Correlation Analysis between Spontaneous Nystagmus Characteristics and Semicircular Canal Dysfunction in Patients with Vestibular Neuritis: A Quantitative Study Using Electronystagmography and Video Head Impulse Test

Objective: To compare the characteristics of spontaneous nystagmus (SN) in patients with vestibular neuritis (VN) at different disease stages and to investigate its correlation with semicircular canal dysfunction. Methods: A total of 115 VN patients were enrolled, who were divided into acute phase (1 – 7 days), subacute phase (8 – 30 days) and chronic phase (>30 days) according to the course of disease. Quantitative assessment of SN was performed using electronystagmography (ENG), with particular focus on the slow phase velocity (SPV) in the horizontal plane. Simultaneously, vestibular-ocular reflex function was systematically evaluated through video head impulse test (vHIT), with quantitative measurements of angular vestibulo-ocular reflex (aVOR) gain and asymmetry of the affected semicircular canals. Results: Among 115 patients, 67 (58.3%) were in acute phase, 29 (25.2%) in subacute phase and 19 (16.5%) in chronic phase. The mean age of patients in the acute phase was significantly lower than that in the chronic phase (p = 0.028), while there was no significant difference between the subacute phase and the other two groups. 98 patients (85.2%) had SN, 62 patients (92.5%) in acute phase, 26 patients (89.7%) in subacute phase and 10 patients (52.6%) in chronic phase. SPV in acute phase was significantly higher than that in subacute phase (p = 0.003) and chronic phase (p < 0.001), but there was no significant difference between chronic phase and subacute phase. In 112 patients with VN, the horizontal semicircular canals were affected, and the mean aVOR gain and asymmetry of the damaged side were 0.47 ± 0.14 and 0.35 ± 0.14, respectively. The aVOR gain of injured side in chronic phase was significantly higher than that in acute phase (p < 0.001) and subacute phase (p = 0.007), but there was no significant difference between acute phase and subacute phase (p = 0.950). The asymmetry in chronic phase was significantly lower than that in acute phase (p = 0.001) and subacute phase (p = 0.018), and there was no significant difference between acute phase and subacute phase (p = 0.312). SPV in horizontal component was negatively correlated with the aVOR gain of damaged horizontal semicircular canals (r = -0.273, p = 0.007), and positively correlated with aVOR asymmetry (r = 0.291, p = 0.004). Conclusion: The existence of SN is helpful for diagnosis of VN, and its intensity can reflect the degree of vestibular impairment.