Tiny Falx Meningioma Causing Massive Interhemispheric Subdural Hematoma: A Case Report

Bleeding from meningiomas is well known, but massive subdural hemorrhage from a very small meningioma is rare. A 61-year-old woman presented with a sudden-onset headache and slight right hemiparesis without a history of trauma. Computed tomographic scan showed bilateral acute/subacute interhemispheric subdural hematoma, but contrast-enhanced computed tomography (CT) scan, non-enhanced magnetic resonance imaging (MRI) and digital subtraction angiography failed to detect the cause. The hematoma was conservatively treated. Three weeks later, CT scans showed a vestige of the hematoma along the falx. However, repeated angiogram revealed a tumor stain on the falx supplied by the middle meningeal arteries, leading to the tentative diagnosis of meningioma. The tumor was removed and histologically diagnosed as angiomatous meningioma. It is rare that falx meningioma causes massive interhemispheric subdural hematoma, and the diagnosis of the causative lesion is challenging if tumor is small. We review the literature and discuss the characteristics.