Pulsed Electromagnetic Fields to Reduce Diabetic Neuropathic Pain and Stimulate Neuronal Repair: A Randomized Controlled Trial

Abstract 

Weintraub MI, Herrmann DN, Smith AG, Backonja MM, Cole SP. Pulsed electromagnetic fields to reduce diabetic neuropathic pain and stimulate neuronal repair: a randomized controlled trial.

Objective

To determine whether repetitive and cumulative exposure to low-frequency pulsed electromagnetic fields (PEMF) targeting painful feet can reduce neuropathic pain (NP), influence sleep in symptomatic diabetic peripheral neuropathy (DPN), and influence nerve regeneration.

Design

Randomized, double-blind, placebo-controlled parallel study.

Setting

Sixteen academic and clinical sites in 13 states.

Participants

Subjects (N=225) with DPN stage II or III were randomly assigned to use identical devices generating PEMF or sham (placebo) 2 h/d to feet for 3 months.

Interventions

Nerve conduction testing was performed serially.

Main Outcome Measures

Pain reduction scores using a visual analog scale (VAS), the Neuropathy Pain Scale (NPS), and the Patient's Global Impression of Change (PGIC). A subset of subjects underwent serial 3-mm punch skin biopsies from 3 standard lower limb sites for epidermal nerve fiber density (ENFD) quantification.

Results

Subjects (N=225) were randomized with a dropout rate of 13.8%. There was a trend toward reductions in DPN symptoms on the PGIC, favoring the PEMF group (44% vs 31%; P=.04). There were no significant differences between PEMF and sham groups in the NP intensity on NPS or VAS. Twenty-seven subjects completed serial biopsies. Twenty-nine percent of PEMF subjects had an increase in distal leg ENFD of at least 0.5 SDs, while none did in the sham group (P=.04). Increases in distal thigh ENFD were significantly correlated with decreases in pain scores.

Conclusions

PEMF at this dosimetry was noneffective in reducing NP. However neurobiological effects on ENFD, PGIC and reduced itching scores suggest future studies are indicated with higher dosimetry (3000–5000 G), longer duration of exposure, and larger biopsy cohort.

Key Words: Electromagnetic fields, Rehabilitation

List of Abbreviations: DPN, diabetic peripheral neuropathy, ENFD, epidermal nerve fiber density, HbA1C, glycosylated hemoglobin, IGF-I, insulin-like growth factor I, IGF-II, insulin-like growth factor II, NGF, nerve growth factor, NP, neuropathic pain, NPS, Neuropathy Pain Scale, PEMF, pulsed electromagnetic fields, PGIC, Patient's Global Impression of Change, VAS, visual analog scale, VEGF, vascular endothelial growth factor