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the dorsal sensory branch leaves the nerve some few inches above the annular ligament and is therefore spared by the projectile.
Immediately after the injury there is no tendency to deformity. Gradually, however, in the majority of the untreated cases a contraction of the fourth and fifth fingers occurs (see Fig. 25). This was so marked in a number of patients that when they were referred to me the nails of the affected fingers were cutting into the palm and the patients were clamoring for amputation. The flexion contracture of the fourth and fifth fingers is a paralytic phenomenon peculiar to the ulnar nerve. It may be due to scar tissue formation in the flexor muscles and their consequent shrinking, but this explanation, like others, is purely hypothetical. The later cases of ulnar paralysis are also characterized by the marked atrophy of the interossei and of the muscles of the thenar and hypothenar eminences. A "main en griffe,” as described by Duchenne, I have never seen, even in cases untreated for two and three years after the injury.
3. Median Nerve.—There is regularly a marked interference with the flexion of the fingers, particularly of the thumb, index, and middle fingers. Flexion of the wrist is possible owing to the action of the strong flexor carpi ulnaris. The sensory disturbance as a rule corresponds accurately to the distribution of the nerve and is found over the thumb, index, middle, and radial half of the ring fingers on the palmar surface. A portion of the palm on the radial half is also anæsthetic.
Although the pronating muscles are also paralyzed by a lesion to the nerve occurring above the elbow, great care must be exercised in testing for their function, since an agile patient can almost always by a clever use of the brachioradialis swing bis arm from the supinated position into the pronated. To prevent this vicarious action of the brachioradialis (supinator longus), the patient's arm must be so twisted that the dorsum looks toward the ceiling, not with the thumb toward the inner side, but with the elbow so bent that the thumb points away from the body. In this position, pronation must overcome the weight of the arm, whereas in other positions, the weight of the arm assists in pronation.
. 4. Musculocutaneous. There is a weakness of flexion of the elbow, but not a complete paralysis, owing to the presence of the non-paralyzed muscles which spring from the internal and external condyles of the humerus (pronator radii teres, flexor carpi radialis, brachioradialis, extensor carpi radialis longus and brevis). Sensory disturbances are usually not to be found owing to the overlapping by other nerves.
5. Circumflex.—There is a paralysis of the deltoid and of the teres minor. The latter is difficult to diagnose but paralysis of the deltoid prevents the full abduction of the arm. The action of the supraspinatus combined with that of the trapezius suffices to abduct the arm to 90°; for complete abduction, however, the deltoid is essential. The
disturbance is not constant.
For some peculiar reason, isolated injuries to this nerve are seldom seen in military surgery. Stewart and Evans, in their series of 316 cases, and Spitzy of Vienna, in 250 cases, report not a single instance of injury to the circumflex. Foerster of Breslau, reporting 1490 cases, of which 355 were injuries to the musculo-spiral states that lesions of the circumflex occurred in only an insignificant number.
6. Brachial Plexus.-Injuries are quite frequent, either from wounds above the clavicle or in the axilla. The arm hangs absolutely helpless by the side, there is complete anesthesia of the hand, forearm, and usually of a portion of the upper arm. Depending upon the site of the injury, there may or may not be involvement of the pectoral muscles and of the serratus magnus. In case the latter is involved, the patient shows the characteristic winged-scapula deformity.
7. Great Sciatic.-Even in those cases where the injury occurs near the sacro-sciatic foramen, the flexors of the knee are not completely paralyzed, because in the first place a number of branches to the hamstrings are given off from the nerve immediately after it leaves the pelvis and in the second place the gracilis and sartorius, supplied by nerves of the lumbar plexus retain their normal function. The foot is completely paralyzed in all cases, and is anæsthetic except over a small area on the inner aspect supplied by the internal saphenous When the injury occurs in the middle third of the thigh, there is no perceptible weakening of the hamstring muscles.
8. External Popliteal.-Dorsal movement of the foot (dorsal flexion) and eversion are impossible, owing to the paralysis of the tibialis anticus, extensor proprius hallucis, extensor longus digitorum, and the peronei. The anæsthetic area covers the entire dorsum of the foot and of the toes.
9. Musculocutaneous (of the calf).-Eversion of the foot is weakened but not inhibited, owing to the fact that the extensor longus digitorum and the peroneus tertius (both supplied by the anterior tibial nerve) also act as everters. The anæsthetic area covers the dorsum of the foot and the toes except the contiguous surfaces of the great and second toes.
10. Anterior Tibial.-Dorsal flexion of the foot is impossible. There is an anæsthetic area on the contiguous areas of the great and second toes, as indicated above.
11. Internal Popliteal.—The symptoms vary, depending upon the site of the injury. If this occurs above the point where the branches to the gastrocnemius leave the nerve (near the upper limit of the popliteal fossa) the plantar motion of the foot is impossible. If below this point, the foot can be brought into a position of equinus, but the motion is weakened and flexion of the toes is impossible. The anæsthetic area is the same in both instances and covers approximately the sole of the foot.
12. Posterior Tibial. There is normal motion of the Achilles tendon, pulling the foot into the equinus position, but owing to the paralysis of the flexor longus hallucis and flexor longus digitorum the toes cannot be bent. Adduction is possible, despite the paralysis of the tibialis posticus, owing to the action of the tibialis anticus and of the Achilles tendon.
The diagram (Fig. 26) summarizes the terminal distribution of the motor branches of the sciatic nerve and enables the surgeon to diagnose the lesion almost at a glance.
13. Rare Nerve Injuries.-(a) Intercostals.—There is no appreciable sensory disturbance but electrical and mechanical stimulus of the muscles in question fail to cause a contraction.
(6) Phrenic.-Unilateral injury can be beautifully demonstrated by X-ray pictures of the diaphragm which show a diminished excursion on the injured side.
(c) Cervical Sympathetic.—The eye is slightly sunken on the affected side, there is a slight ptosis which the patient, however, can voluntarily overcome, since the voluntary fibres of the levator palpebri are not affected but only the involuntary fibres supplied by the sympathetic. The pupil is slightly smaller than the normal. There may be flushing or sweating of the half of the face affected.
Fig. 26.—Diagram illustrating the terminal branches of the great sciatic
and their motor distribution.
14. Cranial Nerves. Of these, only the facial and the spinal accessory are of orthopedic interest. Injuries to the facial result in paralysis of all the small muscles of the face, including the orbicularis palpebrarum. When the spinal accessory has been injured, there is some interference with abduction of the arm, but owing to the double supply of the trapezius through the cervical plexus as well as through the spinal accessory it is not completely paralyzed. For a consideration of the other cranial nerves, the reader is referred to any of the well-known neurological text-books.
THE IMMEDIATE TREATMENT OF NERVE INJURIES General Principles.—To prevent the development of deformity, maintain the maximum muscular tone, and create the most favorable opportunity for recovery, treatment of traumatic injuries to nerves should begin immediately after their occurrence. The principle enunciated many years ago by Hugh Owen Thomas and constantly emphasized by Sir Robert Jones, must invariably receive the consideration of the surgeon. This teaching of Thomas maintains that when a muscle, temporarily paralyzed, is constantly subjected to undue strain by a position of the limb which puts its fibres constantly on the stretch, the muscle itself degenerates and even when the nerve recovers it will fail to respond to the volition of the individual.
Thus, for instance, in the cases of musculospiral paralysis. due to pressure on the nerve either during narcosis or in deep sleep, the nerve injury will be repaired within six weeks. If immediately after the paralysis has occurred the hand be properly splinted, so as to relax the fibres of the paralyzed extensors, the patient will be able to control his muscles as soon as the nerve paths have regained their normal conductive powers. If, however, the hand be allowed to dangle during this period of nerve recovery, the patient will be unable to extend the hand voluntarily because the overstretched muscle fibres fail to respond to the nerve impulses. In the nerve lesions of military practise the same rule applies as in those cases seen in times of peace. In every instance of musculospiral paralysis or of injury to the anterior tibial, it is absolutely essential to splint the limb in such a way as to relax the affected muscles. In the case of the ulnar nerve, other factors must be considered so that it is not safe to give a general rule applicable to all nerves. In some instances, the surgeon must consider the tendency to deformity or to contracture and adjust his splint so as to prevent this from developing.
Recently it has been maintained (Stoffel) that the union of a divided nerve can be furthered by splinting the limb in such a position as to bring the nerve ends as near together as possible. Thus, in division of the median nerve near the elbow,