Weak nystagmus in the dark persists for months after acute unilateral vestibular loss

Chih-Chung Chen; Anand K Bery; Tzu-Pu Chang

doi:10.3389/fneur.2023.1327735

Weak nystagmus in the dark persists for months after acute unilateral vestibular loss

Front Neurol. 2023 Dec 15:14:1327735. doi: 10.3389/fneur.2023.1327735. eCollection 2023.

Authors

Chih-Chung Chen^{1

2

3}, Anand K Bery⁴, Tzu-Pu Chang^#^{5

6}

Affiliations

¹ Dizziness and Balance Disorder Center, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan.
² Taipei Neuroscience Institute, Taipei Medical University, New Taipei City, Taiwan.
³ Department of Neurology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
⁴ Division of Neuro-Visual and Vestibular Disorders, Department of Neurology, The Johns Hopkins Hospital, Baltimore, MD, United States.
⁵ Department of Neurology/Neuro-medical Scientific Center, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan.
⁶ Department of Neurology, School of Medicine, Tzu Chi University, Hualien, Taiwan.

^# Contributed equally.

Abstract

Background: Weak nystagmus with fixation removed can be seen both in normal individuals and in recovery from a unilateral vestibular insult, thus its clinical significance is unclear in patients with dizziness. We thus sought to compare features of nystagmus at various stages following unilateral vestibular loss (UVL).

Methods: We enrolled thirty consecutive patients after acute UVL with impaired vestibulo-ocular reflex (VOR) gain. The patients were allocated into three groups according to time from onset of symptoms: acute (1-7 days), subacute (8-30 days), and chronic (>30 days). Patients underwent video-oculography (with and without fixation) and video head impulse testing (vHIT) to determine VOR gain. We examined the relationships amongst SPV, VOR gain, and time from symptom onset across groups.

Results: There were 11, 10, and 9 patients in the acute, subacute, and chronic stages of UVL, respectively. With visual fixation, only 8 patients (26.7%) demonstrated nystagmus, all from the acute group. With fixation removed, 26 patients (86.7%) exhibited spontaneous nystagmus, including 90.9%, 90%, and 77.8% of the patients from the acute, subacute, and chronic groups, respectively. Horizontal nystagmus was paralytic (i.e., fast phase contralesional) in 25 (96.7%) cases. Horizontal SPV was negatively correlated with logarithm of time from onset to examination (r = -0.48, p = 0.007) and weakly negatively correlated with ipsilesional VOR gain (r = -0.325, p = 0.08).

Conclusion: In the subacute or chronic stages of UVL, paralytic nystagmus with fixation removed persisted at a low intensity. Therefore, weak nystagmus in the dark may have diagnostic value in chronic dizziness.

Keywords: dizziness; nystagmus; vertigo; vestibular; video-oculography.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study is funded by TCMF-A 111-07(112), Buddhist Tzu Chi Medical Foundation.