Far Lateral Approach for Foramen Magnum Tumors: Evaluation and Outcome

Background: Foramen magnum lesions represent five percent of spinal neoplasms and one percent of intracranial neoplasms. Clinical presentation is insidious as tumors are slowly growing, the classic foramen magnum syndrome occurs with anteriorly located meningioma, which shows asymmetrical weakness with specific marsh. Foramen magnum meningioma’s are classified into intradural, extradural and combined intra extradural and according to location related to dentate ligament into anterior (midline), anterolateral (anterior to dentate ligament) and posterolateral (posterior to dentate ligament). The most common type is the anterolateral intradural tumors. The far lateral approach is a good valid option for anterior and anterolateral tumors as it allows tumor removal with working angle away from cervicomedullary junction, allows proper proximal control for vertebral artery and proper view of the area anterior to brain stem. Objective: Evaluation of far lateral approach in foramen magnum tumors. Patients and Methods: We operated sixteen patients in three years period from January 2012 till February 2015 at Cairo University Hospitals, ten females and six males; age was from 18 to 38 years. All patients were assessed both clinically for neurological deficits and radiologicaly. Postoperative CT scans and MRI were done postoperatively to ensure tumor removal. Follow up was done at three, twelve and eighteen month’s intervals then yearly. Results: We operated sixteen patients ten females (62.5%) and six males (37.5%), age ranged from 18 to 38 years. Thirteen patients had meningioma’s (81.25%) and three had schwannomas (18.75), four tumors (25%) were anterior midline tumors while the others (75%) were anterolateral. Fourteen cases (87.5%) had total removal of the lesions while the other two (12.5%) were sub totally removed due to adherence to the vertebral artery. Fourteen patients had preoperative weakness (87.5%) which improved postoperatively. Conclusion: The far lateral approach is a valid and safe approach for anterior and anterolateral foramen magnum lesions with acceptable rate of risk and complications. The working angle is usually satisfactory and could be extended by bony drilling of the posterior third of the occipital condyle for the anterior tumors with satisfactory results.