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Upper Extremity Peripheral Nerve Injuries

Nerve injuries in the upper extremity occur as the result of a blast, a crushing or penetrating blow, or due to an injury caused by a sharp object. Management is predicated on establishing nerve continuity in an environment that will allow nerve growth and regeneration. Due to Wallerian degeneration that occurs at the time of injury, reinervation of the motor end-plates before 18 months will prevent muscular atrophy and subsequent deformity. Therefore, appropriate initial management of these injuries will confer successful results with minimal functional morbidity.

Classification of Injury (Fig. 18–1)

First Degree: Neuropraxia

These injuries occur secondary to crushing, compressing, or stretching of the nerve. In these scenarios, the nerve architecture is not disrupted and there is nerve incontinuity. Conservative management including splinting of the involved extremity and physical therapy is appropriate. The nerve should recover in 3 months; otherwise, a second, third, or fourth degree injury should be suspected that would require operative intervention.

Second, Third, and Fourth Degree Injuries

Injuries that disrupt the internal architecture of the nerve may be isolated axonal derangement of nerve fascicles with subsequent scar formation (axonotmesis/second degree). However, there may exist a scar conduction block at the fascicular level or across the entire nerve (third and fourth degree). An axonotmetic lesion will heal without surgical intervention by allowing nerve growth through the intact sheath at 1 mm per day or one inch per month. Injuries that heal with a scar block cause incomplete conduction across the nerve. These lesions may require internal neurolysis or excision and direct repair, depending on the conduction drop across the scar. Differentiation of the degrees of these lesions is determined by EMG and nerve conduction studies done at some time interval after the injury, if no nerve function returns.

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Wound Management Hand and Forearm Tendon Injuries Upper Extremity Compartment Syndrome Hand Vascular Injuries and Digit Amputations Anesthesia and Splinting of the Hand and Wrist Hand Infections and Injection Injuries

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