canalolithiasis

Canalolithiasis is a subtype of benign paroxysmal positional vertigo (BPPV) characterized by free-floating otoconia dislodged from the utricle into the semicircular canals, most commonly the posterior semicircular canal. The presence of these otoliths within the canal disrupts endolymph flow during head movements, leading to transient vertigo and nystagmus.

Symptoms are brief episodic vertigo triggered by changes in head position, such as moving from sitting to lying down, turning in bed, or looking up. Attacks last seconds to about a minute and are often accompanied by nausea. Nystagmus is typically direction-changing and torsional with the Dix-Hallpike maneuver, and it tends to fatigue with repeated testing.

Diagnosis is clinical, based on history and positional testing. The Dix-Hallpike test is used to provoke vertigo and the characteristic nystagmus in posterior canal canalolithiasis. Audiometry is usually normal, and imaging is not routinely required unless there are red flags suggesting another or concurrent cause.

Canalolithiasis is distinguished from cupulolithiasis, in which debris adheres to the cupula and produces longer-lasting vertigo with less fatigue on repetition. Other causes of vertigo, such as Meniere's disease, vestibular neuritis, or central nervous system disorders, are considered in the differential diagnosis.

Treatment consists of canalith repositioning maneuvers, such as the Epley or Semont maneuvers, and, for certain canal variants, the BBQ roll. These maneuvers aim to move the otoliths back into the utricle. Most patients experience symptom relief after a few sessions, and recurrence is possible. Vestibular rehabilitation may help in persistent cases, and patients are often advised to avoid provocative positions briefly after a maneuver.