Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 80. Dizziness and Vertigo

Topics: Introduction | Vertigo | Motion Sickness | Benign Paroxysmal Positional Vertigo

Benign Paroxysmal Positional Vertigo

Benign paroxysmal positional vertigo is a common disorder in which vertigo is due to a change in head position.

A change in head position--typically occurring when a person lies down, gets up, turns over in bed, or tips the head backward to look up--triggers most episodes of this disorder. The disorder usually develops when calcium particles, which normally are distributed evenly in the three semicircular canals, form a sludge and clump together in one of the semicircular canals. (The semicircular canals are the part of the inner ear that helps with balance (see Section 19, Chapter 217).) Normally, when the head moves, the calcium particles stimulate nerve receptors (hair cells) inside the canals. These cells send the brain a signal indicating the direction of the head movement. When the particles form a free-floating clump in one area, the signal is exaggerated: It suggests to the brain that the head has moved more than it has. This information does not match that from the eyes, and the mismatch results in a brief episode of vertigo. Sludging can be caused by damage to the lining of the semicircular canals. Such damage may be caused by ear infections, injury, surgery, or blockage of an artery to the inner ear.

This type of vertigo can be frightening, but it is harmless. An episode of vertigo begins 5 to 10 seconds after the head moves and lasts less than a minute. Episodes usually subside on their own in weeks. Occasionally, they persist for months and can cause dehydration due to nausea and vomiting. No hearing loss or noise in the ears (tinnitus) occurs.

Avoiding the positions that cause vertigo can help. People can learn to perform the Epley maneuver, which separates the calcium particles and redistributes them through the semicircular canals. As a result, the particles can be absorbed, then form again, as normally occurs. In about 90 to 95% of people, this maneuver provides immediate relief without the use of drugs. In some people, the vertigo recurs, and the maneuver must be repeated.