Increasing Intensity of TENS Prevents Analgesic Tolerance in Rats

Author(s)

Sato, Karina L. ; Sanada, Luciana S. ^[1] ; Rakel, Barbara A. ^[2] ; Sluka, Kathleen A. ^[3]

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Neurosci & Behav Sci, Sao Paulo - Brazil

^[2] Univ Iowa, Dept Nursing, Carver Coll Med, Iowa City, IA 52242 - USA

^[3] Univ Iowa, Grad Program Phys Therapy & Rehabil Sci, Carver Coll Med, Iowa City, IA 52242 - USA

• Document type: Journal article
• Source: JOURNAL OF PAIN; v. 13, n. 9, p. 884-890, SEP 2012.
• Web of Science Citations: 16

Abstract

Transcutaneous electrical nerve stimulation (TENS) reduces hyperalgesia and pain. Both low-frequency (LF) and high-frequency (HF) TENS, delivered at the same intensity (90% motor threshold {[}MT]) daily, result in analgesic tolerance with repeated use by the fifth day of treatment. The current study tested 1) whether increasing intensity by 10% per day prevents the development of tolerance to repeated TENS; and 2) whether lower intensity TENS (50% MT) produces an equivalent reduction in hyperalgesia when compared to 90% MT TENS. Sprague-Dawley rats with unilateral knee joint inflammation (3% carrageenan) were separated according to the intensity of TENS used: sham, 50% LF, 50% HF, 90% LF, 90% HF, and increased intensity by 10% per day (IF and HF). The reduced mechanical withdrawal threshold following the induction of inflammation was reversed by application of TENS applied at 90% MT intensity and increasing intensity for the first 4 days. On the fifth day, the groups that received 90% MT intensity showed tolerance. Nevertheless, the group that received an increased intensity on each day still showed a reversal of the mechanical withdrawal threshold with TENS. These results show that the development of tolerance can be delayed by increasing intensity of TENS. Perspective: Our results showed that increasing intensity in both frequencies of TENS was able to prevent analgesic tolerance. Results from this study suggest that increasing intensities could be a clinical method to prevent analgesic tolerance and contribute to the effective use of TENS in reducing inflammatory pain and future clinical trials. (c) 2012 by the American Pain Society (AU)

• FAPESP's process: 09/07265-4 - Morphometric assessment of sural and tibial nerves myelinated and unmyelinated fibers in postnatal developing rat after nocicpetion stimuli
• Grantee: Luciana Sayuri Sanada
• Support Opportunities: Scholarships in Brazil - Doctorate