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Introduction Meningiomas are extra-axial central nervous system tumors. Complete resection is often curative with macroscopically complete removal of the tumor, excision of its dural attachment, and any abnormal bone. Radiosurgery is also an option for high-risk patients or in patients with surgically residual disease. Dural tail is a typical radiological sign on contrast-enhanced MRI; it can contain tumor cells or be a reaction due to vascular congestion and edema. Radiosurgical planning treatment varies regarding the identification and coverage of the dural tail. This study aimed to retrospectively analyze a series of 143 patients with WHO Grade I meningiomas treated with different radiosurgical platforms, and dosing parameters focused on planning and dose delivery to the dural tail. Methods From February 2011 to July 2020, 143 patients with histologically confirmed or radiologically assumed WHO Grade I meningiomas were treated using rotating gamma-ray Infini™ (Gamma [MASEP Medical Science Technology Development Co., Shenzhen, China]), TomoTherapy® (Tomo [Accuray Inc., Sunnyvale, CA]), and CyberKnife® (CK [Accuray Inc.]). All plans were retrospectively reviewed to establish the maximum distance (MaxDis) from the prescription dose to the end of the dural tail and the minimum dose at the dural tail (MinDoseT) at this point. We also established the midpoint distance (MPDis) from the prescription dose to MaxDis and the dose at this point (MPDose). Plans were further distinguished when the physician intended to cover the dural tail versus when not. Patients and tumor response were assessed by imaging and clinical and phone call evaluations. Results Of the 143 patients, 81 were treated using Gamma, 34 using Tomo, and 28 using CK. Eighty patients were eligible for follow-up, of whom 58 (72.5%) had an unmistakable dural tail sign. Median follow-up was 1,118 days (range 189-3,496), mean age was 54.5 (range 19-90), and 61 were women, and 19 were men. Overall tumor volume was 6.5 cc (range 0.2-59); mean tumor volumes by different platforms were 2.4, 9.45, and 8 cc; dose prescribed and mean tumor coverage were 14 Gy and 92%, 14.5 Gy and 95%, and 14 Gy and 95.75% with Gamma, Tomo, and CK, respectively. The dural tail was drawn and planned with an attempt to treat in 18 patients (31%); the mean MaxDis, MinDoseT, MPDis, and MPDose were 9.0 mm, 2 Gy, 4.5 mm, and 10.6 Gy, respectively. At last follow-up, tumor control was achieved in 96% of patients for the whole series, and there were no statistical variations regarding tumor volume, dose, conformality, or control when stereotactic radiosurgery was used to cover the dural tail versus when it was not (p=0.105). One patient experienced a Grade 4 Radiation Therapy Oncology Group toxicity as an adverse radiation effect that required surgery, and 11 (7.6%) experienced a Grade 1 toxicity. Conclusions This is our preliminary report regarding the efficacy of radiosurgery for meningiomas using diverse platforms at three years of follow-up; the results regarding tumor control are in accordance with the published literature as of this writing. A conscious pursuit of the dural tail with the prescription dose has not proven to provide better tumor control than not doing so - even small areas of the tumor uncovered by the prescription dose did not alter tumor control at current follow-up. The doses delivered to these uncovered areas are quite significant; further follow-up is necessary to validate these findings.
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Introduction We report our initial series of patients treated with radiosurgery to the Centromedian (CM) and Parafascicular (Pfc) Complex (CM-Pf) of the contralateral thalamus mainly for trigeminal neuralgia that had failed most known forms of conventional treatments. The coordinates were co-registered to a three-dimensional atlas of the thalamus in order to have a better comprehension of isodose curves distribution. Methods A fully automated rotating gamma ray unit was used to deliver a high dose of radiation (140 Gy) using a 4-mm collimator to the CM-Pf of the contralateral thalamus in 14 patients suffering from refractory trigeminal pain and other complex pain syndromes. The best stereotactic coordinates were plotted in a thalamic three-dimensional atlas space along with isodose curves corresponding to 50% of the dose prescription and the dose gradient. Results From November 2016 to July 2019, 14 patients experiencing severe forms of different pain syndromes were treated, and 10 were eligible for follow-up evaluation. Pain deriving from trigeminal neuralgia was present in the majority (80%) of patients and from other complex pain syndromes in the rest (20%). Median follow-up was 384 days (range: 30-994). The Visual Analogue Scale (VAS) score before treatment was 9 (range: 7-10) and standardized to 10. Before treatment, all the patients had a Barrow Neurological Institute Pain Scale (BNI) of 5 (V). The median years suffering from pain was 4.5 years (range: 1-15), the number of procedures including radiosurgery to the trigeminal nerve before thalamotomy was four (range: 1-10). Most patients (90%) reported some form of relief, the average VAS at the time of response was 3.5 (range: 0-9), and the average time to response was 67.3 days (range: 2-210). The neuromodulation effect of radiation was seen in 60% of patients. The average BNI score at response was 2.7 (range: 1-5). The final VAS score at last follow-up was 5.5 (range: 0-10) in six patients. In four patients (40%), the procedure had failed with a final BNI of IV, and V, three patients (30%) had excellent response (BNI of I), and three patients (30%) had worthwhile results with BNI of IIIa and IIIb. The total success rate (BNI of I to IIIb) was 60%, and the number of patients experiencing more than 50% of pain reduction at final follow-up was five (50%). Excluding both patients that were treated for pain outside of trigeminal neuralgia, 75% of the patients responded. The best coordinates on average were X: 5.5 mm from the thalamic border, Y: 3.7 mm anterior to the posterior commissure, and Z: 3.7 mm from the intercomissural line. There were no complications to report. Conclusion Radiosurgery to the CM-Pf of the thalamus was demonstrated to be a safe and relatively effective alternative to treat refractory trigeminal neuralgia. Further studies are needed to optimize target dimensions based on the three-dimensional studies of isodose curves as well as coordinates. Longer follow-up is necessary to evaluate recurrence rates that could not be reached.