A broad range of complaints falls under the categories of dizziness and vertigo.
Dizziness is a broad term that can include:
- a "swimming" sensation in the head
- a floating feeling
- double vision
- a feeling of "everything spinning in circles" or of whirling in space.
Vertigo implies the more specific sensations of either the body or its surroundings turning or the head swaying or revolving. The physical causes of these two symptoms are numerous: problems of the middle and inner ear, dental problems, infections, head injuries, drug effects, and disorders of the cardiovascular, neurologic, and central nervous systems.
Physical Causes of Dizziness and Vertigo
The ear is responsible for our sense of balance as well as hearing. The inner ear includes a structure called the labyrinth, which monitors the brain. When injury or infection disrupts the action of the labyrinth, vertigo may occur.
In Meniere's disease, a common disorder of the labyrinth in adults, excess fluid builds up and increases the pressure within the inner ear, causing vertigo and occasionally a ringing or other noise in the ear (called "tinnitus"). Labyrinthitis is an infection of this same region, often caused by a virus, sometimes associated with an upperrespiratory infection. This can produce severe vertigo, occasionally with some nausea and vomiting during the first episode. The individual may also experience a rapid flickering of the eyes (called nystagmus). Calcium crystals floating within the labyrinth can cause benign positional vertigo. In this condition, a shifting of position, such as rolling over in bed, can produce vertigo and nystagmus moments later, lasting no more than thirty seconds. Several kinds of ear infections, such as otitis media and mastoiditis, can cause vertigo but will additionally cause other distinguishing symptoms, such as drainage of fluid, fever, or redness of the eardrum. Dental problems, such as an abscessed tooth, malocclusion, or temporomandibular joint (TMJ) abnormalities, can also produce vertigo since the teeth are so closely aligned with the ear.
Any head injury can cause a cerebral concussion or a labyrinthine concussion, which may result in vertigo or a sense of feeling dazed, unsteady, or faint.
A number of cardiovascular and neurovascular diseases may affect a person's sense of balance. Hypertension, or high blood pressure, is often a symptomless disease. However, a swimming or woozy sensation may be the initial symptom that brings a patient into a physician's office for evaluation.
If dizziness and lightheadedness are experienced rising in the morning or when changing from a lying to upright position, postural orthostatic hypotension may be the cause. This is a problem of low blood pressure, producing poor circulation of blood through the body. Typically, when a person shifts positions, the blood vessels reflexively contract to maintain proper blood pressure. In hypotension, this mechanism fails to respond appropriately. Since the needed pressure is not maintained, the flow of blood to the brain is temporarily reduced, causing dizziness and even fainting. Diabetes, minor complications in pregnancy, or hardening of the arteries can cause postural hypotension. It can also be a side effect of antidepressant medication, major tranquilizers, and even medications prescribed for high blood pressure (hypertension).
The most serious vascular ailment, requiring immediate medical attention, is stroke. A stroke occurs when the blood supply to the brain is significantly altered, causing damage to the brain itself. Three types of vascular problems produce stroke: cerebral thrombosis, cerebral embolism, and cerebral hemorrhage. In thrombosis, some portion of an artery that supplies blood to the brain has reduced in size. A large deposit of fatty tissue in that portion allows blood to clot, causing a partial or complete blockage of the blood flow to the brain. An embolism occurs when a bit of blood clot or arteriosclerotic plaque from the heart or the wall of a large artery breaks off and travels to an artery within the brain, where it lodges and causes the stroke. In a cerebral hemorrhage, the artery leaks or bursts, causing blood to seep into the surrounding brain tissues.
A transient ischemic attack is usually caused by a small blood clot or piece of fatty tissue (embolus). While passing through the blood vessels in the brain, it briefly becomes lodged and reduces the blood flow through that area. These symptoms resemble those of stroke, but are temporary and do not cause serious harm, since the clot or embolus eventually is dislodged. Although emergency medical attention is not necessary, a transient ischemic attack does require medical evaluation and possible measures to prevent recurrence.
Dizziness alone is insufficient cause to fear stroke. However, if you experience one or more of the following symptoms, you should consult your physician: numbness and/or tingling in any part of the body, blurred vision, confusion, difficulty speaking, loss of movement in the arms or legs. These symptoms can also indicate a panic attack rather than stroke. If you have experienced such a reaction several times and your doctor finds no sign of a physical disorder, you should consider the possibility that some psychological disturbance is precipitating these symptoms.