Difference in sensory, motor and pain threshold for medium frequency electrical stimuli in different pain conditions-A pilot study

Abstract

Background: Different current frequencies are considered to produce a different reaction in tissues. But there is still a lack of knowledge about the reactions of tissues on medium frequency electric currents with different frequencies in special groups of diseases or trauma. Objective: The main objective of the study was to find out the difference of physiological response between normal healthy, chronic low back pain and postoperative pain subjects for a medium frequency (4 KHz) electrical stimuli with 20, 50 and 100 Hz base frequencies. Method: Readings were taken for sensory, motor and pain threshold with three different frequencies 20 Hz, 50 Hz & 100 Hz for normal healthy, chronic low back pain and postoperative pain subjects. Electrodes were applied over the dorsal and ventral side of the ankle in all the maneuvers. For the normality of the data, Shapiro-wilk test was done. Statistical analysis was done using IBM SPSS version 20.0 and significance were set at “p Result: A multivariate ANOVA test showed significant difference statistically between groups; sensory and the motor threshold for back pain was less than normal and postoperative subjects, irrespective of the frequencies used for stimulation. The post hoc analysis between groups showed that chronic low back pain subjects differ from normal individuals in pain threshold (difference 1.617mA, p=.041). Conclusion: The sensory and motor response threshold was more in acute pain subjects and in normal individuals than chronic low back pain subjects. Reduced sensory motor threshold and increased pain threshold in chronic back pain subjects may indicate hyperalgesia and perceptual delay in processing of the electrical stimuli by the nerves system.