Short- and Midterm Analgesic Outcomes of Ketamine Versus Lidocaine Infusion in Chronic Peripheral Neuropathic Pain: A Retrospective Study.

BACKGROUND

Intravenous ketamine and lidocaine infusions are increasingly used for chronic peripheral neuropathic pain, particularly in refractory cases. However, comparative data on their short- and midterm analgesic outcomes in routine clinical practice are limited.

METHODS

This retrospective study included patients with chronic peripheral neuropathic pain who received intravenous ketamine or lidocaine infusion between January and May 2021. Ketamine was administered at 1 mg/kg/h and lidocaine at 3 mg/kg/h for five consecutive days. Pain intensity and neuropathic pain features were assessed using the Numeric Rating Scale (NRS) and the Douleur Neuropathique 4 (DN4) questionnaire at baseline and at 2 weeks, 2 months, and 6 months after treatment. Clinically meaningful pain relief was defined as a ≥ 50% reduction in pain scores.

RESULTS

A total of 102 patients were analyzed (ketamine group, n = 44; lidocaine group, n = 58). Both groups showed significant reductions in NRS and DN4 scores at all follow-up points compared with baseline (p < 0.01). Clinically meaningful pain relief was more frequent in the ketamine group at 2 weeks (p < 0.01), whereas no significant differences were observed at 2 and 6 months (p > 0.05). Adverse effects occurred more often with ketamine, while lidocaine was associated with fewer side effects (p < 0.05).

CONCLUSION

Ketamine provided a greater early analgesic response at 2 weeks, whereas both treatments demonstrated comparable midterm efficacy at 2 and 6 months.

TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT06297915.