The Long and Winding Road: Thoracic Myelopathy Associated With Occipitocervical Dural Arteriovenous Fistula.

OBJECTIVES: Spinal dural arteriovenous fistulas (DAVFs) have diverse presentations. Magnetic resonance imaging (MRI) reveals spinal cord swelling in only 45% to 74% of cases. We present an unusual case of a 57-year old man with a craniocervical junction DAVF in which the edema appeared in the thoracolumbar region, skipping the cervical spinal cord.

METHODS: A case report and literature review from a tertiary referral center are provided.

RESULTS: In our patient, symptoms progressed over 3 months from low back and radicular pain to weakness, saddle anesthesia, and urinary retention. MRI showed T2 hyperintensity from T3-4 to the conus medullaris. The results from initial brain and spine angiograms were negative. Repeated angiography with the patient under anesthesia revealed a DAVF in the craniocervical junction composed of a cervical branch arising from the right vertebral artery and entering the nidus at the foramen magnum. A prominent intradural draining vein extended inferiorly along the posterior aspect of the cervical spinal cord. The patient was taken to the operating room, where the extradural vertebral artery was dissected and a suboccipital craniectomy was performed. After the dura was opened, the arterialized vein was visualized and clipped. Somatosensory evoked potentials and motor evoked potentials remained at baseline throughout the occlusion. The dura and fistula were removed en bloc, and the draining vein was confirmed to lose flow on indocyanine green. Postoperatively, the patient's symptoms completely resolved, and he experienced full strength in the lower extremities and perineal sensation. A review of 19 cases of DAVF at the craniocervical junction with cord edema shows that >90% involve the brainstem or cervical cord. Only 1 other patient had a similar "skip lesion," in which the cord edema first appeared in the thoracic cord.

CONCLUSIONS: This rare presentation highlights the importance of diagnostic persistence when unexplained cord findings are seen on MRI. Repeated angiography and the inclusion of proximal vascular lesions may be considered in the evaluation of isolated thoracic edema.