Does electrode placement influence tens-induced antihyperalgesia in experimental inflammatory pain model?
Maurício L Poderoso Neto, Leonardo Y S Maciel, Kamilla M L Cruz and 3 others
PMID 28460716WHAT IT FOUND
In rats with inflamed knee joints, low-frequency TENS reduced pain responses to pressure whether electrodes were placed on the knee, opposite knee, back, or acupoints.
By day five, the effect had faded.
Key findings
01Low-frequency TENS increased mechanical withdrawal thresholds in rats with inflamed knees when electrodes were placed on the inflamed knee, the opposite knee, the paraspinal muscles, or acupoints; the effect lasted up to day four for the inflamed-knee, opposite-knee, and paraspinal groups and up to day three for the acupoint group.
02By day five, active TENS groups did not show significant differences in mechanical withdrawal threshold compared with control or pre-treatment measures.
03Active TENS increased heat withdrawal latency for the first five days in all active groups except the acupoint group, which showed no difference from pre-treatment.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was an animal experiment, not a study of people with pain. Each group had only six rats. The paper does not report random allocation or concealment. All TENS applications were given under isoflurane anesthesia, and behavioral tests were done 2 hours after anesthesia. The study did not name one primary outcome, and edema results were limited to a measurement that did not show a clear reduction. The acupoint group did not improve heat pain responses, so electrode sites were not equivalent for every outcome.
Declared interests
The authors declare no conflicts of interest. No funding source is reported.
The easy way to misread this
Do not conclude that TENS can be placed anywhere and will keep relieving pain in people. In rats, the acupoint site did not improve heat sensitivity, and by day five the mechanical pain effect had faded.