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

CHAPTER IX

INJURIES TO THE PERIPHERAL NERVE TRUNKS

The occurrence of these injuries has undoubtedly increased in frequency with the employment of bullets of small calibre, and no other class of case more strikingly illustrates the localised nature of the lesions produced by small projectiles of high velocity. Again, no other series of injuries affords such obvious indications of the firm and resistent nature of the cicatricial tissue formed in the process of repair of small-calibre wounds, and in none is the advantage of a conservative and expectant attitude so forcibly impressed upon the surgeon. Implication of the nerves may be primary, or secondary to an injury which left them originally unscathed.

Nature of the anatomical lesions.—In degree these vary in mathematical progression, but the extent of the lesion is not always readily differentiated by the early clinical manifestations, and again the actual damage is not to be estimated by the gross apparent anatomical lesion alone; but, in addition, consists in part in changes of a less easily demonstrable nature, varying with the velocity with which the bullet was travelling and the consequent comparative degree of vibratory force to which the nerve has been subjected. In these injuries, as in those of every part of the nervous system, the degree of velocity appears to gain especial importance both in regard to the general symptoms and the local effect on the functional capacity of the nerve.

This is perhaps a fitting place for the introduction of a few further remarks as to the significance of the term 'concussion' in connection with the injuries produced by bullets of small calibre, since the most striking exemplification of the results following the transmission of the vibratory force of the projectile is afforded by the behaviour of the comparatively densely ensheathed and supported peripheral nerves.

As already pointed out in Chapters VII. and VIII. the chief concussion effects on the nervous tissue of the brain and spinal cord are of a destructive nature, far exceeding those accompanying the injuries designated by the same term seen in the ordinary accidents met with in civil practice, and this damage is comparatively localised in extent.

In the case of the peripheral nerves I have still employed the terms 'concussion' and 'contusion' to designate certain groups of symptoms and clinical phenomena, but any sharp distinction between the two conditions on a morbid anatomical basis is impossible. The results of severe vibratory concussion may, in fact, be more generally destructive than those of contusion, and the subsequent effects more prolonged. A certain length of the affected nerve is apparently completely destroyed as a conductor of impulses, the connective-tissue element alone remaining intact. Under these circumstances a nerve, the subject of the most serious degree of vibratory concussion, which, if cut down upon, may exhibit no macroscopic change, may take a longer period to recover than one in which the presence of considerable local thickening points to direct contact with the bullet, with resulting hæmorrhage into the nerve sheath and perhaps partial gross rupture of nerve fibres.

The therapeutic and prognostic importance of the above remarks, if correct, is obvious. The course of the nerve is preserved by its intact connective-tissue framework, and ultimate recovery by a regeneration of the nerve fibres is more likely to be complete, and will be just as rapid, if nature be relied on and the nerve be left untouched by the hand of the surgeon.

It is, I think, undeniable that nerve trunks may escape severe or irrecoverable injury by lateral displacement. The mere fact that the trunk itself may be perforated by a slit in its long axis would suggest the possibility of displacement of the whole structure, and this no doubt occurred with some frequency. Displacement would naturally be most frequent in the case of nerves, such as those of the arm, which run long courses in comparatively loose tissue. In a remarkable case already narrated, an exploratory operation showed the musculo-spiral nerve in the upper part of the arm to have been driven into a loop which projected into, and provisionally closed, an opening in the brachial artery.