Anne Berquin

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/mm2). 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. Muscle Nerve, 2010

Compliance of normal, dystrophic and transplanted mouse muscles

Parallel and series compliances have been studied in extensor digitorum longus (fast) and soleus (slow) muscles in normal (strain C57BL/10) and dystrophic (strain mdx) mice, and in muscles regenerated after transplantation. Resting elasticity was analysed by measuring the tension-length relationship in unstimulated muscles. Passive tension is larger in mdx and in transplanted muscles than in their normal controls: at 1.15L0, passive tension is 0.12P0 in controls, 0.32P0 in mdx, and 0.40P0 in transplanted muscles. The differences are statistically significant. This indicates that passive tension is mainly determined by the amount of connective tissue. The stress-strain relationship of the series compliance was analysed by the method of isotonic releases during tetani. It is adequately described by a single exponential equation, with a rate constant of about 8P0/P. No difference was found between the various muscles studied. Extension of the series compliance at P0 is 0.02L0. Compliance is about 3% (L0/P0) at 0.2P0, and is not significantly different from zero at P0. Series compliance is thus very low in mouse muscles, substantially lower than in frog and rat muscles. Consequently, it can be neglected in studies of whole mouse muscle in which tension is higher than 0.4P0.