A 50-year-old man with MD. Axial thin-section CT image shows decreased distance between the vertical limb of the posterior semicircular canal and the posterior edge of the temporal bone (black arrow). A 50-year-old man with MD. Axial thin-section CT image shows decreased distance between the vertical limb of the posterior semicircular canal and the posterior edge of the temporal bone (black arrow). S. Vattoth et al. AJNR Am J Neuroradiol 2010;31:211-218 ©2010 by American Society of Neuroradiology