Spontaneous resolution of intracranial hypertension following radiotherapy for posterior parasagittal meningioma: About two cases and review of the literature.

We report the cases of two patients who underwent normofractionated radiotherapy for evolutive asymptomatic parasagittal meningiomas. After completion of radiotherapy, both patients presented severe headache and vomiting episodes without papillar edema. We then decided a "wait-and-scan" strategy because of the slit-ventricles, and symptoms regressed spontaneously. MRI showed significant tumor regression a year after radiotherapy with a newly developed collateral venous drainage system in the first patient and a left, unusually large, superior anastomotic vein in the second. These clinical presentation and radiological evolution are compatible with venous stenosis caused by radiation-induced symptomatic edema, fading after the development of a collateral venous drainage system. The relation between pressure-related headaches and venous anatomy remains unclear in parasagittal meningiomas. These observations underline the importance of the study of venous anatomy when pressure-related headaches are suspected. Further clinical descriptions might help the clinicians to treat these patients' symptoms.