Electrodiagnosis

Electromyogram (EMG) & Nerve Conduction Study (NCS)

What is an electrodiagnostic study?

An electrodiagnostic study has two parts: the electromyogram (EMG) and the nerve conduction study (NCS). 

An electrodiagnostic study is used to evaluate if there is an injury or disease in the peripheral nervous system, which is comprised of all the nerves that branch from the central nervous system (CNS - the brain and the spinal cord). The peripheral nervous system represents the nerves that travel to the arms, legs, torso and head.

Needle Electromyogram (EMG)

The needle electromyogram (EMG) uses a very small, thin needle that is inserted into muscles of the limbs and torso. This needle functions like a recording antenna to evaluate the electrical activity within the muscle, which gives information about the muscle itself as well as the nerve that services that muscle.

The electrical waveforms displayed on the electrodiagnostic instrument have characteristic appearances and sounds, which determine whether or not the nerves are functioning normally or whether there has been injury. The wave forms can also indicate whether the nerve injury is old or new or if the nerve injury is recovering, which helps with prognosis. The number of muscles studied with the EMG depends on the distribution of the abnormalities found.

Nerve Conduction Study (NCS)

The nerve conduction study (NCS) records how effectively electrical signals travel in nerves. A small shock is applied to a nerve and the electrical response is recorded from another location in that same nerve or from a muscle serviced by that nerve. The electrical recordings provide information about the health of the different parts of the nerve cells (neurons).

Several nerves are tested to allow for proper interpretation. When you prepare for your nerve conduction study it is important that you not apply skin cream the day of your NCS because doing so will make it very difficult for the recording electrodes to stick to your skin.

Boris Terebuh, MD

Dr. Terebuh’s interpretation expertise comes from his training, years of experience, and his certification from the American Board of Electrodiagnostic Medicine.

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Dr. Terebuh performs each EMG and NCS himself

After all of the electrodiagnostic data has been collected Dr. Terebuh will cross reference the pattern of the EMG irregularities and the NCS abnormalities with his knowledge of the neuromuscular system to determine a diagnosis.

Expertise is required to properly record and interpret electrodiagnostic information; otherwise incorrect conclusions can be made. Some physicians delegate the nerve conduction study to a technician; however, Dr. Terebuh himself performs both the EMG and NCS for each patient to ensure that all of the electrical information is recorded properly.