The cause for reduced mobility, pain, numbness and tingling of the hands and feet can be challenging to understand, but in some cases, it can be because there is damage to the peripheral nervous system. Gauging if there is damage to a nerve requires the use of a special diagnostics test, which is known as the nerve conduction velocity test.
A nerve conduction velocity (NVC) test is utilized to gauge nerve damage and dysfunction. An NVC test essentially measures electrical signals that move through the peripheral nervous system. This system consists of the motor and sensory nerves that connect the human brain and spinal cord to the body. Nerves within the peripheral nervous system are sensitive and can become easily damaged. Peripheral nerve damage can occur for a number of reasons, including a sports injury and medical conditions, such as diabetes. When something is wrong with them, the functionality of an individual’s sensations, movements and motor coordination can be negatively affected. When peripheral nerves are healthy, they send electrical signals quicker and with greater strength.
During an NCV test, two electrode patches are attached to the skin to stimulate the affected nerve. These electrodes are placed on the skin of the affected nerve. One of the electrodes will stimulate the peripheral nerve with mild electrical stimulation while the other electrode records the electrical activity. This process is repeated for each nerve that needs to be tested. The test then measures the distance between the electrodes and the amount of time it takes for electrical impulses to travel between them, allowing the assessment of an individual’s nerve damage.
An NCV test is often combined with an electromyography (EMG) test, which evaluates the muscles. These two tests are combined to determine if it is nerve or muscle damage resulting in an individual’s reduced mobility or pain.
An NCV test is commonly used to diagnose muscular and neuromuscular disorders. Symptoms associated with these disorders and conditions often include numbness, tingling and continuous pain. If a pinched nerve is suspect, the test may be utilized. Trauma and muscle disorders may also warrant an NCV test.
Conditions that NCV is commonly used to diagnose include:
Guillain-Barré syndrome: This syndrome is characterized by the body’s immune system attacking the peripheral nervous system. Symptoms for Guillain-Barré syndrome include weakness and a tingling sensation in the legs.
Carpal tunnel syndrome: This condition causes pain and numbness in the hands and occurs when the nerve that runs between the forearm and hand, known as the median nerve, becomes squeezed by the wrist due to enlarged tendons or ligaments.
Cubital tunnel syndrome: Like Carpal tunnel syndrome, Cubital tunnel syndrome results when the ulnar nerve, which runs from the neck down to the hand, becomes compressed. Cubital tunnel syndrome results in numbness and tingling in the hands.
Charcot-Marie-Tooth (CMT) disease: This inherited neurological disease affects the motor and sensory nerves and causes weakness in the lower leg and foot.
Herniated disk disease: Herniated disk disease causes the fibrous cartilage surrounding the disks of the vertebrae to break down. When this happens, it results in pressure to the spinal nerve, resulting in pain and damage to the affected nerve.
Chronic inflammatory polyneuropathy and neuropathy: These conditions are the result of diabetes and alcoholism. Characteristics of chronic inflammatory polyneuropathy and neuropathy include numbness and tingling in a single nerve or several nerves at the same time.
Sciatic nerve problems: Many reasons can result in sciatic nerve problems. A common reason is when a ruptured spinal disk presses against the nerve roots that lead to the sciatic nerve, resulting in pain, numbness and tingling.
Before you undergo an NCV test at Orthopaedics Institute of Ohio, your physician will ask you questions regarding what medications you are prescribed, your medical history and certain behaviors you possess that might affect your test results. Questions may include your level of alcohol use, if you use muscle relaxants and if you have a condition such as diabetes. It is essential to let your physician know if you have a pacemaker because the electrodes used during an NCV test can potentially affect the electrical impulses of your medical device.
You should also avoid putting oils and lotions on your skin for several days before the test. Lotions and oils can potentially prevent the electrodes from attaching to your skin. You should also wear loose-fitting clothing, depending on where the NCV test is going to be performed. Additional preparation requests may be made by your physician based on your condition.
Your NCV test will begin with you removing certain clothing, jewelry, eyeglasses and any metal objects that may interfere with your test. You will then be asked to sit or lie down before the test begins. When you are comfortable, your physician will locate the nerve that needs to be studied. When located, they will attach the recording and stimulating electrodes using a special paste. Your physician will determine the length between these two electrodes.
The stimulating electrode will then release brief electrical pulses, which may cause minor discomfort for a few seconds. How your nerve responds to the stimulation will be displayed on a monitor. An NCV test typically lasts 20 to 30 minutes when performed on one limb. If it is performed on all limbs, it can take up to one hour.
When the test is complete, your physician will review your results and provide you with a diagnosis or recommend additional testing. A normal NCV is between the range of 50 to 60 meters per second. A velocity outside of this range suggests that a nerve is damaged or diseased. However, the test does not determine the causes of this damage. While there is no single path to repair a damaged nerve, a treatment plan will be developed to help improve your condition.
An NCV test is a test commonly performed to diagnose conditions that result in numbness, tingling and pain. If you are experiencing these symptoms or are concerned you may have one of the conditions or diseases mentioned above, please contact Orthopaedic Institute of Ohio in Lima, OH, to learn more about the NCV test. We can be reached at 419-222-6622 or by visiting our contact page.