The endolymphatic sac: microsurgical topographic anatomy

Area of Science:

• Neuroanatomy
• Otolaryngology
• Surgical Anatomy

Background:

• The endolymphatic sac is integral to the auditory system and its function.
• Its anatomical location places it within the surgical field for posterolateral cranial base procedures.
• Damage to the endolymphatic sac can lead to significant hearing impairment.

Purpose of the Study:

• To precisely define the anatomical location and dimensions of the endolymphatic sac.
• To provide critical spatial data for neurosurgeons operating on the posterolateral cranial base.
• To enhance understanding of the endolymphatic sac's relationship with adjacent neurovascular structures.

Main Methods:

• Bilateral exposure and dissection of the endolymphatic sac in 10 anatomic specimens.
• Calip er measurements of the sac's center relative to the internal auditory meatus and XIth nerve in the jugular foramen.
• Measurement of distances to the petrous ridge and the petro-sigmoid intersection, along with sac dimensions.

Main Results:

• The endolymphatic sac's average distance from the XIth nerve was 15.7 mm (posterosuperior) and from the internal auditory meatus was 13.3 mm (posterior).
• The sac's center was located 24.1 mm anterior to the petro-sigmoid intersection and 11.5 mm below the petrous ridge.
• Average sac dimensions were 3.83 mm in width and 3.80 mm in height.

Conclusions:

• Detailed anatomical measurements of the endolymphatic sac are established.
• This data offers valuable spatial reference points for surgical navigation in the posterolateral cranial base.
• Accurate knowledge of endolymphatic sac location aids in minimizing surgical risks to hearing function.