Nerve conduction test measures the nerve conduction velocity, and checks the manner of electrical signal transmission in the individual nerves. Nerves, with the help of these electric impulses control the muscles in the body. These electrical impulses make muscles react in specific ways. Nerve or muscle disorder may cause abnormal muscle reaction. Nerve disorders like amyotrophic lateral sclerosis can be detected with this procedure. If there is nerve injury then it is possible to locate the actual size of the nerve damage.
NeedThe purpose behind nerve conduction studies is:
- To detect damage to peripheral nervous system including all the nerves leading away from the brain and spinal cord and small branches of those nerves
- To diagnose nerve disorders like carpal tunnel syndrome or Guillain- Barr syndrome
- To identify the locations of abnormal sensations like numbness, tingling, or pain
- Both EMG and nerve conduction studies diagnose the condition known as post polio syndrome that may develop years after a person has had a polio
Procedure If you have pacemaker, then inform your doctor beforehand. It is not necessary to restrict your foods or fluids before the test. You should not smoke 3 hours before the test. Wear lose fitting clothing to provide the access for the nerves and muscles. Many flat metal disc electrodes are attached to your skin with a tape or special paste. An electrode, which emits shock is placed lightly over the muscles supplied by nerves. The brief repeated pulses are administered to the nerve and the time taken for contraction of the muscle in response to the electrical pulse is recorded. The response speed is known as conduction velocity. For comparison, corresponding nerves of the other side of the body may be studied. Electrodes are removed after completing the study. Nerve conduction studies are performed before EMG test if both tests are being done at a time. Nerve conduction studies require 15 minutes to one hour or more. The time required for the test depends on the number of areas being tested.
Result Normal results for nerve conduction studies refer that the nerves transmit electrical impulses to the muscles or to the sensory nerves at regular speed (conduction velocities). Sensory nerves allows the brain to respond to the sensations such as pain, touch, temperature, and vibration. Different nerves have various conduction velocities. As the age increases there is decrease in the nerve conduction velocities. Abnormal results indicate that the nerve impulse transmission speed (conduction velocity) may be slower or faster than the normal one. The velocity decreases due to injury or nerve damage like carpal tunnel syndrome.
Consideration Nerve conduction test does not have any type of risk. There us hardly any possibility of infections as nothing is inserted into the skin. Voltage of electrical pulses are also kept low to minimize the risk of injury or permanent damage. There are variations in the result of the nerve conduction velocity as normally nerve conduction velocity decreases as the person grows older.
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