Diagnostic tests for vestibular disorders
When you are experiencing vertigo, dizziness, or balance problems it can be very challenging to get a diagnosis. Your vestibular system is complex, and includes the inner ear organs, nerves, and brain. Other body systems can influence your balance and contribute to symptoms of dizziness. Your symptoms and medical history plus a complete vestibular and neurological clinical examination are important when trying to determine the correct diagnosis.
Many people with vestibular symptoms are sent for additional testing. Your doctor may recommend tests of your inner ear hearing and balance function, neurological system (brain, spinal cord, and nerves), or cardiovascular system (heart and blood vessels). These tests can help confirm what is causing your symptoms.
Here are some common tests that may be performed when your doctor is investigating your problem. Read on to learn what each test evaluates and what the test involves.
Audiometry
This is a hearing test. Measuring your hearing is an important part of vestibular testing, as your inner ear is responsible for both hearing and balance. For this test, you sit in a soundproof room and wear headphones. You are asked to listen for sounds and words at different volumes and pitches. Usually the audiologist also checks your eardrum and middle ear using tympanometry - they first look into your ear with an otoscope, then place a small probe in your ear to measure pressure changes and eardrum movement.
VNG - Video-nystagmography
This is a set of tests that evaluates vestibular function by using video to measure eye movements. You wear goggles with video cameras in them, and a computer tracks your eye movements. You are asked to look at and follow different targets. You are also asked to lie down with your head in certain positions. Caloric testing is part of VNG - water or air of different temperatures is introduced into your ear canal which causes eye movement (nystagmus). ENG or electro-nystagmography is a similar test, but involves electrodes placed around your eyes.
vHIT - Video head impulse test
This test involves wearing goggles with a video camera, and a computer that tracks eye movements as your head is moved quickly through a small range of motion. This test evaluates the VOR - how your head and eye movements are coordinated - which is a key function of the vestibular system. vHIT tests the function of your semicircular canals.
Rotary chair
This test uses video goggles or electrodes to record eye movements while your head/body is turned side to side. In many vestibular test centres, rotary chair testing has been replaced by vHIT.
VEMP - Vestibular evoked myogenic potentials
This test involves electrodes placed on the skin around your eyes and on your neck. You are asked to listen to sounds through earphones, and the electrodes record the electrical activity in your muscles. VEMP testing evaluates the function of your otoliths - cVEMP tests the saccule and oVEMP tests the utricle.
ABR - Auditory brainstem response
This tests the function of the hearing pathways in your inner ear and brain. Electrodes are placed on your head to record brain responses as you listen to sound through earphones.
ECochG (ECog) - Electrocochleography
This test uses earphones and electrodes to measure electrical signals from your nervous system in response to sound. This test is often used if your doctor suspects changes in inner ear fluid pressure, called endolymphatic hydrops, which can occur in Meniere’s Disease, secondary/delayed endolymphatic hydrops, or superior semicircular canal dehiscence.
Computerized dynamic posturography
This is a test of your balance that measures body sway under different conditions. You are asked to stand on a pressure sensitive platform - sometimes with different foot positions, with eyes closed, on a foam pad, or with head movements. In some cases, the platform may shift or the visual environment may move.
MRI - Magnetic resonance imaging
MRI uses a magnetic field and radio waves to make images of body structures. If you are being investigated for dizziness, vertigo, or hearing loss this is most often done to evaluate your brain. Some people may also have imaging of their cervical spine (neck). This can show tumours (e.g. vestibular schwannoma), changes in the brain (e.g. from stroke or MS), or changes in other body tissues.
CT - Computerized tomography
CT scans use x-rays and computers to make images showing a cross section of your body. When looking at inner ear structures (for example to diagnose SSCD) this may involve a high resolution CT of the temporal bone (the part of the skull where the inner ear is located). CT may involve contrast, a special substance that highlights the area being scanned.
Blood tests
Depending on your symptoms or other health issues your doctor may order blood tests. These might look at blood sugar, thyroid function, iron levels, vitamin D levels, or vitamin B12 levels.
Cardiac testing
These tests evaluate your heart and circulatory system. You may be sent for these tests because changes in heart rhythm or blood pressure may cause or contribute to dizziness. Electrocardiogram records electrical signals from your heart. Echocardiogram uses ultrasound waves to look at blood flow through your heart. A Holter monitor is a wearable device that records your heart’s rhythm and electrical activity. Tilt table testing evaluates changes in heart rate or blood pressure with body posture.
EMG & nerve conduction studies
These tests measure electrical activity of your muscles and nerves. They may be ordered if there could be changes in sensation or strength in your legs or feet affecting your balance.
Your test results are interpreted, along with your pattern of symptoms and findings on your clinical examination, to help determine the cause of your problem. Vestibular function tests (like VNG, vHIT, VEMP, and ECochG) are typically completed by audiologists and require referral by a doctor. The most comprehensive testing is usually performed in hospital-based clinics like the Centre for Advanced Hearing and Balance Testing at Toronto General Hospital.
You do not need to have vestibular function tests before starting rehabilitation. Your physiotherapist’s complete clinical assessment usually provides enough information to understand what is causing your symptoms and how to help you feel better and get back to what matters most. As a part of your multidisciplinary team, your physiotherapist will communicate with your other health care providers and use test results to inform your vestibular rehabilitation treatment plan.
