MUSCLE DAMPING MEASURED WITH A MODIFIED PENDULUM TEST IN PATIENTS WITH FIBROMYALGIA, LUMBAGO, AND CERVICAL SYNDROME

Study Design. Muscle tension with tenderness may be localized or gener alized as in fibromyalgia. Wartenberg's pendulum test might be appropr iate for quantitating muscle damping, at least in generalized cases. O bjective. Damping values provide a quantitative measure of muscle tens ion and of the response to various treatments. Summary of the Backgrou nd Data. According to recent anatomic and experimental works, intrafus al muscle fibers are double-innervated by gamma motoneurons and sympat hetic fibers. With electromyograph recording, the activity of extrafus al fibers and gamma motoneurons (reflexes) can be assessed and separat ed from the action of the sympathetic system. Methods. An electrogonio meter registers the movements of the freely swinging leg. On the oscil loscope, the patient's nodular curve is compared with an ideal calcula ted dampened curve to find the damping value. Electromyograph surface electrodes for the knee extensors and flexors detect the activity of e xtrafusal fibers and the occurrence of reflexes. Results. In longstand ing severe fibromyalgia, damping values are almost always elevated, at least in one leg. Half or more of patients with chronic lumbago and c ervical syndrome present with increased damping. The surface electromy ograph remains silent (in contrast to spastic patients). Conclusion. T he findings support the hypothesis that muscle tension in rheumatic pa tients results rom over-activity of the sympathetic system (or part of it). Even in clinically localized pain syndromes, muscle damping is o ften increased in the legs. The test is valuable for quantitating musc le tension and the effectiveness of therapeutic methods.