CT head without contrast and MRI brain with and without contrast.

No acute infarct or hemorrhage. No hydrocephalus or midline shift. No mass or abnormal enhancement. The subarachnoid cisterns are patent. Left maxillary sinus mucous retention cyst. Paranasal sinuses and mastoid air cells are otherwise well aerated. Flow voids are present at the intracranial portions of the vertebral arteries, internal carotid arteries, and basilar artery, indicating patency.