Sensory Organization Performance
The SOP test is a functional test of your balance. You will be asked to remove your shoes, and complete a short series of balance tasks. Some involve closing your eyes, marching in place, or standing on a piece of thick foam. The Audiologist looks for patterns of sway or instability that help distinguish the cause of your balance problem, as well as the effect it may be having on your everyday activities.
Often considered the “gold standard” of balance testing, VNG assesses both the eyes and the ears. If a true inner ear problem is found, VNG can usually isolate which ear is the culprit. It also helps screen for other “central” causes of dizziness that may be related to the brain or neurologic function. You will wear a special pair of goggles that are equipped with video cameras, and the Audiologist will monitor your eye movement throughout the evaluation. Believe it or not, your eyes can give a lot of information about the function of your vestibular (balance) system. The test battery includes three sections:
- Oculomotor testing requires you to watch a series of moving lights that appear on a light bar mounted to the office wall. They may move up and down or side to side; the Audiologist will explain each subtest so you know what to watch. This portion of the battery is quite simple.
- Positional testing is completed to assess whether your body position affects your inner ear response. You will be asked to lie on your back, roll on your side, and lie with your head slightly extended backward.
- Caloric irrigations are certainly the most interesting of the VNG tests. You will lie on your back, somewhat inclined. The audiologist will run cool and warm water into your ears, which allows us to assess the function of one ear versus the other. It is the least comfortable part of testing, but it gives us the most valuable information. Some patients experience a sensation of floating or tilting as a result of having the water in the ears, but some patients feel nothing at all. If the calorics do make you feel strange, the sensation will only last for a few minutes at a time, and it is a perfectly natural reaction to the procedure.
Once the balance testing is completed, the Audiologist is usually able to discuss the results right away. Some test findings require more in-depth analysis, and you may have to wait to discuss the results during your follow up visit with the Otolaryngologist. That ENT visit is also an opportunity for you to receive further clarification about your test findings, learn more about your treatment options, and ask questions you may have forgotten to ask your Audiologist on the day of testing.
What causes dizziness and balance problems?
To understand all the things that could possibly go wrong with the balance system, it is important to understand how your balance works in the first place. The brain depends on three systems in your body to maintain your balance and keep you upright:
- The inner ear contains a hearing organ and a balance organ. The balance portion is a tiny motion detector that senses movement as well as gravity. Any time you move, your ears know which way you moved, how fast you moved, when you started, and when you stopped. All of this information is then sent to the brain.
- The eyes also make a large contribution. You have to be able to see clearly, for one thing. Second, your eyes help your brain distinguish vertical from horizontal. And third, your eyes must be able to make very quick, controlled movements in order to keep up with moving objects in your environment.
- Somatosensation and proprioception are big words that simply refer to your body’s sense of space. This encompasses your weight distribution, gravity, and the muscle tension from all of your joints.
Your brain needs input from the inner ear, the eyes, and your somatosensory system in order to stay balanced. However, these three systems also have to communicate amongst themselves, and they must be in agreement when they send signals to the brain. If any one system becomes weak or impaired, the brain has a difficult time interpreting the resulting signal. That’s when you feel dizzy or off-balance.
INNER EAR CAUSES OF DIZZINESS
Benign Paroxysmal Positioning Vertigo (BPPV)
Also known simply as Positional Vertigo, BPPV is the most common cause of dizziness in people over the age of 65. Within the balance organ, there are tiny crystals or “ear rocks” that help us sense motion and gravity. On occasion, these crystals pop loose from where they belong and migrate into a different part of the balance organ. Most cases of BPPV are idiopathic, meaning that it happened at random, but we can also see BPPV when a head injury jars the crystals loose, or as a result of vestibular neuritis (see below). BPPV causes movement-induced vertigo, and the most common complaint is of dizziness when rolling over in bed. Other problem movements are bending over, looking up, or being reclined in a dentist’s chair or beauty salon shampoo sink. Fortunately, BPPV is very easy to diagnose, and most cases can be treated with a quick and simple in-office procedure.
Vestibular Utilization Deficits
The inner ear (vestibular system) is a use-it-or-lose-it mechanism. Because it is a motion detector, the only way to keep it strong is by giving it lots of motion input to respond to. Most Americans become rather restricted in their movement starting in their third or fourth decade; we spend the majority of our day either sitting down or walking in a straight line. Think back to when you were a child, doing somersaults and cartwheels, swinging on a swing set, or rolling on the floor while wrestling with your siblings. Odds are that the mere thought of doing those things now makes your head spin. After decades of avoiding such movements, the brain can start to ignore any signal coming from the vestibular system. Patients with vestibular utilization deficits find themselves using walls or nearby objects for support while walking, and they tend to have more trouble walking in the dark or on soft surfaces like grass or carpet. While these symptoms can also be caused by an actual inner ear weakness, they are often simply a result of a sedentary American lifestyle. Fortunately, there is a form of physical therapy called vestibular rehabilitation that has proven extremely effective in remedying the problem.
Vestibular neuritis is a condition in which the vestibular nerve, leading from the inner ear to the brain, becomes inflamed and no longer transmits signals properly. The onset of symptoms is usually quite sudden, and includes whirling vertigo (room spinning) that can last for several hours. The spinning is often accompanied by nausea and vomiting, and gets worse with head or body movements. Symptoms gradually improve over a few days or weeks, and most people recover completely within about six weeks. Those who still have lingering symptoms may be candidates for vestibular rehabilitation.
Labyrinthitis is an infection of the inner ear itself (often referred to as the labyrinth). Symptoms are abrupt in onset and include whirling vertigo, as well as nausea and vomiting. What sets labyrinthitis apart from vestibular neuritis is that the patient also experiences a sudden significant hearing loss in one ear. Balance symptoms do improve over time, but vestibular rehabilitation is recommended for patients who do not completely recover from the dizziness. Unfortunately, the hearing loss usually remains, and some patients may benefit from using a hearing aid.
Named for a French physician, Meniere’s isn’t so much a disease as it is a compilation of symptoms. The trademark signs of Meniere’s are:
- Episodes of violent whirling vertigo that last from a few hours to a few days
- Fluctuating hearing loss that worsens when the vertigo occurs, affects low frequency (bass pitch) hearing more than high frequencies (treble pitches), and is typically in one ear only
- Tinnitus (ear noise) that usually sounds like roaring or rushing water
- A feeling of fullness in the affected ear
The underlying cause is still being debated, but it is agreed that symptoms occur when the inner ear becomes over-filled with its own natural fluid, a process known as endolymphatic hydrops. This increased pressure causes a delicate inner ear membrane to rupture, much like a water balloon springing a leak. There are numerous treatments for Meniere’s disease, including diet restrictions, medication, surgical procedures, and vestibular rehabilitation. After proper diagnosis and a thorough review of medical history, the Otolaryngologist (ENT) will help determine which treatment method will be most effective. The hearing loss can sometimes be addressed by wearing a hearing aid on the affected ear.