A 3-dimensional computed tomographic procedure for planning retrosigmoid craniotomy

Area of Science:

• Neurosurgery
• Radiology
• Anatomy

Background:

• Retrosigmoid craniotomies traditionally rely on external cranial landmarks.
• The location of these landmarks, like the asterion, varies significantly relative to the underlying transverse-sigmoid sinus complex.
• This anatomical variability poses a risk of sinus injury during surgical planning.

Purpose of the Study:

• To introduce and validate a novel procedure for planning retrosigmoid craniotomies.
• To utilize 3-dimensional (3D) computed tomographic (CT) imaging to project the transverse-sigmoid sinus complex onto the external cranial surface.
• To enhance the safety and accuracy of retrosigmoid craniotomy by providing a more reliable surgical guide.

Main Methods:

• A 3-step procedure involving marking the sinus on internal 3D CT images.
• Transferring these internal marks to the external cranial surface using axial images.
• Verifying the accuracy of the transferred external marks on 3D reconstructions.

Main Results:

• Craniotomies planned with the 3D CT imaging procedure accurately matched surgical findings in 8 patients.
• Morphometric analysis in 30 additional patients revealed significant individual variations in the position of the transverse-sigmoid sinus junction relative to traditional landmarks.
• The study confirmed the unreliability of standard anatomical landmarks for precise sinus localization.

Conclusions:

• Standardization of retrosigmoid craniotomy based on variable anatomical landmarks increases the risk of sinus injury.
• The proposed 3D CT imaging-based procedure offers a more accurate and reliable method for surgical planning.
• This technique serves as a valuable tool for improving the safety of retrosigmoid craniotomies.