Operative Neurosurgery 29:399–407, 2025
CT-based validation of Hartel’s anatomical landmarks shows the foramen ovale is closer to the tragus and more medial than previously described. Revised needle trajectories, targeting 2–2.5 cm anterior to the tragus and between the inner canthus and midpupillary lines, may improve safety and accuracy in trigeminal procedures.
• Hartel surface anatomical landmarks for foramen ovale (FO) localization were assessed using CT scans in 99 adults (198 foramina).
• The FO is typically closer to the external auditory canal (mean 23.26 mm) and more medial (mean 25.43 mm from midline) than Hartel’s original description.
• FO is usually located between the eye’s inner canthus (IC) and midpupillary (MP) lines, not directly along the MP line as previously thought.
• Recommended needle trajectory: 2–2.5 cm anterior to tragus and targeting a point between the IC and MP lines, avoiding excessive medial/posterior displacement.
• A posteromedial “Danger Zone” exists within 20 mm of the midline and EAC, where vascular injury risk increases.
• Imaging guidance (fluoroscopy, CT) remains essential for safe and accurate needle navigation.
• These adjustments may improve procedural accuracy, safety, and patient outcomes for percutaneous trigeminal procedures.
• Further clinical and cadaveric validation is needed for these technique modifications.
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