2011 年 26 巻 1 号 p. 39-47
We evaluated the effect of magnetic stimulation on neuropathic pain using a unique magnetic stimulation apparatus. This system produced an alternating magnetic field of an appropriate uniform intensity that we applied to a rat model of chronic constrictive nerve injury (CCI). We performed an experiment on rats that showed reduction in the paw withdrawal threshold to mechanical stimuli, thermal hyperalgesia and cold hypersensitivity 2 weeks after nerve injury. Animals that underwent CCI were divided into three groups: non-stimulation control (NSC, n=8), low-strength magnetic stimulation (LSM, n=9), and high-strength magnetic stimulation (HSM, n=9). Alternating magnetic stimulation was delivered to the lateral sides of both femurs, operated and unoperated, near the sciatic nerves, at different intensities (ca. 25 mT and 70 mT; 50 Hz) for 30 min every 5 days. Treatment with magnetic stimulation reversed the decreased withdrawal threshold of mechanical allodynia, the effect being more significant in the HSM group as compared to the NSC group on day 5. Magnetic stimulation improved the paw withdrawal latency to thermal stimuli on day 1, though the effect was not significant. Magnetic stimulation had no obvious effect on cold hypersensitivity.
In conclusion, alternating magnetic stimulation improved neuropathic pain in CCI rats. The advantage of magnetic stimulation is that since it is non-invasive, it could be a suitable method for the non-pharmacological treatment of chronic pain.
