Eight medical centers contributed data from 162 patients with cerebellar AVMs managed with SRS. Of these patients, 65% presented with hemorrhage. The median maximal nidus diameter was 2 cm. Favorable outcome was defined as AVM obliteration and no posttreatment hemorrhage or permanent radiation-induced complications (RICs). Patients were followed clinically and radiographically, with a median follow-up of 60 months (range 7–325 months).

RESULTS

The overall actuarial rates of obliteration at 3, 5, 7, and 10 years were 38.3%, 74.2%, 81.4%, and 86.1%, respectively, after single-session SRS. Obliteration and a favorable outcome were more likely to be achieved in patients treated with a margin dose greater than 18 Gy (p < 0.001 for both), demonstrating significantly better rates (83.3% and 79%, respectively). The rate of latency preobliteration hemorrhage was 0.85%/year. Symptomatic post-SRS RICs developed in 4.5% of patients (n = 7). Predictors of a favorable outcome were a smaller nidus (p = 0.0001), no pre-SRS embolization (p = 0.003), no prior hemorrhage (p = 0.0001), a higher margin dose (p = 0.0001), and a higher maximal dose (p = 0.009). The Spetzler-Martin grade was not found to be predictive of outcome. The Virginia Radiosurgery AVM Scale score (p = 0.0001) and the Radiosurgery-Based AVM Scale score (p = 0.0001) were predictive of a favorable outcome.

CONCLUSIONS

SRS results in successful obliteration and a favorable outcome in the majority of patients with cerebellar AVMs. Most patients will require a nidus dose of higher than 18 Gy to achieve these goals. Radiosurgical and not microsurgical scales were predictive of clinical outcome after SRS.

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Seyed H. Mousavi, Berkcan Akpinar, Ajay Niranjan, Vikas Agarwal, Jonathan Cohen, John C. Flickinger, Douglas Kondziolka and L. Dade Lunsford

OBJECTIVE

Contrast enhancement of the retrogasserian trigeminal nerve on MRI scans frequently develops after radiosurgical ablation for the management of medically refractory trigeminal neuralgia (TN). The authors sought to evaluate the clinical significance of this imaging finding in patients who underwent a second radiosurgical procedure for recurrent TN.

METHODS

During a 22-year period, 360 patients underwent Gamma Knife stereotactic radiosurgery (SRS) as their first surgical procedure for TN at the authors' center. The authors retrospectively analyzed the data from 59 patients (mean age 72 years, range 33–89 years) who underwent repeat SRS for recurrent pain at a median of 30 months (range 6–146 months) after the first SRS. The isocenter was 4 mm, and the median maximum doses for the first and second procedures were 80 Gy and 70 Gy, respectively. A neuroradiologist and a neurosurgeon blinded to the treated side evaluated the presence of nerve contrast enhancement on MRI series at the time of the repeat procedure. The authors correlated the presence of this imaging change with clinical outcomes. Pain outcomes and development of trigeminal sensory dysfunction were evaluated with the Barrow Neurological Institute (BNI) Pain Scale and BNI Numbness Scale, respectively. The mean length of follow-up after the second SRS was 58 months (95% CI 49–68 months).

RESULTS

At the time of the repeat SRS, contrast enhancement of the trigeminal nerve on MRI scans was observed in 31 patients (53%). Five years after the SRS, patients with this enhancement had lower actuarial rates of complete pain relief after the repeat SRS (27% [95% CI 7%–47%]) than patients without the enhancement (76% [95% CI 58%–94%]) (p < 0.001). At the 5-year follow-up, patients with the contrast enhancement also had a higher risk for trigeminal sensory loss after repeat SRS (75% [95% CI 59%–91%]) than patients without contrast enhancement (26% [95% CI 10%–42%]) (p = 0.001). Dysesthetic pain after repeat SRS was observed for 8 patients with and for 2 patients without contrast enhancement.

CONCLUSIONS

Trigeminal nerve contrast enhancement on MRI scans observed at the time of a repeat SRS for TN was associated with less satisfactory pain control and more frequently detected facial sensory loss. Residual contrast enhancement at the time of a repeat SRS may warrant consideration of dose reduction or further separation of the radiosurgical targets.

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Cheng-Chia Lee, Jason P. Sheehan, Hideyuki Kano, Berkcan Akpinar, Roberto Martinez-Alvarez, Nuria Martinez-Moreno, Wan-Yuo Guo, L. Dade Lunsford and Kang-Du Liu

OBJECTIVE

Cavernous sinus hemangiomas (CSHs) are rare vascular tumors. A direct microsurgical approach usually results in massive hemorrhage and incomplete tumor resection. Although stereotactic radiosurgery (SRS) has emerged as a therapeutic alternative to microsurgery, outcome studies are few. Authors of the present study evaluated the role of SRS for CSH.

METHODS

An international multicenter study was conducted to review outcome data in 31 patients with CSH. Eleven patients had initial microsurgery before SRS, and the other 20 patients (64.5%) underwent Gamma Knife SRS as the primary management for their CSH. Median age at the time of radiosurgery was 47 years, and 77.4% of patients had cranial nerve dysfunction before SRS. Patients received a median tumor margin dose of 12.6 Gy (range 12–19 Gy) at a median isodose of 55%.

RESULTS

Tumor regression was confirmed by imaging in all 31 patients, and all patients had greater than 50% reduction in tumor volume at 6 months post-SRS. No patient had delayed tumor growth, new cranial neuropathy, visual function deterioration, adverse radiation effects, or hypopituitarism after SRS. Twenty-four patients had presented with cranial nerve disorders before SRS, and 6 (25%) of them had gradual improvement. Four (66.7%) of the 6 patients with orbital symptoms had symptomatic relief at the last follow-up.

CONCLUSIONS

Stereotactic radiosurgery was effective in reducing the volume of CSH and attaining long-term tumor control in all patients at a median of 40 months. The authors' experience suggests that SRS is a reasonable primary and adjuvant treatment modality for patients in whom a CSH is diagnosed.

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Marshall J. Huang, Hideyuki Kano, Seyed H. Mousavi, Ajay Niranjan, Edward A. Monaco III, Yoshio Arai, John C. Flickinger and L. Dade Lunsford

OBJECTIVE

The goal of this retrospective cohort study was to assess long-term outcomes in patients with vestibular schwannoma (VS) who underwent stereotactic radiosurgery (SRS) after initial microsurgical resection.

METHODS

From the authors' database of 1770 patients with VS, the authors retrospectively analyzed data from 173 Gamma Knife SRS procedures for VS after 1 (128 procedures) or multiple (45 procedures) microsurgical resections. The median length of the interval between the last resection and SRS was 42 months (range 2–329 months). The median length of clinical follow-up was 74 months (range 6–285 months). Progression-free survival after SRS was determined with Kaplan-Meier analysis.

RESULTS

At the time of SRS, the hearing of 161 patients (93%) was Gardner-Robertson Class V, and 81 patients (47%) had facial neuropathy (i.e., facial function with House-Brackmann [HB] grades of III–VI), 87 (50%) had trigeminal neuropathy, and 71 (41%) reported imbalance or disequilibrium disorders. The median tumor volume was 2.7 cm3 (range 0.2–21.6 cm3), and the median dose to the tumor margin was 13 Gy (range 11–20 Gy). Radiosurgery controlled growth of 163 (94%) tumors. Progression-free survival after SRS was 97% at 3 years, 95% at 5 years, and 90% at 10 years. Four patients with delayed tumor progression underwent repeat SRS at a median of 35 months (range 23–64 months) after the first SRS. Four patients (2.3%) with tumor progression underwent repeat resection at a median of 25 months (range 19–33 months). Among the patients with any facial dysfunction (indicated by HB grades of II–VI), 19% had improvement in this condition after SRS, and 5.5% with some facial function (indicated by HB grades of I–V) developed more facial weakness. Among patients with trigeminal neuropathy, 20% had improvement in this condition, and 5.8% developed or had worsened trigeminal neuropathy after SRS.

CONCLUSIONS

Stereotactic radiosurgery offered a safe and effective long-term management strategy for VS patients whose tumors remained or recurred after initial microsurgery.

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Nitin Agarwal, Sumana S. Kommana, David R. Hansberry, Ahmed I. Kashkoush, Robert M. Friedlander and L. Dade Lunsford

OBJECTIVE

Closing the knowledge gap that exists between patients and health care providers is essential and is facilitated by easy access to patient education materials. Although such information has the potential to be an effective resource, it must be written in a user-friendly and understandable manner, especially when such material pertains to specialized and highly technical fields such as neurological surgery. The authors evaluated the accessibility, usability, and reliability of current educational resources provided by the American Association of Neurological Surgeons (AANS), Healthwise, and the National Institute for Neurological Disorders and Stroke (NINDS).

METHODS

Online neurosurgical patient education information provided by AANS, Healthwise, and NINDS was evaluated using the LIDA scale, a website quality assessment tool, by medical professionals and nonmedical professionals. A high achieving score is regarded as 90% or greater using the LIDA scale.

RESULTS

Accessibility scores were 76.7% (AANS), 83.3% (Healthwise), and 75.0% (NINDS). Average usability scores for the AANS, Healthwise, and NINDS were 73.3%, 82.6%, and 82.9%, respectively, when evaluated by medical professionals and 78.5%, 80.7%, and 75.9%, respectively, for nonmedical professionals, respectively. Average reliability scores were 58.5%, 53.3%, 72.6%, respectively, for medical professionals and 70.4%, 66.7%, and 78.5%, respectively, for nonmedical professionals when evaluating the AANS, Healthwise, and NINDS websites.

CONCLUSIONS

Although organizations like AANS, Healthwise, and NINDS should be commended for their ongoing commitment to provide health care–oriented materials, modification of this material is suggested to improve the patient education value.

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Or Cohen-Inbar, Cheng-Chia Lee, Seyed H. Mousavi, Hideyuki Kano, David Mathieu, Antonio Meola, Peter Nakaji, Norissa Honea, Matthew Johnson, Mahmoud Abbassy, Alireza M. Mohammadi, Danilo Silva, Huai-Che Yang, Inga Grills, Douglas Kondziolka, Gene H. Barnett, L. Dade Lunsford and Jason Sheehan

OBJECTIVE

Hemangiopericytomas (HPCs) are rare tumors widely recognized for their aggressive clinical behavior, high recurrence rates, and distant and extracranial metastases even after a gross-total resection. The authors report a large multicenter study, through the International Gamma Knife Research Foundation (IGKRF), reviewing management and outcome following stereotactic radiosurgery (SRS) for recurrent or newly discovered HPCs.

METHODS

Eight centers participating in the IGKRF participated in this study. A total of 90 patients harboring 133 tumors were identified. Patients were included if they had a histologically diagnosed HPC managed with SRS during the period 1988–2014 and had a minimum of 6 months' clinical and radiological follow-up. A de-identified database was created. The patients' median age was 48.5 years (range 13–80 years). Prior treatments included embolization (n = 8), chemotherapy (n = 2), and fractionated radiotherapy (n = 34). The median tumor volume at the time of SRS was 4.9 cm3 (range 0.2–42.4 cm3). WHO Grade II (typical) HPCs formed 78.9% of the cohort (n = 71). The median margin and maximum doses delivered were 15 Gy (range 2.8–24 Gy) and 32 Gy (range 8–51 Gy), respectively. The median clinical and radiographic follow-up periods were 59 months (range 6–190 months) and 59 months (range 6–183 months), respectively. Prognostic variables associated with local tumor control and post-SRS survival were evaluated using Cox univariate and multivariate analysis. Actuarial survival after SRS was analyzed using the Kaplan-Meier method.

RESULTS

Imaging studies performed at last follow-up demonstrated local tumor control in 55% of tumors and 62.2% of patients. New remote intracranial tumors were found in 27.8% of patients, and 24.4% of patients developed extracranial metastases. Adverse radiation effects were noted in 6.7% of patients. During the study period, 32.2% of the patients (n = 29) died. The actuarial overall survival was 91.5%, 82.1%, 73.9%, 56.7%, and 53.7% at 2, 4, 6, 8, and 10 years, respectively, after initial SRS. Local progression–free survival (PFS) was 81.7%, 66.3%, 54.5%, 37.2%, and 25.5% at 2, 4, 6, 8, and 10 years, respectively, after initial SRS. In our cohort, 32 patients underwent 48 repeat SRS procedures for 76 lesions. Review of these 76 treated tumors showed that 17 presented as an in-field recurrence and 59 were defined as an out-of-field recurrence. Margin dose greater than 16 Gy (p = 0.037) and tumor grade (p = 0.006) were shown to influence PFS. The development of extracranial metastases was shown to influence overall survival (p = 0.029) in terms of PFS; repeat (multiple) SRS showed additional benefit.

CONCLUSIONS

SRS provides a reasonable rate of local tumor control and a low risk of adverse effects. It also leads to neurological stability or improvement in the majority of patients. Long-term close clinical and imaging follow-up is necessary due to the high probability of local recurrence and distant metastases. Repeat SRS is often effective for treating new or recurrent HPCs.

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Dale Ding, Robert M. Starke, Hideyuki Kano, John Y. K. Lee, David Mathieu, John Pierce, Paul P. Huang, Caleb Feliciano, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, Danilo Silva, Mahmoud Abbassy, Symeon Missios, Douglas Kondziolka, Gene H. Barnett, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

Because of the angioarchitectural diversity of Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs), the management of these lesions is incompletely defined. The aims of this multicenter, retrospective cohort study were to evaluate the outcomes after stereotactic radiosurgery (SRS) for SM Grade III AVMs and to determine the factors predicting these outcomes.

METHODS

The authors analyzed and pooled data from patients with SM Grade III AVMs treated with SRS at 8 institutions participating in the International Gamma Knife Research Foundation. Patients with these AVMs and a minimum follow-up length of 12 months were included in the study cohort. An optimal outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs). Data were analyzed by univariate and multivariate regression analyses.

RESULTS

The SM Grade III AVM cohort comprised 891 patients with a mean age of 34 years at the time of SRS. The mean nidus volume, radiosurgical margin dose, and follow-up length were 4.5 cm3, 20 Gy, and 89 months, respectively. The actuarial obliteration rates at 5 and 10 years were 63% and 78%, respectively. The annual postradiosurgery hemorrhage rate was 1.2%. Symptomatic and permanent RICs were observed in 11% and 4% of the patients, respectively. Optimal outcome was achieved in 56% of the patients and was significantly more frequent in cases of unruptured AVMs (OR 2.3, p < 0.001). The lack of a previous hemorrhage (p = 0.037), absence of previous AVM embolization (p = 0.002), smaller nidus volume (p = 0.014), absence of AVM-associated arterial aneurysms (p = 0.023), and higher margin dose (p < 0.001) were statistically significant independent predictors of optimal outcome in a multivariate analysis.

CONCLUSIONS

Stereotactic radiosurgery provided better outcomes for patients with small, unruptured SM Grade III AVMs than for large or ruptured SM Grade III nidi. A prospective trial or registry that facilitates a comparison of SRS with conservative AVM management might further clarify the authors' observations for these often high-risk AVMs.

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Michael Kerin Morgan, Marcus Andrew Stoodley and John William Fuller