Evoked Potential Testing
Auditory Evoked Potential testing (AEP testing) is used to determine if specific parts of the vestibular system are functioning properly. Evoked potentials, sometimes called evoked responses, record the amount of time the nerves take to respond to electrical and sound stimulations. The size of the response is measured as well. The test results can be useful in the diagnosis of Multiple Sclerosis (MS) and many other neurological disorders. They are commonly used to rule out or confirm the presence of disease or damage to the central nervous system.
When Auditory Evoked Potential Testing Is Used
The vestibular system, found in the inner ear, helps the body maintain balance and stability. When someone presents sudden or worsening difficulties with balance, Auditory Evoked Potential testing may be used to determine if the vestibular system is working properly. Using the results of the test, audiologists can see if there has been a “block” along the pathways that lead to the brain. Common “blocks” include tumors, infections, and degeneration to the nerve itself.
The central nervous system consists of the spinal cord and the brain. There are two sets of circuitries that travel through the spine to the brain: the first set sends signals to the brain, and the second sends signals from the brain. When certain types of symptoms begin to occur, an evoked potential study can be performed to measure the health of this circuitry, or the VIIIth nerve pathway.
Auditory Evoked Potential testing is also sometimes used to evaluate the hearing of infants.
How Auditory Evoked Potential Testing Works
During Auditory Evoked Potential testing, hearing is stimulated by listening to test tones through earphones. The responses from brain waves are recorded using electrodes, which are taped to the scalp and earlobes and connected to a computer. Testing can typically be completed in less than an hour, and no recovery period is necessary.
The audiologist will look at the time between the stimulation and the response, known as latency, which demonstrates the speed at which the nerves pass a signal. The records of latency are known as evoked potentials or responses. If they fall outside the normal range, the doctor will try to determine why. To interpret the results and diagnose a medical condition, the doctor may take into account the patient’s clinical history, a neurological examination, an MRI, and other pertinent clinical or laboratory information. Afterward, the doctor will discuss the results with the patient as well as any next steps, such as additional testing or a personalized treatment plan.