Surgical Experiences in South Africa, 1899-1900 / Being Mainly a Clinical Study of the Nature and Effects of Injuries Produced by Bullets of Small Calibre

by George Henry Makins

I. Simple concussion.—Anatomically, or histologically, no information exists as to the changes which give rise to the often transitory symptoms dependent on this condition. We are reduced to the same theories of molecular disturbance and change which have been invoked to account for similar affections of the central nervous system. The causation of concussion is, however, materially influenced in its degree by the velocity of flight of the bullet and consequent severity of the vibratory force exerted. Hence actual contact of the bullet with the nerves is not necessary for its production, as is seen in the temporary complete loss of functional capacity in the limbs in many cases of fracture, where the vibrations are rendered still more far-reaching and effective as the result of their wider distribution from the larger solid resistance afforded by the bone. The relative density and resistance offered by the different parts of the bone acquire great significance in this relation, since local shock due to nerve concussion is far more profound when the shafts are struck than when the cancellous ends furnish the point of impact.

The form of concussion which most nearly interests us in this chapter is that affecting single nerve trunks in wounds of the soft parts alone, and here the passage of the bullet is, as a rule, so contiguous to the nerve that there is difficulty in drawing a strict line of demarcation between such cases and those dealt with in the next paragraph.

II. Contusion.—Clinically this was the form of nerve injury both of greatest comparative frequency and of interest from the points of view both of diagnosis and prognosis.

The seriousness of a contusion depends on two factors: first, the relative degree of violence exerted upon the nerve, which is dependent on the force still retained by the travelling bullet; and, secondly, on the extent of tissue actually implicated. The range of fire at which the injury was received determines the importance of the first factor; the second varies with the degree of exactness with which the nerve is struck, and on the direction taken by the bullet. Naturally transverse wounds affect a small area; while an oblique or longitudinal direction of the track may indefinitely increase the extent of injury to the nerve trunk, and hence acquire prognostic significance in direct ratio to the amount of tissue which needs to be regenerated.

As to the actual anatomical lesion resulting in the cases which we designated clinically as contusion I can give no information. On many occasions when the symptoms were considered of such a nature as to render an exploration advisable, no macroscopic evidence of gross injury was obtained. It was therefore impossible to draw a definite line of demarcation between such cases and those which we considered merely concussion. It could only be assumed that the vibration transmitted to the nerve had occasioned such changes as to destroy its capacity as a conductor of impressions.

In some cases the presence of a certain amount of interstitial blood extravasation was suggested clinically by early hyperæsthesia and signs of irritation; in others the paralysis was of such a degree as to lead to the inference that a complete regeneration of the existing nerve would be necessary prior to the restitution of functional capacity.

In a certain proportion of the injuries the development of a distinct fusiform swelling in the course of the nerve pointed to the existence of considerable tissue damage, while in others this was evidenced clinically by early signs of neuritis.

III. Division or laceration.—The varying mechanical conditions affecting the last class of injury play a similar rôle here. Thus the degree of laceration depends on the direction of the wound track, and as all lacerations are accompanied by contusion, the relative velocity retained by the travelling bullet assumes the same importance.

I saw every degree of injury to the trunks, from notching to complete solution of continuity, and in some cases destruction and disappearance of pieces from one to two or more inches in length. Such lesions as the latter were most common in the forearm. In this segment of the limbs tracks of varying degrees of longitudinal obliquity are readily produced, whether the patient be in the upright or prone position, since the upper extremities are commonly in forward action whichever position is assumed.

The most peculiar form of injury consisted in perforation of the trunk without gross destruction of its fibres, and without in many cases prolonged or permanent loss of functional capacity. I cannot speak with any confidence as to the comparative frequency of occurrence of this form of injury, but judging by the analogous perforations of the vessels, it is probably not uncommon in trunks large enough to allow of its production. The trunk nerves of the arm, and the great sciatic nerve, were probably the most frequent seats of such wounds. As, however, a very short experience of the futility of early interference in the case of nerve lesions warned me against exploration before a date at which observations of this nature were unsatisfactory, I gained less experience on this point than I could have wished.