Comparison of vHIT deficits with Ramsay Hunt syndrome with dizziness, vestibular neuritis, and idiopathic sudden sensorineural hearing loss with vertigo.

Background: Ramsay Hunt syndrome with dizziness (RHSD), vestibular neuritis (VN), and idiopathic sudden sensorineural hearing loss with vertigo (SHLV) all present with acute vestibular symptoms, and no study has compared the semicircular canal (SCC) deficits among them.

Objective: This study aimed to use video head impulse test (vHIT) to compare the SCC injury patterns in RHSD, VN, and SHLV.

Methods: Twenty-three RHSD patients, 44 VN patients, and 70 SHLV patients were enrolled. The vestibulo-ocular reflex gain and incidence of corrective saccades of anterior, horizontal, and posterior SCC (ASCC, HSCC, and PSCC) were examined using vHIT. Pathological vHIT results referred to decreased VOR gain and presence of corrective saccades.

Results: (1) The pathological rate of each SCC in RHSD group was the highest. (2) Impairment pattern of SCCs can be divided into 7 types based on vHIT results. The pattern of ASCC + HSCC + PSCC disability was the most common in RHSD patients (12/23, 52.2%). In the VN group, the HSCC deficit alone was the most common (16/44, 36.4%), followed by HSCC + ASCC impairment (13/44, 29.5%). In SHLV patients, the most common type was the PSCC deficit alone (26/70, 37.1%). (3) The system cluster analysis revealed that the injury of all SCCs in RHSD patients, the deficit of HSCC alone in VN patients, and the impairment of PSCC alone in SHLV patients showed the farthest distance from other injury patterns.

Conclusion: SCCs deficit showed more severe and extensive vestibular impairment in RHSD compared with VN and SHLV, suggesting these three peripheral acute vestibular disorders may have different pathophysiologic mechanisms.