Preservation of the Posterior Meningeal Artery During Excision of a Foramen Magnum Meningioma: A Case Report.

A 56-year-old woman presented with a foramen magnum meningioma associated with headache and left hypoglossal nerve palsy. A vessel arising from the intradural vertebral artery was identified as the posterior meningeal artery based on an integrated assessment of its origin, course, and relationship to the tumor on three-dimensional angiography and at surgery. During temporary occlusion, the left abductor pollicis brevis motor-evoked potential (MEP) was present at 8 min and absent at 9 min. It was again detectable in the recording obtained 7 min after clip release, but subsequent responses were not consistently discernible. Stimulation intensity had been increased after signal loss, and dissection continued during occlusion, limiting attribution of the MEP changes to vessel occlusion or release. The vessel was preserved, and Simpson Grade IV resection was performed. Histomorphology supported meningothelial meningioma, CNS WHO Grade 1; the Ki-67 labeling index was 1%. This case illustrates vessel-preservation decisions informed by anatomical correlation and repeated neurophysiological assessment when vascular function is uncertain.