Spontaneous Upbeat Nystagmus and Selective Anterior Semicircular Canal Hypofunction on Video Head Impulse Test: A New Variant of Canalith Jam?

ABSTRACT: We describe a rare case of spontaneous upbeat nystagmus (UBN) attributable to a canalith jam involving the anterior semicircular canal (ASC) in a patient in whom comprehensive vestibular assessment was useful to identify the underlying pathomechanism. A 56-year-old woman with unsteadiness following repositioning procedures for left-sided benign paroxysmal positional vertigo (BPPV) presented with spontaneous UBN that showed slight right torsional components. A vestibular test battery detected isolated left ASC hypofunction on a video-head impulse test (Video-HIT). We postulated a persistent utriculopetal deflection of the left ASC cupula, which was attributable to entrapment of debris in a narrow canal tract, with consequent sustained inhibition of the ampullary afferents. Although spontane

SUBMITTER: Castellucci A 

PROVIDER: S-EPMC9271735 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature