Benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is characterized by positional vertigo (brief attacks of rotatory vertigo triggered by head position changes in the direction of gravity) and is the most common peripheral cause of vertigo. There are two types of BPPV pathophysiology: canalolithiasis and cupulolithiasis. In canalolithiasis, otoconial debris is detached from the otolithic membrane and floats freely within the endolymph of the canal. In cupulolithiasis, the otoconial debris released from the otolithic membrane settles on the cupula of the semicircular canal and the specific gravity of the cupula is increased. Consensus has been reached regarding three subtypes of BPPV: posterior-canal-type BPPV (canalolithiasis), lateral-canal-type BPPV (canalolithiasis) and lateral-canal-type BPPV (cupulolithiasis). In the interview-based medical examination of BPPV, questions regarding the characteristics of vertigo, triggered movement of vertigo, duration of vertigo and cochlear symptoms during vertigo attacks are important for the diagnosis of BPPV. The Dix-Hallpike test is a positioning nystagmus test used for diagnosis of posterior-canal-type BPPV. The head roll test is a positional nystagmus test used for diagnosis of lateral-canal-type BPPV. When the Dix-Hallpike test is repeated, positional nystagmus and the feeling of vertigo typically become weaker. This phenomenon is called BPPV fatigue. The effect of BPPV fatigue typically disappears within 30 min, at which point the Dix-Hallpike test again induces clear positional nystagmus even though BPPV fatigue had previously caused the positional nystagmus to disappear. For the treatment of BPPV, sequential head movements of patients can cause the otoconial debris in the semicircular canal to move to the utricle. This series of head movements is called the canalith repositioning procedure (CRP). The appropriate type of CRP depends on the semicircular canal in which the otoconial debris is located. The CRP for posterior-canal-type BPPV is called the Epley maneuver, and the CRP for lateral-canal-type BPPV is called the Gufoni maneuver. Including a time interval between each head position in the Epley maneuver reduces the immediate effect of the maneuver. This finding can inform the development of methods for reducing the effort exerted by doctors and the discomfort experienced by patients with posterior-canal-type BPPV during the Epley maneuver.