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Modern surgical techniques enable safe excision of convexity meningiomas, researchers report

Tuesday, October 14 2008 | Comments

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What's This? Modern image-guided, minimally invasive surgical techniques can be used to safely remove convexity meningiomas with very low operative mortality, but recurrence rates depend on the type of meningioma, based on the findings of a recently published retrospective study.

Researchers from Harvard Medical School retrospectively reviewed 163 cases (females, n=120) of convexity meningiomas operated on at Brigham and Women's Hospital in Boston, Massachusetts, between 1986 and 2005. The median age of the patients at diagnosis was 57 years (range, 20 to 89 yrs). Overall, the female:male ratio was 2.7:1, but for the patients with atypical and malignant tumors, the female:male ratio was 1:1. The median age of the patients with benign tumors was 56 years, whereas the median age of the patients with atypical or malignant tumors was 72 years.

Only tumors with minimal attachment to the dura of the sinus, or the draining veins, that were able to be detached easily and completely during surgery were considered to be convexity meningiomas. All of the surgeries were performed through standard craniotomies using microsurgical techniques, and image-guided surgery was used on all cases during the last 5 years of the study period (n=48). The majority of the tumors were located in the frontal lobe, followed by the parietal, temporal, and occipital lobes. Eighty-five were located on the left side and 80 were on the right side. The median maximum tumor diameter was 3.5 cm (range, 0.5 cm to 7.5 cm).

A total of 172 surgeries were performed. The tumors were found to be benign in 144 of the cases (88.3%), atypical in 16 (9.8%), and anaplastic/malignant in 3 (1.8%). Six of the benign tumors had borderline atypical features.

The median follow-up was 28 months (range, 1 to 13 yrs). Seventy-five of the patients (46%) were followed for >=3 years. There were no deaths in the 30-day postoperative period. Eleven of the patients died during the total follow-up period, including 10 deaths in patients aged >=65 years. None of the deaths was related to the tumor or the surgical procedure.

The overall complication rate was 9.4% and included 3 cases (1.7%) of new neurological deficits, all of which were cases of increased hemiparesis in patients who had presented with preoperative motor deficits. Each of these cases also involved large tumors (maximum diameter, >4 cm), and 2 were in elderly patients (aged 72 and 84 years) with invasive tumors.

The rate of major morbidity was 5.5% and included intracranial hematoma that required postoperative evacuation (n=1), postoperative infection (n=5), and cardiac complications (n=2). There was no significant difference in the morbidity for the patients aged <65 years and those aged >65 years.

The 5-year recurrence rate was 1.8% for benign meningiomas, 27.2% for atypical meningiomas, and 50% for anaplastic meningiomas. The 2 cases of benign tumor recurrence involved tumors with borderline atypical features and high MIB-1 indices. These cases had a 5-year recurrence-free survival rate of only 55.9%, which the authors said more closely approximated the survival rate of atypical tumors. For the entire cohort, the 5-year actuarial survival rate was 90%.

This study, which the authors characterized as the largest study of convexity meningiomas in the literature, demonstrated that convexity meningiomas can be safely removed using modern image-guided techniques, with low operative mortality.

However, although the researchers found that the benign convexity meningiomas with a Simpson grade I complete excision had a very low rate of recurrence, the atypical and malignant tumors had significantly higher recurrence rates. They suggested that borderline atypical tumors be considered to behave more like atypical rather than benign lesions and recommended obtaining longer-term follow-up data to more accurately determine the recurrence rates of benign meningiomas. (Morokoff AP, et al. Neurosurgery 2008;63:427-434.)

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