Diabetic peripheral neuropathy: amelioration of pain with transcutaneous electrostimulation. (1997)

Abstract

OBJECTIVE:
To evaluate the efficacy of transcutaneous electrotherapy for chronic painful peripheral neuropathy in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS:
Thirty-one patients with symptoms and signs of peripheral neuropathy were randomized to the electrotherapy or sham treatment (control) group. The electrostimulation was given by a portable unit (H-Wave machine) than generated a biphasic, exponentially decaying waveform (pulse width 4 ms, 25-35 V, > or = 2 Hz). Patients treated each of their lower extremities for 30 min daily for 4 weeks at home. Nine patients from the sham-treatment group participated for a second period, during which all of them received the active electrotherapy. Patient’s degree of pain and discomfort was graded on a scale of 0 to 5.

RESULTS:
In the sham-treated group (n = 13), the neuropathic symptoms improved in five (38%) patients, and the pain score declined from 2.92 +/- 0.13 to 2.38 +/- 0.26 (P < 0.04), suggesting a procedure-related placebo effect. In the electrotherapy group (n = 18), symptomatic improvement was seen in 15 (83%) cases, 3 of which were completely asymptomatic; the pain score declined from 3.17 +/- 0.12 to 1.44 +/- 0.25 (P < 0.01) and the posttreatment pain scores were considerably lower (P < 0.03), indicating a substantial treatment effect over and above any placebo influence. Patients in the electrotherapy group reported greater reduction in symptoms (52 +/- 7% vs. 27 +/- 10% in control subjects, P < 0.05) on an analog scale. Moreover, the electrotherapy decreased pain scores (from 3.0 +/- 0.62 to 1.56 +/- 0.32, P < 0.02) in nine patients who had received sham treatment earlier.

CONCLUSIONS:
A form of transcutaneous electrotherapy ameliorated the pain and discomfort associated with peripheral neuropathy. This novel modality offers a potential non-pharmacological treatment option.

My comments:

This study didn’t look at function but rather attempted to lessen/eliminate pain in patients with the painful form of neuropathy (some patients don’t hurt but only have numbness). As noted in the abstract, 83% of those treated with electric stimulation improved and 17% became completely asymptomatic.

Parameters used in the study were:

• Waveform:  biphasic exponentially decaying
• Duty Cycle:  continuous (I think)
• Pulse Duration:  400 uS
• Intensity:  35 mA (max)
• Rate:  user adjustable from 2-70 Hz
• Treatment Length:  30 minutes
• Training Frequency:  Daily
• Training Length:  4 weeks
• Electrodes:  4 electrodes; 2 placed on the distal quadriceps, 1 on the neck of the fibula and 1 centered gastrocnemius muscle (size not given)

My treatments are shorter in duration using biphasic square waveforms and EMS patterns designed to increase strength, but my patients report pain relief similar to the above researchers. The reason I use the EMS strength protocols is because they have been found to be better than TENS at decreasing pain.  For neuropathy, I really want to try to not just decrease pain but also increase muscle mass to help with function, to elicit strong muscle contractions, and to pump blood into the area in an attempt to improve circulation.  I think all of these things should help with neuropathic pain. Also I use 4 large electrodes (4” circular) and right now prefer to place 2 on the gastrocnemius, 1 on the tibialis anterior, and 1 on the sole of the foot. One thing I notice with my lower extremity neuropathy patients is they often need an especially strong stimulator to get a good muscle contraction. The 35 mA used in this study I expect will decrease pain, but I think they would get better results if they increased their pulse width to 450 mA, and intensity as tolerated up to around 60-70 mA.  Also while I have not tried it yet, I suspect an ideal EMS program would not be just one set of parameters, but rather alternate between 2 or more, with some settings directed at increasing strength, and with others directed more towards improving circulation and cardiovascular benefits.  

The study was only 30 days long, and while my patients usually report immediate relief ongoing treatment seems to continually lessen symptoms. My patient who I am following with regards to increased sensation has been doing the electric stimulation at home every other day for 3 months, and we plan to retest going forward. So I do think home use of a stimulator is ideal because they often pay for themselves quickly and ideal use I would expect to be at least 3 times per week if not daily. So while I frequently do the treatment in my office, a lot of what I do is help patients decide what kind of EMS/TENS machine and accessories they need, help them program the machine, and teach them how to set up the electrodes for home use.