If you're suffering from dizziness or imbalance, your doctor may recommend vestibular testing.
Your response is probably, "What's that?"
Sharon Congdon, the technician who performs vestibular testing at Houston Methodist, likens it somewhat to an X-ray. Though not as common, vestibular testing is a standard diagnostic tool that can help give your doctor a better idea what's going on inside your body — your inner ear, specifically.
Your inner ear isn't only important for hearing. Believe it or not, it plays a crucial role in helping you keep your balance.
"We have a cool system in our inner ears," says Congdon. "Each ear contains a little gyroscope that senses rotational and linear movement. When one side isn't working properly, it can affect a person's spacial orientation and balance."
Hence, the dizziness and lack of balance that can result. But these symptoms aren't always due to inner ear issues. The potential culprits can also be related to vision, the brain, heart, medications you're taking and more.
"Vestibular testing is one of the steps in determining whether the issue is really in your inner ear," says Congdon. "It's a piece of the puzzle that can help your doctor come up with the right diagnosis."
What is vestibular testing?
Vestibular testing is a series of tests that evaluate whether the balance organs in the inner ear are functioning properly.
"For instance, the tests can help identify if you have a weakness in your right inner ear that's causing dizziness or making you feel off balance and leading to falls," explains Congdon.
Or that there's no issue in your inner ears at all.
"There's actually no direct way to measure inner ear function," says Congdon. "Instead, we take advantage of a specific reflex in the brain that links inner ear function and eye movements. The eyes essentially become my window into the inner ear."
The major components of vestibular testing include:
- Videonystagmography (VNG) – uses goggles to track eye movement as certain tasks and tests are performed
- Vestibular evoked myogenic potentials (VEMP) – uses electrodes and sound stimulus to measure a response that travels from the neck muscles to the inner ear
"Each of these larger tests are made up of a lot of little tests," says Congdon. "The testing is extensive and fairly long, taking between 1.5 to 2 hours to complete."
How is vestibular testing done?
Each component of the testing comes with specifics, but Congdon offers a few examples of what to expect during vestibular testing.
"During VNG, one thing we look for is nystagmus, a specific eye movement that relates the eyes and inner ear fluid together," explains Congdon. "When the inner ear is stimulated in a certain way, this fluid and the eye should move the same."
Applying cold or hot air to the inner ear is one such stimulus. As inner ear fluid responds to this air, the eye should also move in response, causing a temporary nystagmus recorded by the goggles.
"With VEMP, we're checking a pathway that runs from the neck muscles to a balance organ in the inner ear that's sensitive to sound," explains Congdon. "Using earphones, we apply different sounds and record how muscles in the neck respond as another indirect measure of inner ear function."
For the most part, vestibular testing follows a fairly standard testing protocol and the technician is assessing the results in real-time.
"If the results are looking normal, we simply move through the tests," says Congdon. "If not, there are more sophisticated tests I can use to dig deeper, like rotary chair testing."
Most of the basic tests performed during vestibular testing stimulate the inner ear at fairly low frequencies. This is sometimes all that's needed to evaluate inner ear function, but not always. Congdon says rotary chair testing is helpful because it stimulates the inner ear at higher frequencies.
"When we move our head around, we move it at some pretty high frequencies," says Congdon. "By adding rotational chair testing, I'm able to measure responses more broadly."
For instance, measuring eye movement while rotating a person in a chair can inform Congdon about how fast their eyes are moving, how quickly their eyes are able to catch up and the shape of their eye movement.
"Rotary chair testing is a unique test that provides the doctor with more information about how the inner ear is functioning," adds Congdon. "This can give them a better sense of what the problem might be."
What happens after vestibular testing?
At the end of testing, the technician compiles the results for your doctor who then reads and summarizes the findings.
"The patient doesn't walk out with their results, but, here at Houston Methodist, we typically schedule the patient to go over the results with their doctor right after testing," says Congdon. "The doctor will share the results and use them to come up with a diagnosis and treatment plan at this time."
The most common balance disorders diagnosed include:
- Benign paroxysmal positional vertigo (BPPV)
- Vestibular migraine
- Ménière's disease
But there are many others. Additionally, dizziness and imbalance can be caused by things other than issues within the inner ear. In these cases, other tests may be needed, such as imaging and blood tests.