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Abstract
Objective To test the hypothesis that patterns of semicircular canal (SCC) and otolith impairment in unilateral vestibular loss depend on the underlying disorders, we analyzed peripheral-vestibular function of all 5 vestibular sensors.
Methods For this retrospective case series, we screened the hospital video-head-impulse test database (n = 4,983) for patients with unilaterally impaired SCC function who also received ocular vestibular-evoked myogenic potentials and cervical vestibular-evoked myogenic potentials (n = 302). Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with hierarchical cluster analysis and correlated with the underlying etiology.
Results Acute vestibular neuropathy (AVN) (37.4%, 113 of 302), vestibular schwannoma (18.2%, 55 of 302), and acute cochleovestibular neuropathy (6.6%, 20 of 302) were most frequent. Horizontal SCC impairment (87.4%, 264 of 302) was more frequent (p < 0.001) than posterior (47.4%, 143 of 302) and anterior (37.8%, 114 of 302) SCC impairment. Utricular damage (58%, 175 of 302) was noted more often (p = 0.003) than saccular impairment (32%, 98 of 302). On average, 2.6 (95% confidence interval 2.48–2.78) vestibular sensors were deficient, with higher numbers (p ≤ 0.017) for acute cochleovestibular neuropathy and vestibular schwannoma than for AVN, Menière disease, and episodic vestibular syndrome. In hierarchical cluster analysis, early mergers (posterior SCC/sacculus; anterior SCC/utriculus) pointed to closer pathophysiologic association of these sensors, whereas the late merger of the horizontal canal indicated a more distinct state.
Conclusions While the extent and pattern of vestibular impairment critically depended on the underlying disorder, more limited damage in AVN and Menière disease was noted, emphasizing the individual range of loss of function and the value of vestibular mapping. Likely, both the anatomic properties of the different vestibular end organs and their vulnerability to external factors contribute to the relative sparing of the vertical canals and the sacculus.
Glossary
- ACVN=
- acute cochleovestibular neuropathy;
- AVN=
- acute vestibular neuropathy;
- aVOR=
- angular VOR;
- CI=
- confidence interval;
- CPA=
- cerebellopontine angle;
- cVEMP=
- cervical VEMP;
- EVS=
- episodic vestibular syndrome;
- IVN=
- inferior-branch vestibular neuropathy;
- MD=
- Menière disease;
- oVEMP=
- ocular VEMP;
- SCC=
- semicircular canal;
- SVN=
- superior vestibular nerve;
- TBI=
- traumatic brain injury;
- UVL=
- unilateral vestibular loss;
- VEMP=
- vestibular-evoked myogenic-potential;
- vHIT=
- video-head-impulse test;
- VOR=
- vestibulo-ocular reflex;
- VS=
- vestibular schwannoma
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
CME Course: NPub.org/cmelist
- Received January 31, 2020.
- Accepted in final form July 10, 2020.
- © 2020 American Academy of Neurology
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