My daughter dislocated her knee in a motorcycle accident. The surgeon is waiting to see if there are any signs of nerve damage before doing any more surgery. She told us there are electrical studies that can be done to help identify any loss of nerve function. Why are we waiting? Shouldn’t this testing be done sooner than later? What if we wait too long and it’s too late?

Electrodiagnostic studies are tools available for testing nerve and muscle function. Nerve conduction velocity (NCV) is a measure of nerve function. This test can show how fast and how far messages are traveling along the nerve to the muscle. Electromyography (EMG) tests are a measure of electrical impulses that result in muscle contraction.

These tests can be used to find out how severe is the nerve injury and to monitor the patient’s progress during recovery. Changes in NCV and EMG don’t usually show up until about three weeks after the injury. That’s why doctors wait to order these tests. This time period is referred to as the latency period.

During those three weeks, the surgeon will continue to monitor the patient, perform neurologic tests, and look for signs of recovery. If continued, daily progress is being made, these additional electrodiagnostic tests may not even be needed. If recovery is too slow or not apparent, EMG and NCV can help determine if some other treatment is needed and/or tell a bit about the prognosis.

Testing can confirm if there has been a complete cut of the nerve. If that’s the case, then surgery is advised. Incomplete injury requires more of a watchful waiting period. Usually, with an incomplete injury, the nerve regenerates at a rate of one millimeter per day. The surgeon will measure the distance from the injured nerve to the first muscle it controls. Calculating the distance and estimated time of arrival for the nerve at that site gives some indication of when to expect motor recovery to occur.

A physical therapist can work with your daughter using electrical stimulation. This can help prevent atrophy of the muscles normally innervated by the injured nerve. The patient can take a handheld electrical stim device home for use while waiting for the nerve to heal and strength to recover.