In the inner ear there are three semicircular canals. Three semicircular canals are located in areas that are mutually perpendicular to each other. At the base of each Semicircular canals, there is a widened portion which called ampula. In ampula there cupula, is a tool to detect the movement of fluid in semicircular canals as result of head movement. For example, when someone turned his head to the right, the fluid in the right canal semicircularis will be left, so Cupula will deflecting towards ampula. Deflection is translated in a signal goes to the brain so that the sensation arises head turned to the right. With the availability of particles or debris in Semicircular canals, will reduce or even create cupula deflection towards the head instead of the actual direction of motion. It gives a signal that is not in accordance with the direction of head movement, so that arise in the form of vertigo sensation.
There are two theories that explain the pathophysiology of BPPV, namely canalolithiasis theory and cupulolithiasis.
In 1962, Schuknecht submited cupulolithiasis theory to explain the pathophysiology of BPPV. cupulolithiasis is the presence of particles attached to the crista ampullaris cupula. Schuknecht found basophilic particles are attached on cupula through inspection photomicrography. With the availability of these particles then semicircular canals become more sensitive to gravity. This theory analogy as there is a heavy object attached to the top of a pole. Because heavy objects, so that the column position to be difficult to be maintained in a neutral position. The pole will be leading to the stick side of things. Therefore cupula difficult to return to a neutral position. Consequently arise nystagmus and dizziness (dizziness).
The theory presented by Epley in 1980. He said the symptoms of BPPV is caused by the presence of free moving particles (canalith repositioning) in semicircular canals. For example, if there are canalith in semicircular canals posterior. When the head in an upright sitting position, then canalith repositioning located at the lowest position in posterio semicircular canals. When head positioned to supinate position, position changes are as far as 90 °. After a few seconds, the attractive gravitational canalith repositioning to the lowest position. This causes endolymph in semicircular canals, avoid ampula, which results in deflection cupula. This cupula deflection caused some nystagmus. When the head is returned to the initial position, it would be opposite direction and there was nystagmus in the opposite direction.
This theory explains the availability of more latent time between changes in head position with the incidence of nystagmus. Parnes and McClure in 1991 strengthens this theory found a free particle in semicircular canals poster while performing the surgery canals.
f there is head trauma, for example, after concussion, otocania found on utriulus and sacculus are detached. Detached Otocania enter Semicircular canals as canalith. With canalith inside Semicircular canals will cause vertigo in BPPV. It is this underlying post-traumatic BPPV head.