Comorbid Cupulolithiasis Is Rare in Patients With Horizontal Semicircular Canal Canalolithiasis

Considering that otolith particles pass through the canal until attaching to the cupula in the canal-side horizontal semicircular canal (HSCC) cupulolithiasis, comorbidity of HSCC canalolithiasis and cupulolithiasis may occur. We aimed to investigate the incidence of comorbidity of cupulolithiasis in patients with HSCC canalolithiasis and to improve treatment efficacy.

Retrospective study.

Tertiary referral academic center.

Ninety-seven consecutive patients with HSCC canalolithiasis between March 2017 and March 2019 were included.

Coexistence of HSCC cupulolithiasis was hierarchically investigated. 1) Spontaneous reversal of initial nystagmus is observed bilaterally in a head-roll test (HRT), 2) nystagmus is in the same direction at each of the three times the supine position was tested, and 3) both bowing and leaning nystagmus with opposite direction are observed.

Of 97 patients with HSCC canalolithiasis, 2 patients (2%) had comorbid HSCC cupulolithiasis.

Although coexistence of HSCC canalolithiasis and cupulolithiasis should be considered when spontaneous reversal of nystagmus direction is observed without position change during a HRT, the incidence of coexistence is very low. However, canalith repositioning maneuvers for both canalolithiasis and cupulolithiasis should be performed in cases with comorbidity.