The Efficacy And Safety Of Botulinum Toxin Type A In Chronic Peripheral Neuropathic Pain: A Summary Of Randomized Controlled Trials

Abstract

Neuropathic pain (NP), including chronic peripheral neuropathic pain (PNP) such as painful diabetic polyneuropathy (DPN), is a debilitating chronic condition that significantly impairs patients' quality of life (QoL) and disrupts sleep. (1) Standard systemic pharmacological treatments (e.g., tricyclic antidepressants or SNRIs like duloxetine) often provide only modest clinical efficacy; the reported Number Needed to Treat (NNT) for 50% pain relief ranges from 3.6 to 10.6. (2) Botulinum Toxin Type A (BTX-A), acting locally to inhibit neurotransmitter release, has emerged as a promising alternative localized treatment.(3,4)

Purpose: The objective of this work was to synthesize the evidence concerning the efficacy and safety profile of subcutaneously (SC) or intradermally (ID) administered BTX-A in the management of chronic PNP, with a specific focus on DPN, based on available randomized controlled trials (RCTs).(3)

Results: A meta-analysis incorporating data from RCTs demonstrated that BTX-A significantly reduces pain intensity compared to placebo, both at 1 month (WMD -1.87, 95% CI [-2.91; -0.83]) and 3 months (WMD -1.38, 95% CI [-1.95; -0.81]). (3)This efficacy was particularly greater for diabetic polyneuropathy (MD -2.48). In a DPN trial, 100 U of intradermal BTX-A significantly improved self-reported pain (VAS), sleep quality (PSQI), and the physical dimension of QoL (SF-36) over 12 weeks (P < 0.001).(1) BTX-A was generally safe and well tolerated. The most frequent adverse event was pain during injection, the incidence of which did not differ significantly from placebo (RR 0.99).(3)

Conclusions: Subcutaneous BTX-A injections provide a clinically significant and safe therapeutic alternative for chronic PNP, particularly for the population suffering from diabetic neuropathy. However, the current body of evidence is considered of moderate quality due to the small sample sizes and significant heterogeneity in toxin doses and injection protocols. Further larger-scale, standardized RCTs are necessary to optimize dosing and confirm the long-term durability of the treatment for clinical standardization.(5)