The relationship between mastoid pneumatization and the position of the sigmoid sinus.

Using high-resolution computed tomography, we measured the cross-sectional area of mastoid air cells and the shortest distance between the external auditory canal and the anterior edge of the sigmoid sinus (DIST), and then compared the right-left difference in 70 patients with unilateral chronic otitis media and 23 cases without middle ear disease. DIST was significantly short where there was poor mastoid pneumatization (P < 0.0001), regardless of whether it was the right or left ear. Furthermore, on the well-pneumatized temporal bone, the increase in size of the cross-sectional area was closely correlated with the increase in DIST (r = 0.495). We suggest that the relative position of the external auditory canal and the sigmoid sinus is affected by middle ear inflammations in childhood.