Improving results in patients with foramen magnum meningiomas by translating surgical experience into a classification system and complexity score.

Foramen magnum meningiomas (FMMs) are challenging lesions and controversy still exists regarding their optimal management. In the present paper, we propose some principles of surgical treatment of FMMs. We analyzed our series of 39 patients: the average maximum diameter was 31.1 mm (sd, 10.7). In two cases, there was extradural extension. We operated all anterior lesions through dorsolateral approach to craniovertebral junction and all posterior lesions through midline suboccipital approach and C1 laminectomy, following the prevalence of side of the tumor. There were no complications except for one case of post-operative hypoglossus paresis. We translated our experience with surgery of foramen magnum meningiomas into a classification system and a complexity score, in order to assign a score to each individual case and plan the surgical strategy. When the complexity score is 5 or more, we propose subtotal removal, in consideration of the benign nature.