Endoscopic Epidural Anterior Transpetrosal Approach (Endoscopic Kawase's Approach) for Meningiomas Around the Petrous Apex

BACKGROUND AND OBJECTIVES: The anterior transpetrosal approach (ATPA) is a standard technique for petrous apex lesions, but conventional microscopic ATPA (mATPA) remains technically demanding. The authors previously developed a purely endoscopic subdural ATPA (esATPA) and subsequently modified it into an endoscopic epidural ATPA, which can be termed endoscopic Kawase's approach (eKawase). This study aims to describe the surgical technique of eKawase and compare its outcomes with those of esATPA and mATPA. METHODS: This retrospective study included 30 patients with meningiomas around the petrous apex treated through mATPA (n = 10), esATPA (n = 10), or eKawase (n = 10) between 2014 and January 2026. Clinical characteristics, operative results, and complications were compared among the 3 groups. RESULTS: Operative time was significantly shorter in the endoscopic groups (esATPA and eKawase) than in the microscopic group. Blood loss and resection rates were comparable across all groups. Superior anatomic orientation in eKawase, achieved by visualizing landmarks such as the greater superficial petrosal nerve and arcuate eminence similar to mATPA, allowed for more extensive bone removal compared with esATPA. Consequently, eKawase facilitated access to tumors extending posterior to the internal auditory canal, a feature significantly less common in the esATPA group. While postoperative temporal lobe edema showed a trend toward being higher in the eKawase group, all related neurological symptoms were transient. CONCLUSION: eKawase is a feasible and effective minimally invasive alternative to mATPA, offering better anatomic orientation than the subdural route. While esATPA is effective, eKawase may provide an advantage for tumors with significant posterior extension. Meticulous venous assessment and atraumatic dissection are essential to prevent temporal lobe edema.