Abstract
Generally, the temporal bone with inferiorly located middle fossa is termed the dangerous temporal bone. Anteriorly located sigmoid sinus, which is rarely encountered, is also a type of dangerous temporal bone. We report two patients with an anteriorly located sigmoid sinus. Case 1 was a 51-year-old female with bilateral chronic otitis media. An anteriorly located sigmoid sinus was observed on the right side on preoperative temporal CT. Case 2 was a 28-year-old female with right chronic otitis media. A right high jugular bulb and bilateral anteriorly located sigmoid sinus were observed on CT. We performed lateral tympanotomy carefully in these two patients without massive hemorrhage. It is very important to consider the anteriorly located sigmoid sinus and high jugular bulb to operate the tympanoplasty safely to avoid accidental hemorrhage.
