Emergency War Surgery NATO Handbook: Part III: General Considerations of Wound Management: Chapter XX: Wounds and Injuries of Peripheral Nerves

Introduction

United States Department of Defense

The majority of war wounds affecting the nerves do not require immediate operation. While soft tissue, bony, and vascular injuries associated with the neural lesion require emergency exploration, neural repair, if indicated, can be carried out electively. There are, however, important exceptions to this rule.

High-velocity missile injuries to nerves in combat are generally not neat and sharp. The nerve, if not directly transected by the projectile, is stretched by cavitation forces but remains grossly intact. Early on, there is no way to determine intraoperatively whether to resect such a lesion. Early repair of nerves transected by penetrating missiles is not satisfactory because of the difficulty associated with deciding how far back to trim the injured nerve before reaching potentially healthy fascicular tissue. As a result, acute repair under these circumstances runs the risk of anastomosing contused tissue of questionable viability. With time, however, the damage to the nerve stump will be delineated so that the amount of proximal neuroma or distal glioma requiring resection will become obvious. Ideal timing for such repairs is 2-3 weeks after injury. If a transected nerve is found during the course of debridement and/or repair of other non-neural injuries, it is best to "tack" stumps down with non-resorbable monofilament suture, to adjacent tissue planes and to place each stump at a different level. This maintains length, an important consideration since most nerves will retract after transection. By placing the stumps in different planes and, wherever possible, away from acutely repaired or traumatized vessels, tendons, bone, or muscle, neuroma formation is prevented. Sling sutures, holding the stumps together until an elective repair can be performed at a later date, are to be discouraged, since they tend to produce neuromas. These neuromas, when they occur, will require resection that often produces a larger gap than if the stumps had been left to retract. Placing the nerve stumps in a setting free of other traumatized or recently-repaired tissues minimizes the development of scar around the stumps and tends to reduce the subsequent length of required resection.

It is important to obtain a baseline neurologic assessment of the limb. The following questions must be answered: What nerve(s) is involved? What is the distribution of motor, sensory, and autonomic loss? Is the loss complete or incomplete distal to the level of the lesion? Partial losses which represent incomplete lesions tend to recover spontaneously with time, whereas complete losses probably will not, and will usually require surgical intervention. Electromyography (EMG) and conduction studies will not be of help in the first few weeks after injury since the Wallerian degenerative process takes time to produce deinnervational changes, at least for major nerves.

The suspected in-continuity lesion should be observed over time to see whether clinical or electrophysiological improvement is demonstrable prior to exploration and intraoperative evaluation by stimulation and recording of nerve action potentials (NAP). During this follow-up period, it is important to maintain motion in the injured extremity to prevent joint stiffness, tendon shortening, and pain. It is especially important to close soft-tissue wounds associated with neural damage as soon as practical so that physical therapy can be initiated early. There is no indication for putting the paralyzed or partially paralyzed limb, or the nonrepaired nerve, to continuous rest. If devices such as cock-up wrist splints are used to keep the limb in a position of function, they should be dynamic and, whenever possible, removed several times a day for range of motion (ROM) exercises to the limb. If a splint or cast is necessary because of concomitant fracture(s) or acute vascular or tendon repair, then the joints both proximal and distal to the immobilized portion of the limb must be put through a full ROM at least three or four times per day. This is especially important for joints that have lost their innervation, for these tend to freeze or stiffen much more readily than normally innervated joints. ROM is also necessary for the limb with a bluntly transected nerve, since disabling joint stiffness can occur as early as two weeks after injury.

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Operational Medicine 2001

Health Care in Military Settings

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