The cochlea in skull base surgery: an anatomy study.

Area of Science:

• Neurosurgery
• Anatomy
• Otology

Background:

• Middle fossa approaches are common for accessing tumors and lesions near the internal acoustic meatus.
• These approaches carry risks of cochlear damage, leading to hearing loss, and injury to adjacent neural structures.
• Precise anatomical knowledge is essential for mitigating these surgical risks.

Purpose of the Study:

• To delineate the anatomical relationships of the cochlea within the middle fossa.
• To identify critical areas of the cochlea at risk during middle fossa and petrosectomy approaches.
• To provide guidance for surgeons to avoid cochlear damage and adjacent structure injury.

Main Methods:

• Examination of twenty adult cadaveric middle fossae.
• Utilized magnifications ranging from ×3 to ×40 for detailed visualization.
• Focused on the spatial relationship between the cochlea and surrounding neurovascular structures.

Main Results:

• The cochlea is situated inferior to the middle fossa floor, between the facial nerve and greater petrosal nerve (GPN).
• A significant portion of the cochlea lies adjacent to the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal GPN.
• The basal and middle turns of the cochlea are most vulnerable during drilling for middle fossa and anterior petrosectomy procedures.

Conclusions:

• A thorough understanding of cochlear anatomy and its relationship to surrounding structures is vital.
• This knowledge aids in preventing cochlear damage and subsequent hearing loss in middle fossa surgery.
• It also helps minimize injury to adjacent nerves during surgical interventions involving the cochlea.