Mild age related involutional changes are noted in brain parenchyma. No recent established territorial infarction or intracranial hemorrhage is seen. No mass effect or midline shift is noted. Gross morphology of the posterior cranial fossa structures is within normal limits. Polypoidal mucosal thickening of the left maxillary sinus; the remaining paranasal sinuses and bilateral mastoid air cells are well-aerated and clear. Exaggerated external occipital protuberance (occipital spur-type III).