To perform a systematic review to evaluate the clinical efficacy, both short- and long-term, of SRS for the treatment of chronic intractable pain.
A systematic search in PubMed, Web of Science, and PsycINFO was performed using keywords and controlled vocabulary. The search included peer-reviewed articles reporting clinical outcomes of SRS for chronic pain with a minimum 3-mo follow-up for nonmalignant and 1 mo for malignant pain.
Six articles (113 patients) were evaluated on the basis of radiation target (thalamus vs pituitary) and pain etiology (malignant vs nonmalignant). Across studies, at least 35% of patients were reported to have lasting significant pain relief. By cohort, clinical success was achieved in 51% of pituitary SRS, at least 23% of thalamic SRS, 39% of nonmalignant, and at least 33% of malignant pain patients. Adverse events were noted in 21% of patients; the majority related to hormonal deficits from pituitary SRS.
Despite decreased utilization, SRS is effective for select patients with chronic pain and is associated with an acceptable complication rate. Pituitary SRS is superior in patients with cancer-related pain (87% success), while thalamic SRS is superior in patients with nonmalignant pain (65% success). Because reports of SRS for pain largely stem from a period before the common use of neuromodulatory and intrathecal therapies, the efficacy in patients who fail such therapies remains unclear and requires further characterization.