Time-Varying, Biaxial Magnetic Stimulation in Refractory Carpal Tunnel Syndrome: A Novel Approach. A Pilot Study

Abstract

A pilot study was conducted to determine whether a cumulative 1-h daily exposure to a portable biaxial pulsed magnetic field stimulator over the carpal tunnel region for a 2-week period could reduce neuropathic pain scores and influence sleep interruption and possibly be an alternative conservative therapy option. Patients with advanced carpal tunnel syndrome (CTS) have often failed conservative therapy and are left with refractory numbness, tingling, and burning pain with disability. Previously, we demonstrated that constant application of static permanent magnets to the wrists for a 1-month period reduced neuropathic pain (NP) and improved motor distal latency of the median nerve compared with placebo. Since pulsed time-varying magnetic fields are capable of inducing changes within biological tissues and influencing signal transduction and reducing musculoskeletal pain, we postulated that nociceptive sensory fibers within the carpal tunnel could be influenced at a neuronal level. Thirty-five symptomatic hands (23 subjects) with medical and/or surgically refractory symptoms were enrolled in this nonplacebo trial. Baseline daily NP and sleep interruption scores (VAS 0-10) were tabulated. A distal median nerve latency was performed at baseline and at end of trial. A portable device (Palm Mag) was given to each patient to take home and apply daily for 1 h. This device generates a minimum to maximum sweep of 8-23 Hz at the target area. There is a maximum sweep of 1400 rotations/s. Daily VAS scores were maintained and statistical analyses (two-tailed t-test) were performed. Twenty-nine hands (19 subjects) completed this 2-week study with 6 dropouts (4 subjects). There was a significant reduction in NP scores, especially in the moderate–severe cohort, VAS 5.0-10, (P < 0.05). Sleep interruption scores were also reduced (P < 0.01). There were no changes in neurological examination or electrophysiological testing serially. There were no safety issues. Despite absence of placebo controls, these novel preliminary pilot data demonstrating short-term antinociceptive benefit suggest the feasibility of future trials using randomized, placebo-controlled design. If biologically positive, it would suggest that time-varying magnetic fields targeting the carpal tunnel region will be a future conservative therapeutic option.