Endoscopic-Assisted Resection of Anterior Foramen Magnum Meningiomas through a Midline Suboccipital Subtonsillar Approach

Objectives: To demonstrate the feasibility of safe resection of anterior foramen magnum meningiomas through an endoscopic-assisted posterior midline suboccipital subtonsillar approach.

Design: Illustrating the surgical steps and outcome of this approach.

Setting: Evidence of CSF cleft between the tumor and brainstem/spinal cord on T2Wi MRI and homogeneous contrast enhancement. Semi-sitting positioning with extensive electrophysiological neuromonitoring and transesophageal echocardiogram. Preoperative tracheotomy can be considered in cases of preoperative dysphagia/respiratory distress. A standard midline incision with bilateral suboccipital craniotomy and C1-laminotomy is performed. After partial resection and elevation of the tonsils, tumor is debulked unilaterally around the lower cranial nerves and the vertebral artery, devascularized from the clival dura, and then dissected from the brainstem. Endoscopic-assisted removal of its anterior portion follows. The same procedure is repeated from the opposite site for the contralateral portion, before approaching the purely anterior part with endoscope assistance.

Participants: Four consecutive patients.

Main Outcome Measures: Grade of tumor resection and outcome (mRS).

Results: Clinical outcome and grade of resection are comparable to other series of patient treated with other foramen magnum approaches.

Conclusion: Anterior foramen magnum meningiomas can be safely removed through this relatively faster midline approach with bilateral exposure of lower CNs and vertebral arteries and lower approach-related morbidity (no condyle drilling). The surgical corridor is created by the tumor during debulking reducing need for brain retraction and the removal of the anterior dural attachment coagulated under the microscope is verified and completed endoscopically with pituitary curettes (Simpson II).

No conflict of interest has been declared by the author(s).