Intraspinosum Middle Meningeal Artery Ligation: A Simple Technique to Control Bleeding in the Middle Fossa During the Anterior Transpetrosal Approach

BACKGROUND: Although the greater superficial petrosal nerve (GSPN) is an important landmark of the anterior transpetrosal approach (ATPA), bleeding from the interdural space around the foramen spinosum (FS), the GSPN, and the foramen ovale impedes the identification of the GSPN, during epidural dissection in the ATPA. OBJECTIVE: To describe the technique of intraspinosum middle meningeal artery (MMA) ligation, which enables us to control bleeding from the interdural space. METHODS: During epidural dissection, we identified the FS and partially drilled the lateral side of the FS. Next, we cut the convergence site of the neurovascular structures such as the MMA, middle meningeal vein, and the meningeal branch of the mandibular nerve with the periosteal dura within the FS and continued dural detachment epidurally to expose the petrous apex. Bleeding control around the FS and postoperative facial nerve paresis were assessed for 96 patients treated with the ATPA. Additionally, histological study was performed around the FS using Masson's trichrome stain. RESULTS: In all cases, in which this technique was used, bleeding from the interdural space was well controlled and no persistent facial nerve paresis was identified. In the histological study, we confirmed that the MMA, the middle meningeal vein, and the meningeal branch of the mandibular nerve converged into the FS and many venous channels existed in the interdural space around the FS and the foramen ovale. CONCLUSION: Intra-FS MMA ligation is an effective method for control of bleeding from the interdural space of the middle fossa during the ATPA.