Aortic aneurysm causing compressive myelopathy.

A previously healthy 65-year-old man was admitted to the neurology department with history of acute-onset of severe pain in both flanks 2 months ago. He had developed flaccid paraplegia, urinary retention, and diminished sensation below D10 since last 15 days. There was no associated fever. On examination, the systolic blood pressure was 10 mmHg less in the lower limb (the popliteal artery blood pressure was 116/80 mmHg). There was no abdominal bruit. The lower limbs had reduced muscle tone bilaterally, grade 0 power, and the tendon reflexes were absent. Pain and touch sensations were diminished below the level of D10. The joint position and vibration were impaired in both the lower limbs. Vertebral tenderness was noted at D10 and D11 of the spine. Routine blood investigations revealed mild anemia with ESR 42 mm in the first hour. The search for malignancy and myeloma panel was negative. The magnetic resonance imaging (MRI) of the thoracic spine was done for the evaluation of paraplegia. The MRI showed a partial collapse of the D10 vertebra and the retropulsed fragment was causing compression of the spinal cord. There was increased T2 signal intensity in the spinal cord at this level. The intervertebral discs were preserved [Figure 1a]. Incidental note was made of aneurysmal dilatation of the abdominal aorta at that level. It was seen as dilated aortic lumen showing vascular flow void on axial T2WI with circumferential thickening of the aortic wall [arrow in Figure 1b]. Computed Tomography (CT) angiography was done for further evaluation that revealed fusiform dilatation of the entire descending thoracic aorta and abdominal aorta till aortic bifurcation with the peripheral non-enhancing area and discontinuous rim of calcification. The findings were suggestive of peripherally thrombosed aortic aneurysm causing erosion of the adjacent D11 vertebra and collapse of D10 vertebra with bony fragments compressing the spinal canal from the anterior aspect [Figure 1c–e]. The patient was referred for surgical intervention.

Figure 1

(a) sagittal and (b) axial T2WI MRI of the thoracic spine showing partial collapse of the D10 vertebra and the retropulsed fragment is causing cord compression and increased cord signal at this level. Incidentally noted aneurysmal dilatation of the aorta (arrow in b); (c-e) computed tomography (CT) angiography showing peripherally thrombosed aortic aneurysm causing erosion of the adjacent D11 vertebra and collapse of the D10 vertebra with bony fragments compressing the spinal canal from the anterior aspect

Discussion

Aortic aneurysm causing erosion and complete destruction of the vertebra is rare. A few cases of thoracic or abdominal aortic aneurysms associated with vertebral destruction have been reported. Most of them were mycotic and a result of tubercular spondylodiscitis.[1] Here, we present a case of thoracoabdominal aortic aneurysm causing vertebral destruction, cord compression, and paraplegia as the initial presentation.

Back pain is such a frequent complaint that serious and infrequent causes like aneurysms are underestimated. These patients are also hemodynamically stable and asymptomatic. Spondylodiscitis, trauma, osteoporosis, and metastasis account for most of the vertebral compression fractures.[23] Infective or mycotic aortic aneurysm rarely causes vertebral erosion. The possible mechanism of vertebral destruction is chronic repetitive pressure from the aortic aneurysmal pulsation and ischemia. In the present case, the presence of atherosclerotic calcification in the aortic wall, preservation of intervertebral disk space adjacent to the collapsed and eroded vertebra and absence of any prevertebral and paravertebral collection or soft tissue indicate aortic aneurysm as the cause of vertebral destruction. CT angiography in a multidetector CT scanner is the modality of choice for the diagnosis of an aortic aneurysm to localize the extent of the lesion and assessment of complications.[4] An MRI is necessary to diagnose compressive myelopathy. The surgical repair of the aortic aneurysm and reconstruction of the vertebral column are presently the treatments of choice.

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Conflicts of interest

There are no conflicts of interest.