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Foramen Magnum Meningioma

Last Updated: February 18, 2020

Resection of a Large Foramen Magnum Meningioma

Meningiomas comprise up to 20% of all intracranial tumors. Although only about 1 to 3% of meningiomas are located at the foramen magnum (FM), this tumor subtype comprises about 75% of all benign, intradural, extramedullary tumors of the cervicomedullary junction.

Like other meningiomas, foramen magnum meningiomas (FMMs) are more frequent in females and rare in children. The neural anatomy around the FM includes the lower cranial nerves, caudal medulla, rostral spinal cord, fourth ventricle, cerebellar tonsils, and inferior vermis. The vascular anatomy includes the vertebral arteries, posterior inferior cerebellar arteries (PICAs), and posterior spinal arteries. Although these structures are vulnerable to mass effect from FMMs, the slow growth rate of the tumor and subtle neurologic findings typically prevent early diagnosis.

Foramen magnum meningiomas originate from the dura of the lower third of the clivus and any portion of the FM circumferentially. Upper cervical spine meningiomas can extend cranially and are commonly called spinocranial FMMs.

For purposes of surgical planning, F...