Surgical Management of Foramen Magnum Tumors



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Treatment of foramen magnum lesions requires a variety of surgical approaches, including the midline suboccipital, paramédian suboccipital, far-lateral, extreme lateral, and transoral approaches. Between 1976 and 2000, we resected 264 foramen magnum tumors (transoral series was not included). The selection of a specific approach is based on a combination of the surgeon's preference; the lesion's location, size, and presumed histopathology; and whether a lesion is extradural, intradural, or intramedullary. Purely extradural lesions are treated with an approach determined by location (i.e., transoral for anterior lesions, and suboccipital for posterior lesions). However, the transoral approach provides limited working space, and a posterolateral approach may be preferred for some anterior extradural lesions. For intradural lesions, another disadvantage of the transoral approach is risk of cerebrospinal fluid leak. As a result, an anterior intradural lesion is best treated with a posterolateral approach. The choice of approach for intramedullary lesions is dictated by the \"two-point method,\" in which the surgical trajectory is determined by a line drawn between the center of the lesion and the point where the lesion comes closest to the surface. The floor of the fourth ventricle is extremely eloquent and is avoided when possible. Although each of the approaches to the foramen magnum has advantages, the far-lateral approach is the workhorse for access to the anterior, lateral, and posterolateral foramen magnum. This approach is reliable, safe, fast and provides control of the vertebral artery. The far-lateral approach can be tailored with various degrees of condylar resection, depending on the lesion being treated. We rarely remove more than the posterior one-third of the condyle, and no postoperative instability has resulted. The far-lateral approach can be combined with other approaches as needed. The extreme lateral approach, requiring mobilization of the vertebral artery and aggressive condylar resection, is rarely necessary. Resection of foramen magnum tumors is facilitated with the use of electrophysiological monitoring and EEC burst suppression. Image guidance aids with tumor localization, resection, and identification of surrounding structures. For tumors and approaches affecting the lower cranial nerves, temporary tracheostomy and a feeding tube should be considered proactively. The anterior spinal artery must always be protected. Finally, when treating foramen magnum lesions, \"exposure is everything\" and should be obtained through bone removal rather than brainstem retraction.

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