Unilateral Multicanalicular Vestibular Lithiasis of Right Horizontal and Posterior Semicircular Canals: An Unusual Case

Abstract Vestibular lithiasis (canalolithiasis as well as cupulolithiasis) commonly exists in monocanalicular forms involving one of the three semicircular canals, frequent posterior, less frequent horizontal, and very rarely anterior. It is treated with canal clearing maneuvers intended to reposition the otoconia from the semicircular canal (where they have inappropriately entered) through the utricular exit in the nonampullary arm of the semicircular canal to the utricle (where they normally remain as a part of utricular gelatinous matrix). The cases of multicanalicular vestibular lithiasis with the involvement of more than one semicircular canal require meticulous identification of the involved canals and multiple different canal-clearing maneuvers for effective treatment. A 70-year-old male patient with no significant history of previous medical or otologic illnesses or head trauma presented with a 1-day history of vertigo with positional aggravation. A one-time performed diagnostic supine head roll test elicited three different patterns of positional nystagmus, each with an accurate localizing and lateralizing value. Diagnosis of unilateral multicanalicular vestibular lithiasis of right horizontal and posterior semicircular canals was entertained based on the pattern of the elicited positional nystagmi on the supine roll test. The upbeating torsional nystagmus that localizes the involvement to the posterior semicircular canal was paradoxically elicited by supine head roll test and not by the Dix–Hallpike test. As horizontal semicircular canalolithiasis causes severe symptoms, its treatment preceded that of concurrent posterior semicircular canalolithiasis. The patient was successfully treated with multiple sessions of canalith repositioning maneuvers (CRMs) spread over 24 hours. It is important to perform both positional tests, namely Dix–Hallpike maneuver, and supine head roll test, in cases suspected to have multicanalicular vestibular lithiasis. The positionings may need to be repeated several times to unveil multiple nystagmi, each with different localizing and lateralizing values. Identifying treatment priorities with CRM for the individual semicircular canals is crucial, and the canal that is liable to cause severe symptoms needs early clearance of the otoconial debris. If a CRM fails to clear a semicircular canal, an alternative maneuver may need to be executed. Clinicians involved in the care of cases with multicanalicular vestibular lithiasis should be well versed with all possible backup maneuvers for clearing each of the three semicircular canals.