Convexity and Parasagittal Meningiomas

The application of radiosurgery to convexity and parasagittal meningiomas is more controversial compared to skull base tumors as adverse effects induced by radiations appear more frequently in these tumors. Symptomatic post-treatment edema (PTE) causing seizures, focal deficits, and intracranial hypertension is actually a rather common complication of radiosurgery of convexity and parasagittal meningiomas. Our results suggest that the factor associated with the risk of developing PTE is mostly associated to characteristics of meningioma rather than to the treatment modalities. Thus, recommendations are mainly related to the indications rather than to specific treatment parameters. An appropriate patient selection represents, accordingly, the way to achieve safe treatment and long-term disease control. Variables to be associated with the likelihood of edema development include tumor volume, tight brain-tumor interface, and atypical histology. Patients with small- to medium-sized tumor recurrence and residual tumor after open surgery are good candidates for radiosurgery. In particular, tumors invading the superior sagittal sinus can be safely treated after removal of the extrasinusal portion of the tumor. On the other hand, for large parasagittal or falx meningiomas with peritumoral edema as well as for convexity meningiomas with tight brain-tumor interface, radiosurgery should not be recommended.