The natural history and growth rate of asymptomatic meningiomas: a review of 60 patients.

Little is known about the natural history and growth rate of asymptomatic meningiomas. To better delineate this problem, the authors reviewed the clinical records and imaging studies of the last 60 patients diagnosed with asymptomatic meningiomas at their institution. There were 45 women and 15 men, whose ages ranged from 38 to 84 years, with a mean age of 66 years. The most common tumor location was convexity (25 patients), but virtually all locations were represented. Three patients were lost to follow up. The average clinical follow-up review of the remaining 57 patients was 32 months (range 6 months to 15 years). None of the patients became symptomatic from an enlarging tumor during their follow-up period. Typically, once a meningioma was diagnosed, follow-up scans were obtained at 3 months, 9 months, and then yearly or every other year thereafter. Forty-five patients underwent follow-up scans, with comparison of tumor size to that found on the initial scan, over a period ranging from 3 months to 15 years. Thirty-five patients have shown no growth in their tumor size, with an average imaging follow up of 29 months (range 3-72 months). Ten patients have shown tumor growth calculated as an increase in the maximum diameter of the tumor. This growth ranged from 0.2 cm over 180 months to 1 cm over 12 months, with an average of 0.24 cm per year. Average imaging follow up for these patients was 47 months (range 6 months to 15 years). The authors conclude that patients with asymptomatic meningiomas need close clinical and radiological follow up to rule out other disease processes and to rule out rapidly enlarging tumors. Although the average follow-up time was short, the vast majority of these tumors appeared to show minimal or no growth over periods of time measured in years. With modern noninvasive imaging techniques, these tumors can be safely observed until they enlarge significantly or become symptomatic.