Benign Paroxysmal Positional Vertigo (BPPV)
What is Benign Paroxysmal Positional Vertigo (BPPV)?
Referred to many as the "rocks or crystals in your ear," BPPV is a common cause of vertigo in adults. BPPV occurs when otoconia (calcium deposits in the inner ear) that have come loose from the otolithic organs become trapped inside one or more of the endolymph-filled semicircular canals. Free floating otoconia inside a semicircular canal add extra mass to the system. In their normal state, the semicircular canals are not reactive to gravity; however, the mass of misplaced otoconia make the semicircular canals reactive to gravity, resulting in overstimulation with head movement. Even after the head has stopped moving, endolymph will continue to flow, sending signals to the brain that the head is still moving. This spinning sensation is called vertigo. The onset of BPPV is largely idiopathic. This means that the reason for onset is unknown. Other events related to the onset of BPPV include but are not limited to:
Upper respiratory infection
Textbook BPPV is characterized by episodic, room-spinning vertigo that follows a specific head movement. Episodes of vertigo are typically brief, lasting less than one minute or less. Patients typically feel free of symptoms in between vertiginous episodes.
BPPV can be revealed via positional testing, an integral part of a VNG assessment. During positional testing the patient’s head is moved in varying dynamic and static positions to determine which canal contains misplaced otoconia. When a patient experiences vertigo, the eyes reflexively move in a specific pattern called nystagmus. Vertigo following head movement is abnormal. The resultant nystagmus can be measured and used to determine which semicircular canal the misplaced otoconia reside. Specific head movements target specific semicircular canals. For example: The Dix-Hallpike maneuver (pictured below) tests for the most common type of BPPV: posterior canal BPPV. Whereas the head roll test is used to identify horizontal canal BPPV.
vHIT assesses the integrity of the vestibulo-ocular reflex (VOR) relative to each semicircular canal. For more information regarding the VOR and its relationship with the semicircular canals please refer to the vestibular anatomy (←hyperlink) section. During vHIT, the patient wears goggles that are used to measure eye movements. The provider instructs patient to keep eyes focused on a visual target and then moves the patient’s head in short, quick motions. The measurement of eye movement is then compared to head movement. In a patient with normal VOR function, eye movement should be equal but opposite of head movement, allowing the patient’s eyes to stay focused on the visual target despite head movement. In a patient with impaired VOR function, patient’s eyes will lose focus on visual target when head is moved. BPPV can result in impaired VOR function related to the semicircular canal with misplaced otoconia.
Once the involved semicircular canal is determined via positional testing, BPPV can be treated with canalith repositioning maneuvers. The type of repositioning maneuver utilized depends on what canal is involved. The Epley Maneuver is used to treat posterior canal BPPV, the log roll is used to treat horizontal canal BPPV. The point of canalith repositioning maneuvers is to move the head in a way that guides the misplaced otoconia out of the affected semicircular canal.