Measuring Electrical Activity in the Body
Electrodiagnostic
examinations measure electrical activity generated by muscles and nerves. They
generally involve seeing how different parts of the body react to stimuli.
Depending on the patient’s condition, a UT
Southwestern physician might order one or more electrodiagnostic examinations
to determine how muscle or nerve damage might be contributing to symptoms such
as numbness, pain, or weakness. Some of the most commonly prescribed
electrodiagnostic tests include an EMG exam, a nerve conduction study, and an
evoked potential study.
Electrodiagnostic Services
Electrodiagnostic tests offered at UT
Southwestern include:
- Auditory
evoked potential (AEP): Auditory
signals are transmitted to the ears to detect hearing problems.
- Brainstem
auditory evoked response (BAER): Auditory
signals are transmitted to the ears to detect brain stem problems.
- Electroencephalography
(EEG): Electrodes (electrical
measuring devices) are attached to the scalp to measure brain functions.
- Electromyography
(EMG): Surface electrodes are
placed on the skin or tiny needle electrodes are inserted into muscle to
measure activity in the muscle.
- Electroretinogram
(ERG): Anesthetic drops are placed
in the eyes, and electrodes are used to detect a loss of cells in the retina.
- Nerve
conduction studies (NCS): Electrodes
are used to measure activity in the nerves.
- Somatosensory-evoked
potential (SEP): EEG
electrodes measure the brain’s response to a stimulus applied to the skin.
- Visual-evoked
potential (VEP): EEG
electrodes measure the brain’s response to a flash of light or a visual pattern.
Conditions We Treat
Electrodiagnostic
testing can help diagnose the following conditions:
Electrodiagnostic Testing: What to Expect
Most
electrodiagnostic testing is painless and quick. Patients having an
electromyographic (EMG) test might feel only brief and mild discomfort as the
physician inserts a tiny needle into various muscles. The needles are used only
to record electrical activity in the muscles and not to deliver any treatment.