Automated Stereotactic Gamma Ray Radiosurgery to the Pituitary Gland in Terminally Ill Cancer Patients with Opioid Refractory Pain

Everything old is new again. revisiting hypophysectomy for the treatment of refractory cancer-related pain: a systematic review

Cancer-related pain is a common and debilitating condition that can significantly affect the quality of life of patients. Opioids, NSAIDs, and antidepressants are among the first-line therapies, but their efficacy is limited or their use can be restricted due to serious side effects. Neuromodulation and lesioning techniques have also proven to be a valuable instrument for managing refractory pain. For patients who have exhausted all standard treatment options, hypophysectomy may be an effective alternative treatment. We conducted a comprehensive systematic review of the available literature on PubMed and Scielo databases on using hypophysectomy to treat refractory cancer-related pain. Data extraction from included studies included study design, treatment model, number of treated patients, sex, age, Karnofsky Performance Status (KPS) score, primary cancer site, lead time from diagnosis to treatment, alcohol injection volume, treatment data, and clinical outcomes. Statistical analysis was reported using counts (N, %) and means (range). The study included data from 735 patients from 24 papers treated with hypophysectomy for refractory cancer-related pain. 329 cancer-related pain patients were treated with NALP, 216 with TSS, 66 with RF, 55 with Y90 brachytherapy, 51 with Gamma Knife radiosurgery (GK), and 18 with cryoablation. The median age was 58.5 years. The average follow-up time was 8.97 months. Good pain relief was observed in 557 out of 735 patients, with complete pain relief in 108 out of 268 patients. Pain improvement onset was observed 24 h after TSS, a few days after NALP or cryoablation, and a few days to 4 weeks after GK. Complications varied among treatment modalities, with diabetes insipidus (DI) being the most common complication. Although mostly forgotten in modern neurosurgical practice, hypophysectomy is an attractive option for treating refractory cancer-related pain after failure of traditional therapies. Radiosurgery is a promising treatment modality due to its high success rate and reduced risk of complications.

Radiomodulation in Mixed, Complex Cancer Pain by Triple Target Irradiation in the Brain: A Preliminary Experience

Introduction

Up to 30% of terminally ill cancer patients experiencing intense pain might be refractory to opioid treatment. Complex cancer pain can be a mixture of somatic, visceral, and neuropathic pain with few or no effective alternatives to ameliorate pain. Radiosurgery to treat refractory pain in cancer has been reported with different degrees of success. Radiomodulation in pain could be defined as a fast (<72 h), substantial (>50%) pain relief by focal irradiation to a peripheric, and/or central mediated pain circuitry. Based on our previous experience, mixed, refractory cancer pain is usually unresponsive to single target irradiation of the hypophysis. We treated three patients using a multi-target approach.

Methods

Three terminally ill oncological patients experiencing refractory, complex, mixed pain from bone, abdomen, thorax, and brachial plexus were treated with triple target irradiation which consisted of irradiating with a maximum dose (Dmax) of 90 Gy to the hypophysis using either an 8 mm collimator with gamma ray (Infini) (Shenzhen, China: Masep Medical Company) or a 7.5 circular collimator with Cyberknife (Sunnyvale, CA: Accuray Inc.), the other two targets were the mesial structures of the thalamus bilaterally using a 4 mm collimator with Infini and the 5 mm circular collimator with CK delivering 90 Gy Dmax to each region. Patients had a VAS of 10 despite the best medical treatment.

A correlation was made between the 45 Gy and 20 Gy isodose curves of the two different technologies to the Morel stereotactic atlas of the thalamus and basal ganglia for further understanding of dose distribution reconstructions in accordance with the São Paulo-Würzburg atlas of the Human Brain Project were performed. Lastly, a scoping review of the literature regarding radiosurgery for oncological pain was performed.

Results

Radiomodulation effect was achieved in all patients; case 1 had a VAS of five at 72 h, three at 15 days, and three at the time of death (21 days after treatment). Case 2 had a VAS of six at 72 h, five at 15 days, and four at the time of death (29 days after treatment). Case 3 had a VAS of five at 72 h, six at 15 days, and six at the time of death (30 days). Morphine rescues for cases 1 and 2 were reduced to 84%, and 70% for case 3. Overall, there were no adverse effects to treatment although excessive sleepiness was reported by one patient. After reading the title and abstract, only 14 studies remained eligible for full-text evaluation, and only nine studies met inclusion criteria after full-text reading. For most reports (seven), the target was the hypophysis and in two reports, the target was the thalamus either with single or bilateral irradiation.

Conclusions

In complex, for refractory oncological pain of mixed nature (nociceptive, neuropathic, and visceral), very few, if any, treatment alternatives are currently available. We provide a small proof of concept that multitarget intracranial radiosurgery might be effective in ameliorating pain in this population. The doses administered per target are the lowest that have shown effectiveness thus far, a different strategy might be needed as opposed to single target “large” dose approach that has been tried in the past for complex mixed refractory oncological pain. By no means, in our experience, these treatments traduce in elimination of pain, clinical results might make pain to be more bearable and respond better to pain medication.

Machine Learning for the Detection and Segmentation of Benign Tumors of the Central Nervous System: A Systematic Review

Simple Summary

Machine learning in radiology of the central nervous system has seen many interesting publications in the past few years. Since the focus has largely been on malignant tumors such as brain metastases and high-grade gliomas, we conducted a systematic review on benign tumors to summarize what has been published and where there might be gaps in the research. We found several studies that report good results, but the descriptions of methodologies could be improved to enable better comparisons and assessment of biases.

Abstract

Objectives: To summarize the available literature on using machine learning (ML) for the detection and segmentation of benign tumors of the central nervous system (CNS) and to assess the adherence of published ML/diagnostic accuracy studies to best practice. Methods: The MEDLINE database was searched for the use of ML in patients with any benign tumor of the CNS, and the records were screened according to PRISMA guidelines. Results: Eleven retrospective studies focusing on meningioma (n = 4), vestibular schwannoma (n = 4), pituitary adenoma (n = 2) and spinal schwannoma (n = 1) were included. The majority of studies attempted segmentation. Links to repositories containing code were provided in two manuscripts, and no manuscripts shared imaging data. Only one study used an external test set, which raises the question as to whether some of the good performances that have been reported were caused by overfitting and may not generalize to data from other institutions. Conclusions: Using ML for detecting and segmenting benign brain tumors is still in its infancy. Stronger adherence to ML best practices could facilitate easier comparisons between studies and contribute to the development of models that are more likely to one day be used in clinical practice.

Radioneuromodulation by Dual-Target Irradiation in Pain Crisis From Trigeminal Neuralgia

Background Radioneuromodulation (RNM) can explain the immediate pain relief experienced by a subgroup of patients after stereotactic radiosurgery (SRS) for trigeminal neuralgia (TN). In this study, our main objective was to demonstrate that a minimum of a 50% reduction in TN pain can be achieved consistently in under 72 hours by targeting the affected nerve, the contralateral centromedian nucleus, and parafascicular complex in patients experimenting a prolonged refractory pain crisis. Methodology We treated eight patients experiencing severe TN pain crisis in whom percutaneous procedures had failed or were unwanted with SRS with an intention to procure pain relief in under 72 hours. The affected trigeminal nerve was targeted using a 4-mm collimator with an 80 to 90-Gy dose; an additional target was defined in the mesial portions of the thalamus and irradiated using the 4-mm collimator with a 120 to 140-Gy dose. Results The median duration of TN was 60 months, the median duration of pain crisis was 10.7 weeks despite the best medical treatment, and the mean presenting visual analogue score (VAS) was 10 at the time of treatment. The median follow-up was 135 days (range, 65-210). Twenty-four hours after treatment, two (25%) patients had no pain (VAS 0), three (37.5%) had mild pain (VAS 1 to 3), and three (37.5%) had moderate pain (VAS 4 to 7). Forty-eight hours after treatment, all patients reported pain relief, seven (87.5%) reported >50%, and one (12.5%) patients reported 30% relief. The three-month median VAS score was 3 (range, 0 to 5). At the last follow-up, there were no adverse events to report. Conclusions Dual irradiation to the affected trigeminal nerve and contralateral mesial structures of the thalamus may provide fast pain relief for patients experiencing a prolonged pain crisis from TN, which veers away from the concept that the SRS pain relief effect is generally delayed and holds no place in the management of such patients. Although this is a small series with a limited follow-up duration, no adverse effects were noted. RNM can be defined as the capacity to alter neuronal activity through targeted delivery of a stimulus of radiation at a duration too brief to be explained by the development of a focal lesion. The immediate pain relief and its habitual oscillatory nature of lesser pain recurrence in most patients until enough time elapses for pain stabilization clinically demonstrates that the pain circuitry is altered and remains functional, thus accomplishing a neuromodulation effect even at the face of an apparent doses suspected to be ablative. Further research is needed to understand if this clinical effect is achieved with a suspected sub-ablative dose.

Gamma Ray Radiosurgery for Trigeminal Neuralgia: Targeting Proximal or Distal to the Dorsal Root Entry Zone

Introduction

Stereotactic radiosurgery for trigeminal neuralgia (TN) has gained interest among patients who are not suitable for surgical procedures. Although two target zones are more recognized - dorsal root entry zone (DREZ) and retrogasserian zone (RGZ) - the optimal targeting technique remains controversial in terms of clinical outcomes and rates of complications. Therefore, various modifications to the radiosurgical technique for TN have been made.

Objective

This study aimed to determine the differences in shoot location (i.e., RGZ vs. DREZ) regarding effectiveness and adverse effects in patients with medically refractory TN. Additionally, we evaluated the effect of the integral dose (ID) on treatment outcomes and complications.

Methods

We present a retrospective cohort study of 49 patients with primary, drug-resistant TN treated with gamma knife radiosurgery targeting the distal and proximal parts of the nerve regarding the DREZ with a prescription dose of 90 Gy (80 to 96 Gy). A subset of these patients (n=38) where the ID could be measured to the nerve was correlated to treatment outcomes and complications.

Results

The median follow-up time was 36 months for RGZ and 51 months for DREZ targets. Neurovascular conflict was identified in 87.5% of the RGZ group and 88.2% of the DREZ group. Using the Barrow Neurological Institute (BNI) pain score, 26 (81.3%) RGZ and 12 (70.6%) DREZ patients were successfully treated (BNI I-IIIb; p=0.02). Seven (21.9%) RGZ and eight (47.1%) DREZ patients reported complete pain relief without medication (BNI I). Time response was 22.3 days for RGZ and 34.1 days for DREZ (p=0.277). There were 10 (31.3%) patients in the RGZ group with associated complications versus six (35.3%) patients in the DREZ group (χ²=0.0826, degree of freedom=1, p=0.773). Treatment outcomes using higher ID were better in the RGZ than DREZ (81.8% vs. 57.1, respectively), and a significant association was found between a higher ID delivered to the nerve and the development of complications (p=0.02).

Conclusion

Based on the obtained results, the RGZ was a more effective targeting area with better treatment outcomes without significant differences in complication rates than DREZ. A higher ID at the RGZ than DREZ had a greater therapeutical effect. Further investigation regarding the optimal target area along the ID delivered and clinical outcomes are required.

Stereotactic Radiosurgery Hypophysectomy for Palliative Treatment of Refractory Cancer Pain: A Historical Review and Update

Medically refractory pain in those with advanced cancer significantly reduces one's quality of life. Therefore, palliative interventions to mitigate cancer pain and reduce opioid requirements are necessary to reduce patient suffering and opioid-induced side effects. Hypophysectomy, a largely forgotten pain procedure with several technical variations, has been repeatedly studied in small series with encouraging results, though historically has been fraught with complications. As a result, the minimally invasive and more tolerable stereotactic radiosurgery (SRS) hypophysectomy has resurfaced as a possible treatment for cancer-related pain. While the mechanism of pain relief is not entirely understood, the hypothalamohypophyseal axis appears to play an essential role in pain perception and transmission and involves C fiber signal processing and downstream modulation of the brainstem and spinal cord via the hypothalamus. This review highlights the role of hypophysectomy in alleviating advanced cancer pain, both in hormonal and nonhormonal malignancy and the current mechanistic understanding of pain relief for the three primary hypophysectomy modalities used historically: surgical and chemical adenolysis, as well as the more recent, SRS hypophysectomy. Given the lack of high-quality evidence for stereotactic radiosurgery hypophysectomy, there is a need for further rigorous and prospective clinical studies despite its ideal and noninvasive approach.