[Study of muscle excitability in response to currents of different duration in the diagnosis of nerve injuries].

The "strength-duration" curve was studied in 154 patients in different periods after injury to the median nerve, ulnar nerve or both nerves. The most probable mean values of strength (U) in changes of the duration (t) of the current 1--6, 7--11 months and more than 12 months after injury were obtained by means of the equation U=a0 + a1t +a2t2 by the least squares method. It was established that the excitability of muscles diminishes continuously but persists more than 15 years after total anatomical interruption of the nerve. Absence of electroexcitability of the forearm muscles as a result of ischemia is not a contraindication for nerve suturation. Suturation of the nerve leads to restoration of sensibility and active contractions of the hand muscles. The deviations in the "strength-duration" curve are signs of partial injury to the nerve. It was found that the more the number of deviations in the "strength-duration" curve and the more its left part on the side of the injury resembles the curve recorded from the symmetrical healthy muscle, the more rapidly is the nerve conduction restored and the more rapidly it improves after nonoperative treatment.