An external reference to identify the internal auditory canal in middle fossa surgery

Area of Science:

• Neurosurgery
• Anatomy
• Temporal Bone Surgery

Background:

• Traditional middle fossa landmarks (facial hiatus, arcuate eminence) demonstrate unreliability in surgical navigation.
• Precise identification of surgical anatomy within the middle fossa is crucial for operative success and patient safety.

Purpose of the Study:

• To establish a novel, reliable external reference point for precise surgical anatomical identification in the middle fossa.
• To validate a new method for locating the malleus head as a primary surgical landmark.

Main Methods:

• Utilized 20 adult temporal bones, identifying the malleus head within the middle fossa.
• Established the lateral cortex of the temporal squamosa at the zygomatic root as the external reference plane.
• Measured the distance and orientation from the reference plane to the malleus head.

Main Results:

• The malleus head was consistently located 18 mm medial to the external reference cortex, along a perpendicular line.
• Extending this line through the malleus head bisected the internal auditory canal, confirming anatomical relationships.
• The technique was successfully applied in six patients undergoing middle fossa surgery.

Conclusions:

• The described external reference method provides precise localization of the malleus head, serving as an optimal initial landmark.
• This technique facilitates safer identification of adjacent critical structures, including the geniculate ganglion, internal auditory canal, and superior semicircular canal.
• The findings offer a valuable tool for enhancing precision in middle fossa surgical procedures.