Acute Onset Headache and Left Eye Swelling

A 21-year-old male search and rescue swimmer presented with a 1-day history of acute onset headache and left eye swelling. He denied any trauma but reported blowing his nose in the shower prior to the onset. The patient reported 2 similar headache episodes without eye swelling 3 months prior. The first was also triggered by blowing his nose, and the second occurred while exercising. Both previous headaches resolved over 2 days and were associated with a self-described audible “water trickling” sound in the left side of his head. The patient denied any weakness, paresthesias, or alteredmental status. On examination, the patient was neurologically intact. He had marked periorbital edema with associated crepitus. His ophthalmologic examination was grossly unremarkable except for diplopia during right lateral gaze. Noncontrast computed tomographic (CT) imaging of the sinuses showed a 1.8 × 1.2 × 2.3-cm, well-delineated, hyperdense lesion centered within the left anterior ethmoid air cells that partially protruded into the medial orbit without significant mass effect on the medial rectus or globe (Figure, A). An extensive left-sided pneumocephalus was identified with possible dehiscences in the posterior margin of the frontal sinus, lamina papyracea, and/or cribiform plate (Figure, B and C). What is your diagnosis? A