A 51-year-old man with no significant past medical history was admitted to our hospital because of gait disturbance and dysuria. He had a 2-year history of low back pain and numbness in both legs. His symptoms worsened 1 week earlier and he suddenly developed gait disturbance associated with bilateral leg weakness. On admission, manual muscle testing revealed paresis with distal dominance. Patellar tendon and Achilles tendon reflexes were not exaggerated. He had urinary retention and his lumbar Japanese Orthopedic Association (JOA) score was only 2/29, indicating severe physical impairment (the lower the score, the more severe the impairment). MRI of the spine revealed a spinal lipoma at the L5 level and a flow void dorsal to the spinal cord at approximately the level of the conus medullaris (Fig. ). MRA revealed tortuous blood vessels within the spinal lipoma (Fig. ). Subsequent angiography showed an arteriovenous shunt from the right lateral sacral artery. The feeding artery entered from the dorsal aspect into the lipoma, and then passed the shun zone, and entered the spinal canal primarily via the juxtamedullary vein (Fig. ).\nDiagnosis was a sAVF within a spinal lipoma, and the patient underwent ligation of the draining vein combined with embolization. Under general anesthesia, a catheter was inserted into the lateral sacral artery and advanced to just before the shunt of the fistula. Because a provocation test with lidocaine hydrochloride (hereafter, xylocaine test) showed depression of the motor-evoked potentials (MEP) in the left anterior tibial and anal muscles, embolization using any liquid embolic agent was deemed to be high risk and, we performed only proximal artery occlusion with a coil. Angiography of the internal iliac artery after embolization revealed slight remaining density in the shunt. Therefore, ligation of the draining vein was additionally performed under microscopic view, with transection of two draining veins in the lipoma. Postoperative angiography confirmed there was no remaining shunt.\nPostoperatively, bilateral lower limb muscle strength was slightly improved, but there was no appreciable improvement in vesico–rectal disturbances. At 1 month after surgery, his lumbar JOA score had improved to 10/29, but angiography revealed an arteriovenous shunt via a collateral route from the right lateral sacral artery (Fig. ). The patient experienced no aggravation of symptoms thereafter. Although his low back pain, leg numbness, and bladder dysfunction persisted, intermittent claudication, muscle weakness, and the ADL score were improved at 1 year after surgery. His lumbar JOA score was further improved to 13/29.
A 33-year-old male presented with a 2-year history of pain in the lumbosacral spine with progressive lower-limb weakness, urinary frequency, and incontinence. Symptoms intensified after exercise and prolonged standing. Lumbar spine MRI demonstrated a tethered cord at the L3 level, a filum terminale lipoma, and edema in the spinal cord. It also showed tortuous veins on the posterior surface of the spinal cord (Figures ).\nThe neurological examination revealed bilateral hip-joint flexion weakness (grade 4 according to modified Medical Research Council system), plantar flexion weakness (grade 3 according to modified Medical Research Council system), and reduced sensation in the S2–S3 dermatomes. The Babinski and Rossolimo signs were present bilaterally. Based on the clinical and radiological signs, a SDAVF was suspected. A DSA confirmed the SDAVF at the S2-S3 level, in the dura supplied by lateral sacral arteries and branches from the internal iliac arteries. Tortuous draining veins were present on the posterior surface of the entire spinal cord and terminated intracranially (Figures ).\nThe patient underwent three endovascular embolizations, each with a different agent. First, embolization was performed with Onyx™ 18, administered in two microcatheters. This treatment resulted in an occlusion of the fistula. The patient significantly improved, but due to poor penetration of the draining vein, after a few weeks, the fistula recanalized and symptoms returned.\nA second embolization was performed 4 months later. The vascular access to the fistula was more complicated. A 25% Phil™ injection was feasible only through the small sacral branches of the left internal iliac artery. This procedure achieved a significant reduction of flow through the fistula. Eighteen months later embolization of the fistula was attempted with diluted glue. Despite good occlusion of the fistula observed in a DSA, the tortuous vessels remained visible in the follow-up MRI (Figures ). The symptoms persisted, and the patient was qualified for surgical treatment.\nThe goal of surgery was to occlude the draining vein and the arterial feeder and to reduce the lipoma. With a median incision, the sacral canal was opened on the right side. The dura was thick, and there were multiple vessels filled with embolic agents. There was one large, bright-red vessel extradurally and one intradurally at the S2-S3 level. A clip was placed upon the arterialized vein intradurally for a couple of minutes. After that, the vessel changed color and the tension decreased. Both intra- and extradural vessels were coagulated. Afterwards, the lipoma was visualized and partially removed. The dura was sutured in a watertight fashion, and the wound was closed in layers.\nThe postoperative course was uneventful, and a few days later, the patient was discharged. After 6 months, a follow up MRI showed the absence of tortuous vessels on the posterior surface of the spinal cord and a significant reduction in the myelopathic changes (Figure ). On follow-up, the patient considerably improved, with no incontinence, some urinary frequency and mild weakness (grade 4 according to modified Medical Research Council system).