[Mechanomyography - results in a normal population and in patients with thyroid dysfunction (author's transl)]

Isometric contraction of the adductor pollicis by stimulating the ulnar nerve was determined in 20 normal adult subjects. We measured mechanical latency, electro-mechanical latency, contraction time, time to half relaxation and isometric twitch force. Besides that we registered the compound muscle action potential and the nerve conduction velocity. The median nerve was used to elicit the nerve action potential and to determine conduction velocity and relative refractory period. In 6 pat. with hypothyroidism and in 7 pat. with hyperthyroidism the above mentioned parameters were measured. There was a significant change concerning contractile properties, i.e. muscular contraction became slower in hypothyroidism and faster in hyperthyroidism as compared to values obtained in the control group. The isometric twitch force was reduced in both conditions. To assure the close relationship between thyroid hormone (L-thyroxin) and muscle contraction a group of patients who have undergone thyroidectomy was investigated in the same way. Muscle and nerve parameters were determined during a levothyroxin-therapy and in a period without any treatment. The same phenomenon was observed, i.e. reduction of twitch velocity in the hypothyroid state. The twitch force was not reduced in this group. The close relationship between thyroid hormone and contractile properties allows a discrimination between hypo-and hyperthyroid state and a control of thyroxin substitution.