Have you ever experienced pain, numbness, or muscle weakness in any part of your body? Not everyone knows that these signs and symptoms could be due to a nerve injury. In these cases, patients are being referred to a nerve specialist (neurologist) for assessment.
The study of nerve injuries is not as easy as compared to other tests. The location of the damage is not always the same as to where the symptom is prominent. For example, a pain in your upper extremities could be due to a damage to the nerves on your cervical spine. It is at the neck level.
Our nerves are somewhat the same to an electrical wire with a protective covering. The axon, which is responsible for transmitting electrical impulses inside our body is covered with a myelin sheath. If the damaged part is just the covering, then healing should be fast and easy. But if it is the axon itself that is injured, recovery is less certain.
Good thing we now have special tests like nerve conduction studies to help us determine the patterns of a nerve injury. Most of the time, the severity of the condition would correlate with the level of nerve damage shown on these tests.
What is NCS?
Nerve Conduction Studies (NCS) is also known as Nerve Conduction Velocity (NCV). It assesses the speed of conduction of electrical impulses.
During the procedure, the nerve will be stimulated using two electrode patches placed on the surface of the skin. One of the electrodes will stimulate the nerve using a mild impulse and the other one will record it. The electrical activity would then be noted. The procedure is repeated for each nerve being examined.
The velocity or speed of the conduction is measured by checking the distance between the two electrodes and the time it took for the impulse to travel between them.
Sometimes, electromyography (EMG) is also done simultaneously with NCS. This measures electrical activities in the muscles. Both tests will help determine the origin and severity of the damage that affects either the nerves or the muscles, or both.
Risks Involved in NCS
There is nothing to worry about the voltage of the electrical pulses being used in NCS. They are very low and tolerable.
Risks involved in these tests may vary depending on your current medical condition. Make sure to discuss them with your physician.
There could be several factors that may interfere with the exam. The most common would include an injury to the spinal cord, changes in body temperature, and pain before the procedure.
If you have a pacemaker or defibrillator in your chest, special precautions may be required.
How to Prepare for NCS?
- All questions should be asked before the procedure
- No fasting or sedation is required
- Normal body temperature should be maintained as a decrease in its level will slow down conduction
- List down all the medications and supplements you are taking
- Wear comfortable clothes that will allow easy access to the areas to be examined
- Do not use oils or lotions a few days before the test
During the Test
NCS or NCV can be done on an outpatient basis. You may be required to stay in for a night at the hospital depending on your condition.
NCS is facilitated by a neurologist, who is a specialist in the brain and nerve diseases.
The test follows this process:
- Removal of any clothing, pieces of jewelry, and other accessories, especially metals, as it may interfere with the test
- Wearing a hospital gown
- Sitting or lying down comfortably for the procedure
- Location of the nerve/s to be examined by a neurologist
- Patching of electrodes on your skin. One is for recording.
- Stimulation of the nerves using a mild electric impulse. Some patients may feel uncomfortable for a few seconds at this stage.
- Recording of responses or electrical activities through a monitor in a form of waves (oscilloscope)
After the Test
- Paste used to patch the electrodes will be cleaned up
- Patients can return to their daily routine immediately after the test unless you are advised to do otherwise
- Additional instructions may be given depending on your condition
When Should You Get Yourself Tested?
NCS or NCV is normally performed together with EMG to differentiate whether the damage is originating from the nerves or the muscles.
Common conditions that can be evaluated through NCS are the following, but not limited to:
- Guillain-Barre Syndrome. Weakness or tingling sensation in the lower extremities. The body’s immune system is recognizing parts of the peripheral nervous system as foreign.
- Carpal Tunnel Syndrome. Pain and numbness in the fingers. The median nerve is being tightly pressed by a swollen ligament or tendon.
- Charcot Marie Tooth Disease. Weakness in the muscles of the lower extremities. A neurological disorder that affects both the motor and sensory nerves. This is hereditary.
- Herniated Disk Disease
- Sciatic Nerve Disorders
- Chronic Inflammatory Polyneuropathy and Neuropathy
- Pinched Nerves
NCS may also be requested to know the underlying cause of severe pain, numbness, and tingling sensation. You might also want to read:
- Spinal Tumor
- Rheumatic Fever