gms | German Medical Science

Objective: To retrospectively evaluate our surgical technique and results in the management of anterolateral foramen magnum (FM) meningioma with the posterolateral approach, and to adapt our prospective management regarding surgical indication, epidural transposition of the vertebral artery (VA), drilling of the occipital condyle and extent of tumor resection.

Methods: Between 1992 and 2008, sixteen women and ten men (aged 28–82), were referred for an anterolateral FM meningioma. All patients were symptomatic, with all meningiomas inserting at C0 (FM rim) and extending to the clivus in 4, to the cervical canal in 10, and to both in 12 cases. Twenty-two were operated by a posterolateral approach including laminectomy, suboccipital hemicraniectomy, medial epidural VA transposition, and partial drilling of the occipital condyle. We analysed: 1) surgical indications; 2) utility of VA transposition and condyle drilling; 3) quality of access and view; 4) microsurgical technical difficulties related to tumor location, extent and consistency; 5) microsurgical challenges at the interface between tumor and spinal cord, cranial nerves, and vessels; 6) morbidity and total removal rate.

Results: Four patients aged above 70 were not operated (3 had few symptoms, 1 had an enormous tumor). Operatively, calcified and fibrous meningiomas generally lengthened dissection (inclusion/stretching of VA, adherences to cranial nerves) increasing complications (1 death, 5 permanent deficits). Total removal was achieved in 16/22 cases (73%). VA transposition (in 19/22) enlarged the access and was helpful in accessing the lower clivus and intradural VA only anteriorly. Condyle drilling of up to 50% did not induce instability, enlarged the intradural view to the anterior FM rim but did not improve tumor dissection and removal, so that systematic drilling decreased with experience.

Conclusions: Our study illustrates that: 1) although posterolateral approach with VA transposition offers a large view to accurately manage the anterior FM rim and lower clivus, surgery of anterolateral FM meningiomas remains a heavy and risky procedure the indication of which must take into account age and severity of symptoms; 2) although not harmful, condyle drilling does not significantly improve surgical results.