Benign Paroxysmal Positional Vertigo
Benign paroxysmal positional vertigo (BPPV) or "Benign paroxysmal vertigo" (BPV) is a condition caused by problems in the inner ear.
Within the labyrinth of the inner ear lie collections of calcium crystals known as otoconia. In patients, the otoconia are dislodged from their usual position within the utricle and they migrate over time into one of the semicircular canals (the posterior canal is most commonly affected due to its anatomical position). When the head is reoriented relative to gravity, the gravity-dependent movement of the heavier otoconial debris within the affected semicircular canal causes abnormal (pathological) fluid endolymph displacement and a resultant sensation of vertigo. This more common condition is known as canalithiasis.
In rare cases, the crystals themselves can adhere to a semicircular canal cupula rendering it heavier than the surrounding endolymph. Upon reorientation of the head relative to gravity, the cupula is weighted down by the dense particles thereby inducing an immediate and maintained excitation of semicircular canal afferents afferent nerve. This condition is termed cupulolithiasis.