Endoscopic transmastoid posterior petrosal approach for locally aggressive tumors in the petrous part of the temporal bone involving the internal auditory canal, jugular foramen, and hypoglossal canal.

OBJECTIVE: The posterior petrosal approach is an established surgical method offering wide access to skull base lesions through mastoid air cells. The authors describe their experience with the endoscopic transmastoid "posterior petrosal" approach (EPPAP) for skull base tumors involving the internal auditory canal (IAC), jugular foramen, and hypoglossal canal. METHODS: The EPPAP was performed for 7 tumors (3 chordomas, 2 chondrosarcomas, 1 schwannoma, and 1 solitary fibrous tumor). All surgical procedures were performed under endoscopic visualization with mastoidectomy. The compact bone of the mastoid air cells and posterior surface of the petrous bone are carefully removed behind the semicircular canals. When removal of cancellous bone is extended superomedially through the infralabyrinthine space, the surgeon can expose the IAC and petrous portion of the internal carotid artery to reach the petrous apex (infralabyrinthine route). When removal of cancellous bone is extended inferomedially along the sigmoid sinus, the surgeon can safely reach the jugular foramen (transjugular route). Drilling of the inferior surface of petrous bone is extended further inferoposteriorly behind the jugular bulb to approach the hypoglossal canal and parapharyngeal space through the lateral aspect of the occipital condyle (infrajugular route). RESULTS: Of the 7 tumors, gross-total resection was achieved in 4 (57.1%), subtotal resection (> 95% removal) in 2 (28.6%), and partial resection (90% removal) in 1 (14.2%). Postoperatively, 2 of 3 patients with exudative otitis media showed improvement of hearing deterioration, as did 2 patients with tinnitus. Hypoglossal nerve palsy and swallowing difficulty were improved after surgery in 2 patients and 1 patient, respectively. In 1 patient with severe cranial nerve deficits before surgery, symptoms did not show any improvement. CONCLUSIONS: The authors present their preliminary experience with EPPAP for skull base tumors in the petrous part of the temporal bone and the lateral part of the occipital condyle involving the cranial nerves and internal carotid arteries. The microscope showed a higher-quality image and illumination in the low-power field. However, the endoscope could offer wider visualization of the surgical field and contribute to minimizing the size of the surgical pathways, necessity of brain retraction, and eventually the invasiveness of surgery. Thus, the EPPAP may be safe and effective for skull base tumors in the petrous region, achieving balance between the radicality and invasiveness of the skull base surgery.

Endoscopic transsphenoidal anterior petrosal approach for locally aggressive tumors involving the internal auditory canal, jugular fossa, and cavernous sinus.

OBJECTIVE Reports about endoscopic endonasal surgery for skull base tumors involving the lateral part of petrous apex remain scarce. The authors present their experience with the endoscopic transsphenoidal anterior petrosal (ETAP) approach through the retrocarotid space for tumors involving the internal auditory canal, jugular fossa, and cavernous sinus. METHODS The authors performed the ETAP approach in 10 patients with 11 tumors (bilateral in 1 patient) that extensively occupied the lateral part of petrous apex, e.g., the internal auditory canal and jugular fossa. Eight patients presented with diplopia (unilateral abducens nerve palsy), 3 with tinnitus, and 1 with unilateral hearing loss with facial palsy. After wide anterior sphenoidotomy, the sellar floor, clival recess, and carotid prominence were verified. Tumors were approached via an anteromedial petrosectomy through the retrocarotid triangular space, defined by the cavernous and vertical segments of the internal carotid artery (ICA), the clivus, and the petrooccipital fissure. The surgical window was easily enlarged by drilling the petrous bone along the petrooccipital fissure. After exposure of the tumor and ICA, dissection and resection of the tumor were mainly performed under direct visualization with 30° and 70° endoscopes. RESULTS Gross-total resection was achieved in 8 patients (9 tumors). In a patient with invasive meningioma, the tumor was strongly adherent to the ICA, necessitating partial resection. Postoperatively, all 8 patients who had presented with abducens nerve palsy preoperatively showed improvement within 6 months. In the patient presenting with hearing loss and facial palsy, the facial palsy completely resolved within 3 months, but hearing loss remained. Regarding complications, 3 patients showed mild and transient abducens nerve palsy resolving within 2 weeks, 3 months, and 6 months. Postoperative CSF rhinorrhea requiring surgical repair was observed in 1 patient. No patient exhibited hearing deterioration, facial palsy, or symptoms of lower cranial nerve palsy after surgery. CONCLUSIONS The ETAP approach can offer a simple, less invasive option for invasive skull base tumors involving petrous regions, including the internal auditory canal, jugular fossa, and cavernous sinus. The ETAP approach can reach more extensive areas in the extradural regions around the petrous bone. The authors' results indicate that the transsphenoidal retrocarotid route is sufficient to approach the petrosal areas in select cases. Further expansion of the surgical field is not always necessary. However, experience with intradural lesions remains limited, and the extent of tumor resection largely depends on tumor characteristics. Application of the ETAP approach should thus be carefully determined in each patient, taking into consideration the size of the retrocarotid window and tumor characteristics.