Lateral Meningioma

In the case of meningiomas, the tumor origin can be found anywhere along the surface of the dura. A general rule is that the neuraxis is displaced to the side opposite to the tumor origin.

Therefore, posterior meningiomas put pressure on the spinal cord anteriorly and for this reason are better approached directly with a laminectomy. Posterolateral and lateral meningiomas displace the neuraxis anteromedially and medially, respectively. A posterolateral approach is advocated, by laminectomy possibly extended on the tumor side to the medial aspect of the facets. With anterolateral meningiomas, the posterior displacement of the neuraxis requires a more location-specific approach because surgical access is limited. In this situation, still a posterior

At this level it is important to use a Mayfield head holder and to position the head in a neutral position to avoid tumor-induced spinal cord pressure. Fluoroscopy is used in accurately targeting pathological levels. Usually, only two vertebrae must be exposed. The laminectomy may be extended laterally to facets on the side of tumor. The dura mater is usually incised longitudinally over the tumor. The dural edges are retracted laterally with several 4/0 silk sutures. Lateral lesions may require section of the dentate ligaments to provide exposure. Sutures from dentate ligament to opposite dura keeps the surgical space open and offers good control of anterior dura as result of gentle rotation of the spinal cord. Great care must be taken to avoid traction & compression on spinal cord itself. Cottonoids are placed at each end of the tumor to avoid intradural soiling. Most of the time, the arachnoid can be separated and the resection completed in the extra-arachnoidal plane. The tumor surface is cauterized and incised with a knife or microscissors. Samples are sent to the pathologist for immediate analysis. In lateral meningiomas, the tumor debulking is performed with either microinstruments or an ultrasonic aspirator, starting along the dural base if possible.

Bleeding of feeding vessels is gently controlled with bipolar cauterization. In this way, the tumor is progressively devascularized and becomes mobile. The pressure at the tumor–spinal cord interface and at the dural insertion base is then