Hemodynamic changes associated with pregnancy, meaning blood flow changes, explain the growth of benign tumors in pregnant women. The study also identified some key characteristics associated with rapid growth of meningiomas in pregnant women.

Meningiomas are relatively common, usually benign tumors that arise in the tissues lining the brain (meninges). They cause problems when they growth large enough to affect brain functions. Several reports over the years have described meningiomas enlarging or becoming symptomatic during pregnancy. For this reason—and because meningiomas occur  more often in women than men—it has sometimes been assumed that rapid tumor growth is related to changes in hormone levels during pregnancy. This study sought to evaluate this theory and also to look at other characteristics of meningiomas in pregnant women.

The research team used the records of four university medical centers to identify 17 women with meningiomas requiring surgery during pregnancy, or shortly afterward. Surgery for meningioma was successful in 16 of the 17 patients; the remaining patient died before surgery. Most of the women developed meningioma-related symptoms during the third trimester of pregnancy or within 8 days after delivery. The most common symptoms of enlarging meningioma were changes in vision and facial paralysis or other cranial nerve palsies.

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Most of the tumors were located in the skull base region and were typical, low-grade benign tumors. At surgery, the tumors showed an unusual hypervascular pattern, which was not seen in meningiomas in nonpregnant patients. There was also a high rate of edema in and around the tumor.

These and other findings strongly suggested that the rapid tumor growth resulted from potentially reversible hemodynamic changes related to pregnancy. The pattern did not support the theory that meningioma growth resulted from hormone-induced cellular proliferation.

The results may help to explain the uncommon but well-documented occurrence of rapid meningioma growth during pregnancy. Since most meningiomas do not cause any symptoms, they may go undetected. Even if they are detected, they may require no treatment unless they grow.

Together with previous evidence, the findings may have implications for the management of meningiomas in women of child-bearing age. The primary author, Eriks A. Lusis, MD, of Washington University School of Medicine and his coauthors wrote, “[F]or the vast majority of women of child bearing age, we would not consider the presence of residual or unresected meningioma to be a contraindication to pregnancy.” In contrast, for patients with evidence of tumor growth or swelling, the authors suggest they might consider treating the tumor before pregnancy.

This study was published in Neurosurgery (2012;71(5):951-961).