Transcanal Transpromontorial Approach for Resection of Tumors of the Inner Ear, Internal Auditory Canal, and Cerebellopontine Angle: An Evolution in Technique

Objective: The aim of this study is to investigate the outcomes of surgical resection of tumors of the inner ear, internal auditory canal, and cerebellopontine angle via the transpromontorial approach.

Study Design: Single institutional retrospective chart review.

Setting: Tertiary referral center.

Subjects and Methods: All adult patients with tumors of the inner ear, internal auditory canal, or cerebellopontine angle who underwent transcanal transpromontorial resection from 2016 to 2020 with preoperative magnetic resonance imaging (MRI). The approach involves removing all ear canal skin, tympanic membrane, and ossicles, followed by wide canalplasty to expose second genu of facial nerve, jugular bulb, tympanic facial nerve, and the vertical petrous carotid artery. The stapes is removed, and the cochlea is fully opened to expose the fundus of the internal auditory canal. The hypotympanum is opened to expose the anterior, inferior, and posterior aspect of the internal auditory canal from the porus to the fundus. After tumor dissection, the Eustachian tube is obliterated and the middle ear and ear canal is filled with abdominal fat. The ear canal is closed with a laterally based tragal skin flap which is sutured to the cut edge of the conchal skin. The primary outcome measure was postoperative House-Brackmann (HB) facial nerve score, extent of resection, operative times, residual tumor on MRI, and complications.

Results: Ten patients underwent transcanal transpromontorial resection of tumors of the inner ear, internal auditory canal, or cerebellopontine angle—seven patients had vestibular schwannomas, two had cochlear schwannomas, and one had a cavernous hemangioma of the internal auditory canal. Nine patients had class D hearing and one patient had class C hearing preoperatively. Median tumor diameter and volume were 15.3 mm (9–17.6) and 0.5 cm³ (0.1–0.9), respectively. The median follow-up was 12.2 months (0.6–23.8). All patients had a gross total resection, and for six patients with postoperative MRI, none had residual disease. Three patients (HB 2—2 patients, HB 5—1 patient) developed facial nerve weakness immediately following surgery, but at last follow-up, only one had any weakness (HB 2). The one patient who developed HB 5 weakness immediately following surgery had preoperative hemifacial spasm and facial weakness (HB 3). Two patients developed CSF leak, both of which required return to the operating room for repair, and one patient developed chemical meningitis. Median length of stay was 4 days (2–7), and median OR time was 291 minutes (129–566). Initially, the procedure was performed predominantly with the endoscope, which was gradually replaced with the microscope for portions of the case (skeletonizing internal auditory canal, tumor dissection) before completing replacing the endoscope with the microscope. Six tumors were removed with endoscopic assistance and four were removed completely with the microscope. Additionally, operative times were significantly negatively associated with case order (coefficient—27.8 minute/case, p = 0.046, R ² = 0.41) on linear regression.

Conclusion: Transcanal transpromontorial approach is an effective and safe option for the management of small tumors of the inner ear, internal auditory canal with limited CPA extension in patients with poor hearing.

Die Autoren geben an, dass kein Interessenkonflikt besteht.

Publikationsverlauf

Artikel online veröffentlicht:
12. Februar 2021