What Is the Nerve Conduction Velocity Test?
A nerve conduction velocity test measures the velocity of electrical impulses as they travel through the nerves in the body. The neurologist can evaluate if any nerve injury has occurred, where it has happened, and to what extent based on the results produced after the test.
The area where the nerve root exits the spinal cord is the area where the peripheral nerves begin. These nerves allow one to regulate their muscles and detect their surroundings. Nerves that are healthy send electrical messages faster and with more strength than nerves that are injured.
The nerve conduction velocity test helps the doctor distinguish between a nerve fiber injury and a myelin sheath injury, which is the protective coating that surrounds the nerve. It can also assist the doctor in distinguishing between a neural disorder and a disorder in which the muscles have been damaged by a nerve injury. It is crucial to make these distinctions in order to get an accurate diagnosis and plan the patient's therapy.
How Is the Nerve Conduction Velocity Test Performed?
The nerve is stimulated electrically, and the electrical impulse which goes downstream from the stimulus is assessed in this test. Surface patch electrodes similar to those used in an electrocardiogram are commonly utilized, and they are put on the skin surface over the nerve in various areas. With a very small electrical impulse, one electrode activates the nerve. The other electrodes record the electrical activity that results due to nerve stimuli. Speed of impulse transmission is calculated using the distance between the electrodes and the time taken for electrical impulses to pass between electrodes.
Nerve disorders or increased stress on the nerve might cause a decrease in transmission speed. A nerve conduction velocity test is frequently performed in conjunction with an electromyography (EMG). Electromyography is used to rule out or discover muscle disorders that may be present as a result of muscular or neurological disease.
Why Is a Nerve Conduction Velocity Test Performed?
Numbness, burning sensations, or tingling are some of the symptoms that may trigger a health care expert to perform a nerve conduction velocity test. The nerve conduction velocity test can be used to diagnose actual nerve problems such as peripheral neuropathy and mononeuritis multiplex, as well as cases where nerves have been compressed mechanically. Because low body temperatures impair nerve conduction, a normal body temperature must be ensured for the nerve conduction velocity test.
The following conditions can be detected with a nerve conduction velocity test:
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Peripheral Neuropathies
Peripheral nerves transfer signals from the brain and spinal cord to the rest of the body and vice versa. People with injured peripheral nerves may experience numbness, weakness, and pain in their feet and hands. While these are the most usual places for symptoms to appear, they can also appear in other places. Symptoms can usually be improved with therapy, particularly if they are caused by underlying disorders like diabetes, autoimmune diseases, or vitamin deficiencies. Nerve conduction velocity testing can determine the amount of nerve fiber injury.
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Guillain-Barré Syndrome
Guillain-barré syndrome (GBS) is a type of autoimmune disease in which the immune system targets the peripheral nervous system. Tingling and weakness in the legs are the earliest indicators of this disorder. Although recovery from Guillain-barré syndrome is gradual, most patients recover completely. However, the most severe cases might result in paralysis and impairment. A nerve conduction velocity test can aid in the diagnosis of the Guillain-barré syndrome. Electrical signals along Guillain-barré syndrome affected nerves are slower than those on unaffected nerves.
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Herniated Disc Disorder
Difficulties with the discs between the vertebrae are referred to as herniated disc disease. The various bones that compose the spine are known as vertebrae. Herniated discs irritate adjacent nerves, resulting in numbness and weakness in the arms and legs. Herniated discs are found most commonly in the lumbar spine region, which is the lower back area, although they can also arise in the cervical spine or the neck.
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Carpal Tunnel Syndrome
The median nerve extending from the forearm to the hand becomes constricted at the wrist, resulting in carpal tunnel syndrome. Numbness, tingling, and discomfort in the finger and thumb that may radiate into the arm are all symptoms of carpal tunnel syndrome. Carpal tunnel syndrome can cause nerve damage and impair a person's ability to grasp or retain objects in the long run. A nerve conduction velocity test can assess nerve function in the median nerve and assist a clinician in deciding the best course of treatment for the disorder.
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Sciatica Nerve Issues
Sciatica is a disorder that affects the longest nerve in the human body, the sciatic nerve. The sciatic nerve extends from the lower back region to the hips, legs, buttocks, and foot on both sides. Herniated discs in the low back and low spine are frequently linked to sciatic nerve pain. Because discs in the lower spine and back fall out of place, they put pressure on the nerves around the disc, and sciatic nerve pain and herniated discs frequently occur together. Sciatic nerve discomfort travels down the legs from the lower back. Pain can range from minor to severe. A nerve conduction velocity test can be used to determine whether the sciatic nerve is compressed or damaged. It can also detect any nerve-related issues. Electromyography and nerve conduction velocity tests can both be used to figure out what is causing sciatic nerve pain.
How to Prepare Oneself for a Nerve Conduction Velocity Test?
One must maintain a healthy body temperature. Too much cold affects neurotransmission and might lead to erroneous outcomes. If the patient has a pacemaker, cardiac defibrillator, or any other implanted device, such as deep brain stimulation, inform the doctor. One may need to take extra precautions ahead of the test if they have one of these gadgets. On the day of the test, do not apply any moisturizer, lotions, perfume, or sunscreen to the skin.
How Does It Feel During a Nerve Conduction Velocity Test?
It is possible that the impulse will seem like an electrical shock. Depending on how powerful the impulse is, one may experience some discomfort. Once the test is completed, the patient should experience no discomfort. Electromyography is frequently performed after the nerve conduction velocity test. A needle is inserted into a muscle, and the patient is instructed to contract that muscle. During the test, this process might be quite unpleasant. After the test, the patient may experience muscle discomfort or bruising at the place of needle insertion.
What Are the Risks Involved With a Nerve Conduction Velocity Test?
The voltage utilized in nerve conduction velocity testing is extremely low, posing very little danger. However, any concerns in the patient's mind should be discussed with the doctor who is requesting the procedure. When doing a nerve conduction velocity test, people who have cardiac defibrillators or pacemakers may need to take extra measures. Additional factors that may alter test findings include pain prior to the operation and body temperature.
Conclusion:
Overall, a nerve conduction velocity study is a valuable tool for a neurologist to establish whether nerve damage has occurred and to diagnose a variety of disorders. The neurologist may also propose an electromyograph to determine whether only the nerves are impaired or whether the muscles are also impacted, depending on the circumstances. The procedure itself is short, painless, and minimally invasive.
