Simpson grade

Extent of surgical meningeoma resection

Grade 1

Macroscopically complete removal, including excision of dural attachment and abnormal bone.

Grade 2

Macroscopically complete removal, with coagulation of the dural attachment.

Grade 3

Macroscopically complete removal, without coagulation of dural attachment / extradural extensions (abnormal bone).

Grade 4

Partial removal.

Grade 5

Biopsy or decompression only.

Reference

Greenberg's Handbook of Neurosurgery, 7th edition