Is the nystagmus pattern in hemi-labyrinthectomized subjects during positional alcohol nystagmus 2 similar to that found in patients with cupulolithiasis in the lateral semicircular canal?

Abstract

Conclusion: A positional nystagmus pattern compatible with a condition of a heavy cupula (cupulolithiasis) in the lateral semicircular canal could be reproduced in hemi-labyrinthectomized subjects during positional alcohol nystagmus 2 (PAN 2). The nystagmus pattern was opposite to that found in the same subjects during PAN 1. The affected side could not be judged by applying Ewald's second law. Objectives: To mimic the condition of a heavy cupula in the lateral semicircular canal by using unilaterally deafferented subjects during PAN 2 and compare (a) results reported in the literature with those of patients with cupulolithiasis, and (b) the nystagmus findings in the same subjects during PAN 1. Methods: Five hemi-labyrinthectomized subjects were studied during PAN 2 when they kept their heads pointed straight forward or turned sideways in the prone and supine positions, respectively. Results: When the subjects were examined with their heads turned in the supine or prone positions, the alcohol-induced nystagmus pattern was compatible with that of cupulolithiasis. When the head was pointed straight forward in the prone and supine positions, the nystagmus directions were opposite to those found during PAN 1. Directional preponderance was not seen for the apogeotropic nystagmus for either ampullofugal or ampullopetal deviation of the cupula.

Keywords::

• Heavy cupula
• light cupula
• apogeotropic nystagmus
• persistent positional
• Ewald's second law

Acknowledgments

Thank you to Mrs Mariana Hansson and Mrs Kerstin Granath for carefully carrying out the vestibular tests.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.