Injectable Biologics for Neuropathic Pain: A Systematic Review

Background: Neuropathic pain is a complex condition that can be refractory to conventional management and can cause persistent suffering in patients. Current pharmacologic treatments can provide temporary symptomatic relief; however, the mechanism of these therapies does not address the underlying cause of neuropathic pain. The use of injectable biologics for neuropathic pain has multiple proposed mechanisms for analgesia including attenuation of inflammatory mediated processes, arrest or delay of the degenerative process, inhibition of apoptotic pathways, and augmentation of the survival and recovery of injured and uninjured nerves. Study Design: A systematic review of human studies involving the use of injectable biologics for neuropathic pain. Methods: A comprehensive search of several data bases including Ovid MEDLINE ® and Epub Ahead of Print, In Process & Other Non-Indexed Citations and Daily, and Ovid Embase from inception to November 24, 2020. Results: The initial search yielded 3,450 studies with an additional 6 studies identified through other resources. Twenty-seven studies were included after independent review by two of the investigators. The included studies assessed the efficacy of injectable biologics for the treatment of neuropathic pain defined as pain reduction. Secondary outcome measures included functional improvement as well as safety of the procedures. A qualitative assessment of the literature without meta-analysis was performed due to the heterogeneity of the data. Conclusion: According to the GRADE criteria, there is very low certainty of evidence in support of the efficacy of injectable biologics for treatment of neuropathic pain. Future efforts should focus on creating a standardized methodology and study design with respect to preparation, dosage and route of administration of biologics. This will serve as a catalyst for higher quality randomized trials with generation of more useful data to help drive informed clinical decision making.