BACKGROUND: Peripheral nerve stimulation (PNS) has been increasingly used to manage acute and chronic pain. However, the level of clinical evidence to support its use is not clear. OBJECTIVES: To assess the clinical evidence of PNS in the treatment of acute or chronic pain. STUDY DESIGN: A systematic review of the efficacy and safety of PNS in managing acute or chronic pain. METHODS: Data sources were PubMed, Cochrane Library, Scopus, CINAHL Plus, Google Scholar, and reference lists. The literature search was performed up to December 2019. Study selection included randomized trials, observational studies, and case reports of PNS in acute or chronic pain. Data extraction and methodological quality assessment were performed utilizing Cochrane review methodologic quality assessment and Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB) and Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment for Nonrandomized Studies (IPM-QRBNR). The evidence was summarized utilizing principles of best evidence synthesis on a scale of 1 to 5. Data syntheses: 227 studies met inclusion criteria and were included in qualitative synthesis. RESULTS: Evidence synthesis based on randomized controlled trials (RCTs) and observational studies showed Level I and II evidence of PNS in chronic migraine headache; Level II evidence in cluster headache, postamputation pain, chronic pelvic pain, chronic low back and lower extremity pain; and Level IV evidence in peripheral neuropathic pain, and postsurgical pain. Peripheral field stimulation has Level II evidence in chronic low back pain, and Level IV evidence in cranial pain. LIMITATIONS: Lack of high-quality RCTs. Meta-analysis was not possible due to wide variations in experimental design, research protocol, and heterogeneity of study population. CONCLUSIONS: The findings of this systematic review suggest that PNS may be effective in managing chronic headaches, postamputation pain, chronic pelvic pain, and chronic low back and lower extremity pain, with variable levels of evidence in favor of this technique. KEY WORDS: Acute pain, chronic pain, neuromodulation, peripheral nerve stimulation

Complex regional pain syndrome (CRPS) remains a challenging clinical pain condition. Multidisciplinary approaches have been advocated for managing CRPS. Compared with spinal cord stimulation and intrathecal targeted therapy, IV treatments are less invasive and less costly. We aimed to systemically review the literature on IV therapies and determine the level of evidence to guide the management of CRPS. We searched PubMed, Embase, Scopus, and the Cochrane databases for articles published on IV therapies of CRPS up through February 2015. The search yielded 299 articles, of which 101 were deemed relevant by reading the titles and 63 by reading abstracts. All these 63 articles were retrieved for analysis and discussion. We evaluated the relevant studies and provided recommendations according to the level of evidence. We conclude that there is evidence to support the use of IV bisphosphonates, immunoglobulin, ketamine, or lidocaine as valuable interventions in selected patients with CRPS. However, high-quality studies are required to further evaluate the safety, efficacy, and cost-effectiveness of IV therapies for CRPS.