Objective: We evaluated the clinical efficacy and the unwanted side effects of transcutaneous electrical nerve stimulation (TENS) in a consecutive group of patients with intractable pain due to different pain syndromes.
Methods: Two hundred eleven patients with different pain syndromes, coded according to the International Association for the Study of Pain (IASP), were treated with TENS, using a standardized protocol. After a 6-month treatment period, an independent investigator estimated the effect of TENS in retrospect through assessment of patient files, standardized questionnaires, and diaries. In addition, a physical examination to determine the IASP code was performed, and unwanted side effects were evaluated.
Results: TENS showed a favorable response in the majority of patients with pain caused by peripheral nerve damage (53%), anginal pain resulting from ischemic heart disease (75%), and pain of the musculoskeletal system due to mechanical degenerative causes (69%). TENS employed in patients with prominent psychological and social distress, and for pain caused by central and autonomic dysfunction, alleviated pain in only 10-25% of the patients. Side effects occurred in 35% during the initial period of the treatment and were usually able to be resolved, especially with thorough supporting instructions during the initial treatment period.
Conclusions: In this study, the beneficial effect of TENS appeared to be related to the etiology of the underlying pain. The effect of TENS was maintained for > 6 months in the majority of patients with an immediate favorable response. Supporting instructions are crucial for long-term success.