OBSERVATIONS ON INJURIES OF THE RADIAL NERVE DUE TO GUNSHOT WOUNDS AND OTHER CAUSES 1

S ummary 1. The case histories, course of regeneration, end result and treatment have been recorded for 62 patients with radial nerve injuries who have been under continuous observation for periods ranging from two to four years. The examinations throughout have been conducted by the same observer. 2. In all cases conservative treatment was adopted (unless the nerve was known to be severed), which meant that exploration was not contemplated within six months. 3. The end results were: in 45 cases the injured nerve recovered spontaneously without exploration; in two cases a severed nerve was sutured immediately after the injury; a further 15 nerves were explored, and of these, two were in a state of continuity not requiring repair, five were sutured, two grafted and six subjected to tendon transplantations owing to irreparable damage to the nerve. The two grafted nerves and two of those sutured did not recover and ultimately required tendon transplantations. 4. The relative merits of early and late exploration of clinically complete lesions have been discussed. Evidence is presented which lends emphasis to the belief that the majority of injured nerves will recover spontaneously if treated conservatively, and that if early exploration is undertaken it is advisable to preserve the continuity of the nerve, regardless of the pathological changes present, until it has been given an opportunity to recover spontaneously. While early exploration, by permitting prompt suture, is of value in cases of complete severance of the nerve, it is urged strongly that nerves found in continuity should not be disturbed. 5. A delay of six months before suture is not necessarily prejudicial to the end result. The time element is only one of many variable factors affecting the restoration of function following suture, and further investigation is required to evaluate correctly the influence of this factor. 6. Attention is directed to the dangers of too‐prolonged immobilization and the value of physiotherapy is stressed. 7. When axones have been interrupted, significance is attached to the initial delay, which has been denned as the time between the injury and the entry of the regenerating axones into that portion of the nerve distal to the site of injury. (For the purposes of the paper the time taken for the completion of those muscular changes upon which the restoration of voluntary contraction depends, has also been included.) A method for calculating this delay has been described. ( a ) The duration of the initial delay was a measure of the severity of the nerve lesion. ( b ) The initial delay was related to the time taken by the regenerating axones to reinnervate the entire motor field subsequent to the onset of recovery. In general, long and short initial delays were associated with long and short periods of reinnervation respectively. ( c ) An initial delay of up to ten weeks followed the mildest cases of “axonotmesis”, which were usually due to the simplest types of injury, such as those associated with simple fractures of the humerus. More severe injuries, such as those due to gunshot wounds associated with fractures of the humerus, infection and extensive scarring, were followed by an initial delay of approximately four months. This was also the usual period of delay following suture. It is, however, difficult to differentiate between simple and severe nerve lesions, since the nature and severity of the causative injury was not a reliable guide. 8. The maximal period intervening between the injury and the onset of spontaneous recovery (latent period), which proceeded to completion, was ten months. In the majority of nerves regenerating spontaneously, however, recovery had appeared by the end of six months. 9. The probable date of recovery (spontaneous or after suture) can be calculated from a knowledge of (i) the presumed initial delay, (ii) the level of the lesion, and (iii) the rate of regeneration. Information relating to these three factors has been provided. 10. The approximate time when voluntary contraction may be expected in the last muscle to be reinnervated may be calculated by adding 11 to 23 weeks, according to the type and severity of the nerve lesion, to the date of the onset of recovery in the first muscle to recover. 11. The regeneration of motor fibres was not always accompanied by a corresponding recovery of sensory function.