[The retrolabyrinthine approach. Its value in the treatment of lesions of the lateral sinus].

The Authors conceive the petrous bone as made of four segments bounded by two vertical plans, one passing through the anterior wall of the internal auditory canal and the posterior wall of the external auditory canal, the other passing through the inner aspect of the tympanic cavity and the outer aspect of the labyrinthe. Drilling away one or several segments realizes a trans-petrous approach which always begins by drilling away the posterior-external segment, the retro-labyrinthine segment. Drilling away only the retro-labyrinthine segment realizes retro-labyrinthine approach which entirely put into sight the circumference of the bending of the lateral sinus. Thus, it is possible to perfectly and more easily deal with lesions localized in this region. The skin incision is made two fingerbreadths above and behind the external ear. The scalp uncovers the mastoid as far as the posterior ring of the external auditory canal. The superficial drilling uncovers the temporal dura, the lateral sinus and the occipital dura and between them the sinuso-dural angle. Then the mastoid is drilled away as far as the antrum is opened. Its aditus internally sided by the loop of the external semi-circular canal serves to localize the external surface of the labyrinthe. Finally, the retro-labyrinthine approach is bounded by the posterior wall of the external auditory canal anteriorly, by the external surface of the labyrinthe internally, by the dura of the superior surface of the petrous bone superiorly and by the bended part of the lateral sinus and the dura of the posterior surface of the petrous bone posteriorly. The closure is made with a dural graft then with bony dust mixed with biologic glue, then the petrectomy is plugged with under-skin fat and then the superficial planes are carefully stitched. The authors report 5 cases of meningiomas of the lateral sinus, 1 case of hemangiopericytoma and 2 dural arteriovenous fistulas which demonstrate the interest of this approach to lesions developed on this part of the lateral sinus.