Authors: Silva Diogo, Fontana Ana Paula, Gomes Maria Katia, Lapa e Silva José Roberto,Tierra-Criollo Carlos Julio.
Semmes-Weinstein monofilaments have been widely used in clinical practice to evaluate touch sense in healthy subjects and in the population of risk of neuropathies as Diabetes Mellitus and leprosy patients. It is an effective and low-cost clinical tool indeed, however, it is an instrument of low sensitivity with subjective responses. In the 1980s, a procedure was proposed for the psychophysical assessment of touch sense by sine-wave electric current stimulation. This assessment was based on studies that suggested sinusoidal electric stimuli of several different frequencies would excite sensory fibers of different diameters, increasing the selectivity of the stimulation. This study aims to evaluate and describe touch sense perception threshold of a healthy Brazilian cohort using sine-wave electric stimulation. Reference values of Current Perception Threshold (CPT) were registered in upper limb nerves of 100 healthy subjects, 57 (male) and 43 (female). All subjects had the ulnar, median, and radial nerves evaluated with a sine-wave electric stimulator called NEUROSTIM® to quantify the CPT for the frequencies 1Hz, 250Hz and 3000Hz.
The CPT reference values for the Ulnar Nerve varied between 484µA - 1003µA for the 3000Hz frequency, 168µA - 322µA for the 250Hz and 122µA - 571µA for the 1Hz frequency. For the Median Nerve varied between 468µA - 1321µA for the 3000Hz frequency, 168µA - 386µA for the 250Hz and 168µA - 437µA for the 1Hz frequency. For the Radial Nerve varied between 516µA - 1350µA, 144µA - 533µA and 173µA - 342µA for each frequency respectively.
The NEUROSTIM evaluation protocol seems to be effective, objective, and able to be replicated for touch sense evaluation in healthy subjects. Having CPT reference values to a Brazilian adult healthy cohort can help professionals in the clinics to have a better understanding, management and treatment of diseases affecting touch sense, such as leprosy, diabetes mellitus and others.