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Dural arteriovenous fistulas (DAVFs) are a relatively rare intracranial vascular malformation. The various treatment options for DAVFs include observation, compression therapy, endovascular therapy, radiosurgery, or surgery. A combination of these therapies may also be used. The treatment choice for DAVFs depends on the type of fistula, the severity of symptoms, DAVF angioarchitecture, and the efficacy and safety of treatments. The use of stereotactic radiosurgery (SRS) in DAVFs started in the late 1970s. There is a delay before the fistula gets obliterated after SRS and there is a risk of hemorrhage from the fistula till the fistula gets obliterated. Initial reports described the role of SRS in small DAVFs without severe symptoms, which were inaccessible by endovascular or surgical measures or in combination with embolization in larger DAVFs. SRS can be appropriate for indirect cavernous sinus DAVF fistulas (Barrow type B, C, and D). Borden types II and III and Cognard types IIb-V DAVFs have a high risk of hemorrhage and are traditionally considered less favorable to be treated with SRS as immediate treatment is required to decrease the risk of hemorrhage. However, recently SRS has been tried in these high-grade DAVF as a monotherapy. Factors that have a positive impact on the obliteration rates of DAVF following SRS are the location of DAVF with the cavernous sinus DAVF having much better obliteration rates than DAVF located at other locations, Borden Type I or Cognard Types III or IV DAVFs, absence of CVD, hemorrhage at the time of initial presentation, and target volume lesser than 1.5 mL., Competing Interests: None

Objective: To determine whether biological effective dose (BED) was predictive of obliteration after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs)., Patients and Methods: We studied patients undergoing single-session AVM SRS between January 1, 1990, and December 31, 2014, with at least 2 years of imaging follow-up. Excluded were patients with syndromic AVM, previous SRS or embolization, and patients treated with volume-staged SRS. Biological effective dose was calculated using a mono-exponential model described by Jones and Hopewell. The primary outcome was likelihood of total obliteration defined by digital subtraction angiography or magnetic resonance imaging (MRI). Variables were analyzed as continuous and dichotomous variables based on the maximum value of (sensitivity-[1-specificity])., Results: This study included 352 patients (360 AVM, median follow-up, 5.9 years). The median margin dose prescribed was 18.75 Gy (interquartile range [IQR]: 18 to 20 Gy). Two hundred fifty-nine patients (71.9%) had obliteration shown by angiography (n=176) or MRI (n=83) at a median of 36 months after SRS (IQR: 26 to 44 months). Higher BED was associated with increased likelihood of obliteration in univariate Cox regression analyses, when treated as either a dichotomous (≥133 Gy; hazard ratio [HR],1.52; 95% confidence interval [CI], 1.19 to 1.95; P<.001) or continuous variable (HR, 1.00, 95% CI, 1.0002 to 1.005; P=.04). In multivariable analyses including dichotomized BED and location, BED remained associated with obliteration (P=.001)., Conclusion: Biological effective dose ≥133 Gy was predictive of AVM obliteration after single-session SRS within the prescribed margin dose range 15 to 25 Gy. Further study is warranted to determine whether BED optimization should be considered as well as treatment dose for AVM SRS planning., (Copyright © 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Competing Interests: There are no conflicts of interest

Objective: The aim of this study is to report the pattern, timing, responsible radiation parameters, and dosimetric results on the outcome of alopecia following gamma knife radiosurgery (GKRS) for various intracranial pathologies. A literature review of radiation-induced alopecia and observation of this complication with GKRS are also included., Materials and Methods: The authors report 6 cases of GKRS-induced focal temporary alopecia without dermal fibrosis or clinical scarring and with no long-term squeal., Results: In all the cases, the scalp received ≥3 Gy radiation exposure. Post GKRS alopecia is a temporary, noncicatricial, focal, reversible phenomenon observed within 2 weeks of the treatment. This acute complication is dose-dependent and reflects damage to the hair follicle. It is only seen with treated volumes in the superficial location. Hair regrowth occurs within two months with no long-term complications and change in hair quality being noted., Conclusion: Compared to whole brain radiotherapy, chances of alopecia are significantly less after GKRS. Despite a sharp dose fallout, a single fraction high-dose radiosurgery with GKRS may expose the skin appendages to more than 3 Gy radiation exposures, which may injure the hair follicles irrespective of the growth phase (anagen, telogen, or catagen) they are in. A careful planning that includes sparing of the dermal appendages and hair roots up to 4-6 mm depth in the skin may prevent this complication. Patients with superficial lesions should be well informed about the reversible nature of this possible complication, with near-normal hair growth being established within 2 months of treatment., Competing Interests: There are no conflicts of interest

Background and Purpose- The aim of this international, multicenter, retrospective matched cohort study is to directly compare the outcomes after stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVM) in pediatric versus adult patients. Methods- We performed a retrospective review of patients with AVM who underwent SRS at 8 institutions participating in the International Gamma Knife Research Foundation from 1987 to 2014. Patients were categorized into pediatric (<18 years of age) and adult (≥18 years of age) cohorts and matched in a 1:1 ratio using propensity scores. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes. Results- From a total of 2191 patients who were eligible for inclusion in the overall study cohort, 315 were selected for each of the matched cohorts. There were no significant differences between matched pediatric versus adult cohorts with respect to the rates of favorable outcome (59% versus 58%; P=0.936), AVM obliteration (62% versus 63%; P=0.934), post-SRS hemorrhage (9% versus 7%; P=0.298), radiological radiation-induced changes (26% versus 26%; P=0.837), symptomatic radiation-induced changes (7% versus 9%; P=0.383), or permanent radiation-induced changes (2% versus 3%; P=0.589). The all-cause mortality rate was significantly lower in the matched pediatric cohort (3% versus 10%; P=0.003). Conclusions- The outcomes after SRS for comparable AVMs in pediatric versus adult patients were not found to be appreciably different. SRS remains a reasonable treatment option for appropriately selected pediatric patients with AVM, who harbor a high cumulative lifetime hemorrhage risk. Age seems to be a poor predictor of AVM outcomes after SRS.

Background and Purpose: A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) indicated the superiority of medical management in reducing the risks for strokes and other neurological deficits over observation alone. The aim of our study was to verify the rationale for stereotactic radiosurgery (SRS) for small unruptured arteriovenous malformation., Methods: A retrospective review was performed for 292 patients with unruptured arteriovenous malformations referred for SRS. The risks for cerebral hemorrhages were statistically compared before and after SRS., Results: Of the 292 patients in whom arteriovenous malformation was found unruptured at initial diagnosis, 17 sustained hemorrhages in the period between the diagnosis and the initial therapeutic intervention (annual bleeding rate, 2.1%; 95% confidence interval [CI], 1.2%-3.4%). Of the remaining 275 patients, 240 were initially treated with SRS, and 16 sustained a hemorrhage after SRS (annual bleeding rate, 1.1%; 95% CI, 0.6%-1.8%), but only 2 sustained a hemorrhage after angiographic obliteration (annual bleeding rate, 0.3%; 95% CI, 0.04%-1.2%). Comparing the risk of hemorrhage between the periods before and after SRS, a 53% risk reduction was achieved after SRS (hazard ratio, 0.47; 95% CI, 0.24-0.94; P=0.03), and 85% reduction was achieved after angiographic obliteration (hazard ratio, 0.15; 95% CI, 0.02-0.53; P=0.002)., Conclusions: SRS can significantly reduce the risk of stroke in the patients with small unruptured arteriovenous malformations. To definitively determine the clinical benefits of SRS, a longer follow-up will be necessary. However, based on our results, we can recommend SRS for patients who face a latent risk for stroke from this intractable vascular disease., (© 2016 American Heart Association, Inc.)