[Analysis of spontaneous nystagmus and the frequency characteristics of affected semicircular canals in patients with vestibular neuritis].

Objective: To investigate the spontaneous nystagmus (SN) and the frequency characteristics of affected semicircular canals in patients with vestibular neuritis (VN). Methods: This is a cross-sectional study. A total of 61 patients with VN admitted to the Department of Neurology of Shanxi Bethune Hospital from June 2020 to October 2021, 39 were male and 22 were female, with a mean age of (46±13) years old and male to female ratio of 1.77∶1. According to SN characteristics, 61 patients were divided into non-nystagmus group(nSN), horizontal nystagmus group(hSN) and horizontal-torsional nystagmus group (htSN). Clinical data were collected, and SN, unilateral weakness (UW), directional preponderance (DP), and video head impulse test (vHIT) gain were used as observation indicators. Statistical analysis by SPSS23.0 software. Normal distributed quantitative data (age, semicircular canal gain, SN intensity) were expressed by x¯±s, non-normal distributed quantitative data (disease course, UW, DP) were expressed by M(Q₁,Q₃), qualitative data were expressed by rate and composition ratio, difference analysis by one-way ANOVA, rank sum test, Chi-square test or Fisher's exact probability method, considered by P value<0.05. Results: (1)The disease course of nSN, hSN and htSN was 7.0 (4.0, 12.5), 6.0 (3.5, 11.5), and 3.0 (2.0, 6.5) days respectively, and there were statistical differences (χ2=7.31,P=0.026).(2)The horizontal nystagmus intensity of htSN was (16.8±8.6)°/s, which was significantly higher than that of (9.8±4.7)°/s in hSN (t=3.71, P<0.001). There was no significant difference in the positive rate of UW between the three groups (P=0.690), and there was a significant difference in the positive rate of DP in the three groups (χ2=12.23, P=0.002). The horizontal nystagmor intensity in the htSN was positively correlated with the vertical nystagmus intensity (r=0.59, P=0.001).(3)The gain of the affected horizontal canal of the three groups was statistically different (F=8.28, P=0.001), and the gain of the horizontal canal of hSN and htSN was significantly lower than that of nSN (t=2.74, P=0.008; t=4.05, P<0.001); The gain of the affected anterior canal in the three groups was statistically different (F=5.32, P=0.008). The gain of the anterior canal in both nSN and hSN was significantly higher than that in htSN (t=3.09, P=0.003; t=2.15, P=0.036). The horizontal canal gain of htSN is positively correlated with the anterior canal gain (r=0.74, P<0.001).(4)The affected semicircular canals in the two groups with no-vertical-component nystagmus (nSN and hSN) and the htSN were counted. The composition ratio of the affected semicircular canals in the two groups was different (χ2=8.34, P=0.015). Conclusion: The occurrence of SN in patients with VN is related to many factors, such as the disease course, low and high frequencies, and the severity of the condition in the affected semicircular canal.