Endoscope-assisted Transmastoid Infralabyrinthine approach to the petrous apex: A new corridor for multicompartmental jugular foramen tumors.

Introduction: Multicompartmental jugular foramen tumors may extend anteriorly and superiorly toward the petrous apex, posing significant challenges for traditional surgical corridors. Research question: The authors study the feasibility of endoscope-assisted transmastoid infralabyrinthine approach (e-TIA) to access the superior aspect of petrous apex. Materials and methods: Five cadaveric specimens were studied. A reference object was placed transnasally at the petrous apex to assess surgical exposure. To assess the working space of e-TIA, cross-sectional area was measured using three-dimensional reconstruction. Furthermore, we reviewed three patients with multicompartmental jugular foramen tumor in which this corridor was used. Results: The e-TIA, initiated with a 30° endoscope using the chopstick technique, accessed the superior petrous apex, Meckel's cave, and the internal carotid artery (ICA) from its cervical to lacerum segments. Radiological analysis demonstrated that the approach trajectory shifts at the cochlea level. Cross-sectional area analysis revealed that the e-TIA corridor provides sufficient space for manipulation of the endoscope, suction, and drill. Clinically, near total resection was achieved in all cases without new neurological complications. Discussion and conclusion: The e-TIA offers a systematic extension to the superior petrous apex and the ICA from its cervical to the lacerum segments. utilizing an angled endoscope to enhance visualization. When combined with an anterolateral approach, this dual-corridor strategy provides a unique "looking-up" line of sight to the petrous bone. Overall, the e-TIA represents a promising option in selected multicompartmental jugular foramen tumors with petrous apex extension.