World Health Organization Grade I Convexity Meningiomas: Study on Outcomes, Complications and Recurrence Rates.

Background: The clinical significance of the Simpson grading system of extent of meningioma resection and its role as a predictor for recurrence of World Health Organization (WHO) grade I meningiomas have been questioned in the past, as microsurgery and knowledge of pathologic details have advanced.

Methods: Clinical and radiologic information on 112 patients with WHO grade I convexity meningiomas who underwent surgery over the past 20 years was retrospectively reviewed.

Results: The recurrence rate in the grade 0-I resection group was 2.9%, whereas in the grade II-IV resection group, the recurrence rate was 31% (P = 0.0001). In Cox regression analysis, Simpson grade 0-I resection was revealed as a significant predictor of recurrence-free survival (P = 0.021). The hazard ratio for recurrence after II-IV resection was 10.98 times higher than grade 0-I. Like the Simpson grading of resection, a similar trend of recurrence (grade I, 1.6% vs. grade II-IV, 28%, P = 0.0001) was observed in the Shinshu grade of resection. In univariate analysis, female gender and use of neuronavigation were also identified as independent predictors of recurrence-free survival after resection of WHO grade I meningiomas. Six months after surgery, use of antiepileptic medication was less in grade 0-I compared with other grades.

Conclusions: When histologic grade is fixed, the Simpson grading system is the prime predictor for recurrence of meningioma after resection. Grade 0-I resection is also beneficial in cutting off antiepileptic medication in patients with convexity meningiomas. Although complete tumor resection (grade 0-I) is the goal, the surgical approach should be tailored to each patient depending on the risks and surgical morbidity.