Your orthopaedist may recommend electrodiagnostic testing for various conditions that can result from pressure on a nerve, particularly in the arm, elbow or wrist. These conditions are called “compressive neuropathies” and include:
- carpal tunnel syndrome (pressure on the median nerve as it passes between the wrist bones and under the transverse ligament)
- thoracic outlet syndrome (pressure on the brachial plexus, a cluster of nerves that passes under the collarbone at the shoulder)
- ulnar nerve entrapment (pressure on the ulnar nerve as it passes behind the elbow)
- cervical radiculopathy (pressure on the nerve roots as they exit the spinal column at the neck)
Electrodiagnostic testing also can be used to determine the extent of injury to a nerve after an accident and to study the effects of diseases such as diabetes. Your health insurance company or HMO may require electrodiagnostic testing to confirm a diagnosis before authorizing medical or surgical treatment.
The nurse conducting the test will apply sticky electrodes to the skin in various places along the nerve pathway. The nerve is then stimulated with an electric current. As the current travels down the nerve pathway, the electrodes placed along the way capture the signal and time how fast the signal is traveling. In healthy nerves, electrical signals can travel at up to 120 miles per hour. If the nerve is damaged, however, the signal will be slower and weaker. By stimulating the nerve at various places, the doctor can determine the specific site of the injury. Nerve conduction studies also may be used during treatment to test the progress being made.
Although you may initially be startled by the suddenness of the stimulation, it is not painful and most people are comfortable during the testing procedure. The shock is similar to one received when you touch a doorknob after walking across carpeting.
Questions abut NCS
How Should I Prepare for Nerve Conduction Studies?
After showering on the day of your examination, do not use any creams, moisturizers or powders on your skin.
The procedure will be carried out on your hands. Therefore please do not wear any bracelets.
If you have any bleeding disorders, let the examining physician know prior to testing. If you take blood thinners, even any aspirin or aspirin like medications let the examining physician know. You may be asked to stop blood thinners and aspirin products prior to your examination. If you have a pacemaker or other devices that are implanted in your body to deliver medications, let the examining physician know. Any history of back or neck surgery should be discussed with the examining physician, as the examination may need to be modified. Also, any recent fevers or chills may indicate current bodily infection and should be mentioned to the examining physician.
Is the test painful?
The test is not painful, but may produce some discomfort. The stimulator uses two AA batteries to administer the electrical current.
When will the Results be available?
Generally the results are available within 15 minutes.