Three clinicopathologic case reports are compared with 28 cases described in the literature. Clinical features are sudden sensory onset, rapid and complete flaccid paraplegia, sometimes ascending signs, transient highly inflammatory CSF, and continuous, rapid evolution. The anatomical findings include massive spinal transverse necrosis, usually thoracic but sometimes more extensive, the grey matter being little affected, with moderate histiocytic proliferation in the early stage but no perivascular lymphoplasmocytic reaction. On the whole, the vascular abnormalities seem secondary, and there is no obvious vascular etiology. The nosological position of this entity is imprecise, but it seems to be related to demyelinating diseases.