by Mannheimer, Jeffrey S., PhD,; 2005
The application of weak, low frequency electrical stimulation at the cellular level in animal, plant and E.Coli has been shown to stimulate the synthesis of adenosine triphosphate (ATP). In direct relationship, microamperage electrical nerve stimulation (MENS) has received anecdotal and clinical support as a pain reducing modality that has not been subjected to scientific study. The theoretical therapeutic effect of MENS is based upon the chemiosmotic theory of ATP synthesis by creating a proton gradient at the inner mitochondrial membrane. Magnetic resonance spectroscopy (MRS) represents the gold standard to quantify the metabolic effects of exercise and electrical stimulation on ATP synthesis as determined by fluctuation of Pi/PCr. An increase in Pi/PCr is indicative of an elevated rate of ATP production. 31P magnetic resonance spectroscopy (MRS) was used to examine the levels of inorganic phosphate (Pi), phosphocreatine (PCr) and intracellular pH (pHi) of the human masseter muscle. A cohort (n = 23) consisting of normal subjects and those with a temporomandibular disorder (TMD) were tested in a single application, randomized design with active and placebo comparison during a one hour exposure. Data in the form of phosphorus spectra were acquired at baseline, during the 20-32 and 48-60 minute time-points, with active stimulation and placebo protocols administered at a sub-sensory level via surface electrodes adjacent to the masseter muscle, thereby employing repeated measures. Pi/PCr values were calculated at each time-point and clinical measures consisting of visual analogue scale (VAS), active vertical mandibular range of motion (ROM) and pressure pain threshold (PPT) of the masseter were obtained at pre-and post-exposure for the TMD group. Exposure to MENS revealed a significant (p = .05) elevation of Pi/PCr in both normal and TMD subjects at the 48-60 minute time-point, which was not apparent with placebo exposure. Significant increases in ROM and PPT as well as a decrease in VAS, was apparent for the TMD group exposed to active stimulation. Due to the small sample size and limited statistical power, results should be considered with caution, pending replication and verification by further study.
Xanya Sofra Weiss
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