Medial (intra-cisternal) acoustic neuromas

Area of Science:

• Neurosurgery
• Neurology
• Otolaryngology

Background:

• Acoustic neuroma (AN) is a common tumor of the cerebellopontine angle.
• Medial or intra-cisternal AN is a rare subtype with distinct clinical and radiological features.
• Understanding the characteristics of medial AN is crucial for surgical planning and patient counseling.

Purpose of the Study:

• To review the clinical characteristics of medial acoustic neuroma (AN).
• To compare the presentation and outcomes of medial AN with non-medial AN.
• To evaluate the surgical outcomes, particularly facial nerve function preservation.

Main Methods:

• Retrospective review of 466 acoustic neuroma cases treated over 20 years.
• Identification of 6 patients (1.3%) meeting criteria for medial AN.
• Analysis of clinical presentation, magnetic resonance imaging (MRI) findings, and surgical outcomes.

Main Results:

• Medial AN patients exhibited a higher incidence of cerebellar and cranial nerve dysfunction (trigeminal, facial) alongside hearing loss at initial presentation.
• MRI revealed medial AN as cystic masses in the cerebellopontine cistern, typically without internal auditory canal involvement.
• Complete tumor removal was achieved in all cases, but facial nerve function preservation was unsatisfactory.

Conclusions:

• Medial AN presents clinically with unique neurological deficits and imaging findings.
• Despite successful resection, functional outcomes, especially facial nerve preservation, highlight challenges.
• Medial AN may represent a distinct clinical subtype impacting functional prognosis.