Posterior Endoscopic Condyle-Sparing Approach (PECSA) to the Hypoglossal Canal: A Radiologic and Cadaveric Proof-of-Concept Study

Objectives: To describe a posterior endoscopic condyle-sparing approach (PECSA) to the endocranial hypoglossal canal as a minimally invasive posterior skull base corridor that avoids occipital condyle drilling. Design: Descriptive anatomical proof-of-concept study comprising independent radiological trajectory analysis and cadaveric dissection. Setting: Academic neurosurgical skull base laboratory. Participants: Five randomly selected de-identified clinical CT angiography/magnetic resonance imaging datasets and two adult formalin-fixed, silicone-injected cadaveric heads. Main Outcome Measures: Feasibility was defined as the establishment of a posterior suboccipital endoscopic corridor without occipital condyle resection, with visualization of the hypoglossal nerve and its canalicular entry point. Results: Radiologic planning descriptively identified a posterior midline entry point approximately 2 cm inferior to the inion, projecting to the ipsilateral squamous occipital bone and aligning with the hypoglossal canal while avoiding the brainstem and vertebral artery. The trajectory required approximately 10° to 12° of mediolateral angulation and a steep 50° to 70° craniocaudal bone-incidence angle. Cadaveric dissections confirmed that the corridor could be established without condylar drilling. Endoscopic visualization of the hypoglossal rootlets, hypoglossal nerve, canalicular entry point, vertebral artery, posterior inferior cerebellar artery, and spinal accessory nerve was achieved. Craniotomy-assisted validation confirmed the target anatomy and demonstrated relevant hypoglossal canal variation. Conclusions: PECSA demonstrated preliminary anatomical feasibility as a condyle-sparing route to the endocranial hypoglossal canal. This approach may offer a diagnostic corridor for selected lesions, but further quantitative cadaveric studies, hemostasis, biopsy simulation, and clinical validation are required before patient application.