Effect of a single session of ear acupuncture on pain intensity and postural control in individuals with chronic low back pain: a randomized controlled trial

This Brazilian study investigated whether a single session of auricular acupuncture could reduce pain and improve balance in people with chronic low back pain. Low back pain is a highly prevalent health problem affecting millions of people worldwide, causing not only physical discomfort but also alterations in postural control and balance. Auricular acupuncture is a technique based on the premise that the human body is represented on the external ear as an inverted fetus, with specific points corresponding to different anatomical regions. Eighty adults aged between 18 and 50 years with chronic low back pain for at least 12 weeks and pain intensity of 4 or higher on a 0-to-10 scale were randomized into two groups.

The experimental group received auricular acupuncture with needles inserted at three specific points: analgesic point (point 29), shenmen point (point 40), and lumbar point (point 55). The control group received placebo treatment with switched-off ultrasound applied to the painful lumbar region. Both interventions lasted 20 minutes. Pain intensity was assessed before and immediately after treatment using a numerical scale from 0 to 10.

Postural control was assessed through balance tests on a force platform, with participants in different positions (parallel feet or semi-tandem) and visual conditions (eyes open or closed). Results showed that both groups had pain reduction after treatment, but reduction was significantly greater in the group receiving auricular acupuncture. The median pain reduction was 2 points in the auricular acupuncture group versus 1 point in the placebo group, a statistically significant difference (p=0.032). The effect size was considered small (r=0.21) according to Cohen's criteria.

Regarding postural control, no significant differences were found between groups, indicating that pain reduction was not sufficient to improve balance. This finding suggests that postural control alterations in people with chronic low back pain may be related to long-term neuroplastic changes in the postural control system, which are not immediately reversible with acute pain reduction. The study has important methodological strengths, including adequate randomization, assessor blinding (with an accuracy rate of only 56.25%, indicating successful blinding), appropriate sample size calculation, and intention-to-treat analysis. The only adverse event reported was dizziness in one participant in the auricular acupuncture group, which may or may not be related to the treatment.

The clinical implications are relevant, as they demonstrate that even a single session of auricular acupuncture can provide temporary relief of chronic low back pain. This is particularly important considering that auricular acupuncture has minimal side effects, is relatively inexpensive, and can be applied in various settings without requiring the patient to undress or remain lying down for long periods. Although the effect is small, it may be clinically useful as adjunctive therapy or in situations where analgesic medications cannot be used.