Is the Simpson Grading System Applicable to Estimate the Risk of Tumor Progression After Microsurgery for Recurrent Intracranial Meningioma?

We analyzed the applicability of the Simpson grading system to estimate the risk of tumor recurrence after microsurgery for recurrent meningiomas. Correlations between the Simpson grade and the extent of resection (EOR) (gross total resection [Simpson grade I and II] vs. subtotal resection [Simpson grade ≥III]) with tumor relapse after microsurgery for meningioma recurrence were investigated compared with the findings in primary diagnosed tumors. Location-specific differences were further elucidated in subgroup analyses. A total of 829 individuals (88% in group A) with primary diagnosed meningioma and 109 patients with first postoperative recurrence (12% in group B) who underwent surgery were included. In group A, both Simpson grade (P = 0.003) and EOR (P < 0.001) correlated strongly with recurrence. In group B, Simpson grade correlated with tumor location (P = 0.030), and the risk of subtotal resection was greater in the posterior fossa (odds ratio, 5.26; P = 0.018) and skull base (odds ratio, 6.16; P = 0.002) meningiomas. Older age at tumor relapse (hazard ratio [HR], 1.05; P = 0.001), male sex (HR, 2.19; P = 0.02), and grade 2/3 histologic findings (HR, 2.18; P = 0.02). However, neither the Simpson grade nor dichotomized EOR correlated with further tumor recurrence. The frequency of postoperative complications was similar in both groups. Surgery for recurrent meningiomas is not generally associated with an increased risk of postoperative complications compared with resection of primary diagnosed tumors. However, the Simpson grade and EOR in recurrent meningiomas correlated poorly with further tumor relapse. The lower prognostic value of the tumor remnants left behind during microsurgery for recurrent meningiomas should be considered when operating on lesions that can be surgically challenging. •We analyzed the applicability of the Simpson grade after surgery for recurrent meningiomas.•The Simpson grade is a poor predictor of second recurrence after surgery for recurrent meningioma.•Surgery for recurrent meningioma is safe.•A retentive surgical treatment should be considered for resection of recurrent meningioma in surgical challenging locations.