Horizontal semicircular canal jam: Two new cases and possible mechanisms

Michael C Schubert; Janet Helminski; David S Zee; Elisabetta Cristiano; Antonio Giannone; Giuseppe Tortoriello; Vincenzo Marcelli

doi:10.1002/lio2.352

Horizontal semicircular canal jam: Two new cases and possible mechanisms

Laryngoscope Investig Otolaryngol. 2020 Jan 16;5(1):163-167. doi: 10.1002/lio2.352. eCollection 2020 Feb.

Authors

Michael C Schubert^{1

2}, Janet Helminski³, David S Zee^{1

4

5

6}, Elisabetta Cristiano⁷, Antonio Giannone⁷, Giuseppe Tortoriello⁸, Vincenzo Marcelli⁸

Affiliations

¹ Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery The Johns Hopkins University School of Medicine Baltimore Maryland.
² Department of Physical Medicine and Rehabilitation Baltimore The Johns Hopkins University School of Medicine Baltimore Maryland.
³ Physical Therapy Program Midwestern University Downers Grove Illinois.
⁴ Department of Neurology The Johns Hopkins University School of Medicine Baltimore Maryland.
⁵ Department of Neuroscience The Johns Hopkins University School of Medicine Baltimore Maryland.
⁶ Department of Ophthalmology The Johns Hopkins University School of Medicine Baltimore Maryland.
⁷ Department of Otolaryngology Antonio Cardarelli National Relief Hospital Naples Italy.
⁸ Department of Otolaryngology, ASL-NA1 Ospedale del Mare Naples Italy.

Abstract

Introduction: Benign paroxysmal positional vertigo (BPPV) of the horizontal semicircular canal (hSCC) can present with otoconia blocking its lumen (canalith jam), with signs and symptoms that make it difficult to distinguish from central nervous system pathology.

Objective: Here we report two cases of canalith jam affecting the hSCC and offer a theoretical mechanism based on known vestibular neurophysiology.

Methods: We use video-oculography to document the canalith jam and show the moment the otoconia loosen.

Results: Canalith jam is a rare form of BPPV remedied with repositioning maneuvers.

Conclusion: Clinicians should consider canalith jam as a mechanism for BPPV when the nystagmus is (a) Direction fixed with fixation removed and during positional testing; (b) Velocity dependent on supine head position; (c) Converts to geotropic directional changing nystagmus.