Differences in vestibulo-ocular reflexes between vestibular neuritis and labyrinthitis

To expand our understanding of the pathophysiological mechanisms underlying vestibular neuritis and labyrinthitis by identifying any difference in the vestibulo-ocular reflex for each semicircular canal.

Retrospective analysis.

The Department of Otorhinolaryngology - Head and Neck Surgery, Chosun University Hospital, from January 2015 to December 2021.

We included 23 vestibular neuritis and 27 labyrinthitis patients who had been hospitalized. Pure-tone audiometry, a bithermal caloric test, and a video head-impulse test were performed within 5 days of symptom onset.

In the vestibular neuritis group, mean vestibulo-ocular reflex gains were decreased to 0.51 in the ipsilesional horizontal canal and 0.55 in anterior canal, leading to marked asymmetry, whereas the gain of the ipsilesional posterior canal was relatively preserved at 0.85. In the labyrinthitis group, the mean vestibulo-ocular reflex gain was 0.72 in the ipsilesional horizontal canal, 0.73 in the ipsilesional anterior canal, and 0.55 in the ipsilesional posterior canal. We observed statistical differences in the vestibulo-ocular reflex gain and incidence of corrective saccades on the ipsilesional side in three semicircular canals between the groups (p = .002 for horizontal canal, p = .003 for anterior canal, and p < .001 for posterior canal). The receiver operating characteristic curve showed that pure-tone audiometry, ipsilesional posterior canal gain, and gain asymmetry of posterior canal were excellent parameters for distinguishing labyrinthitis from vestibular neuritis.

Vestibular neuritis and labyrinthitis patients have different degrees and patterns of video head-impulse test involvement in the three semicircular canals, suggesting that the two distinct disorders may have different etiologies.