What is an EMG?
Most people are familiar with CAT scans or MRIs. EMG tests are another diagnostic tool that are, perhaps, not as well known.
What Is An EMG/NCS?
EMGs and Nerve Conduction Studies (NCSs) are diagnostic procedures that are often done at the same time and are used to assess the health of the muscles and the nerve cells (motor neurons) that control them. Because motor neurons transmit electrical signals that cause muscles to contract, an EMG can record these and turn the signals into sounds, graphs, or numerical values to be interpreted.
During an EMG, a needled electrode is inserted into a muscle to record the electrical activity. The activity is recorded muscle during rest, slight contraction, and forceful contraction. This data used to help detect any neuromuscular abnormalities.
In a NCS, electrodes are taped to the skin and the speed and strength of signals between two points is measured. When a signal travels at a slower rate that it should, the nerve may be damaged.
Why Might Your Doctor Order An EMG/ NCS?
Typically, these tests are used to diagnose a nerve or muscle disorder, so a doctor may order them if he/she is looking for an explanation for the following:
- Tingling
- Numbness
- Muscle weakness
- Muscle pain or cramping
- Some types of limb pain
- Involuntary twitching
- Paralysis
What Are EMGs Used For?
They are used, in connection with other tests, to diagnose or rule out muscle disorders, nerve disorders, or disorders affecting the connection between the two, including:
- Muscular dystrophy
- Radiculopathies (when it involves motor fibers)
- Herniated discs
- Spinal stenosis
- Carpal tunnel syndrome
- Cubital tunnel syndrome
- Neuropathies
- Pinched nerves
- ALS
- Guillain-Barre syndrome
- Myasthenia gravis
- How well a patient is recovering from a nerve injury
While who is authorized to perform EMGs varies by state, EMGs/NCSs are typically performed by a specialist or a specially trained physician, usually a neurologist, qualified to interpret the data.
These posts are for informative purposes only and should not be used as a substitute for consultation with and diagnosis by a medical professional. If you are experiencing any of the symptoms described above and have yet to consult with a doctor, do not use this resource to self-diagnose. Please contact your doctor immediately and schedule an appointment to be evaluated for your symptoms.
References:
Mayoclinic.com
Webmd.com
Healthline.com
Providence.org
