Clinical study of spinal dural arteriovenous fistula-with special reference to neurological symptoms and magentic resonance imaging

We have evaluated the backgrounds, neurological symptoms, signs, and magnetic resonance images (MRI) in six cases of spinal dural arteriovenous fistula. The subjects were 2 males and 4 females, and the mean age was 67.2 years old. The cardinal subjective symptoms were progressive motor weakness of lower extremities (2 cases), paroxyomal weakness of lower extremities (3 cases), sensory disturbance of polyneuritic type (2 cases), and intermittent claudication (1 case). Administration of beverages and drugs, which might include vasodilators and taking baths, worsened the symptoms and signs in 3 cases and 2 cases respectively. Concerning to MRI findings, high signal intensities or swellings were observed at mid-thoracic area to upper conus of the spinal cord in all cases. These changes, which would be induced by edema caused by high venous pressure, were especially prominent in the central area of the cords. By these mechanisms, sensory disturbance like polyneuritic type caused by the disturbance in deep areas of posterior columns might more prominent than the disorder of spinothalamic tracts placed in superficial areas of cord in the early stage of the disease. These abnormal intensities of MRI were higher than the level of clinical symptoms and signs. The difference was about 6.5 segments. For this reason, the upper border of the spinal cord lesions could not be identified by the neurological symptoms. Although the clinical features and MRI findings are relatively characteristic, flow void signs by high resonance MRI and abnormal blood vessels by spinal angiography will be necessary to diagnose this disease confidently.