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transneural stitch advocated by such authorities as Wilms and Sherren; also there is an excellent possibility that some other method of nerve suture may be introduced superior to either of these. Certain it is that the results of nerve suture by our present methods are none too good. Under all circumstances, sufficient of the injured nerve must be excised to render healthy axis-cylinder processes visible. The crosssection of the healthy nerve is quite characteristic; the individual nerve bundles stand out as white, sharply circumscribed areas, separated by intervening bands of connective tissue containing the nutrient vessels. The hæmorrhage from the proximal stump is profuse, and should be controlled in the case of a large nerve by ligature of the spurting vessel; in the case of the smaller nerves, by the application of pledgets of adrenalin. A suture should not be attempted until the hæmorrhage has been controlled, since the presence of a hæmatoma between the nerve ends endangers the success of the operation.
Excision of the nerve to this extent frequently renders it difficult to unite the two ends. Flexion of the limb may help to bridge the gap; in the case of the median nerve, 2 inches can readily be overcome; in the case of the sciatic, 312 or even 4 inches. Traction can also be exerted on the nerve stumps without much danger, although no great force should be applied to the proximal stump, since according to Warrington, too much tension produces a degeneration of the anterior horn cells. To assist in approximating the stumps, it is advisable to place traction sutures about 14 inch from the cut surface of the nerve. These are best inserted before the scar tissue has been excised, so that the healthy crosssection of the nerve should be exposed to the air as short a time as possible. They are inserted by taking two longitudinal bites of perineurium (see Fig. 85), two in each of the nerve stumps, so placed that when an assistant grasps the two attached to the proximal and a second assistant grasps the two attached to the distal, traction upon them will bring the nerve ends in apposition. The perineural stitch which I myself have usually employed is illustrated in Fig. 85. Very fine silk is used; the needle passes in about 16 inch from the cut perineural surface, emerges between the perineurium and the nerve trunk, passes into the other stump at this same plane, and emerges again 116 inch from the cut edge. The suture is tied at once and if properly inserted should produce no inversion of the perineurium but a very slight eversion. As few sutures as possible should be inserted, consistent with an accurate approximation of the perineurium on all sides. It must be remembered that the more stitches inserted the greater the danger of scar tissue formation. Particular care must be exercised not to tear the nerve fibres. If the nerve is once
Traction Sutures Fig. 85.—The perineural method of nerve suture for complete division of a nerve. The two perineural stitches on the deep surface of the nerve have already been drawn tight. One suture above has been inserted and two others would be required to secure approximation. Note the four traction sutures passing through the perineurium about 14 inch from the cut surface.
lacerated by unfortunate handling, it is practically impossible to insert a successful suture. When the perineural stitches have been inserted (usually three or four for the median or musculospiral, six to eight for the sciatic), the traction sutures are removed.
The transneural stitch differs radically from the perineural one, in that the needle is carried directly through the entire thickness of the nerve without regard to the nerve bundles. Its advocates claim comparatively little traumatization of the nerve paths and the great advantage of more accurate apposition. Certain it is that the perineural stitch does not give absolute approximation, since the nerve fibres within the perineurium retract a little when the nerve is subjected to marked tension, and thus a small intraneural gap is left even when an external view shows perfect approximation of the perineurium. In the case of a large nerve such as the sciatic, it is, I think, advisable to combine the perineural stitch with the transneural so as to overcome this gap between the nerve ends.
In instances where it is impossible to approximate the nerve ends because of extensive loss of substance, some bridging method must be followed. Here, too, no one dares speak with the voice of authority. I can only state my own personal experience
Fig. 86.—Specimen from sciatic nerve of dog removed at autopsy 12 weeks after implanting the nerve ends into a calf's artery filled with agar-agar. (Edinger's method.) The photograph illustrates the failure of the two ends to unite.
with methods of this kind. First, as to the technic proposed by Edinger, namely, the insertion of a tube of agar-agar between the divided nerve ends. Despite the excellent theoretic basis for this method, it gives poor results both in the animal experiments in which I tried it (see Fig. 86) and in those operations on human beings performed by other surgeons which I have had occasion to examine. The method of investing the nerve ends in a fascial sheath, as followed by Dean Lewis of Chicago, has not, so far as I know, been given sufficient trial in human beings to justify it as a sound procedure, although its brilliant success in animals would argue in its favor. It must be emphasized, on the other hand, that the possibility of nerve regeneration in dogs is much greater than in human beings. Thus, for instance, it is the rule when the anterior crural nerve of a dog is divided that union occurs within a comparatively short time, even without nerve suture; whereas in human beings such spontaneous cure, so far as I know, seldom occurs.
The method which I have followed is based upon the physiological fact that the essential factor in nerve regeneration is an intimate union of the axones of the proximal stump with those of the distal. That the latter are degenerated does not seem to be of significance. I have therefore transplanted seg
Fig. 873.- Diagram illustrating the method of bridging a gap in a nerve by a transplantation of multiple segments of a sensory nerve. Two segments of a sensory nerve have already been cut and sutured together. The arrows indicate the lines of incision for two more segments. The incisions pass through the entire thickness of the nerve but leave the perineurium on one side intact. To hold the nerves together very fine perineural sutures are inserted.
Transplanted segments of
Fig. 87b.-Diagram illustrating the method of bridging a gap in a nerve by transplantation of multiple segments of a sensory nerve. The segments sutured together to form a trunk corresponding in diameter to the injured nerve are held in place by perineural stitches similar to those shown in Fig. 85.
ments of other nerves of the body to fill in the gap between the ends of the divided nerve. For this purpose it would, of course, be impossible to use a motor trunk without producing paralysis. I have therefore sacrificed sensory nerves; in the arm, the radial or internal cutaneous; in the foot, the external saphenous. Since the cross-section of these sensory nerves is seldom equal to that of the trunk which is to be bridged, it is usually necessary to construct a cable of appropriate diameter by employing multiple segments (two to eight) of the sensory nerve.
The technic is as follows: A sensory nerve is laid bare for a sufficient extent, depending upon the number of segments which must be utilized to give a cross-section corresponding to that of the injured nerve. It is freed from its bed, completely divided at one end, and then doubled on itself to form a loop slightly longer than the gap to be bridged (see Fig. 87). At the closed end of the loop, the nerve is again divided, except on one side, where the perineurium is maintained intact. This step of the operation requires some practice but is perfectly feasible. Two fine perineural stitches are taken, holding the first segment in intimate contact with the second at its upper
FIG. 88.-Result of transplanting the external saphenous nerve for a 4-inch gap in the course of the musculospiral. The photographs were taken six months after the operation.
and lower extremities. The nerve is then further lifted out of its bed so that a third segment, corresponding in length to the first two, can be measured off, and sutured to these. In a similar way a fourth or fifth segment can be united to the preceding (see Fig. 87a). For this, Kirby silk and the finest needles, such as those used in arterial sutures, should be employed. The nerve cable thus constructed is implanted into the gap between the ends of the divided nerve and held in place by the typical perineural suture (see Fig. 876). I have