Besides aging, there are no major risk factors known for BPPV, although previous episodes of head trauma, or the inner ear infection labyrinthitis, may predispose to the future development of BPPV. Mechanism
The inside of the ear is composed of an organ called the vestibular labyrinth. The vestibular labyrinth includes three semicircular canals, which contain fluids and fine hairlike sensors that act as a monitor to the rotations of the head. An important structure in the inner ear includes the otolith organs that contain crystals that are sensitive to gravity. These crystals are responsible for sensitivity to head positions, and can also be dislocated, causing them to lodge inside one of the semicircular canals, which causes dizziness. Diagnosis
The condition is diagnosed by the persons history, and by performing the Dix–Hallpike test or the roll test, or both. The patient can also be asked to induce vertigo by performing a movement that the patient knows to induce vertigo. The eyes of the patient can then easily be observed for which kind ( horizontal, vertical, or diagonal ) of nystagmus is present, to determine which semicircular canal ( horizontal, superior, or posterior ) is affected. The Dix–Hallpike test is a common test performed by examiners to determine whether the posterior semicircular canal is involved. It involves a reorientation of the head to align the posterior semicircular canal (at its entrance to the ampulla) with the direction of gravity.
The examiner then quickly rotates the head 90° to the right side and checks again for vertigo and nystagmus. In this roll test, the person may experience vertigo and nystagmus on both sides, but rotating toward the affected side will trigger a more intense vertigo. Similarly, when the head is rotated toward the affected side, the nystagmus will beat toward the ground and be more intense.As mentioned above, both the Dix–Hallpike and roll test provoke the signs and symptoms in subjects with archetypal BPPV. The signs and symptoms people with BPPV experience are typically a short-lived vertigo and observed nystagmus. In some people, although rarely, vertigo can persist for years. Assessment of BPPV is best done by a medical health professional skilled in the management of dizziness disorders, commonly a physiotherapist, audiologist, or other physician.The nystagmus associated with BPPV has several important characteristics that differentiate it from other types of nystagmus. Latency of onset: there is a 5–10 second delay prior to onset of nystagmus
Nystagmus lasts for 5–60 seconds
Positional: the nystagmus occurs only in certain positions
Repeated stimulation, including via Dix–Hallpike maneuvers, cause the nystagmus to fatigue or disappear temporarily
Rotatory/torsional component is present, or (in the case of lateral canal involvement) the nystagmus beats in either a geotropic (toward the ground) or ageotropic (away from the ground) fashion
Visual fixation suppresses nystagmus due to BPPVAlthough rare, CNS disorders can sometimes present as BPPV.