Gamma Knife Radiosurgery for Hypothalamic Hamartoma: A Multi-Institutional Retrospective Study on Safety, Efficacy, and Complication Profile.

BACKGROUND AND OBJECTIVES: Gamma knife radiosurgery (GKRS) is a safe and effective treatment option for hypothalamic hamartomas (HH), but there is no consensus opinion on its timing, dosage, and follow-up. The aim of this study was to define the safety, efficacy, outcome, and complication profile of GKRS in this patient population. METHODS: This retrospective multicentric study involved 39 patients with the mean age of 16 ± 14.84 years. Early seizures resulted in an earlier age of diagnosis in 97% of patients. At baseline, no endocrine abnormalities were seen in 75% of patients while 18.9% showed precocious puberty (PP). The median target volume was 0.55 cc (0.1-10.00 cc), and a median margin dose of 16 Gy (8.1-20.0 Gy) was delivered in a single session. All patients were evaluated for clinical, endocrinological, and radiological outcomes. RESULTS: The median follow-up was 5 (0.1-15) years. The median target volume of the cohort was 0.55 (0.35-1.77) cc. The largest HH was of 10 cc. 24/39 (61.5%) were small HH (Regis I-III). At presentation, 94.8% patients suffered from seizures (87.18% with gelastic seizures). 7/39 patients (17.9%) were presented with both PP and epilepsy. Only one (2.6%) patient presented with PP alone. 29 patients had more than 3-year follow-up. All received ≥16 Gy targeting complete HH. 28% of patients showed regression in HH volume. Patients with Regis grade I-III and longer follow-up (>75 months) showed gradual improvement in seizures. 16/29 patients (55.2%) achieved good seizure control (Engel I/II) while 13 (44.8%) were in Engel III/IV status. Nine patients needed adjuvant treatment because of poor seizure control. Eight patients suffered from transient increase in seizures. One patient developed poikilothermia, and 2 patients developed new onset hormonal deficiency. CONCLUSION: GKRS is a safe and effective modality for treatment of HH with significant improvement in seizure control with minimal disruption of endocrine profile. It provides an excellent safety, efficacy, and complication profile, especially for small HH. Latency of results and its adjuvant nature remain the areas of research and breakthroughs among contemporary treatment options.

Diffusivity metrics alterations three months after GammaKnife radiosurgery for trigeminal neuralgia may predict pain relief.

Objectives: Early identification of patients who will experience delayed-onset pain relief after GKRS for trigeminal neuralgia (TN) will allow optimal patient management, and avoidance of unnecessary procedures. A non-invasive tool to identify late responders to GKRS is currently unavailable. We sought to evaluate MRI based diffusivity metrics obtained at the 3-month post-GKRS time point as predictors of treatment response. Methods: Pre-procedural and 3-month post-procedural 3T MRI examinations were obtained in 43 patients with TN. Diffusion tensor metrics including axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) were extracted from the bilateral trigeminal nerve intra-pontine fibers, cisternal radiosurgical targets (or corresponding contralateral nerve segments), and non-targeted cisternal nerve segments. A favorable treatment response was defined as pain intensity on the Barrow Neurological Institute (BNI) scale of I-II at last follow-up. Pain relief and treatment response at last follow-up were examined for correlation with the 3-month post-GKRS diffusivity metrics. Results: At a median clinical follow-up of 5 months (range 0.5 to 24.5 months), all patients who did not experience pain relief at last follow-up had significantly reduced cisternal AD values (p=0.04) at the 3-month brain Diffusion Tensor image. In patients with classic TN, reduced mean cisternal AD (p=0.032), RD (p=0.026), and FA (p=0.042) values at the 3-month DTI follow-up were associated with BNI >2 at last follow-up. In addition, decreased mean cisternal AD (p=0.036), RD (p=0.029), and FA (p=0.037) were noted in patients with classic TN that failed to achieve a decrease of 2 points on the BNI scale at last follow-up. Conclusion: Alterations of diffusivity metrics on the treated trigeminal nerve 3 months after GKRS for classic TN significantly correlated with no response to GKRS at last follow-up. Further studies to clarify the value of DTI as a non-invasive tool to predict response to treatment in patients with TN managed with GKRS are warranted.

Training Neurosurgery and Radiation Oncology Residents in Stereotactic Radiosurgery: Assessment Gathered from Participants in AANS and ASTRO Training Course.

OBJECTIVE: Stereotactic radiosurgery (SRS) represents an expanding approach for neurosurgeons and radiation oncologists. We evaluate educational gaps of senior residents drawn from each specialty as part of a focused SRS course. We also evaluate the strengths and limitations of SRS training in current residency programs of the course residents and faculty. METHODS: The American Association of Neurological Surgeons and American Society of Radiation Oncology jointly held a senior resident course in SRS. Residents were nominated by program directors from across the United States. Thirty residents were chosen to participate in the course. The residents were surveyed before and after the course. Faculty (n = 14) were also surveyed to ascertain their perspectives on current training in SRS. RESULTS: Most (96.7%) of the residents planned to perform SRS when finished, and 94% anticipated SRS indications to expand. Regarding SRS technique, 47% reported average/above average understanding of intracranial SRS; only 17% expressed similar understanding of spinal SRS. Before the course, 76.6% noted below average/average ability to recognize and manage SRS complications. Twenty-three percent of the faculty indicated that graduating residents from their programs were unprepared to perform radiosurgery. Residents' self-assessed understanding of brain SRS indication (P = 0.000693), SRS techniques (P = 0.000021), spinal SRS indications (P = 0.000050), spinal SRS techniques (P = 0.000019), and complication recognition and management (P = 0.00033) significantly improved following the course. CONCLUSIONS: Knowledge and training gaps in SRS appear evident to the senior residents and faculty of both specialties. We believe that other educational opportunities for SRS experience are necessary to optimize clinical competency, as well as meet future clinical staffing needs for this expanding, multidisciplinary approach. Further evaluation of gaps in SRS is necessary through a larger, nationwide survey of U.S. neurosurgeons, program directors, and residents.