Research summary: Exposure to inhomogeneous static magnetic field ceases mechanical allodynia in neuropathic pain

Miklós Antal1, János László2

1Department of Anatomy, Histology and Embryology, University of Debrecen,
Debrecen, Nagyerdei krt. 98, 4012-Hungary
2Section for Mathematics, Hungarian Academy of Sciences,
Budapest, Nádor u. 7, 1051-Hungary

Summary of article appearing in Biolelectromagnetics, Vol. 30, No. 6, pp 438-445
Nearly one third of the human population experiences severe chronic pain in some point in life. For many patients, pain continues to produce severe distress, dominating and disrupting the quality of their lives. Much of currently available clinical treatment is only partially effective and may be accompanied by adverse side effects or have abuse potential. The search for reliable, safe and effective treatments for neuropathic pain remains a major challenge, and, not surprisingly, patients have been continuously exploring alternative approaches. Among a number of other treatment strategies, magnetic therapy is increasingly used to alleviate pain.

Magnetic field therapy as a self-care intervention has led to the conduct of more than 50 randomized controlled human trials. Results obtained from studies that tested the analgesic efficacy of static magnetic field (SMF) therapy in chronic pain are inconsistent. However, since the parameters of the applied SMFs and the pain models that were supposed to be treated varied from investigation to investigation, results obtained from these earlier studies are far from being reliable and hardly comparable.

To avoid the obvious problems in the interpretation of the results of earlier studies, we investigated the effectiveness of SMF exposure in pain attenuation by utilizing a fully controllable, reproducable, and thus reliable experimental approach. First, we used an apparatus for the generation of an inhomogeneous SMF, the parameters of which has been carefully tested and adjusted to whole-body exposure of experimental animals. Secondly, we tested the effectiveness of SMF exposure on a well established animal model of neuropathic pain (partial nerve ligation in mice), and studied how the whole-body exposure to SMF may influence pain responsiveness in the experimental animals. Our results showed that exposure to inhomogeneous SMF in the first postoperative week could not prevent the development of pain. However, the effectiveness of a daily exposure to inhomogeneous SMF was much more prominent, when it was applied between postoperative days 15 and 28. In this case, pain threshold was already noticeably increased after the first treatment and it practically reached the control values by the end of the fortnight long exposure period.

Although we can not identify the mechanisms and sites of action at the moment, it is likely that whole-body SMF exposure may have an influence on the chemical reorganization mechanisms of pain processing neural circuits.  It may act on the pain processing apparatus of the central nervous system after the development of central sensitization, and inhibit processes that maintain the increased sensitivity to external stimuli in neuropathic pain.