Surgically Resected Skull Base Meningiomas Demonstrate a Divergent Postoperative Recurrence Pattern Compared with Superficial Meningiomas

Objective: This study aims to identify differences in the recurrence pattern of surgically resected skull base meningiomas compared with superficial intracranial meningiomas.

Methods: This study was a retrospective hospital-based analysis of all patients referred to our institution from January 1990 to June 2014 for surgical resection of meningiomas. The database constituted both patients with a first time presentation and those with evidence of recurrence presenting for a surgical evaluation. Tumor proliferation index (based on the MIB-1 index) and the overall time to recurrence of the cohort of surgically resected skull base and superficial meningiomas were documented. Kaplan–Meier curves and life tables were constructed for analysis of survival. SPSS v22.0 was used for statistical analysis.

Results: Overall, 398 intracranial meningiomas—269 (68%) superficial and 129 (32%) skull base—were available for review. Follow-up time ranged from 1 week to 250 months. Skull base lesions were found to have a significantly lower average MIB-1 index compared with their superficial counterparts (0.0413 vs. 0.0620, p = 0.001). Meningiomas in all the locations demonstrated a recurrence rate of 30% at an average of 100 months of follow-up. Subsequent to this point, however, the recurrence of skull base meningiomas demonstrated a plateau (250 months of follow-up) whereas superficial lesions were found to have a recurrence rate of 80% at 230 months of follow-up (p = 0.038).

Conclusion: As reflected by the difference in the MIB-1 index, surgically resected skull base meningiomas demonstrated a less aggressive behavior compared with superficial lesions. This was reflected in the clinical recurrence rate of 80% for the latter. This suggests that while skull base lesions may not necessarily need to be followed beyond 100 months, superficial meningiomas would require a greater long-term follow-up given their higher propensity for recurrence. Molecular markers such as the MIB-1 index are important parameters in this decision as well.