Osteoplastic mastoidectomy followed by single-flap temporo-suboccipital craniotomy: combined supra- and infratentorial approach.

The combined supra- and infratentorial transpetrosal approach requires a subtemporal-suboccipital craniotomy and a mastoidectomy to unroof the dural sinuses. We describe a modified surgical technique that reduces the bone defect in the mastoid area and decreases the risk of violating the dural sinuses. Before the craniotomy, a surface mastoidotomy - the removal of the outer layer of the mastoid process - is carried out using a drill and a chisel for later reconstruction of the mastoid process. This is followed by a deep mastoidectomy in conjunction with petrosectomy to unroof the sigmoid sinus. Through a cavity made by the mastoidectomy, the lateral sinus is dissected from its bony groove. A single flap temporo-suboccipital craniotomy is performed necessitating few burr holes or none. Upon closure the temporo-occipital bone flap and mastoid flap are fixed together. The surface mastoidotomy followed by single-flap temporo-occipital craniotomy minimizes the bone defect in the mastoid area. In addition, beginning such a procedure with a mastoidectomy facilitates safe dissection of the outer dura covering the sinuses and adherent to the bony groove.