Transtemporal approach to treat petroclival lesions under endoscope:clinical anatomical study

Objective: To provide anatomical information for the treatment of petroclival lesions under endoscope while the audition and balance function can be preserved. Methods: The operations were simulated in 20 adult cadaveric specimens and correlative data were measured. The angle of endoscopic surgery, the scope of the surgery were studied. Results: The distance from superior petrosal. sinus to endolymphatic sac was 9.53±2.64 mm, from sigmoid sinus to endolymphatic duct was 10.62±2.09 mm, to common crus was 13.89±2.34 mm. The distance from duramater to posterior semicircular canal and common crus were 4.07±1.26 mm and 5.58±1.49 mm respectively. The distance from temporal bone surface to sigmoid sinus was 5.27±1.60 mm. The width of sigmoid sinus was 11.97±2.10 mm. The height of sigmoid sinus was 24.78±4.21 mm.The distance between sigmoid sinus and back wall of external acoustic meatus was 13.59±3.03 mm.The angle between petrous ridge and arrow line was 63.07±9.30 degrees and it should be the angle of endoscope. Conclusions: We can get an enough scope to treat petroclival lesions as well as save the labyrinth. Anterior displacing singmoid sinus may cumber the surgery. The surgery will be helpless if the lesions lie in internal acoustic meatus.