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By Dr M Sai Sravanthi
Consultant Neurophysician
What is a nerve conduction study? Why is the test performed? How is the test conducted? What happens during the test? How to Prepare for the Test? Understanding Results Frequently Asked Questions

What is a nerve conduction study?

A nerve conduction study (NCV) test determines how quickly electrical signals flow through a nerve. This test is used in conjunction with electromyography (EMG) to evaluate the muscles for abnormalities.

Why is the test performed?

This test is performed to determine whether or not the nerves have been damaged or destroyed. The test is occasionally used to evaluate nerve or muscle illnesses, such as:

How is the test conducted?

Surface electrodes are adhesive patches applied on the skin over nerves or muscles at various locations. To stimulate the nerve, a very moderate electrical impulse is administered via additional patches or a portable stimulator.

The electrodes record the resultant electrical activity of the nerve. The total time it takes for electrical impulses to travel between electrodes and the distance between electrodes are used to calculate the speed of nerve messages. It is typical to test multiple different nerves.

EMG is a recording made from needles inserted into muscles. This is frequently performed concurrently with NCV.

What happens during the test?

It's possible that the impulse will feel like an electric shock. Depending on how powerful the impulse is, you may experience some discomfort. When the test is over, you should feel no discomfort.

EMG is frequently performed after the nerve conduction exam. A needle is inserted into the muscle and you are instructed to contract that muscle. Throughout the exam, this process might be unpleasant.

Following the test, you may have muscular discomfort or bruising at the place where the needle was inserted.

How to Prepare for the Test?

You must maintain your regular body temperature. Too much cold disrupts nerve conduction and can provide erroneous findings. Inform your doctor if you have a defibrillator, pacemaker, or any other implanted device, such as a deep brain stimulator. If you have one of these gadgets, you may need to take extra precautions before the test. On the day of the test, do not apply any lotions, sunscreen, perfume, or moisturiser to your skin.

Understanding Results

Normal Outcomes

NCV is proportional to the nerve's diameter and degree of myelination (the existence of a myelin coating on the axon). Newborns have levels that are around half of those of adults. Adult values are often attained by the age of three or four.
Normal value ranges may change slightly between laboratories. Discuss the significance of your individual test findings with your doctor.

Abnormal Findings

The most common cause of aberrant findings is nerve injury or destruction, which includes:

  • Axonopathy (damage to the long portion of the nerve cell)
  • Demyelination (damage and loss of the fatty coating around the nerve cell)
Several different disorders can cause nerve injury or destruction, including:
  • Diabetes
  • Uremia (from kidney failure)
  • Traumatic nerve injury
  • Guillain-Barré syndrome
  • Diphtheria
  • Carpal tunnel syndrome
  • Brachial plexopathy
  • Chronic inflammatory polyradiculoneuropathy
  • Primary amyloidosis
  • Secondary systemic amyloidosis

Frequently Asked Questions

1. What is nerve conduction velocity (NCV)?

Nerve conduction velocity (NCV) is a medical test that measures how fast an electrical impulse travels through your nerves. It is used to evaluate nerve damage and nerve-related disorders.

2. How is nerve conduction velocity measured?

NCV is measured by placing electrodes on the skin over the nerve being tested. A small electric shock is then applied to the nerve, and the resulting electrical activity is recorded by the electrodes. The speed of the electrical impulse is then calculated based on the distance between the electrodes and the time it takes for the electrical activity to travel between them.

3. What is normal nerve conduction velocity?

Normal NCV values can vary depending on the nerve being tested and the individual being tested. Generally, a normal NCV value is considered to be between 50 and 60 meters per second (m/s) for sensory nerves and between 40 and 50 m/s for motor nerves.

4. What are some conditions that can affect nerve conduction velocity?

NCV can be affected by a number of conditions, including nerve damage, nerve compression, autoimmune disorders, and genetic disorders. Some examples of conditions that can affect NCV include carpal tunnel syndrome, and Guillain-Barre syndrome.

5. What are the risks of nerve conduction velocity testing?

NCV testing is generally considered safe, but there is a small risk of infection at the site where the electrodes are placed. Some people may also experience mild discomfort or pain during the test.

6. How long does a nerve conduction velocity test take?

The test typically takes between 30 minutes to an hour, depending on how many nerves are being tested.

7. Is nerve conduction velocity testing painful?

NCV testing may cause some discomfort or mild pain, as the electric shock that stimulates the nerve can feel like a mild electrical jolt. However, the discomfort should be brief and generally subsides quickly once the test ends.

8. Can nerve conduction velocity testing diagnose nerve damage?

NCV testing can help diagnose nerve damage or nerve-related disorders, but it is not always definitive. Other tests, such as electromyography (EMG) or imaging tests, may be necessary to confirm the diagnosis.

9. What is the cost of a nerve conduction velocity test?

The cost of the nerve conduction velocity test is Rs. 1500 to Rs. 3500. However, the cost can vary from place to place.

10. Where can I get a conduction velocity test?

You can get a conduction velocity test at Medicover Hospitals.