The Effect of Anteriorly Located Sigmoid Sinus on Postoperative Hearing Gains: A Case-Control Study.

There are many studies on the effects of temporal bone anatomical variations on a mastoid pneumatization. Considering the effects of the anatomic variations on mastoid pneumatization, it is considered that many anatomic variations may affect graft success rates and postoperative hearing threshold gains. We aimed to evaluate the effects of various anatomic variations on postoperative hearing gains among patients undergoing tympanoplasty. This retrospective cohort study conducted in a tertiary-care university hospital. This study enrolled 57 patients who underwent primary type 1 tympanoplasty operation using the temporal muscle fascia. The patients were divided into two groups as those with an anteriorly located sigmoid sinus (group 1), and no anatomic variation (group 2). Airway gain values at the frequency range of 250 Hz-8000 Hz and pure tone average (PTA) value were calculated preoperatively and at postoperative sixth month. The gains attained by the patient groups with anatomic variations were compared with group 2. There were significant differences between Group 1 and Group 2 in terms of the airway frequencies of 250, 500, 2000, 4000 Hz, and PTA value. We detected a lesser postoperative hearing gain in patients with an anteriorly located SS. We believe that anatomic variations that may affect middle ear and mastoid cavity may also affect postoperative hearing gain.