Clinical Experience of High Frequency and Low Frequency TENS in Treatment of Diabetic Neuropathic Pain in Russia

Background: Transcutaneous electrical nerve stimulation (TENS) is presently one of the main methods of treatment for neuropathic pain in type II diabetes mellitus. The discussion about which TENS frequency is more effective in the treatment of neuropathic pain has been ongoing for many years. Despite this, the response of different aspects of neuropathic pain to various TENS modalities has not been sufficiently studied. Aim: To analyze changes in characteristics of neuropathic pain depending on the frequency of TENS. Materials and methods: Seventy-five Russian diabetic patients with painful distal axonal neuropathy were enrolled in the study. Patients were assigned to three groups: in the HF TENS group, 25 patients received standard drug therapy (Alpha-lipoic acid, Pentoxifylline, Vitamin B12, Gabapentin) + high-frequency TENS (HF); in the LF TENS group, 25 patients received standard drug therapy (Alpha-lipoic acid, Pentoxifylline, Vitamin B12, Gabapentin) + low-frequency TENS (LF); in the control group, 25 patients underwent just standard drug therapy (Alpha-lipoic acid, Pentoxifylline, Vitamin B12, Gabapentin). Pain intensity was calculated before and after treatment with visual analogue scale (VAS), McGill pain questionnaire (MPQ), Douleur Neuropathique 4 Questions (DN4) and Pain Drawing. Results: TENS increased the therapeutic effect of standard drug therapy, in the treatment of neuropathic pain, by 65.9% and prolonged its efficacy by 31% for up to 6 months after treatment. HF TENS had a more pronounced analgesic effect than LF TENS based on VAS (34.7%), sensory (57.6%) MPQ dimensions and DN4 (21%). Affective MPQ dimension with the use of LF TENS was lower than HF TENS by 34.7% immediately after treatment, by 47.3% after 2 months and by 34.8% after 6 months of the follow-up period. Conclusion: There are significant differences between HF and LF TENS based on pain assessment using various pain scales. This reflects the distinctive effects of different TENS modalities on different aspects of neuropathic pain.