(A) Canalith repositioning procedure illustrated for treatment of the right posterior canal. 20 Vibration applied to the mastoid process of the involved side does not affect the outcome of the procedure and is no longer considered necessary. 21 To enable the otoconia to settle, each position is maintained for at least 30 seconds. This procedure requires a 180-degree turn of the head 19– 21 and a return to a sitting position from lying on the uninvolved side. With each position, the otoconia settle to the lowest part of the canal, move around the arc of the PC, and finally deposit in the vestibule. The clinician moves the patient through a series of 4 positions. 2A), was designed to use gravity to treat canalithiasis of the PC. The canalith repositioning procedure (CRP), developed by Epley 18 ( Fig. The patient alternated between left side lying and right side lying. The patient repeatedly moved from sitting at the edge of the bed to lying on the side (side lying) with the head rotated 45 degrees toward the ceiling. Historically, the first maneuvers used for BPPV were the Brandt-Daroff exercises, 10 which were designed to habituate symptoms. These maneuvers move otoconia out of the affected canal and back into the vestibule, where it is thought that the particles dissolve. Once the involved canal is identified, BPPV often is treated with particle repositioning maneuvers. 14 The interrater reliability for interpreting the direction of eye movement ranges from a mean percentage of agreement of 43% (fair) to a mean percentage of agreement of 81% (substantial), depending on the level of expertise. 13 For the DHT, the estimated sensitivity and specificity are 79% (95% confidence interval =65–94) and 75% (CI=33–100), respectively. 13 With repeated positioning, PC BPPV temporarily becomes less intense and disappears. 7, 8 The diagnostic criteria for PC BPPV are vertigo associated with characteristic ocular nystagmus that is torsional (toward the dependent ear) and directed upward, consistent with the excitation of the ampullary organ of the PC 9 a 1- to 40-second latency before the onset of vertigo and nystagmus 10– 12 and vertigo and nystagmus with a duration of less than 60 seconds. The Dix-Hallpike maneuver, 6 referred to as the Dix-Hallpike Test (DHT) in this article, is the standard from which the diagnosis of posterior canal (PC) BPPV is made and differentiated from other conditions. Reprinted with permission from American Dizziness and Balance. Mechanisms of benign paroxysmal positional vertigo. Reorientation of the canals causes the otoconia to move to the lowest part of the canals, creating a drag on the endolymph, resulting in fluid pressure on the cupula, and activating the ampullary organ. The second is canalithiasis, 5 in which the otoconia freely sediment in the canals. Reorientation of the canal relative to gravity deflects the cupula, exciting or inhibiting the ampullary organ. The first is cupulolithiasis, 4 in which the dislodged otoconia directly attach to the cupula, weighting this membrane. There are 2 primary theories for the mechanism of BPPV. In BPPV, calcite particles (otoconia), which normally weight this membrane, become dislodged and sediment in the canals, changing the dynamics of the canals. The weighted sensory membrane of the maculae normally acts to detect gravitational forces on the head. The fluid-filled canals normally act to detect rotation of the head through the deflection of sensory hair cells embedded within a gelatinous membrane, the cupula. 3īenign paroxysmal positional vertigo is caused by abnormal mechanical stimulation of 1 or more of the 3 semicircular canals within the inner ear ( Fig. 2 Patients with BPPV experience delays in diagnosis and treatment, the mean delay being 92 weeks, and they frequently are inappropriately treated with vestibular suppressant medications. 1 Benign paroxysmal positional vertigo can affect the quality of life of elderly patients and is associated with reduced activities of daily living, falls, and depression. 1 It is the most common vestibular disorder, accounting for one third of vestibular diagnoses in the general population. In the general population, the lifetime prevalence of BPPV is 2.4%, and the 1-year incidence is 0.6%. Benign paroxysmal positional vertigo (BPPV) is characterized by brief periods of vertigo triggered by a change in the position of a person's head relative to gravity.
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