Electrodiagnosis and Electromyography (EMG) Nerve Conduction
Electromyography (EMG) and Nerve Conduction Studies (NCS) are oftentimes requested to determine if patient’s symptoms are secondary to a nerve problem. Symptoms such as pain, numbness and tingling, weakness or incoordination can all suggest a problem related to the nervous system. EMG/NCS examines the nerves of the Peripheral Nervous System (outside the brain and spinal cord). Most large nerves can be studies from the neck and back and down the limbs. Nerves give sensation/feeling and also give muscles their input to contract. When a nerve is compressed or damaged its response to stimulation and electrical activity as recorded on the needle exam will change. A skilled electromyographer can determine not only where the nerve is damaged but also how old the damage is and whether it is mild or more severe.
The exam takes between 20 minutes to an hour depending on the number of nerves examined. The NCS requires a small electrical stimulation be applied to the arm or leg much like a static shock. The response is recorded on the EMG equipment and will determine if the nerve is healthy or abnormal. The EMG is performed by inserting a small wire thru the skin into the muscle while the patient rests and then the patient gently contracts the muscle. The results of these 2 parts of the electrodiagnostic exam will determine if the nerve is damaged and if so where and how badly. The referring physician will use this information to decide the treatment of choice be it conservative care or surgery
There is some discomfort with the test but most patients have little if any difficulty completing the exam. The physician should explain what they are doing throughout the study and answer questions should they arise as this can lesson apprehension and fear. The stimulus can be slowly adjusted to avoid more uncomfortable “shocks” and there are needle exam techniques that can also lessen the discomfort. Most all patients indicate that it was not as bad as it sounds.
As the information obtained during the EMG can be critical in determining an accurate diagnosis when nerves are involved all efforts should be made to examine the areas where symptoms are. However the costs of the exam increase with each NCS so prudent use of the studies is also called for. If interested in our flat fee EMG service please contact us.