How do spinal schwannomas progress? The natural progression of spinal schwannomas on MRI.

Abstract

Little is known about the progression of spinal schwannomas. The aim of this study was to determine the natural progression of spinal schwannomas and establish the risk of tumor growth. This study retrospectively analyzed data from 23 patients (12 men and 11 women, 40-89 years old) with schwannomas detected by MRI. The mean follow-up period was 5 years (range 2-10 years). The absolute and relative growth rates of the tumors were calculated. The average tumor size was 1495 mm(3) at the initial visit and 2224 mm(3) at the final follow-up. The average absolute growth rate was 139 mm(3) per year, and the average relative growth rate was 5.3% per year. Tumors were classified into 3 groups based on enhancement patterns: isointense/hyperintense (iso/high; 11 cases), rim enhancement when enhancement was peripheral (high/rim; 5 cases), and heterogeneous/heterogeneous (hetero/hetero; 7 cases) based on Gd-enhanced T2-weighted MRI. The average absolute growth rates of the 3 lesion groups were 588 mm(3), 957 mm(3), and 3379 mm(3), respectively (p < 0.01). Although the tumors classified as iso/high and high/rim on T2-weighted Gd-enhanced MR images were small and grew very little, most tumors with hetero/hetero classification increased in size. Hetero/hetero-type tumors should be followed closely and may require surgery.