From Origin to Resection: A Technical Note on the Implications of the Origin of Foramen Magnum Meningioma

Objectives: Foramen magnum meningiomas (FMMs) pose surgical challenges because of their location adjacent to important neurovascular structures. Knowledge of their course and tailored surgical techniques are important for safe resection. This report discusses the origin and pathogenesis of FMMs and discusses the associated surgical implications. Methods: We suggest that the developmental origin of FMMs may correlate with the transitional point between the extradural/extracranial (V3) and intradural/intracranial (V4) segments of the vertebral artery (VA), lateral to the artery entry into the dural space. This hypothesis is based on anatomical observation and intraoperative correlation in our experience. Results: This case illustrates the surgical significance of this potential site of origin, which requires exposing the atlanto-occipital joint, meticulously resecting the synovium overlying the dura, and using a tailored dural incision above the V3 segment to provide maximum definition of the tumor attachment. The endoscope facilitates removing tumor attachment that is hidden from direct microscopic visualization. These strategies protect the VA and surrounding structures while allowing safe and effective resection. Conclusion: The origin of selected FMMs at the transitional point between the extradural and intradural VA segments makes the far-lateral craniotomy approach an effective technique for resection. In these ventrolateral FMMs, the dural attachment localizes near this transitional point. A far lateral approach with endoscopic visualization allows for precise tumor excision with a lower risk to adjacent neurovascular structures. Recognition of this potential origin may assist in refining dural incision strategy and optimizing surgical exposure while minimizing manipulation of adjacent neurovascular structures.