Transcutaneous Magnetic Stimulation (tMS) in Alleviating Post-Traumatic Peripheral Neuropathic Pain States: A Case Series

Background. Peripheral nerve injury can result in the formation of neuroma/nerve entrapment, a persistent peripheral neuropathic pain state which is often refractory to invasive interventions or medications. Therefore, there is a need in the field of pain management to develop innovative noninvasive therapy in treating post-traumatic peripheral neuropathic pain states. A new intervention, transcutaneous magnetic stimulation (tMS), is derived from the use of transcranial magnetic stimulation in which a rapid discharge of electric current is converted into dynamic magnetic flux for modulating neuronal functions. Methods. Low-frequency (0.5 Hz) tMS was developed over the site of neuroma/nerve entrapment in five patients who have failed both steroid injection and conventional pain medications. Four hundred pulses of stimulation were delivered per treatment session. Each patient received three to four sessions of treatment over a period of 2 months. Pre- and post-intervention spontaneous pain levels were assessed with a numerical rating pain scale Result. Five patients with post-traumatic neuroma/nerve entrapment pain received the treatment. Average pre and postscores (+/- standard deviation) on the NRS were 5.00 (+/- 1.41) and 0.80 (+/- 1.10), respectively, with an average pain reduction of 84 (+/- 21.91)% in the NRS after three to four treatments within 2 months. This analgesic effect appeared to be sustainable with repeated treatment delivered at a 6- to 8-week duration. Pretreatment tactile allodynia found in three patients resolved after the initial 2-month treatment sessions. Conclusion. tMS offers a noninvasive treatment option for neuroma-related neuropathic pain conditions. Randomized controlled studies are required in further validating the efficacy of this treatment modality. Additional studies are also needed to assess the underlying electrophysiological mechanisms of the observed analgesic benefit.