INTRODUCTION: In this study, we aimed to compare the internal acoustic canal (IAC) measurements of the affected and unaffected sides of patients with unilateral vestibular neuritis (VN) on magnetic resonance imaging (MRI).
METHODS: January 2017 and December 2019, a total of 120 patients (65 males, 55 females; mean age 58.3±12.5 years; range, 21 to 83 years) who were diagnosed with VN according to clinical findings, video head impulse test (vHIT), and MRI findings were enrolled in this study. All measurements were performed on the axial constructive interference in steady state (CISS) sequences. The IAC inlet, mid-canal, and outlet widths were measured at the most distinctive cross-section of the facial nerve and superior vestibular nerve bifurcation. While calculating the length of IAC, the points were taken on the basis of where the inlet and outlet widths of the canal were measured.
RESULTS: According to the vHIT results, a single semicircular canal (SCC) was affected in 102 (85%) patients, while more than one SCC was affected in 18 (15%) patients. The inlet, mid-canal and outlet values of the affected side were significantly lower than those of the unaffected side (p<0.05). Regarding the IAC length measurement, there was no significant differences between the affected and unaffected sides (p>0.05). All of these parameters were slightly higher in males; however, this difference was not statistically significant (p>0.05).
DISCUSSION AND CONCLUSION: Our study results showed that the widths of the IAC were lower in the affected side of patients with unilateral VN. These findings may help to explain why acute VN cases occur only unilaterally, suggesting that a small sectional diameter of the IAC is a potential risk factor for VN.