Quantitative sensory testing in patients with chronic neck pain before and after the application of the acupressure pad—A randomized, controlled pilot study

Abstract

In the treatment of chronic neck pain alternative and complementary therapies receive increasing attention. One device based on the principles of Traditional Chinese Medicine is the Acupressure Pad. The pad with more than 1000 plastic needles is applied by the patient on the painful part of the body. Its supposed mode of action is thought to be similar to acupuncture or acupressure. It is likely that the pad yields its analgesic effect through direct mechanical stimulation of nociceptors which might affect the transmission and processing of sensory information on the spinal level, which likely will induce measureable changes in mechanical pain and perception thresholds. Therefore we investigated whether a 2-week application of the pad leads to changes in neck pain and sensory thresholds. Methods In total 40 patients (mean age 46.6±11.6 years) suffering from chronic neck pain for longer than 3 months participated in the study and were randomized to either treatment or waiting list control group. On day 1 actual pain rating was recorded on a 0–10 visual analog scale (VAS) followed by different methods of quantitative sensory testing (QST): mechanical detection threshold with von Frey filaments (MDT), vibration detection threshold (VDT) and pressure pain threshold (PPT) at the point of maximal pain, 10 cm next to the pain maximum and two control areas (hand, foot). The treatment group then received detailed information about the application of the acupressure pad. A daily application of at least 30 min over a period of 14 days was recommended. Fourteen days later the recording of VAS rating and QST measurement were repeated. Results Analysis of the change in recorded pain ratings showed a significant group difference (p=0.008) with a decrease in pain only for the treatment group (−31%). PPT significantly increased at pain maximum (p=0.011) and 10 cm close to the pain maximum (p=0.039), but not at the control areas. No such effects were found for VDT and MDT. Conclusion The present data suggest that an effect of the acupressure pad application is not only seen in VAS ratings but also in PPT. The elevated PPT after treatment supports the idea of a direct influence on transmission and processing of sensory information on the spinal level by reflex therapies such as the acupressure pad.