What is a Nerve Conduction Study?

Orthopaedic & Spine Center

 

Jenny L.F. Andrus, MD

Physicians order many diagnostic tests to help them pinpoint exactly what condition or illness a patient may have when the answer isn’t immediately clear. A Nerve Conduction Study (NCS) is basically that – a way of determining the speed and intensity of nerve signals being carried away from the brain, through the spinal cord and through the outlying nerve branches. 

We know how nerves function, where most nerves are “supposed” to be in the human body and we have averages for how quickly and strongly they should respond, so we can measure a patient against those standards to check for nerve damage.  An NCS is part of a test called an EMG – Electromyography, which tests muscle interaction with nerves.  The two tests are typically performed together. In this article, I will discuss the NCS, why it is ordered, what to expect during the test and what the results will tell you and your doctor.

The Nerve Conduction Study is ordered by a physician typically when the patient describes a neuropathic or nerve-related pain, numbness, tingling or loss of function in a particular body part.  The physician may ask the patient to perform certain physical movements and ask many questions about the problem but may want an objective measurement of the patient’s nerve response to confirm or rule out the suspected diagnosis.  A NSC is typically ordered when these conditions are suspected: (this list is not all inclusive, but these are more commonly seen)

  • Carpal Tunnel Syndrome
  • Herniated spinal disc disease
  • Sciatica
  • Guillain-Barre’ Syndrome
  • Charcot Marie Tooth Disease
  • Neuropathies and Polyneuropathies

It is simple to prepare for this test.  Let your doctor know if you have any type of bleeding disorder. If you are on blood thinners other than aspirin, you may be asked to stop taking them for three days before this test, as it is typically done in conjunction with an EMG, which requires needle sticks and may cause bleeding.  Notify your physician if you have a pacemaker or any other implanted electrical device.

No special clothing, fasting, diet or drink is required.  We do ask that your skin be free from lotions, oils, or creams because they can interfere with the conductivity of the electrode pads.  We also ask that you not wear rings, bracelets or a wristwatch to your test.  Try to keep your hands and feet warm before the test. 

The patient will be laid on a table and made comfortable.  The physician will apply electrodes to the body part to be tested and will run a mild current between the two electrodes. This may be uncomfortable, like a quick shock, but should not be painful.  The electrodes will be moved around, and the procedure repeated until the physician has the information needed regarding the nerves, their strength or any damage that they may have.  This test typically takes 15-20 minutes, and when combined with an EMG, may take up to an hour.

Because I administer the test, I am looking at the results in real time and I can share those with the patient.  I will also send the results to the ordering physician so that they can contact the patient to discuss next steps in treatment for their particular condition.

Occasionally, the patient will need band-aid over one of the needle stick sites from the EMG, but this is to be expected. After the test, the patient is free to go home.  There may be some muscle soreness and tenderness after the test, which is normal.  The patient may ice the sore area intermittently, if the skin is protected by a barrier, for the next 24 hours. An OTC pain reliever will also help with the soreness, if needed.

As with any procedure, there are risks and complications.  Although quite rare, with the EMG, the risks are bleeding and infection.  The patient should contact me immediately if they continue to bleed, run a fever over 101.5°, or if a needle stick site gets red, hot and inflamed and oozes pus.  We will immediately take steps to address any complications that may arise from their NCS.

 

Make an appointment with Dr. Andrus or another OSC provider by clicking the “Request Appointment” button below or by calling (757) 596-1900.

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