Teaching NeuroImages: Spinal cord syrinx secondary to a spinal dural arteriovenous fistula

A 60-year-old man presented with a 2-year history of progressive lower limb weakness, numbness, urinary retention, and chronic constipation with superimposed episodes of severe paraparesis. MRI showed a cervicothoracic syrinx with flow voids (figure). Spinal angiography revealed a type I spinal dural arteriovenous fistula (SDAVF), which was treated with surgical ligation. The patient demonstrated dramatic clinical improvement and resolution of the syrinx. We are aware of one other case report of syrinx associated with SDAVF with similar outcome.1 Thoracic SDAVF often occurs in men in the seventh decade, with leg weakness exacerbated by exercise,2 and may be a treatable cause of syrinx.