A Patient with Spinal Arteriovenous Malformation Treated with Lumbar Vertebral Surgery Due to Misdiagnosis

Spinal arteriovenous malformation (AVM) is a rare disease that arises more commonly from the lower thoracic and upper lumbar spine. It is classified based on the development pattern and the shunt location. The developmental mechanism of the symptoms is thought to be as follows. Spinal venous return is impaired by high-pressure arterial blood flowing into the coronary sinus via a shunt and venous pressure is promoted, which causes spinal cord symptoms to progress gradually. Listlessness, pain, and an abnormal sensation of the lower limb are possible initial symptoms. Spinal AVM may cause intermittent claudication and bladder and rectal disturbance, and differentiation from lumbar degenerative diseases and arteriosclerosis obliterans is required, which may cause difficulty with diagnosis. We encountered a patient in whom intermittent claudication was treated with lumbar decompression and fixation at another hospital, but symptoms did not improve. The patient was diagnosed with spinal AVM at our hospital and symptoms were improved by surgery. Because the symptoms did not improve despite being treated with surgery for spinal canal stenosis, we strongly suspected spinal intermittent claudication, and we performed a spinal CT and MRI after myelography for the entire spinal cord, and identified the lesion in the thoracic spinal cord. Regarding the postoperative outcome and prognosis of spinal dural AVF, early diagnosis and early treatment have been proposed as prognostic factors because the postoperative outcome is poor in patients with high preoperative severity and a long duration of illness. In our patient, the preoperative JOA score was 6, showing high preoperative severity, and the duration of illness was 1.5 years before diagnosis, which may explain the limited improvement of the JOA score to 20 at final follow-up. In a case with these characteristics, we suggest that close examination of the entire spinal cord is needed for effective treatment.