[Systematic review of the effectiveness of local anaesthetics in the treatment of neuropathic pain or phantom pain].

backgroundChronic pain is still a relevant medical and socioeconomic problem. The treatment focuses not only on pain reduction but also on functional treatment goals. Neuropathic pain includes biological, social and psychological aspects. In September 2023, the updated S3 guidelines for the management of peripheral nerve injuries were published. Multimodal pain management strategies encompassing systemic and local pharmacological, physiotherapeutic and occupational therapeutic interventions, are part of the guidelines. A central question addressed the widely debated treatment option using perineural local anaesthetics.

objectiveThe aim of the study was to evaluate the effectiveness of local anaesthetic infiltration in the treatment of neuropathic pain following nerve injuries through a systematic literature review and evaluation of the evidence by a meta-analysis. MATERIAL AND

methodsAfter formulating a PICO (patient/population, intervention, comparison and outcomes) question (Infobox 1) within the guideline group, a selective literature analysis of controlled trials in databases (PubMed, Cochrane Central Register of Controlled Trials-CENTRAL) was conducted until 31 July 2023. The literature was assessed by two reviewers and systematic reviews were examined for additional references. The studies were assessed using the Risk of Bias Tool 2.0 of the Cochrane Collaboration for randomized trials and the evidence was classified according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

resultsA total of 357 publications were identified in the literature search. After removing duplicates (n = 15) 327 publications were evaluated. The literature analysis showed heterogeneity with respect to the pain localization, local anaesthetics and reported outcomes. In an in-depth literature analysis one relevant study was identified and included in the evaluation of the evidence. This study enrolled and randomized 144 patients between December 2013 and October 2018 and evaluated the effectivity of the continuous infusion of local anaesthetics (lidocaine 2% with epinephrine 2.5 µg/ml as an initial bolus in both study groups followed by an infusion of ropivacaine 0.5% in the intervention group over 6 days) on the intensity of the phantom pain in comparison to the placebo group with a continuous infusion of saline over 6 days. The mean pain intensity and pain-related dysfunctions were reduced in the intervention group after 4 weeks. In the intervention group 25 patients and in the placebo group 40 patients received the crossover treatment after 4 weeks.

conclusionInfiltration with local anaesthetics represents a potential therapeutic option for neuropathic pain and phantom pain after amputations. A randomized, blinded, placebo-controlled study from 2021 demonstrated lower pain intensity and a reduction in pain-related functional limitations after 4 weeks of continuous perineural local anesthetic infiltration. Further studies are necessary to establish a higher level of evidence regarding the effectiveness of minimally invasive pain treatment with local anaesthetics. In particular, long-term follow-up is necessary to be able to draw conclusions with respect to the analgesic efficacy of infiltration with local anaesthetics.