Specialized Nerve Tests

Nerve tests are a safe and effective diagnostic tool for assessing the function of nerve structures. The most common are electromyography (EMG), nerve conduction velocity (NCV), and somatosensory evoked potential (SSEP) tests. Each evaluates different attributes of nerve function to isolate injury, grade severity, and distinguish from non-neurological causes of dysfunction.

Preparation is relatively simple, involving only bathing prior to testing to remove oils from the skin which may interfere with results. Patients with bleeding disorders, taking blood thinners, electronic implants such as pacemakers, and heart conditions should notify their physician prior to testing.

Electromyography (EMG)

EMG is used for the evaluation of muscle activity. A machine called an electromyogram is used to measure electrical activity of the muscles in question, and may be performed as intramuscular EMG or surface EMG. In the intramuscular form, electrodes are placed directly into the muscle under study, while surface EMG measures across the skin. The latter form is less useful, and not as commonly performed as a result. EMG allows for the identification and distinction between various muscle diseases, such as muscular dystrophy and myasthenia gravis, among others. In addition, it is very helpful for isolating pinched nerves or inflamed muscles.

Nerve Conduction Velocity (NCV)

The NCV is used to evaluate the condition of the nerves themselves. An impulse is propagated through the nerves in question, and the speed of travel is measured to determine if the nerves are functioning normally, or if there is some sort of latency, a condition often due to demyelination. NCV is typically performed alongside EMG for a broader scope of study.

Somatosensory Evoked Potentials (SSEP)

SSEP is a test that checks the connection between the brain and spinal cord with the rest of the body. It is often performed during surgery to ensure that the sensory component of nerves is functioning properly. SSEP may also be combined with EMG and NCV to diagnose spine problems.