About half the time, doctors can't find a specific cause for BPPV.

When a cause can be determined, BPPV is often associated with a minor to severe blow to your head. Less common causes of BPPV include disorders that damage your inner ear or, rarely, damage that occurs during ear surgery or during prolonged positioning on your back. BPPV also has been associated with migraines.

The ear's role

Inside your ear is a tiny organ called the vestibular labyrinth. It includes three loop-shaped structures (semicircular canals) that contain fluid and fine, hair-like sensors that monitor the rotation of your head.

Other structures (otolith organs) in your ear monitor movements of your head — up and down, right and left, back and forth — and your head's position related to gravity. These otolith organs — the utricle and saccule — contain crystals that make you sensitive to gravity.

For a variety of reasons, these crystals can become dislodged. When they become dislodged, they can move into one of the semicircular canals — especially while you're lying down. This causes the semicircular canal to become sensitive to head position changes it would normally not respond to. As a result, you feel dizzy.

Jul. 10, 2012

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