Exposure to an Inhomogeneous Static Magnetic Field Increases Thermal Pain Threshold in Healthy Human Volunteers

In the present experiment, the effect of a single 30 min inhomogeneous static magnetic field (SMF) exposure on thermal pain threshold (TPT) was examined in 15 young healthy human volunteers. The SMF had a maximum peak-to-peak amplitude of 330 mT with a maximum gradient of 13.2 T/m. In either of two experimental sessions (SMF or SHAM), four blocks of 12 TPT trials were carried out under SMF or SHAM exposure on all fingertips of the dominant hand, excluding the thumb. TPT and visual analog scale (VAS) data were recorded at 0, 15, and 30 min exposure time, and 30 min following exposure. SMF treatment resulted in a statistically significant increase in TPT during the entire exposure duration and diminished within-block thermal habituation, leaving pain perception unchanged. These results indicate that SMF-induced peripheral neuronal or circulatory mechanisms may be involved in the observed TPT increase by setting the pain fibre adaptation potential to higher levels. Bioelectromagnetics 32: 131-139, 2011. (C) 2010 Wiley-Liss, Inc.