Jacobson's nerve clues to the round window niche

Area of Science:

• Otolaryngology
• Anatomy
• Surgical Navigation

Background:

• The round window niche is crucial for cochlear implantation surgery.
• Visibility of the round window niche can be obscured during dissection via the facial recess.
• Jacobson's nerve presents a potential alternative landmark.

Purpose of the Study:

• To measure the distance between Jacobson's nerve and the round window niche.
• To assess the relationship between this distance and manubrium orientation.
• To investigate correlations with mastoid pneumatization.

Main Methods:

• Anatomical dissection of 41 adult temporal bones.
• Measurement of distances using a fenestrometer-type instrument under operative microscope.
• Radiographic assessment of mastoid pneumatization.

Main Results:

• Jacobson's nerve was identifiable in 81/82 temporal bones.
• Average distance from Jacobson's nerve to the round window niche was 2.1 mm (range 0-3.2 mm).
• No significant correlation found between distances, mastoid size, or manubrium orientation.

Conclusions:

• Jacobson's nerve is a consistently identifiable landmark.
• If visible on the promontory, Jacobson's nerve is within 3.3 mm of the round window niche with 95% certainty.
• This nerve serves as a reliable guide for cochlear implantation surgery.