About ElectroDiagnostics

The term "ElectroDiagnostic testing" includes 2 different tests:

  • EMG (Electromyogram)
  • NCS (Nerve Conduction Study)


There are a wide variety of conditions that are assessed with this testing. Quite frequently, the examination is requested because the patient is experiencing symptoms that suggest nerve involvement (numbness, tingling, weakness and/or pain) or muscle involvement (weakness and/or pain).

The recommended Policy for ElectroDiagnostic Medicine American Association of Neuromuscular & ElectroDiagnostic Medicine states that:

"The ElectroDiagnostic medicine (EDX) evaluation is an important and useful extension of the clinical evaluation of patients with disorders of the peripheral and/or central nervous system. EDX tests are often crucial to evaluating symptoms, arriving at a proper diagnosis, and in following a disease process and its response to treatment in patients with neuromuscular (NM) disorders."


Conditions that NCS/EMG tests are useful in helping diagnose include:

  • Nerve disorders - this can be a local problem such as a trapped nerve (carpal tunnel at the wrist, ulnar nerve at the elbow, peroneal nerve at the knee), or a more generalized problem, such as part of a medical condition e.g. diabetes
  • Nerve roots most commonly in the neck and lower back
  • Nerve Plexus (major nerve trunks) in the arm or leg
  • Muscle disorders
  • Neuromuscular junction (the communication between the nerve and the muscle) disorders such as myasthenia gravis


NCS
- (Nerve Conduction Study) is a non-invasive test performed to evaluate the integrity and function of the peripheral nervous system in your arms and legs. There are several types of nerves but generally speaking, the two major types that are tested are the motor and sensory nerves in your extremities. Motor nerves carry signals from the brain to the muscle to enable contraction and movement, and sensory nerves relay information such as pain, temperature, pressure to the brain.


EMG
- (Electromyography) is a diagnostic study that is used to record the electrical activity of muscles and provides information about the function of those muscles. An EMG is often performed when patients have unexplained muscle weakness.

The EMG test can pick up electrical signals in the muscle either in its resting state or with activation of the muscle. As mentioned earlier, it is useful for looking at both the nerve and the muscle but this portion of the test, being invasive, is not always employed, unless clinically necessary. Any readily accessible nerve can be tested.


How is the test performed?

During the test the examiner actually sees and hears how your muscles and nerves are working, using a specialized computer. In many cases the examination will include areas away from where you are having symptoms because nerves can be very long.

Any readily accessible nerve can be tested.