How long does vng testing take




















Savani, MD David L. Carswell, PsyD Shawn S. Pulaski, PsyD Carrie L. Roper, PsyD Jessica N. Videonystagmography VNG. VNG Preparation Your doctor has scheduled you for a test called videonystagmography. In order to achieve the best test results, you should carefully follow these instructions: Contact lenses should NOT be worn 3 days prior to testing or on the test day.

Glasses should be worn during the 3 days and during the test. Wearing flat or low heeled shoes is recommended. Please wash your face thoroughly. Avoid solid foods or milk for 2 to 4 hours before the test. Please do not have any coffee, tea, cola, or caffeine after midnight on the day of the test. You shouldn't take aspirin or medication containing aspirin for two days before the test. You shouldn't consume alcoholic beverages or liquid medication containing alcohol for two days before testing.

Clean both ears How to use ear drops, Murine or any ear wax removal system Patient should lie on one side of a couch or bed A few drops of the ear drop solution should be placed in the external canal of the ear enough to fill the canal. Place a cotton ball in the ear canal to seal it. Bedside testing is generally more sensitive than ENG versions of these tests too.

These are all done upright with the head chin stabilized against voluntary head movement. Typical devices used for to produce visual stimuli are computer driven projectors, an array of light emitting diodes, and laser spots. The computer projector is the worst of the three, but by far the most convenient. In a dimly lit room, all three work reasonably well.

Here patients look at a visual target for at least 10 seconds, and then simply look straight ahead in the dark for at least another 30 seconds.

While is very simple, the result of comparing fixation and complete darkness is very valuable and it can diagnose vestibular neuritis as well as a host of more unusual types of nystagmus. Patients look as far as they can to one side for 10 seconds, then return to the center for 10 seconds. Then they look to the other side for 10 seconds, and again return to the center. A sequence of spots displaced at roughly 4 second intervals is shown, and the patient asked to follow them.

Both horizontal and vertical displacements are usually used, although not interleaved. Random directions and timing is used to make the test unpredictable. Patients watch a bright spot that moves smoothly across a screen, at a selection of velocities and frequencies.

There are several methodologies here -- best of all is a laser galvanometer. However, computer projectors work reasonably well. We are unenthused about LED arrays used to generate this stimulus. The vibration test is done using similar methodology to the spontaneous nystagmus test, but entirely in the dark.

First one has the patient look straight ahead in the dark. Next one vibrates over the left neck. One then waits another 5 seconds, and switches to the other neck. There are then four segments to the recording - -dark, vibration left, dark, vibration right. This is an emerging test -- very useful!

These procedures can cause trouble because dizzy patients sometimes get dizzier when their inner ear is stimulated. If available, an anti-vomiting drug that doesn't affect ENG testing may be helpful.

Positional testing is generally much more sensitive at the bedside, but it is often done as part of the ENG anyway. The reason why the bedside is more sensitive, is because the clinician can see torsion. The ENG doesn't measure torsion, and usually the tiny little computer generated images shown on the ENG monitor are useless for torsion too. The goal of positional testing is first to detect positional nystagmus, and if there is positional nystagmus, to determine if it is due to the ear usually BPPV , brain central positional nystagmus , or neck cervical nystagmus.

There are several methods of doing this, but we will only document the methodology that we recommend:. The figure above illustrates the Dix-Hallpike test, which is the core positional test. In this test, a person is brought from sitting to a supine position, with the head turned 45 degrees to one side and extended about 20 degrees backward. One records for 30 seconds or until the nystagmus stops, and then returns the person to upright and records for 10 seconds or until the nystagmus stops.

Then one repeats the same process in the other direction. A positive Dix-Hallpike tests consists of a burst of nystagmus jumping of the eyes. The eyes jump upward as well as twist so that the top part of the eye jumps toward the down side. If there is horizontal nystagmus during the Dix-Hallpike, one should also do the supine roll test as well as the vertebral artery test.

The caloric test is the only part of the ENG that one can't do often better at the bedside. One should do a very good job on this critical procedure! It takes a very long time, it is messy, and patients usually are unenthused about them. So, there is temptation to cut corners, but it is a terrible idea! We recommend doing the test with water as long as the ear drums are not perforated , and doing at least 4 irrigations, in this order, with the start of each always at least 10 minutes from the previous start.

The reason for this order others are possible is so that each irrigation does not "add" to the previous irrigation. If one were to, lets say, follow cold-right with warm left, and perhaps were a bit rushed and didn't wait for 10 minutes, the two irrigations might add.

Another problem is that the "reversal" phase of a caloric irrigation might add on to the next one. The technician is verifying that small calcium carbonate particles called otoconia are not suspended in the fluid and causing a disturbance to the flow of the fluid. Caloric Testing The technician will stimulate both of your inner ears one at a time with warm and then cold air.

They will be monitoring the movements of your eyes using goggles to make sure that both of your ears can sense this stimulation. This test will confirm that your vestibular system for each ear is working and responding to stimulation. This test in the only test available that can decipher between a unilateral and bilateral loss. Follow us Facebook Twitter YouTube. Employee Portal. Blaine Clinic st Ave.



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