Cystic trochlear nerve schwannoma. Case report

Area of Science:

• Neurosurgery
• Neuropathology

Background:

• Schwannomas of the trochlear nerve are rare, with only 26 reported cases.
• Five previously reported cases exhibited a cystic component with a solid portion.
• Complex skull base approaches are typically used for schwannoma removal.

Observation:

• A 52-year-old female presented with diplopia, facial palsy, hearing loss, right-sided hemiparesis, and gait instability.
• MRI revealed a 2.5-cm left-sided extra-axial lesion compressing the brainstem at the pontomesencephalic junction.
• The lesion was successfully resected via a retrosigmoid craniotomy.

Findings:

• Postoperative neurological deficits significantly improved.
• At 28-month follow-up, the patient experienced only mild diplopia and right facial hypesthesia.
• This case highlights a rare pontomesencephalic cystic trochlear schwannoma.

Implications:

• The retrosigmoid approach provides a simpler and effective surgical option for cystic trochlear schwannomas.
• Successful resection led to considerable improvement in neurological function.
• This case expands the understanding of rare brainstem-related schwannoma presentations and management.