OBJECTIVES: To define anatomic parameters indicating or limiting the use of anterior and retrofacial accesses to sinus tympani (ST). MATERIAL: Anatomic study (30 temporal bones). MAIN OUTCOME MEASURE: The profundity of the ST, the distance between the sigmoid sinus and facial nerve (SS-F), the distance from posterior semicircular canal to the facial nerve, and the capacity of adequate visualization of the ST. RESULTS: Sinus tympani depth was significantly smaller (<or=0.83 mm) when visualization was possible by anterior approach. Measurements of SS-F greater than 10 mm and ST profundity greater than 1 mm indicated accessibility of posterior approach. CONCLUSION: Posterior extension of ST and the relation SS-F were the most important measures when the surgical accessibility of the ST was envisaged. Sinus tympani can be accessed through an anterior approach when the depth is less than 1 mm or by means of a posterior access when profundity is 1 mm or greater and the relation of SS-F is 10 mm or greater.
OBJECTIVES: To define anatomic parameters indicating or limiting the use of anterior and retrofacial accesses to sinus tympani (ST). MATERIAL: Anatomic study (30 temporal bones). MAIN OUTCOME MEASURE: The profundity of the ST, the distance between the sigmoid sinus and facial nerve (SS-F), the distance from posterior semicircular canal to the facial nerve, and the capacity of adequate visualization of the ST. RESULTS: Sinus tympani depth was significantly smaller (<or=0.83 mm) when visualization was possible by anterior approach. Measurements of SS-F greater than 10 mm and ST profundity greater than 1 mm indicated accessibility of posterior approach. CONCLUSION: Posterior extension of ST and the relation SS-F were the most important measures when the surgical accessibility of the ST was envisaged. Sinus tympani can be accessed through an anterior approach when the depth is less than 1 mm or by means of a posterior access when profundity is 1 mm or greater and the relation of SS-F is 10 mm or greater.