Progressive bulbar dysfunction caused by a predominantly venous vascular malformation of the medulla oblongata.

We describe a 58-year-old patient with a rare predominantly venous vascular malformation of the medulla oblongata, which caused a progressive bulbar dysfunction consisting of hiccoughs, dysphagia, hoarseness, dysarthria, gait ataxia and dysuria over a period of 11 months. On autopsy, a large dilated vein with focal marked intimal fibroelastic thickening was present on the ventral surface of the medulla. Microscopically, moderate proliferation of capillaries and veins was observed which was confined primarily to the medulla. The veins displayed abnormal dilatation and tortuosity; prominent thickening of vessel walls was also present in the veins and capillaries. The venous abnormalities were prominent in the parenchyma of the medulla, but much less apparent in its subarachnoid space. Multifocal neuronal loss and gliosis were observed, most prominently in the inferior olives, hypoglossal, dorsal vagal and ambiguus nuclei. The histopathologic findings suggested that abnormal venous drainage within the parenchyma of the medulla was the most critical factor for the pathogenesis of this patient's neurologic symptomatology.