Since 1957, Simpson grading system is considered a predictive system for meningiomas recurrences. However, since then, there has been a great development of surgical equipment and neurosurgical technique, so the re-evaluation of this grading system should be considered.
Simpson Grading System for removal of meningiomas.
Macroscopically complete removal of tumour, with excision of its dural attachment, and of any abnormal bone. Includes resection of venous sinus if involved.
Macroscopically complete removal of tumour and its visible extensions with coagulation of its dural attachment.
Macroscopically complete removal of the intradural tumour, without resection or coagulation of its dural attachment or its extradural extensions.
Partial removal, leaving intradural tumour in situ.
Simple decompression, with or without biopsy 1).
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 grade 1 meningiomas has been questioned in the past, as microsurgery and knowledge of pathological details have advanced.
When histological grade is fixed, Simpson's grading system is the prime predictor for recurrence of meningioma after resection. Grade 0-I resection is also beneficial to cut off anti-epileptic medication in patients with convexity meningiomas. Although complete tumor resection (grade 0-I) is the goal, surgical approach should be tailored to each patient depending on the risks and surgical morbidity 3).
A Simpson Grade II rather than Grade I resection more than doubled the risk of recurrence at 10 years in the overall series (18.8% vs 8.5%). The impact of aggressive resections was much stronger in higher grade meningiomas.