Growth rate of vestibular schwannoma

• One third of newly diagnosed vestibular schwannomas (VS) will grow in 1–3 years, and one half will grow on 5-year follow-up.
• Age and gender do not influence growth of VS.
• Tumor size and location do not predict tumor growth.
• Growth in the first observation year predicts further tumor growth.
• The average growth rate of a VS is 1 mm/year, whilst the average growth rate of a VS shown to grow is 3 mm/year.

Vestibular schwannoma (VS) is the most common tumor in the extra-axial posterior fossa compartment in adults. Growth rate is paramount to decision making regarding treatment and follow up of these tumors. We conducted a comprehensive review of the literature to answer four questions: What percentage of newly diagnosed VS will grow on follow-up? What factors correlate to tumor growth? What is the “normal” growth rate for sporadic VS? What factors characterize VS with rapid growth? Thirty-seven reports, with more than 4000 patients, fit our review criteria. One third of newly diagnosed VS will grow on follow-up of 1–3 years. However, after 5 years, up to one half will grow. Patient age and sex do not influence growth of VS. Hearing loss and vertigo at presentation do not predict tumor growth. It is unclear whether balance disturbance or tinnitus predict tumor growth. Tumor size and location do not predict tumor growth. Growth in the first year of observation is a strong predictor of tumor growth. The average growth rate of a VS is 0.99–1.11 mm/year. However, the expected growth rate for VS that have been shown to grow at first follow-up is 3 mm/year. Factors that may predict tumor growth of above 4 mm/year are cystic and hemorrhagic features in the tumor, and hormonal treatment. VS grow at an average 1 mm/year. VS that have been shown to grow at first follow-up should be considered for treatment, unless contraindicated. Long term follow-up is recommended for VS.