Benign Paroxysmal Positional Vertigo (BPPV). It is one of the most common causes of vertigo. It is characterized by brief intense spells of rotatory vertigo which usually precipitates during an abrupt change in head position. Vertigo occurs when the patient is getting out of bed, turning over in bed and when extending or flexing the neck. BPPV is predominated in females (2:1 female to male ratio).
Aetiology. Mostly it is idiopathic, and the incidence increases with advancing age. Known causes of BPPV are head trauma, ear infection, viral labyrinthitis, stapedectomy, prolonged bed rest, vestibular neuritis and Meniere’s disease. Dislodgement of otoconial debris from the utricle is the common feature in all of these causes.
Pathophysiology. Otoconia are crystals of calcium carbonate present on the macula of the utricle and saccule. In BPPV otoconial debris dislodges from degenerating macula of the utricle and floats freely in the semicircular canals (canalolithiasis). Otoconia most commonly enters in the posterior semicircular canal as compared to horizontal and anterior canals. Since otoconia have three times greater density than that of the endolymph, the cupula becomes sensitive to gravity. When otoconial debris sticks on the cupula of the posterior semicircular canal (cupulolithiasis) in a critical head position with respect to gravity, it results in an abnormal displacement of the cupula and stimulation of the corresponding vestibular afferents. This causes nystagmus and vertigo.