gms | German Medical Science

Objective: 60 years after its initial description, the prognostic value of the Simpson grading in meningioma surgery is increasingly discussed. In particular, a uniform location-independent applicability and the prognostic value in recurrent tumors remains unclear but can distinctly influence surgical strategies.

Methods: Correlation of tumor recurrence with Simpson grading and after dichotomization into gross total (GTR, grade I+II) and subtotal (STR, grade ≥III) resection was investigated in 931 cranial surgeries performed for primary diagnosed and recurrent meningiomas.

Results: In 826 patients with primary diagnosed meningiomas, Simpson grading correlated with tumor location (p<.001). Within a median follow-up of 50 months, recurrence was observed in 107 of 803 patients (13%). Both STR (HR: 1.87; p=.004) and rising Simpson grade (p=.002) correlated with tumor progression. In 268 convexity meningiomas, the frequency of recurrence correlated with Simpson grade (p=.034) but was similar after grade I and II, tended to increase after grade III (HR: 2.35, p=.087) and was higher after grade IV resections (HR: 7.35, p=.003). Hence, the risk of recurrence was higher after STR than after GTR (HR: 4.21, p=.001). No correlation between the Simpson grade and recurrence was found in 102 falx and 38 posterior fossa meningiomas. In 325 skull base tumors, risk of recurrence was only increased after grade IV resections (HR: 3.26, p=.017) and similar after GTR and STR. In 105 patients undergoing surgery for the first meningioma recurrence, Simpson grades were significantly higher than in surgeries for primary diagnosed tumors (p<.001). Tumor location correlated with Simpson grade (p=.003) and risk of STR was increased in skull base (OR: 6.16; p=.002) and posterior fossa (OR: 5.26, p=.018) as compared to convexity meningiomas. Second recurrence was observed in 38 patients (36%) after a median interval of 26 months. No correlation was found between the extent of resection and progression. In 49 grade IV resected skull base meningiomas, recurrence was independent of the postoperative tumor volume (p=.615).

Conclusion: In primary diagnosed meningiomas, the Simpson grading is not equally prognostic in all anatomic locations and best applicable in convexity tumors. A lower impact of STR should be considered during surgery for skull base, posterior fossa and falx meningiomas. The Simpson grading is not applicable to estimate prognosis in recurrent meningiomas.