Vestibular Schwannoma Growth Patterns in 10 Year Follow Up

The natural history of Vestibular Schwannomas (VS) is better understood however tumor growth remains unpredictable. In particular the long term growth patterns are uncertain. The aim of this study was to look for any changes in growth rate over a 10 year period. A retrospective analysis of patients with VS managed in a tertiary referral center was performed. Patients treated with Stereotactic Radiosurgery or microsurgery were excluded. The computerised Radiology imaging System was used to analyze the magnetic resonance imaging (MRI) of patients diagnosed in the past 10 years. The tumor was measured on axial and sagital contrast-T1-weighted MRI to calculate tumor volume. All growth rates were calculated and significant growth was deemed as a change of greater than 15%. Patients were grouped by growth in the first 2 years following diagnosis and by tumor size. All subsequent growth was calculated and compared. In the 10 year period 104 patients with a newly diagnosed VS were identified. Nineteen patients had evidence of tumor regression in the first 2 years with 2 VS from this group showing evidence of growth later at 4 and 6 years. Forty-four patients showed no change in the first 2 years. Fourteen then decreased in size between 4 and 6 years. Nineteen continued to show no further evidence of growth over the 8 year follow up. Eleven patients showed evidence of growth, 9 at 2 years and 2 at 8years follow up. Forty-one patients showed evidence of growth in the first 2 years. Eleven from this group then stopped growing in 6 year follow up. Seven decreased in size in 6 years. Three patients increased over 6 years and then stopped growing. Three showed no evidence of growth in 6 years and started growing again at 8years. Seventeen VS continued to grow at variable rates. Our results compare with other studies and show that VS growth patterns change with time. In particular VS which show evidence of regression can exhibit growth after an interval period.