Visual Evoked Potential (VEP) Test

VEP is a procedure where electrical activity of occipital area of brain is recorded by electrode after visual stimuli. It is a simple test taking approx 40 mints. This is a test to determine the integrity of the nerve transmission from the eye to the brain.

When is the VEP used?

A doctor may recommend that you go for a VEP test when you are experiencing changes in your vision that can be due to problems along the visual pathway. For example:

- Loss of vision
- Blurred vision
- Alterations in colour vision
- Weakness of the eyes, arms or legs (suspicion of multiple sclerosis)

What does the VEP detect?

Stimuli used is either a checkerboard pattern or a LED goggle. Signals are recorded from posterior aspect of scalp. Abnormality in waveform detects even subtle abnormality in optic pathway.

The VEP measures the time that it takes for a visual stimulus to travel from the eye to the occipital cortex. It can give the doctor an idea of whether the nerve pathways are abnormal in any way. For example, in multiple sclerosis, the insulating layer around nerve cells in the brain and spinal cord (known as the myelin sheath) can be affected. This means that it takes a longer time for electrical signals to be conducted from the eyes, resulting in an abnormal VEP.

How to prepare for a VEP test?

You will be given instructions on how to prepare for the test. This will depend on where you are going to get the test done. Some things that you may need to do include:

- Washing your hair the night before, but avoiding hair chemicals, oils and lotions.
- Making sure you get plenty of sleep the night before.
- If you wear glasses, make sure you bring these along with you to the test.
- You are usually able to eat a normal meal and take your usual medications prior to the test.
- However any medications that may make you drowsy should be avoided.
- Arrive on time and try to relax before the test.
- On the day of the test, you should also let the technician know if you have any eye conditions such as cataracts or glaucoma as this can affect the test and should be noted in your records by the doctor.

Side Effects

None noted. After the procedure is done, patients normally return home on the same day. You should be able to drive home safely if you are feeling well after the procedure.

Brainstem Auditory Evoked Potential (BAEP) Test

A BAEP is an evoked potential caused by a sound, usually a series of ‘clicks’. Electrodes positioned on the scalp record responses to the sounds; these are then observed as a reading on an EEG. Responses to sound originate from relay structures within the brainstem.

When is the BAEP used?

A doctor may recommend you go for a BAEP test if you have been experiencing changes in your hearing ability that may be due to problems with a particular nerve pathway. The changes in your hearing may not be complete hearing loss and may not be the same in both ears.

What does the BAEP detect?

From the readings the neurologist can get an idea whether the auditory nerve is functioning properly or not. For example, an acoustic neuroma (a benign tumour of the ear canal) can stretch or compress the auditory nerve resulting in a long time for the processing of aural stimuli.

How to prepare for a BAEP test?

- Wash your hair the night before.
- Eat a normal meal and taking your normal medication on the day of the test should be fine.
- You should let the person conducting the test know if you use a hearing aid or have any obvious hearing problems. The BAEP testing procedure is painless and without side-effects.
- BAEPs can be helpful in the diagnosis of: Hearing loss, Acoustic neuroma, Multiple sclerosis, Sub arachnoid inflammation, Friedreich’s ataxia, hereditary cerebellar ataxia and B2 deficiency.

VEP & BAEP Test in Ahmedabad - Setu Neurology Clinic

Evoked Potentials, VEP & BAEP special tests only at Setu Neurology Clinic. Book appointment with Dr. Vishal Jogi, Neurologist in Ahmedabad.