Background Acute low back pain, characterized by episodes of pain lasting less than three weeks, is one of the most common complaints in the medical care.^1,2 The transcutaneous electrical nerve stimulation (TENS), based on the gate control theory, proposed by Melzack and Wall in 1965, has been used as an adjunctive therapy in the control of back pain, as a non-invasive, inexpensive, safe and easy to apply technique.^3,4

Objectives To evaluate the effectiveness of TENS in pain management of patients with acute low back pain.

Methods A placebo-controlled, randomized, double-blinded intention to treat clinical trial was conducted. Patients with acute low back pain, of both genders, aged between 18 and 65 years, pain between 4 and 8cm in a numerical pain scale (NPS) were included and those with pain of inflammatory, neoplasic or infectious origin; with pacemaker; previous spine surgery; nerve roots; vertebral fracture; which changed the physical activity in the last three months; pregnant women and litigation were excluded. They were randomly allocated to TENS group (TG) or placebo group (PG). In TG, conventional TENS was applied with FIV effect, frequency 100Hz, 60μs pulse width and intensity adjusted according to the threshold for each individual patient without causing pain or muscular contraction. Electrodes were placed crosswise in the paravertebral region. In PG the same procedures were adopted, but without electrical stimulation. Treatment consisted of 10 sessions lasting 30' each (2times/week/5 weeks). Assessments were at: T0 (baseline), T1 to T10 (the beginning and end of each session), T11 (after the last session), T30 (30 days after the last session) and T60 (60 days after the last session). Assessment tools were: NPS, SF-36, Roland-Morris, self-assessment of pain relief (likert scale) and drug consumption.

Results Of the 71 patients included, 28 (39.4%) were male and 43 (60.6%) were female. The age of participants ranged from 19 to 62 years. There was no difference between groups in the level of pain measured by NPS (p=0.607); the scores obtained by the Roland-Morris questionnaire (p=0.619); SF-36, or on the consumption of medication between the groups (p=0.368) – Table 1.

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Conclusions TENS was not effective for the control of pain, improved function and quality of life, self-assessment and reducing the consumption of analgesics in patients with acute low back pain.

References

1. Chou R, et al. Clinical guidelines-diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physycians and the American Pain Society. Ann Intern Med. 147(7): 478-491, 2007.

2. Gautschi OP, et al. Acute low back pain-assessment and management. Praxis. 97(2): 58-68, 2008.

3. SLUKA KA; WALSH D. Transcutaneous electrical nerve stimulationbasic science mechanism and clinical effectiveness. Journal of Pain. 4 (3): 109-121, 2003.

4. SLUKA KA. Systematic morphine in combinations with TENS produces an increased antihyperalgesia in rats with acute inflammation. The Journal of Pain. 1 (3): 204-211, 2000.

Acknowledgements To FAPESP and CNPq for all the support.

Disclosure of Interest None declared