Wedge-shaped medullary lesions in multiple sclerosis.

Multiple sclerosis (MS) is a heterogeneous disease with variable clinical features and magnetic resonance imaging (MRI) findings. We report four MS cases with unusual wedge-shaped lesions in the paramedian ventral medulla oblongata demonstrated on MRI. The clinical features and MRI characteristics of the medullary lesions suggest an impairment of venous drainage. We propose that the formation of these wedge-shaped lesions may be related to the pattern of venous drainage in the ventral medulla and raised venous pressure due to chronic cerebrospinal venous insufficiency which has recently been described in MS.