Recurrent spinal fistula as result of a rare combination of a perimedullary and peridural spinal fistula: case report

We report on a patient with the combination of a peridural and a perimedullary spinal fistula, which manifested consecutively. The clinical course and diagnostic steps reveal important observations helpful in the management of this pathology. A 61-year-old male patient presented with a six-month history of progressive weakness of the lower limbs. Magnetic resonance imaging revealed edema and dilated spinal veins of the lower thoracic spinal cord. Spinal angiography confirmed the diagnosis of spinal dural fistula at level T9 on the left. The patient underwent surgery and the fistula was surgically excised. Two months after initial improvement, the clinical symptoms of lower limb weakness recurred. On re-angiography a spinal perimedullary fistula was found at level T7 that was not apparent on the previous angiogram and on the postoperative control angiogram. The patient underwent surgery again, and the second fistula was also exised. The clinical symptoms subsequently improved. The interesting point in this case was the rare combination of a peridural and a perimedullary spinal fistula. They presented consecutively and could not be identified simultaneously on the first angiogram. Only after closure of the first fistula did the second become apparent. We believe that this may be a result of a postoperative pressure change in the venous system of the cord. After closure of the first fistula, the arterio-venous (AV) shunt of the second fistula developed gradually. The possibility of a second fistula should be considered in the presence of persistant edema of the cord on magnetic resonance imaging (MRI) and subsequent clinical deterioration.