white substance which surrounds the axis cylinder, and a thin membrane which encloses the white substance. The axis cylinder is the essential, the transmitting portion of the nerve, and constitutes about one-third to one-half of the nerve fiber In the fresh state it is transparent, but after post-mortem changes, under a high power, it shows fine longitudinal longitudinal

NO. 1. TRANSVERSE SECTION OF NORMAL NERVE. striations. The white substance of Schwann is apparently made up of fluid fat, and acts as an insulator to the axis cylinder; the white substance of Schwann is interrupted at regular intervals by the nodes of Ranvier. The neurilemma which surrounds and holds in place the white substance of Schwann is composed of nucleated endothelial cells, and, like the axis cylinders, suffers no interruption at the nodes of Ranvier. If we study the formation of nerve cords from nerve fibers, we find that a number of fibers are united into a bundle by connective tissue called the endoneurium. A number of these primary bundles are enclosed by a laminated sheath containing lymph spaces and called the perineurium. Secondary bundles are finally grouped into nerve cords surrounded by connective tissue, the epineurium.

DEGENERATION OF MOTOR NERVE FIBERS AFTER INJURY OR DIVISION.

It has come to be one of the fundamental laws of the physiology and pathology of the nervous system that a nerve fiber, cut off from

its trophic center, degenerates throughout its entire extent. This fact was first demonstrated by Nasse in 1839 and was afterward confirmed by Waller, Budge, Bruck and others. The degenerative process consists essentially in a breaking up of the myeline or white substance of Schwann into drops of fat. The axis cylinders also break up into fragments and both disappear by absorption. This degenerative process is much more pronounced in that portion of a motor nerve distal to the place of section, while the proximal portion, which still retains its connection to the so-called trophic centers, undergoes but little degenerative change. The inception of this process may be seen as early as the fifth day, and is frequently complete by the tenth or fourteenth day.

The tissue normally innervated by a divided nerve also undergoes degenerative changes; the surface temperature falls from 2 to 7 degrees F. and the part feels cold; in the skin there are burning, pricking pains, formication, increase of sweat or at times abnormal dryness, œdema, redness or abnormal pallor. Such cutaneous affections as eczema, herpes, zoster, pemphigus and echthyma may appear, or disturbances of nutrition with the formation of eschars, ulcerations or gangrene. Inflammatory and trophic disturbances may also take place in the periosteum and bones. In the joints serous effusions may occur, taking the form of chronic hydrarthrosis or plastic exudates with organization producing ankylosis, may appear. These processes in the bones and joints occur only as final results in unhealed nerves. Immediately after division. of

NO. 2. NERVE FIBER.

a motor nerve, its excitability to external chemical, electrical and mechanical stimuli is increased, while its normal function is suspended. After degeneration has become well advanced, the excitability disappears.

Clinical experience and experimental ob

servation would seem to demonstrate that if a nerve is immediately sutured after division or in cases of excision, if the interval is immediately bridged over with some suitable porous material, complete degeneration of the entire peripheral portion does not take place. The re-establishment of sensory and motor function, within a few hours or at most days, in a

NO. 3. FLAP METHOD.

considerable number of these cases would seem to prove this. Function is too quickly restored for the regeneration of a completely degenerated nerve. If the sciatic nerve of a dog be divided, the ends will be immediately separated by about an inch, in consequence of the elasticity and contractility of the nerve tis

If the wound is closed without any attempt being made to unite the divided nerve, and the parts be examined at the end of two weeks, both ends of the nerve will be found bulbous, the proximal bulb being the larger. The distal portion of the nerve will have lost its pearl-like, glistening appearance and will appear dull and sodden, and will have shrunken at least one-third in size. If the nerve be immediately sutured after division, the macroscopic degenerative appearances are much less pronounced, the nerve retaining practically its normal appearance.

REGENERATION OF A DEGENERATED NERVE.

This depends almost wholly upon the approximation or indirect connection of the two ends of the divided nerve. Regeneration always begins in the proximal portion of the nerve, and probably depends upon a strong forward growth of the axis cylinders, which are capable of being projected across a very considerable interval to the distal portion of the nerve if there be a scaffolding of loose tissue to direct them. Reaching the distal portion of the nerve the axis cylinders are directed by the empty nerve sheaths and connective tissue

spaces to the very extremity of the nerve, ending in muscle, skin or gland. At first many of the axis cylinders are naked, but later become surrounded by a myeline sheath. A few investigators hold that nerve regeneration is brought about by a proliferation of the nucleated endothelial cells of the neurilemma, these cells sending out strong offshoots, which become the new axis cylinders. They also hold that the process of regeneration is carried on in both extremities of the divided nerve, though to a less extent in the distal.

SPONTANEOUS REGENERATION OF NERVES WITH

OUT SUTURE.

Clinical experience has demonstrated the possibility of the restoration of the conductivity of nerves after division without suture. The experience of Keen, Weir Mitchell, Morehous, Notta and others, has proven that this condition may occur in exceptional cases. Notta saw an instance of spontaneous regeneration within six months after division of all the nerves of the arm. Tiedmann, in August, 1827, exposed the brachial plexus of a dog in the axilla and divided each nerve, excising from them a piece two to two and a half centimeters long. Complete paralysis of sensation and motion followed, but in the course of a year and a half both sensation and motion returned. Six months after the return of function, the dog was killed and the nerves found united by medullated nerve fibers. Schiff excised five centimeters of the Vagus nerve in a dog, and after several months demonstrated the restoration of the conductivity of the nerve. Langenbeck and Hueter observed restoration of the conductivity after

NO. 4. BRIDGE OF SILK.

laceration of the brachial plexus in a Prussian. officer, who was wounded by a cannon ball in the storming of the Düppeler redoubt on April 18, 1864. In September of the same year the arm was completely paralyzed. After one year and a half the function of the arm was so far restored that the patient became fit for active duty and served as an officer in the campaign of 1866 He was killed

while battalion commander in the battle of Worth. These recoveries, however, are extremely rare and do not invalidate the rule, that irreparable paralysis is always to be expected after division of a nerve without suture.

THE TIME AND THE OPERATIVE METHODS FOR RESTORING THE CONTINUITY OF NERVES

AFTER INJURY OR RESECTION.

In point of time the suturing of a nerve has been divided into primary, or that done imme

NO. 5.

MICROSCOPIC APPEARANCE OF SPECIMEN WHERE DECALCIFIED BONE WAS USED.

diately after the injury, and secondary, or that done at some subsequent period. Primary suture was first practiced by Baudens in 1836 with negative results. Nélaton and Langier repeated the operation in 1863 and 1864, respectively. Fine silk was used, the suture being brought out of the wound and left to come away subsequently by suppuration. Primary suture of a divided nerve should always be practiced, if possible, before degenerative changes have taken place in the distal portion of the nerve. Catgut is the most suitable suture material, if there is no undue tension upon the nerve ends; otherwise, fine silk may be used. The indispensable requisites for success are, first, that the nerve ends be brought evenly and squarely together, without any folding or turning in of the ends; second, that they be maintained in perfect apposition by suture, and, third, that the operation be perfectly aseptic. The turning in or folding of the nerve ends will lead the young axis cylinders off into the adjacent muscle (should they form) instead of into the distal portion of the nerve The occurrence of suppuration in the wound will delay or prevent union, or destroy it if it has already occurred.

The results of primary suture of nerves are surprisingly good, function, as a rule, being restored in from 7 to 21 days A surgeon

may undertake the primary suturing of a divided nerve, if he do it properly and aseptically, with almost the same degree of confidence that he would set a broken bone or do any one of the ordinary operations of sur

gery.

Secondary suture of a divided nerve was first performed by Nélaton in 1865. The results in secondary suture, though longer delayed and not so satisfactory as in primary suture, in consequence of the degenerative changes which have taken place, have nevertheless been excellent in about 66 per cent of the reported cases. I am able to add one successful case to those already recorded.

A boy aged 17 came to me in July, 1893, ten months after suffering a severe injury to his right arm by having it drawn forcibly in between a heavy, rapidly moving belt and its pulley. Although the skin was not broken, the arm was severely crushed, and immediately after the injury showed paralysis of the muscles supplied by the musculo-spinal nerve. When the patient came under my care the loss of function was absolute. The bulbous upper extremity of the nerve was easily felt two inches above the elbow. The nerve was cut down upon and the extremities found nearly two inches apart. The lower portion of the nerve was much atrophied; the end was freshened, the upper bulb cut away, and after flexing the forearm, the ends were brought together with fine silk sutures. Commencing restoration of function was noticeable in six weeks, and at the end of seven months was very satisfactory.

If the ends of a divided nerve cannot be ap

NO. 6. BRIDGE OF MUSCLE.

proximated in consequence, either of a portion of the nerve having been resected or a loss of continuity by injury having occurred, one of various methods may be resorted to. Leterant proposed and practiced the flap method, splitting and turning down one-half of the nerve to bridge the gap The results of this operation, both clinically and experi

NO. 7.

mentally, have not been encouraging. In three dogs in which I resected one inch and a half of the sciatic and turned down a flap from the proximal portion to bridge the defect, there was failure of function in one after three months; in the second there was partial restoration of function after two months; in the

TRANSVERSE SECTION THROUGH REGENERATED NERVE IN A BRIDGE OF MUSCLE. SPECIMEN TAKEN ON THE TWENTY-FIRST DAY.

third, function was restored after 35 days. The reasons for these frequent failures in the flap method are obvious. The portion of nerve turned down as a flap does not remain vitalized, but degenerates. The degenerated flap, having its connection with the side instead of with the end of the nerve, is illy suited to, lead the shooting axis cylinders to the distal end. It would probably lead to more satisfactory results if the flap could be turned up from below. The method does great injury to the nerve, is more difficult of technique than many others, requires exposure of a greater portion of the nerve, and can only be practiced on nerves of considerable size. It has but a narrow range of applicability, and the results will often be disappointing.

TRANSPLANTATION OF A NERVE FROM ONE OF THE LOWER ANIMALS.

This operation has been done by Gluck, Kaufman, Tillmanns, Ward, Moullin, Robson, Atkinson, Landerer and others. On March 1 I resected one inch and a half of the sciatic

nerve of a dog and transplanted the sciatic nerve from a rabbit, using silk sutures. On April 19, fifty days after the operation, there was still complete failure of function, and the dog was killed. The transplanted portion of nerve had been absorbed, both ends of the nerve in the dog were bulbous, a condition which prevails where there is failure of restoration of function. The interval between the nerve ends was bridged over with a small amount of cicatrical tissue. The operation, though a failure in this case, is certainly a good one, and is sure to be successful in a large number of cases. The interval can be bridged accurately, and, although the transplanted nerve will degenerate, it will afford an excellent scaffolding in which the growing axis cylinders will be led to the distal end of the nerve. In opposition to it, it may be said that it requires a live animal, necessitates two operations and an unnecessary amount of technique Atkinson, in excising the hip joint, cut out by accident one inch of the sciatic nerve. The excised portion was sutured in position with subsequent restoration of sensation. Landerer engrafted a piece of the sciatic from a rabbit into the radial nerve of a woman to bridge a gap three and a half centimeters long. Sensation returned in three weeks and active motion was possible in ten weeks.

BRIDGING OVER THE DEFECT WITH STRANDS OF CATGUT OR SILK.

This method was proposed by Assaky, who used catgut. Experimentation has shown that in order to get subsequent restoration of function in a resected nerve, provided the ends are not too widely separated, it is necessary to