What it is
Dizziness is an umbrella term for any number of sensations related to balance and spatial orientation. It includes lightheadedness and blacking out as well as feeling disoriented, weak, or unbalanced. Dizziness can also include a spinning sensation even when you are still as well as other unusual sensations.
The inner ear consists of two parts: hearing and balance. The balance system, also known as the vestibular system, is comprised of three canals (Horizontal, Superior, Posterior), set in different planes. Together, these balance canals keep track of every rotational movement of your head, sending signals through the vestibular nerve to the brain. The vestibular system allows you to turn your head and keep your balance.
Also within this system are two small compartments called maculae (Saccule, Utricle). The maculae contain sensory cells and tiny calcium crystals in a gelatinous matrix that sense linear head movements and gravity. If these crystals become dislodged, floating freely within the vestibular system, it disrupts your sense of balance, causing a condition called benign paroxysmal positional vertigo, or BPPV.
Types of balance issues
Maintaining your balance requires the coordination of several systems: the inner ears to sense your head movements, the eyes to see the world around you, and proprioception, or the ability to sense your feet on the ground. To function properly, proprioception must receive nerve impulses from your muscles and joints in the limbs, neck and spine, which enable you to sense your orientation in space. If any one of these three parts of the system develops a weakness (eyes, ears, or proprioception), you may feel dizzy or unsteady on your feet, or more precisely, you experience imbalance.
When more than one area weakens, the symptoms may be more pronounced. Motion sickness, for example, results from a problem with the brain integrating the signals coming from the eyes with those of the inner ear.
Like presbycusis (the loss of hearing as we age), presbystasis is the loss of balance as we age. It results from the loss of the sensory cells in the vestibular system of the inner ear. The severity of this loss, when combined with loss of vision or neuropathy or other issues of the balance system, can worsen. Balance exercises, however, can help delay or lessen the impact of age-related loss of balance and are recommended for individuals of any age.
That wooziness you get if you stand up too quickly or you blow up too many balloons and leaves you feeling lightheaded can be caused by many conditions. Low blood pressure brought on by antihypertensive medications is the most common. Along with aging, other causes of lightheadedness include low blood sugar, heart arrhythmias and migraine headaches. Lightheadedness can sometimes lead to blacking out (syncope).
Among the less common causes of lightheadedness are head injury, stroke, tumors and multiple sclerosis. It’s essential to identify the cause of your lightheadedness so that you receive the proper treatment.
The sensation of spinning when you know that you and your surroundings are still is called vertigo. Most often this can be described as seeing the world spin around you, as if you are on a Merry-Go-Round. It is commonly caused by an inner ear problem, including such conditions as Ménière’s syndrome, labyrinthitis, positional vertigo, and vestibular neuritis. Migraines are another possible source of vertigo as are rare cases of tumors of the inner ear nerves. Tinnitus and hearing loss often accompany inner ear sources of vertigo.
How it is diagnosed
After completing a medical history and physical exam, your physician will perform additional tests to identify the cause of your dizziness in order to put together an appropriate plan for treatment. You will most likely have a hearing test to assess the current status of your ears along with balance tests. Imaging tests (CT or MRI) and blood tests are also sometimes needed.
Videonystagmography (VNG) is the most common balance test for dizziness. The function level of the inner ear is determined by examining the reflex arc between the ears and the eyes. This is done by monitoring eye movements after placing different temperatures of air into the ear canal, causing a brief sensation of dizziness. Vestibular Evoked Myogenic Potentials (VEMP) and rotary chair testing are other possible tests that could be performed to measure the inner ear’s function that also use reflex pathways.
*Refer to Audiology Testing page for more information.