Vestibular mapping in patients with unilateral peripheral-vestibular deficits.

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 five vestibular sensors.

METHODS

Retrospective case-series. Screening of the hospital video-head-impulse test database (n=4983) 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%, 113/302), vestibular schwannoma (18.2%, 55/302) and acute cochleo-vestibular neuropathy (6.6%, 20/302) were most frequent. Horizontal SCC-impairment (87.4%, 264/302) was more frequent (p<0.001) than posterior (47.4%, 143/302) and anterior (37.8 %, 114/302) SCC-impairment. Utricular damage (58%, 175/302) was noted more often (p=0.003) than saccular impairment (32%, 98/302). On average 2.6 (95%-CI=2.48-2.78) vestibular sensors were deficient, with higher numbers (p≤0.017) for acute cochleo-vestibular neuropathy and vestibular schwannoma than for AVN, Menière's disease and episodic-vestibular-syndrome. In hierarchical cluster-analysis, early mergers (posterior SCC/sacculus; anterior SCC/utriculus) pointed to closer pathophysiological 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's disease was noted, emphasizing the individual range of loss-of-function and the value of vestibular-mapping. Likely, both the anatomical 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.