An adaptive procedure for routine measurement of light-touch sensitivity threshold

Quantitative sensory testing with Semmes-Weinstein monofilaments suffers from several pitfalls. Our aims were to assess the reliability of these filaments for touch-pressure threshold detection, develop and validate a rapid and accurate procedure for measurements at the bedside, and establish normative data. After calibration of the monofilaments, an adaptive staircase algorithm was validated and used to establish normative data in healthy subjects. Calibration showed significant differences between manufacturer- and investigator-produced data. The relative humidity significantly affected the force exerted by the filaments. The adaptive procedure showed good accuracy and substantial time-saving. Touch-pressure thresholds showed significant gender differences (mean +/- 2 SD for females/males: 2.82-12.3/3.09-17.78 g/mm(2)). The influence of body site and age is small. Accurate use of Semmes-Weinstein monofilaments requires prior calibration, correction for humidity, and use of a validated procedure. In this study we provide normative data that can be used with our algorithm.