Evaluation of the Mastoid Emissary Canals with Computerized Tomography in Patients with Chronic Otitis Media.

 The mastoid emissary veins (MEVs) pass through the mastoid emissary canal-mastoid foramen (MEC-MF) in the mastoid region of the skull. MEVs can give rise to complications during surgical procedures. The purpose of our study was to investigate the morphological and morphometric characteristics of MECs of patients with clinical chronic otitis media (COM) using high-resolution computed tomography (HRCT).  Patients diagnosed with COM and undergoing temporal HRCT were identified by retrospectively scanning our hospital's automation system. Patients undergoing temporal HRCT for reasons other than COM, infection or tinnitus were identified for the control group by scanning the PACS archive. Sixty-two mastoid regions were examined in 38 unilateral and 12 bilateral COM patients, and 100 mastoid regions in the 50 patients in the control group. The presence of an accessory MEC-MF and MEC-MF diameters was evaluated in both groups.  Main MEC diameters on the side of the ear with COM were 1.6 mm, and total accessory and main MEC diameters were 1.8 mm, both values being significantly higher than in the control group. Presence of accessory MEC on the side of the ear with COM was determined at 61.8%, significantly higher than in the control group.  Preoperative awareness of cranial venous drainage abnormalities is important to reduce surgical complications. Our study shows that MECs may be wider in diameter in patients with COM. MECs in COM patients must be identified before surgery to the mastoid region.