Growth Patterns of Small Intracanalicular Vestibular Schwannomas

Area of Science:

• Neurosurgery
• Radiology
• Oncology

Background:

• Vestibular schwannomas are tumors arising from the vestibulocochlear nerve.
• Intrameatal vestibular schwannomas are a subset located within the internal auditory canal.
• Small intrameatal vestibular schwannomas require careful management due to potential growth and symptoms.

Purpose of the Study:

• To describe the natural history of small intrameatal vestibular schwannomas (5 mm or less).
• To evaluate tumor growth patterns and treatment conversion during active surveillance.
• To inform management guidelines for this specific tumor subset.

Main Methods:

• Retrospective case series at a tertiary referral center.
• Inclusion of patients with small intrameatal vestibular schwannomas (≤5 mm) and ≥3 years of MRI surveillance.
• Observational study focusing on tumor growth and treatment decisions.

Main Results:

• Tumor growth observed in 36% (n=27/74) of patients over a median 79-month surveillance period.
• Twelve percent (n=9/74) of patients transitioned to surgical or radiotherapy treatment at a median of 77 months post-diagnosis.
• Demonstrates a significant rate of growth and need for intervention in a subset of these tumors.

Conclusions:

• Findings support continued active surveillance for small intrameatal vestibular schwannomas.
• Recommends maintaining current magnetic resonance imaging (MRI) surveillance protocols, consistent with those for larger tumors.
• Highlights the importance of long-term monitoring for this patient group.