Sung-Hwan Kim ¹ Hanseob Kim ² Sun-Uk Lee ^1* Euyhyun Park ¹ Bang-Hoon Cho ¹ Kyung-Hee H. Cho ¹ Gerard Jounghyun Kim ² Sungwook Yu ¹ Ji Soo Kim ³

• ¹ Korea University Medical Center, Seoul, Republic of Korea
• ² Department of Computer Science and Engineering, College of Informatics, Korea University, Seoul, Republic of Korea
• ³ Seoul National University Bundang Hospital, Seongnam-si, Gyeonggi, Republic of Korea

Video head-impulse tests (video-HITs) often fail to detect anterior inferior cerebellar artery (AICA) infarction due to peripheral and central vestibular system involvement. Anecdotal studies suggest that video-HITs may reveal bilateral impairment in AICA infarction. However, the diagnostic utility of video-HITs has not been established, particularly when compared to labyrinthitis, which accounts for the majority of acute audiovestibular syndrome (AAVS) cases. We reviewed the medical records of consecutive patients presenting with new-onset acute hearing loss and spontaneous vertigo (i.e. AAVS) between March 2018 and July 2023 at a tertiary hospital in South Korea. Video-HIT patterns were categorized as follows:1) ipsilaterally positive, 2) contralaterally positive, 3) bilaterally normal, and 4) bilaterally positive. Twenty-eight patients with AICA infarction (mean age±standard deviation = 67±15 years; 14 men) and 51 with labyrinthitis (63±17 years; 26 men) were included in the analyses. Among the 28 patients with AICA infarction, 15 presented with AAVS in isolation, without other co-morbid neurologic deficits (15/28, 54%). The vestibulo-ocular reflex (VOR) gains of ipsilesional horizontal canals (HCs) ranged from 0.21 to 1.22 (median = 0.81, interquartile range [IQR] = 0.50–0.89). However, those for contralateral HC gain ranged from 0.57 to 1.19 (median = 0.89 [IQR = 0.73–0.97]). Collectively, HITs were bilaterally positive in 13 patients (including 12 patients with bilaterally positive HITs for the horizontal canal), normal in eight, ipsilesionally positive in six, and contralesionally positive in one patient with AICA infarction. The VOR gains were typically decreased ipsilaterally in 28 (28/51, 55%), normal in 17 (17/51, 33%), and decreased bilaterally in six patients with labyrinthitis (6/51, 12%). Logistic regression analysis revealed that bilaterally positive HITs (p=0.004) and multiple vascular risk factors (p=0.043) were more frequently associated with AICA infarction than labyrinthitis. Among patients presenting with AAVS, bilaterally positive HITs can be indicative of AICA infarction in patients with multiple vascular risk factors.