AR coregistration capabilities are adequate when revised by other intraoperative guidance devices. When performed with "freeware" software and conventional digital cameras, it is relatively inexpensive, which makes it a potential tool for surgical planning and noncontinuous intraoperative guidance in neurosurgery. Its largest drawbacks are the inability to function in deep-seated lesions and its lack of tracking devices, which gives it a noncontinuous coregistration nature.

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. How to cite this article Lovo E E, Torres B, Campos F, et al. (December 19, 2019) Stereotactic Gamma Ray Radiosurgery to the Centromedian and Parafascicular Complex of the Thalamus for Trigeminal Neuralgia and Other Complex Pain Syndromes. Cureus 11(12): e6421. DOI 10.7759/cureus.6421 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.

Introduction We report our initial series of terminally ill cancer patients treated with radiosurgery to the pituitary gland to alleviate pain. Methods A fully automated rotating gamma ray unit was used to deliver a high dose of radiation (150Gy) using an 8 mm collimator to the neurohypophysis in 11 patients suffering from opioid-refractory pain deriving from cancer. Results From November 2016 to November 2018, 11 patients were treated, and 10 were eligible for follow-up evaluation. Pain from bone metastases was present in 70%; others suffered from neuropathic and visceral pain. The median survival was 119.7 days (range: 32 to 370). The visual analogue scale (VAS) was nine (7-10) and standardized to 10; eight patients (80%) responded. The average VAS at the time of response was three (range: 1-6), and the average time to response was 2.8 days (range: 2-5). In the first week, 40% of the patients categorized the result as 'excellent', 30% deemed the result 'good', and 20% reported the result as 'poor'. One patient (10%) referred to the result as 'regular'. Those who responded were able to reduce their medications by at least 25%. The one-month average VAS score was five (range: 1-6), 60% reported a 'good' effect, 20% reported 'excellent' results, and 20% had no response. Of the study participants, 60% maintained their level of medicine consumption at lower than baseline. At the end of life, five patients (50%) presented substantial pain, two (20%) never had a therapeutic effect, and three (30%) died without substantial pain. There were no clinical complications that could be attributed directly to the treatment. Conclusion Radiosurgery to the pituitary gland is effective and safe and warrants further investigation to understand its potential role in palliative care in cancer patients.

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Five decades ago, Franz Halberg conceived the idea of ​​a circadian-based therapy for cancer, given the differential tolerance to treatment derived from the intrinsic host rhythms. Nowadays, different experimental models have demonstrated that both the toxicity and efficacy of several anticancer drugs vary by more than 50% as a function of dosing time. Accordingly, it has been shown that chemotherapeutic regimens optimally timed with the circadian cycle have jointly improved patient outcomes both at the preclinical and clinical levels. Along with chemotherapy, radiation therapy is widely used for cancer treatment, but its effectiveness relies mainly on its ability to damage DNA. Notably, the DNA damage response including DNA repair, DNA damage checkpoints, and apoptosis is gated by the circadian clock. Thus, the therapeutic potential of circadian-based radiotherapy against cancer is mainly dependent upon the control that the molecular clock exerts on DNA repair enzymes across the cell cycle. Unfortunately, the time of treatment administration is not usually considered in clinical practice as it varies along the daytime working hours. Currently, only a few studies have evaluated whether the timing of radiotherapy affects the treatment outcome. Several of these studies show that it is possible to reduce the toxicity of the treatment if it is applied at a specific time range, although with some inconsistencies. In this Perspective, we review the main advances in the field of chronoradiotherapy, the possible causes of the inconsistencies observed in the studies so far and provide some recommendations for future trials.