Minipterional and Sphenoid Ridge Keyhole Approaches: A Comparative Anatomic Study

The pterional craniotomy provides excellent transsylvian exposure but comes with cosmetic and functional drawbacks. Minimally invasive alternatives, including the sphenoid ridge keyhole (SRK) and minipterional (MiniPT) approaches, strive to reduce morbidity while maintaining adequate surgical access. No previous study has directly compared the anatomic exposure offered by MiniPT and SRK.

Eight adult cadaveric heads were dissected. Each specimen underwent SRK, and MiniPT craniotomies were performed sequentially. A neuronavigation system recorded 3-dimensional coordinates of 5 key anatomical targets around the circle of Willis. Surgical exposure area was calculated using vector cross-products, and angular exposure was determined using vector dot products. Measurements were compared between techniques using Student t-tests.

The MiniPT approach offered a significantly larger surgical exposure area compared to the SRK approach (882.3 ± 93.8 mm2 vs 442.2 ± 110.8 mm2; P < .001). MiniPT also provided significantly wider angular exposure for the tuberculum sellae (P = .03), internal carotid artery (P = .01), and contralateral posterior cerebral artery (P = .015). No difference was found for the contralateral middle cerebral artery (P = .85) and the ipsilateral posterior cerebral artery (P = .06). MiniPT consistently delivered broader operative angles, improving multidirectional access to deep anatomical targets.

Compared with the SRK approach, the MiniPT craniotomy provides significantly better surgical exposure and a broader angular access to critical structures around the circle of Willis. These results support the MiniPT as a more effective and versatile minimally invasive alternative for transsylvian approaches that require improved visualization and maneuverability.