Anatomical basis of keyhole approach in treating aneurysms of the ophthalmic segment and its clinical significance

objective: To discuss the feasibility of supraobital keyhole approach in the treatment of aneurysms in the ophthalmic segment and provide the anatomic basis of forsupraorbital keyhole approach. Method: The neurovascular structures in the paraclinoid were observed in 21adult formalin-fixed cadaveric head specimens and their influences on the approach was recorded while many techniques were tried to overcome them. Supraorbital keyhole approach was performed in 9 fresh cadaveric head specimens to verify its feasibility. Result: The distance between the anterior margin of the optic chiasm and the tuberculum sella was 7.0±1.8 mm; the distance between the medial margins of the 2 optic nerves was 12.8±0.7 mm; the intracranial length of the optic nerve was 11.4±2.7 mm; the length of the supraclinoid internal carotid artery was 14.5±1.3 mm; the distance between the radicals of the 2 anterior clinic process was 21.2±0.8 mm; between the tines was 6.1±1.7 mm. The length, the width and the height of the anterior clinoid process were respectively 10.1±0.2 , 11.6±1.4, 4.9±0.7 mm. The resection of the anterior clinoid process, the tuberculum and the falciform ligament can offer a roomy space to work and control the proximal artery; the detailed data about the working area were achieved. Conclusion: The supraorbital keyhole approach is a candidate method to treat aneurysms of the ophthalmic segment.