CHAPTER V.

27,559

VARIETIES OF MECHANICAL INJURIES OF NERVES.

NERVES, like other parts of the body, are subject to a great variety of lesions from physical agencies. In some cases these act without breaking the overlying skin, while in others the cut or wound involves the integuments so as to make what may be called a compound nerve wound, a condition involving, however, none of the added danger which an open wound brings to a broken bone. In fact, a clean cut through a nerve trunk is often far less grave than a contusion sufficiently severe to cause complete loss of power, or even, I might say, to produce less severe consequences.

Direct lesion by a missile of war or by incision.-Gunshot wounds, and, more rarely, sabre cuts, are the most frequent injuries of nerves during war, and they may present every variety in degree of severity, from the slightest abrasion to absolute loss of considerable nerve substance, as was certainly the case in many instances of wounds by conical balls observed by my colleagues and myself at the U. S. A. Hospital for Nervous Diseases. With us, at least, and the same remark applies generally, sabre wounds and bayonet injuries were very rare. I have seen no nerve lesion from the latter weapon, and if we except scalp wounds involving nerves, only one from the sword.

Seat of wounds.-The large number of wounds in the upper half of the body seen by us admit of the explanation that they bore transportation better than did those of

the legs, which involved usually far longer and more serious ball tracks. Perhaps their frequency may have been due in part to the greater proportion of all wounds of the upper limbs. Lesions of the cranial nerves were rarely seen by us, because these injuries were so often accompanied by fatal results at an early date, owing to grave brain or face lesions. One wound of the sympathetic, the only one on record, and several of the seventh nerve, with one of the fifth nerve, complete the sum of our hospital experience in this direction.

In the table of nerve lesions reported by Londe, and also in Hamilton's cases, the proportion of injuries of the upper limbs is far larger than that of the legs; so that in civil practice as well as in war the nerves of the arms especially are most apt to suffer.

Incised wounds of nerves.—In civil life the most common examples of nerve wound arise from thrusting a hand through a glass window-pane, both nerve and vessel being, generally, severed. I have seen one case of this kind, in which the ulnar nerve was divided without the artery being cut. Knife wounds and the like of course exhibit a variety of incisions of nerves, resulting in greater or less loss of sensation and of motor power as the division of the nerve is more or less complete.

Amount of injury.-The extent of injury to a nerve is of course of the utmost importance, and is learned only by the most careful examination of the parts to which the nerve is finally distributed, in order to ascertain what movements are lost and what skin surfaces show defects of sensibility.

I shall have occasion to treat more fully of this subject in connection with gunshot wounds of nerves; but even here, it will be well to notice certain points which, if neglected, are apt to lead us astray. Thus in studying loss of motion, we should remember how closely related are the

regions of the hand, for example, and that many of its parts are stirred by more than one muscle or set of muscles.

In examining the sensibility, too much care cannot be observed, since there is a natural instinct which causes us to use any power of motion we may have in order to press upon and so examine the touching body. Care as to these points, and minute attention to the anatomical distribution of nerves, will usually decide the extent to which a nerve may have been divided, where the accident is a simple incision. Although there is a general impression that a clean cut of a nerve, partial or complete, is likely to result in total restoration of function, I am sorry to state, as my own experience of such cases years after the accident, that the histories of entire restoration are sadly rare, and that most instances of divided nerves, if abandoned to themselves, result in deformities and functional losses such as characterize, though in far graver degree, gunshot lesions. I suspect that the experience

of most physicians will support me in this statement, which is amply sustained by Mr. J. Hutchinson's* series of histories, nearly all of which were glass wounds, resulting in serious and lasting loss of sensation or motion, with marked nutritive changes.

Among cases of this nature, of which I have seen several, but always late in their history, the burning pains are certainly more rare than in wounds by missiles, yet they are not altogether wanting, as Mr. Paget's cases show. The two following examples may answer as illustrations of this class of injury and of the consequences which are apt to follow it. In these, as in other neural lesions, the nerve section is certainly followed by the usual degeneration of the peripheral end, just as is seen in animals.

* Clinical Lectures and Reports, London Hospital, 1866.

Whether in man autogenesis of this extremity occurs when the part remains isolated from the central stem, is as yet unknown; nor have we learned to what degree the defect of arterial circulation, which in one of the cases must have followed ligature of the ulnar and radial arteries, is capable of affecting the process of nerve repair.

Case 4.-Section of median nerve; abscess at the site of the wound; loss of sensation and motion. R. L., farmer, Delaware County, was brought to me by his brother, one of the former patients of our military hospital. Two years before he had been accidentally wounded by a reaping cradle, the point of the scythe entering the forearm and dividing the median nerve just below the elbow. Unfortunately the wound, which was closed with care, suppurated freely at the third week, and an abscess was opened alongside of the older scar. It is said that there was at this time some sensibility on the outside of the forefinger, but it disappeared soon after the abscess formed, and not the least sign of returning function was ever seen in any part supplied by the median nerve. The skin on the radial side of the palm was thick and rough, and the limits of loss of sensation absolutely distinct, while all the muscular dependencies of the cut nerve were in the last degree of atrophy and contraction.

I proposed to my patient to cut down on the nerve and to bring the two ends together, when I hoped by galvanism to complete the cure, which, without the operation, I had failed to effect by prolonged faradisations. He declined to submit to the knife, and finally abandoned all hope of relief.

I felt well assured that the suppuration in this case interfered with, and terminated, the early efforts at repair. The very slight skin changes in this history contrast remarkably with those of the following case:

Case 5.*-Division of the ulnar nerve and vessels and of the median nerve; anesthesia of the parts supplied; inflammation of the tips of three fingers, unattended by sensation; diminution of animal heat in all the parts paralyzed; increase of heat during inflammation, but still not up to the normal standard."A healthy girl, aged twenty-two, cut the ulnar side of her right forearm very deeply on a broken window-pane. The wound was at the upper part of the lower third, and passed across the ulnar vessels and nerve deeply into the mid-structure, probably dividing the median nerve. bled very freely indeed. She was taken to the hospital, where the hemorrhage was arrested and the wound dressed.

It

"She came under my notice three weeks afterwards, the wound being then just healed. The scar was puckered in. She stated, as regards pain, that she had had very little in the wound, but much aching in the palm.

"The hand of the wounded arm looked a little thinner and a little paler, than the other, but there was no other difference to the eye. All the fingers were kept bent slightly in the palm, and she was unable to straighten them, owing, as she believed, to the effort to extend dragging on the scar. In the attempt to extend, the scar was moved. She was able to flex the fingers fairly, but could not contract her palm or bring the thumb into apposition with any of the fingers. The muscular mass between the thumb and forefinger was thin and flabby. The beat of the ulnar artery could be detected below the

scar.

"Sensation.-Immediately below the scar she could feel the prick of a pin, but not acutely; an inch or two lower, she could scarcely feel it. To the radial side, and at all parts above the scar, she could feel well. At the level of the wrist, in front, all sensation was lost, excepting over

* Hutchinson, op. cit., p. 314.