MRS-Screening-Test zur Registrierung der medikamentösen Beeinflussung des Muskeltonus

Summary

In order to determine the effects of muscle relaxants, anti-inflammatory agents, and analgesics on the tone of striated muscle in humans, we developed a simple, two-dimensional muscle-screening test. This computerized test, designated MRS (a German abbreviation referring to the measurement of involuntary-muscle reaction parameters under the influence of gravity), is specifically designed for the musculus quadriceps femoris group and can be carried out quickly, i.e., in approximately 15 min. A cold-light diode affixed to the malleolus externus and one above the lateral knee joint space represent the main reference points. Both the mathematical and graphic recording and the subsequent evaluation are carried out automatically, using a video-computer system with specially designed software. With this system, measurements are made within and beyond human tactile reaction times, which enhances the reproducibility of the results. The program permits intra- as well as interindividual comparisons to be made.

The main parameters measured are the maximum velocity of fall of a lower leg against gravity along the X-axis, its minimum velocity along the Y-axis, and the maximum vector of velocity. In an intraindividual comparison, the tendency of these mathematical parameters to return to normal (the extent to which, and rate at which, this occurs) is regarded as indicative of the muscle-relaxant effect.

The MRS screening test can be used in acute or long-term trials to demonstrate the muscle-relaxant effect of drugs in patients with muscular tension of (pain-induced) peripheral or central origin. The most suitable conditions for acute drug tests with intraindividual comparisons are unilateral syndromes involving the lumbar nerve roots or relevant unilateral periarthritis of the hip, or conditions following cerebrovascular accidents.