Clinical anatomy on keyhole approach in treating basilar bifurcation aneurysms

Objective: To discuss the feasibility of keyhole approach in treating basilar bifurcation aneurysms. Methods: Endoscope-assisted supraorbital keyhole approach and subtemporal approach were performed in 21 adult formalin-fixed cadaveric head specimens and 9 fresh adult cadaveric head specimens to mimic the clipping of basilar bifurcation aneurysms. The exposure scope, work scope and obstruction were recorded while several techniques were tried to overcome them. Results: The distances from the zygomatic process, the supraorbital foramen and zygomaticotemporal suture at the superior margin of the zygomatic arch to ipsilateral and contralateral posterior clinoid process were respectively 61.5±1.7 mm, 92.1±3.6 mm, 33.5±3.1 mm, 73.6±1.1 mm, 95.6±1.7 mm and 52.3±2.2 mm. Six lines can be got from the zygomatic process, the supraorbital foramen and the zygomaticotemporal suture at the superior margin of the zygomatic arch to ipsilateral and contralateral posterior clinoid process respectively. The angles between these six lines and the midline were respectively 36.6±1.2, 8.5±2.3, 82.6±3.0, 45.1±3.0, 30.5± 3.4 and 83.5±4.0 degrees. The endoscope-assisted supraorbital keyhole approach and the subtemporal keyhole approach can arrive the operating area exposed well. Conclusions: The endoscope-assisted keyhole approach can be applied to treat basilar bifurcation aneurysms.