Nerve Conduction Study

This tests the peripheral nervous system of the arms and legs by evaluating the motor fibers. Motor NCV tests are performed using adhesive surface electrodes to record the compound action potentials generated following stimulation with electric current (a very short duration pulse about 0.1 ms) at two or more points of the main trunk of the motor nerve and recording the latencies at a distal muscle supplied by the nerve.

Also evaluates the peripheral nervous system of the arms and legs. The sensory fibers and the conduction of the sensory nerves are evaluated using the same surface electrodes of the Motor NCV in differing montages to record the sensory nerve potentials after stimulation by an even shorter duration pulse (0.05 ms) of electric current at a region of the sensory nerve. The recording can be done either orthodromically or antidromically to best evaluate the nerve being studied.

Needle Electromyography Study

Electromyography (EMG) is a diagnostic procedure in which a small sterile, disposable needle electrode is placed in several select muscles to assess the health of muscles and the nerve cells that control them (motor neurons). EMG results can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission.

Motor neurons transmit electrical signals that cause muscles to contract. An EMG used tiny devices called electrodes to translate these signals into graphs, sounds or numerical values that are then interpreted by a specialist.

What does an EMG test for?

Your doctor may order an EMG if you have signs or symptoms that may indicate a nerve or muscle disorder. Such symptoms may include:

Tingling
Numbness
Numbness
Muscles pain or cramping
Certain types of limb pain

Most Common Disorders Test:

EMG results are often necessary to help diagnose or rule out a number of conditions such as:

Disorders that affected the nerve root, such as a herniated disc in the spine.
Disorders of nerves outside the spinal cord (peripheral nerves), such as carpal tunnel syndrome or peripheral neuropathies.
Diseases affecting the connection between the nerve and the muscle, such as myasthenia gravis.
Disorders that affect the motor neurons in the brain or spinal cord, such as amyotrophic lateral sclerosis or polio.
Muscle disorders, such as muscular dystrophy or polymyositis.

Preperation

Take a shower or bath before your exam in order to remove oils form your skin. DO NOT apply the following:

Oils
Lotions
Creams
Powders
Vaseline

DO NOT shave!

For an Upper Study: Wear an undershirt, camisole, tank top or short sleeve shirt.

For a Lower Study: Wear shorts, sweatpants, or pants that can easily be rolled to the knee.

What to Expect:

Before the procedure:

To prepare for the study, the neurologist will place surface electrodes at various locations on your skin depending on where you're experiencing symptoms. Or the neurologist may insert needle electrodes at different sites depending on your symptoms.

During the procedure:

When the study is underway, the surface electrodes will at time transmit a tiny electrical current that you may feel as a twinge or spasm. The needle electrode may cause discomfort or pain that usually ends shortly after the needle is removed.

After the procedure:

You may experience some temporary, minor bruising where the needle was inserted into your muscle. This bruising should fade within several days. If it persists, contact your primary care doctor.

Electrodiagnostic Services (NCV/Needle EMG)

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