Failed endoscopic sinus surgery: spectrum of CT findings in the frontal recess.

Since its introduction over 2 decades ago, functional endoscopic sinus surgery (FESS) has revolutionized the surgical management of chronic sinusitis. Performed over 200,000 times annually in the United States to treat medically refractory sinusitis, FESS has success rates as high as 98%. When surgical failure occurs, it is typically due to postoperative scarring or unaddressed outflow tract obstruction in the region of the frontal recess. The most common causes of surgical failure in the frontal recess include remnant frontal recess cells, a retained uncinate process, middle turbinate lateralization, osteoneogenesis, scarring or inflammatory mucosal thickening, and recurrent polyposis. Computed tomography (CT) of the paranasal sinuses has become indispensable in evaluation of patients with FESS failure, particularly in the frontal recess, a location that can be difficult to visualize at endoscopy. Familiarity with the complex anatomy of the frontal recess and knowledge of the most common causes of surgical failure are essential for proper interpretation of sinus CT images obtained in patients being considered for revision FESS of the frontal sinus.