What is Dizziness?

Dizziness can be described in many ways, such as feeling lightheaded, unsteady, giddy, or feeling a floating sensation. Vertigo is a specific type of dizziness experienced as an illusion of movement of one’s self or the environment. Some experience dizziness in the form of motion sickness, a nauseating feeling brought on by the motion of riding in a car, in an airplane, a roller coaster, or a boat. Dizziness, vertigo, and motion sickness all relate to the sense of balance and equilibrium.

Your sense of balance is maintained by a complex interaction of the following parts of the nervous system:

• The inner ear (also called the labyrinth), which monitors the directions of motion, such as turning, rolling, forward-backward, side-to-side, and up-and-down motions.
• The eyes, which monitor where the body is in space (i.e., upside down, right side up, etc.) and also directions of motion.
• The pressure receptors in the joints of the lower extremities and the spine, which tell what part of the body is down and touching the ground.
• The muscle and joint sensory receptors (also called proprioception) tell what parts of the body are moving.
• The central nervous system (the brain and spinal cord), which processes all the information from the four other systems to maintain balance and equilibrium.

The symptoms of motion sickness and dizziness appear when the central nervous system receives conflicting messages from the other four systems.

What causes dizziness?

Circulation: If your brain does not get enough blood flow, you feel lightheaded. Almost everyone has experienced this on occasion when standing up quickly from a lying-down position. But some people have lightheadedness from poor circulation on a frequent or chronic basis. This could be caused by arteriosclerosis or hardening of the arteries, and it is commonly seen in patients who have high blood pressure, diabetes, or high levels of blood fats (cholesterol). It is sometimes seen in patients with inadequate cardiac (heart) function, hypoglycemia (low blood sugar), or anemia (low iron).

Certain drugs also decrease the blood flow to the brain, especially stimulants such as nicotine and caffeine. Excess salt in the diet also leads to poor circulation. Sometimes circulation is impaired by spasms in the arteries caused by emotional stress, anxiety, and tension. Some drugs like drugs for high blood pressure have dizziness as a side effect.

If the inner ear fails to receive enough blood flow, the more specific type of dizziness vertigo occurs. The inner ear is very sensitive to minor alterations of blood flow and all of the causes mentioned for poor circulation to the brain also apply specifically to the inner ear.

Neurological diseases: A number of diseases of the nerves can affect balance, such as multiple sclerosis, syphilis, tumors, etc. These are uncommon causes, but your doctor may perform certain tests to evaluate these.

Anxiety: Anxiety can be a cause of dizziness and lightheadedness. Unconscious over breathing (hyperventilation) can be experienced as overt panic, or just mild dizziness with tingling in the hands, feet, or face. Instruction on correct breathing technique may be required.

Vertigo: An unpleasant sensation of the world rotating, usually associated with nausea and vomiting. Vertigo usually is due to an issue with the inner ear. The common causes of vertigo are (in order).

Benign Paroxysmal Positional Vertigo (BPPV): Vertigo is experienced after a change in head position such as lying down, turning in bed, looking up, or stooping. It lasts about 30 seconds and ceases when the head is still. It is due to a dislodged otololith crystal entering one of the semicircular balance canals. It can last for days, weeks, or months. The Epley "repositioning" treatment by an otolaryngologist is usually curative. BPPV is the commonest cause of dizziness after (even a mild) head injury or after an infection of the inner ear or labyrinth.

Meniere's disease: An inner ear disorder with attacks of vertigo (lasting hours), nausea, or vomiting, and tinnitus (loud noise) in the ear, which often feels blocked or full. There is usually a decrease in hearing as well. It can be treated with certain drugs or application of gentamycine or dexamethasone in the middle ear.

Migraine: Some individuals with a prior classical migraine headache history can experience vertigo attacks similar to Meniere's disease. Usually there is an accompanying headache, but can also occur without the headache.

Injury: A skull fracture that damages the inner ear produces a profound and incapacitating vertigo with nausea and hearing loss. The dizziness will last for several weeks and slowly improve as the other (normal) side takes over. BPPV sometimes occurs after head injury.