Extended Retrosigmoid Craniotomy for Resection of a Cochlear Schwannoma

Area of Science:

• Neurosurgery
• Otolaryngology
• Oncology

Background:

• Cochlear schwannomas are rare tumors originating from the cochlear nerve.
• Posterior displacement of the facial nerve by these tumors complicates surgical preservation.
• Vestibular schwannomas extending into the internal auditory canal can mimic cochlear schwannomas.

Purpose of the Study:

• To describe surgical techniques for resecting cochlear schwannomas with posterior facial nerve displacement.
• To emphasize strategies for facial nerve preservation during complex schwannoma surgery.

Main Methods:

• A right extended retrosigmoid craniotomy was performed.
• Intraoperative facial nerve stimulation was used for identification and mapping.
• Tumor debulking was achieved through superior and inferior dissection planes, preserving a thin tumor layer adhered to the nerve.

Main Results:

• The facial nerve was found posteriorly displaced and splayed over the tumor.
• The facial nerve was preserved in continuity, with a thin tumor layer left for protection.
• Postoperative facial nerve function was House-Brackmann grade 2, with no new neurological deficits.

Conclusions:

• Early facial nerve stimulation is crucial for identifying displacement.
• Meticulous debulking via multiple corridors balances tumor resection with nerve preservation.
• Careful consideration of nerve adherence is vital for successful surgical outcomes in cochlear schwannoma resection.