PERCUTANEOUS ELECTRICAL NERVE STIMULATION (PENS)

Abstract

S209 INTRODUCTION: Sciatica due to a herniated nucleus pulposus is a common cause of pain and an important socioeconomic problem [1]. The lifetime prevalence of sciatica in the USA is 40% [2]. While both opioid and non-opioid analgesic medications may temporarily alleviate the symptoms of sciatica, both classes of drugs are associated with many well-known side effects. This randomized, cross-over, sham-controlled study was designed to compare the effectiveness of a novel non-pharmacologic therapy, percutaneous electrical nerve stimulation (PENS) [3], to transcutaneous electrical nerve stimulation (TENS) in the management of the radicular pain associated with sciatica. METHODS: Sixty-four consenting patients with radicular pain due to lumbar disc herniation were treated with three different therapeutic modalities (namely, PENS, sham-PENS and TENS) according to a randomized, cross-over study design. All patients had been maintained on a stable oral analgesic treatment regimen for at least 6 weeks prior to entering this IRB-approved study. The PENS (with electrical stimulation at frequency of 4 Hz) and sham-PENS (no electrical stimulation) treatments involved insertion of 10, 32-ga. acupuncture-like needle probes in a dermatomal pattern corresponding to the pain symptoms. [3] Each treatment was administered for a period of 30 min three times per week for 3 weeks in a random sequence with one week "off" between each treatment. The pre-treatment assessment included the health status survey short form (SF-36), as well as visual analog scales (VAS) for pain, physical activity and quality of sleep. The pain VAS was repeated 5-10 min after each treatment session. At the end of each 3-week treatment block, the SF-36 was also repeated. After the patient had received all three treatment modalities, a global assessment questionnaire was administered. RESULTS: PENS therapy was significantly more effective in decreasing VAS pain scores after each treatment than the sham-PENS (* p-value <0.05, psi p-value <0.01) and TENS ([club] p-value <0.05) therapies. The daily non-opioid oral analgesic requirements were decreased by 50% with PENS compared to only 29% and 8% with TENS and sham-PENS, respectively. In the overall assessment, 73% of the patients reported that PENS was the most effective pain-relieving modality. PENS was also significantly more effective in improving the patient's sense of "well-being" than the other two modalities. The SF-36 evaluations confirmed the superiority of PENS (versus sham-PENS and TENS) with respect to post-treatment functionality. Finally, 71% of the patients stated that they would be willing to pay "out of pocket" to receive PENS therapy compared to only 22% and 3% with TENS and sham-PENS, respectively. (Table 1)Table 1DISCUSSION: The pain and loss of mobility associated with sciatica greatly reduces a person's ability to function at home and at work [4]. This sham-controlled, cross-over study evaluating PENS therapy suggests that it is more effective in improving short-term outcome than conventional TENS in patients with sciatica. Future studies should be designed to examine the cost-effectiveness of these alternative therapies as supplements to conventional oral analgesics and exercise programs.