Anatomic study of the cerebellopontine and internal acoustic canal surgery aided by endoscope with retrolabyrinthine approach

OBJECTIVE To study the relationship between retrolabyrinthine space and the distance from sigmoid sinus to posterior wall of external acoustic canal for providing related information on cerebellopontine angel and internal acoustic surgery aided by endoscope via retrolabyrinthine approach.METHODS Fifteen adult cadaver heads(30 sides) fixed with formalin were studied.All the cadaver heads were undergone radical mastoidectomy,labyrinthine sketelization,and sigmoid sinus anatomized.①The distances from posterior margin of internal acoustic pore to the anterior edge of sigmoid sinus and to the posterior edge of sigmoid sinus were measured.②The distances from anterior edge of sigmoid sinus to the posterior wall of external acoustic canal and to the posterior semicircular canal were also measured.RESULTS ①The distances from posterior margin of internal acoustic pore to the anterior edge of sigmoid sinus and to the posterior edge of sigmoid sinus were(26.74±1.26)mm and(32.46±2.24)mm respectively.②The distances from anterior edge of sigmoid sinus to the posterior wall of external acoustic canal and to the posterior semicircular canal were(15.65±1.26)mm and(10.83±0.85)mm respectively and they had significant correlation(r=0.672,P0.01).CONCLUSION ①The distance is shorter to internal acoustic pore in retrolabyrinthine approach than that in retrosigmoid approach if made sigmoid sinus as borderline.②It can be estimated the retrolabyrinthine space indirectly by measuring the distance from the sigmoid sinus to the posterior wall of external acoustic canal,and that can provide more information for cerebellopontine angel minimally invasive surgery aided by endoscope via retrolabyrinthine approach.