Fig. 1

Comparison of temporal bone CT findings between the two groups (sigmoid sinus preposition + poor mastoid pneumatization) Note: As can be seen from the above figure, the temporal bone CT findings in the healthy control group revealed a predominantly hollow mastoid structure, characterized by numerous transparent, well-defined, and evenly distributed air cells arranged in a honeycomb pattern. In contrast, the MS group displayed a smaller mastoid with fewer air cells, suggesting poor mastoid pneumatization in patients with MS. Additionally, a comparison of findings in the two groups showed that the anterior edge of the sulcus for the sigmoid sinus was approximately 10–14 mm from the posterior wall of the external auditory canal in the healthy control group, while this distance was reduced to less than 10 mm in the MS group, suggesting the presence of sigmoid sinus preposition in patients with MS. Blue arrows indicate the location of vestibular organs and red arrows indicate the location of various structural abnormalities