Neuronavigation-Assisted Transmastoid Resection of a Petrous Apex Cholesteatoma Combined with Single-Stage Dynamic Facial Reanimation: Surgical Video.

Introduction: Petrous apex cholesteatomas are uncommon lesions that pose significant surgical challenges because of their proximity to the facial nerve, inner ear, petrous carotid artery, posterior fossa dura, and lower cranial nerves. The transmastoid approach offers a minimally invasive corridor to selected petrous apex lesions while avoiding more extensive skull base exposures. We present the microsurgical resection of a petrous apex cholesteatoma using a neuronavigation-guided transmastoid approach combined with simultaneous facial reanimation. Case Report: A 57-year-old man came with complete chronic left facial paralysis (House-Brackmann grade V) following mastoid surgery performed at another institution three years earlier. Magnetic resonance imaging demonstrated an expansile lesion involving the mastoid cavity and petrous apex, characterized by low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, absence of gadolinium enhancement, and marked diffusion restriction on non-echo-planar diffusion-weighted imaging, findings highly suggestive of cholesteatoma. Computed tomography revealed a destructive osteolytic lesion extending from the mastoid cavity into the petrous apex. Because of facial paralysis had been complete for more than two years, a single-stage facial reanimation procedure was planned. Dynamic reconstruction of the oral commissure was performed using temporalis muscle tendon transfer reinforced with autologous fascia lata grafting before tumor removal. A revision mastoidectomy was then performed. The surgical corridor to the petrous apex was developed through the infralabyrinthine-retrofacial window, located between the posterior semicircular canal superiorly, the jugular bulb inferiorly, the vertical mastoid segment of the facial nerve anteriorly, and the sigmoid sinus posteriorly. Image-guided neuronavigation provided continuous anatomical orientation and allowed real-time assessment of the depth and extent of tumor resection within the petrous apex. After complete microsurgical removal of the cholesteatoma, a small opening of the posterior fossa dura within Trautmann’s triangle enabled inspection of the operative cavity using 0° and 30° rigid endoscopes. Endoscopic exploration confirmed the absence of residual cholesteatoma within the petrous apex and cerebellopontine angle. Surgical cavity was reconstructed using multilayer closure with autologous fascia, fibrin sealant, abdominal fat graft, and titanium mesh cranioplasty. Results: The postoperative course was uneventful. During five years of radiological follow-up, no evidence of tumor recurrence was observed, and the patient achieved satisfactory facial symmetry with improvement in oral commissure function. Conclusion: The neuronavigation-assisted transmastoid infralabyrinthine-retrofacial approach provides a safe and effective corridor for selected petrous apex cholesteatomas while preserving critical neurovascular structures. The addition of endoscopic inspection improves the detection of residual disease, and simultaneous facial reanimation represents good strategy in patients with long-standing irreversible facial paralysis.