Nonpharmacologic options for painful diabetic neuropathy may compliment drug treatment
Even the best drug therapies provide incomplete pain relief in patients with painful diabetic neuropathy. In patients who do not respond to drug therapy or experience incomplete pain relief despite pharmacologic treatment, nonpharmacologic treatments may fulfill a need, said Miroslav Backonja, MD, departments of neurology, anesthesiology, and rehabilitative medicine at the University of Wisconsin, Madison.
The rationale to support nonpharmacologic strategies is four-fold: 1) pill burden can be lowered, 2) systemic adverse effects are absent or few, 3) no drug-drug interactions can occur, and 4) they have potential to enhance the effects of systemic drugs following the principle of a multimodal approach, he said.
Peripheral electrical muscle stimulation has effects that appear quickly, as early as day 1, said Dr. Backonja. In a comparison of high-frequency muscle stimulation with transcutaneous electrical nerve stimulation (TENS) in 41 patients with type 2 diabetes and sensory pain, each treatment was given for 30 minutes daily for 3 consecutive days. Eighty percent (16/20) of the group randomized to high-frequency muscle stimulation had a 3-point or greater reduction on symptoms scales, compared with 33% (7/21) of those randomized to TENS.
Percutaneous electrical nerve stimulation (PENS) also appears promising. In a sham-controlled trial in 50 adult patients with type 2 diabetes, scores on a visual analog pain scale decreased from a mean of 6.2 at baseline to 2.5 after 3 weeks of PENS given thrice weekly for 30 minutes each, compared with no reduction in the visual analog scale in sham recipients.
A study of spinal cord stimulation in 10 subjects with peripheral diabetic neuropathy that did not respond to conventional treatment resulted in statistically significant pain relief (p < 0.02) in eight; relief of background and peak neuropathic pain was evident in seven of the eight responders at 3 months, 6 months, and 14 months (end of study).
Peripheral infrared photo stimulation was studied in a sham-controlled double-blind study of 27 patients decreased the mean number of sites insensate from 4.7 to 3.1 (p < 0.01) and reduced scores on the visual analog scale from 4.2 at entry to 3.2 after six treatments (p < 0.03) to 2.3 after 12 treatments (p < 0.03). A second sham-controlled trial in 60 patients showed no difference in these measures between the active treatment and the sham-treated subjects.
A multicenter study of peripheral magnetic stimulation in shoe insoles in 375 patients demonstrated a 12% reduction in burning with stimulation versus a 3% reduction in sham-treated patients (p < 0.05) and a 10% reduction in numbness with active treatment versus a 1% increase in the sham controls (p < 0.05).
A prospective, blinded study of surgical decompression in 20 patients with diabetic neuropathy showed an overall improvement in sensibility in the median nerve at the wrist and ulnar nerve at the elbow in treated patients whereas 32% of control (not decompressed) contralateral nerves had measurable progression of neuropathy.
Finally, individualized diet and exercise counseling for 1 year in 32 subjects with impaired fasting glucose correlated with a significant (p < 0.05) reduction in neuropathic pain and a change in sural sensory amplitude (p < 0.03).