Extra-axial cavernous malformations of the foramen magnum: illustrative cases

BACKGROUND Extra-axial cavernous malformations involving the foramen magnum are rare, and preoperative diagnosis becomes difficult when they mimic meningiomas. OBSERVATIONS The authors present 2 cases of extra-axial cavernous malformations involving the foramen magnum. Surgical removal of the lesions was performed via far lateral craniotomy. The authors investigate the disease and elaborate the differential diagnosis. LESSONS The authors recommend that extra-axial cavernous malformations should be considered in the differential diagnosis of lesions in the foramen magnum region. Intraoperative frozen sections are helpful to the diagnosis, and resection warranted a favorable long-term outcome.