Morphometric Analysis of the Retrolabyrinthine Approach to the Posterior Fossa

Area of Science:

• Neurosurgery
• Anatomy
• Radiology

Background:

• The retrolabyrinthine approach offers advantages over the retrosigmoid approach for internal acoustic canal (IAC) and cerebellopontine angle cistern surgeries.
• However, restricted exposure of the ventral brainstem and petroclival region can occur.
• Anatomical variability in Trautmann's triangle (TT) may complicate this approach.

Purpose of the Study:

• To evaluate posterior fossa anatomical parameters that may predict challenges during retrolabyrinthine approaches.
• To identify factors influencing surgical exposure of the IAC and petroclival region.

Main Methods:

• Radioanatomic analysis of 75 cerebral angiotomography exams.
• Identification of parameters potentially reducing surgical exposure areas.

Main Results:

• Significant variations observed in TT area (553%) and jugular bulb height (234%).
• Shorter distances from sigmoid sinus to posterior semicircular canal and high-riding jugular bulbs correlated with smaller exposure areas.
• Dominant/lateral sigmoid sinuses, less pneumatized mastoids, increased petrous slopes, and petroclival angles were associated with narrower angles of attack and smaller petroclival areas.

Conclusions:

• The posterior fossa exhibits considerable anatomical variation.
• These findings are essential for preoperative planning of retrolabyrinthine approaches.
• Consideration of these variations can lead to safer and more effective surgical procedures.