Benign Paroxysmal Positional Vertigo

There are two types of motion receptors in our inner ear; one mainly detects linear acceleration (straight) and the other detects angular acceleration (turning). The receptor for linear acceleration is structured so that there are small crystals (called otoliths or otoconia) that are embedded on a gelatinous material. These in turn rest on the tips of hair cells (cells that have little hairs protruding from their tips). As our body accelerates in a straight line, the mass or weight of the crystals causes the hair cells to be bent, sending an electrical signal to the brain that lets it know we are moving. The other type of receptor is placed within a semicircular canal. There are three canals that are oriented in different planes, each full of fluid. When motion occurs in the plane of one of the canals, it causes the fluid within that canal to shift. That fluid shift bends the hair cells within that canal, which signals the brain that we are turning. 

Inner ear balance system Occasionally the crystals get free from the gelatinous material and drift into one of the canals. No one knows why this happens, but it does seem to happen more commonly after severe illness or trauma. If motion occurs in the plane of the canal with the crystals, that semicircular canal will send a different signal to the brain than the semicircular canal in the other inner ear. When the brain receives this kind of mixed signal, it interprets it as motion (when there is none) and we feel vertigo. This kind of vertigo lasts a few seconds to a minute or two. Moving the head in a certain direction can bring it on. Over time the crystals either migrate out of the canal or are broken down; either way the condition is typically self-limited (meaning that it will resolve on its own without treatment). Someone who has BPPV once is at greater risk to have it happen again.

Maneuvers can be preformed that will move the crystals out of the canals. As a group these maneuvers are called “canalith repositioning procedures” (CRP). The most commonly use CRP is named after Dr. Epley, the neurologist who first developed them. Most otolaryngologist (ENT) physicians and many neurologists are able to do these maneuvers in their clinic. The maneuvers occasionally need to be preformed more than once. They are eventually effective over 90 percent of the time. It is also possible to do these at home if the problem returns.