Role of Preoperative Nerve Conduction Studies for Penetrating Hand Injuries Involving the Median Palmar Cutaneous Nerve.

Penetrating lacerations to the hand are a common cause of nerve injury and can lead to debilitating pain and numbness in the distribution of the nerve affected. Owing to an overlap in the cutaneous innervation from different sensory nerves, clinically identifying the injured nerve can be difficult. We present a novel case of isolated injury to the palmar cutaneous nerve from a penetrating knife injury which was detected using 'comparison waveform' nerve conduction studies. Using this technique, we can isolate injuries to the palmar cutaneous branch of the median nerve (PCBmdn) from the median nerve, dorsal radial sensory nerve, and lateral antebrachial cutaneous nerve. In addition, sensory nerve testing identified conduction block as the mechanism of injury, which resolved after surgery at 8 weeks postoperatively. Preoperative nerve conduction study can discern the level of nerve injury to PCBmdn only, thus eliminating the need for median and radial nerve exploration at the forearm, unnecessary incisions, pain, and scarring. The objective of this case report is to illustrate the value of preoperative comparison waveform nerve conduction study, particularly the PCBmdn, in patients presenting with neurologic deficits who have sustained penetrating lacerations to the hand.