30 Neurosurgery MCQs Answers

Answer: a, e

Peripheral nerve injuries may be categorized functionally. Neuropraxia is a temporary loss of function without axonal injury and structural damage does not occur. Axonotmesis is a disruption of the axon with presentation of the axon sheath. Wallerian degeneration of the distal axon fragment occurs. Stretched or prolonged compression causes this functional and structural loss. Regeneration of the proximal axon occurs, but functional recovery depends on the associated injuries, the amount of healthy proximal axon remaining after injury, and the age of the patient. Neurotmesis is disruption of both the axon and axon sheath with corresponding loss of function and is caused by transection of a nerve. Regeneration occurs, but function rarely returns to normal. Clinically, sensory motor changes correspond with the peripheral nerve involved. Detailed history and a precise neurologic examination can localize the site of injury with accuracy. EMG is not useful within the first three weeks of injury but is highly effective for monitoring the status of the degeneration and regeneration process that occurs later.

Regeneration in a peripheral nerve occurs at 1 mm/day (roughly 1 inch each month), so improvement may not be obvious for months. Factors that adversely affect the return of function include advanced age of the patient, proximal nerve injury, extensive nerve tissue loss, associated soft tissue injury, and mixed sensory motor function. Unfortunately, incomplete neurologic recovery is often the rule.

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