Immediate Changes During Dysesthesia-Matched Transcutaneous Electrical Nerve Stimulation in Refractory Neuropathic Pain: A Retrospective Observational Case Series

Background: Dysesthesia—such as tingling and numbness—remains refractory to pharmacological treatment and poses therapeutic challenges within neuropathic pain. Dysesthesia-matched transcutaneous electrical nerve stimulation (DM-TENS) is a perceptually guided neuromodulation approach in which stimulation parameters are iteratively adjusted to synchronize with the perceived temporal patterns and intensity of the patient’s abnormal sensory experience. However, immediate responses to DM-TENS across heterogeneous neuropathic pain conditions, as well as the feasibility of both direct and indirect (distant-site) stimulation approaches, with the latter suggested by our incidental clinical observations, have not been described. Methods: This retrospective observational case series included consecutive patients with refractory neuropathic pain referred from the pain clinic to the rehabilitation department at our university hospital between December 2024 and August 2025. Dysesthesia intensity was assessed before and during stimulation using the Numerical Rating Scale (NRS), and pain quality was evaluated using the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2). Within-session changes were examined using session-level linear mixed-effects models, with aggregated non-parametric analyses performed as sensitivity analyses. As an exploratory analysis, the consistency of stimulation parameters (frequency, pulse width, and intensity) across repeated sessions was evaluated using intraclass correlation coefficients (ICCs). Results: DM-TENS was well tolerated in all participants, with no stimulation-related adverse events requiring session termination. Fifteen patients underwent 66 DM-TENS sessions, of which 64 provided NRS data. A session-level linear mixed-effects model demonstrated a significant reduction in NRS scores during stimulation (p < 1 × 10⁻⁸). Aggregated sensitivity analyses showed a median NRS change of − 2.0 (interquartile range − 2.75 to − 1.43). Indirect stimulation was applied only in trigeminal neuropathic presentations, where stimulation delivered to the palm was associated with immediate symptom relief. SF-MPQ-2 total scores also decreased significantly during stimulation (p = 0.002). Stimulation parameters showed good to excellent consistency across repeated sessions (ICC range 0.78–0.85). Conclusions: In this retrospective observational case series, DM-TENS was associated with immediate symptom relief across heterogeneous neuropathic pain conditions, including trigeminal, spinal, and peripheral presentations. These findings suggest the potential relevance of individualized, perceptually guided adjustment of stimulation parameters and indicate the need for prospective evaluation incorporating neurophysiological measures.