Computed Tomography Study of the Retrosigmoid Craniotomy Keyhole Approach Using Surface Landmarks

Area of Science:

• Neurosurgery
• Anatomy
• Medical Imaging

Background:

• Previous keyhole studies lack practicality due to accessibility issues and surgical variations.
• Individual differences in surgical procedures limit the applicability of prior keyhole research.

Purpose of the Study:

• To determine surface landmarks for optimal keyhole placement in the retrosigmoid approach.
• To enhance the precision of keyhole positioning in neurosurgical interventions.

Main Methods:

• Reconstructed 3D skull images from 79 patients (149 hemiskulls).
• Analyzed skull-surface landmarks and positional relationships relative to the asterion and mastoid process.
• Defined a keypoint based on the sigmoid sinus groove's superior curvature projected onto the lateral skull surface.

Main Results:

• The asterion was consistently located near the posterior mastoid process extension line (<15 mm vertical distance).
• 93.29% of keypoints fell within a 7 mm radius circle centered at (-0.41, -3.01) on 3D CT images.

Conclusions:

• The spatial proportion of anatomical landmarks accurately guides keyhole localization.
• This method provides crucial technical support for performing the retrosigmoid approach effectively.