Dizziness: Lightheadedness or Vertigo?
Your ears do more than just help you to hear. The Vestibular System is also useful for maintaining balance. Part of the inner ear contains three semi-circular canals. These are full of fluid that react whenever you move your head. As the fluid shifts within the canals, small cilia (or hair-like protuberances from a cell) are activated and send messages to the brain. These messages tell your brain which direction the body is moving.
You know that feeling of dizziness after you have been spinning around? Well, the fluid in your inner ears was also spinning. That made the cilia move in all different directions and briefly confused your brain. When a person has a vestibular disorder, disruptions somewhere within the inner ear structures or along the nerve or brain pathways may occur.
What is the difference?
Dizziness is often used to describe either lightheadedness or vertigo, so it is important to know the difference in symptoms to help narrow down the list of possible problems.
Vertigo is the illusion that you or your surroundings are moving (rotating, spinning, leaning, falling) without actual movement. Vertigo describes a symptom, but is not a final diagnosis. Severe vertigo can cause nausea or even lead to vomiting. You may physically lose your balance or even have trouble walking. Vertigo is not the same as motion sickness, though, as this feeling is not actually triggered by repeated motion. When patients present with vertigo, our goal is to find out why.
Lightheadedness is the sensation of almost fainting or passing out, but without the feeling that your surroundings are moving. It often disappears when you lie down. When lightheadedness gets worse, it can feel like almost fainting and may sometimes cause nausea to the point of vomiting. It is not uncommon for people to get a bit lightheaded, and it usually is not caused by an inner ear problem (i.e. it could be a momentary drop in blood pressure caused by getting up too quickly).
At Midwest ENT Centre, we work with patients who may be experiencing dizziness, imbalance or vertigo episodes. Depending on the patient’s symptoms, the doctor may request further assessment of the inner ear balance system, called the Vestibular System. One of the tests routinely performed by our audiologists here is Videonystagmography (VNG). What a mouthful!
What exactly is VNG testing all about?
VNG is composed of a series of tests used to determine the cause of a patient’s dizziness or balance problems, and whether or not it is due to inner ear disease. It is one of the only tests available today that can decipher between a unilateral (one ear) and bilateral (both ears) vestibular problem. If dizziness is not caused by the vestibular portion of the inner ear, it might be caused by the brain, by medical disorders such as low blood pressure, or by psychological problems such as anxiety. The list of possible causes of dizziness is long, but is made up of inner ear disorders, neurologic disorders, blood pressure/cardiac problems, reactions to medications, and by diabetes.
The test records nystagmus (quick eye jerks) using video imaging technology. There are neural connections between the balance mechanism in the inner ear and the muscles of the eye. A disorder of the balance system results in small eye jerks that are detected by a camera attached to a pair of infrared goggles the patient wears during a series of tasks. So you could say that the eyes are not only a “window into your soul” but also a “window into your vestibular system”!
Videonystagmography: what should I expect?
VNG testing is non-invasive, and only minor discomfort is felt by the patient as a result of wearing the goggles. A patient may also experience weakness, dizziness, or nausea during a VNG test, but this generally passes after a few minutes. If medically possible, patients are advised to abstain from food for four hours prior to the test, as a full stomach is more likely to cause discomfort or nausea. Some may feel as though they are going to fall down during testing, but we take special care to ensure this does not happen. The effects of the test are temporary and the level of discomfort depends on the underlying cause of the symptoms. In the event of prolonged dizziness, we recommend that patients arrange to have someone else drive them home.
There are 4 main parts to a VNG test:
- The saccade test evaluates rapid eye movements.
- The tracking test evaluates movement of the eyes as they follow a visual target.
- The positional test measures dizziness associated with changes in position of the head or body.
- The caloric test measures responses to warm and cold air circulated in the ear canals.
Because the hearing and balance functions of your inner ear are closely related, a hearing test will likely be administered as well. Appointments usually last about 60-90 minutes.
What is BPPV?
Here at Midwest ENT Centre, we assess and diagnose patients with many inner ear and balance disorders. One of the most common causes of dizziness in patients is called Benign Paroxysmal Positional Vertigo, or BPPV. It is present in about 20% of all dizzy patients, but is more likely found in older individuals. This is a condition caused by small calcium crystals floating in the fluids of the inner ear. When a person turns their head, the movement of fluids in the semi-circular canals send a signal to the brain, indicating direction. Loose crystals in the fluid disrupts normal responses, and are interpreted by the brain as dizziness or vertigo.
In addition to these, signs of BPPV can include lightheadedness, imbalance or unsteadiness, difficulty concentrating, and nausea. Although abrupt and sometimes frightening, these sensations usually last for only brief periods of time (usually 30-60 seconds), although unsteadiness may continue for longer.
Activities that bring on symptoms vary in each person, but are precipitated by changes in head position. Rolling over, getting out of bed, bending over, and tilting the head to look up are commonly associated movements with BPPV.
What can be done for BPPV?
During a visit to our clinic, the physician may order further testing of the inner ear balance system to determine the source of a person’s dizziness. As previously discussed, VNG testing may be used to determine whether a person has BPPV or another inner ear balance disorder. If signs and testing indicates BPPV, the physician may order a physical therapy maneuver, which can often quickly alleviate symptoms. The doctor may also recommend other specific exercises intended to reposition the floating crystals so that they are no longer interfering with normal inner ear functions. Physical therapy may also be necessary, to help in developing long-term strategies for patients with balance disorders.
Symptoms usually decrease over time as the inner ear system recovers and crystals are reabsorbed or return to their original placement. However, those who develop BPPV once are very likely to experience it again in the future.
What if my symptoms have improved: should I still go ahead and take the VNG test?
Yes! The VNG test is designed to determine the underlying cause of your dizziness and other symptoms. Although these may have gotten better, the doctor still needs to find what the cause of your initial symptoms were and how the balance system is recovering. BPPV is often characterized as having intermittent symptoms that decrease after a while, only to return again at a later time. Importantly, the VNG results may be able to tell how likely you are to experience another episode in the future.
Sources: The National Dizziness and Balance Center
Vestibular Function: Evaluation and Treatment (2004) Alan Desmond, AuD
Vestibular Disorders Association and American Speech-Language-Hearing Association