Sacral Arteriovenous Fistula Causing Myelopathy: Embolization with Obliteration of the Fistula, Recurrence of the Arteriovenous Shunt, Second Embolization with Complete Obliteration of the Fistula and Excellent Clinical Outcome, but Secondary Development of a Gait Disorder

Abstract

A 53-year-old man presented to a neurologist with right hip flexor paresis, impaired sensitivity of his right thigh, and gait disturbance. Neurography of the L5 nerve root and somatosensory evoked potentials of the tibial nerve were pathological. Although his medical history was unremarkable, he was a smoker and had accumulated 15 pack years. Spinal MRI showed edema of the conus medullaris and the thoracic myelon with enlarged tortuous vessels in the lumbar spinal canal. DSA revealed a sacral arteriovenous fistula (sAVF) supplied by the median sacral artery and drained by an enlarged epidural vein. The sAVF was embolized with nBCA and Lipiodol via the middle sacral artery and right lateral sacral artery. The patient’s right leg paresis improved, and follow-up MRI showed fewer vessels inside the lumbar spinal canal with marked regression of the conus medullaris edema. DSA performed 3 weeks after the embolization confirmed the occlusion of the arteriovenous fistula. However, 16 months later, the patient presented with reduced strength in both thighs, a feeling of pressure in both lower legs, and reduced walking distance. MRI showed recurrent edema of the conus medullaris and enlarged vessels in the lumbar spinal canal. DSA demonstrated recurrence of the sAVF. The sAVF, now supplied via the left lateral sacral artery, was again occluded through nBCA embolization. The patient’s clinical condition improved again, in line with a regression of the intraspinal pathological vasculature and the edema of the myelon, but 2 years later, he again presented with progressive weakness of both legs and decreased walking distance. MRI and DSA showed no recurrence of the sAVF or another arteriovenous shunt of the spinal vasculature. Although the edema of the myelon was no longer apparent on MRI, we hypothesized that there was residual venous hypertension of the spinal cord, possibly due to an ongoing thrombotic phenomena in the perimedullary veins. A personalized treatment strategy of therapeutic anticoagulation with dabigatran was initiated and resulted in significant clinical improvement. Clinical manifestations, imaging findings, and management of sAVFs are the focus of this chapter. The case illustrates the importance of complete assessment of all spinal vasculature, including not only the radicular arteries but also the internal iliac arteries. If one of the multiple feeding arteries is missed, the possibility of recurrence after endovascular embolization of the fistula is high and further treatment may be needed.