Acute aortic occlusion in a patient with chronic paralysis due to spinal cord injury: a case report

Discussion

The occlusion of the aorta and iliac arteries was acute because most of the retrieved thrombus was fresh. Transesophageal echocardiography was not performed because the patient refused the procedure, but he did not have evidence of an embolic source on a limited work-up. Venous thromboembolism is common in patients with SCI [1], but paradoxical embolism was unlikely because he did not have deep vein thrombosis or a patent foramen ovale [11]. CT showed atherosclerotic changes of the aorta and iliac arteries. Therefore, the etiology of AAO in this case was considered thrombotic rather than embolic. Based on the findings of the thrombus and CT scan, we believe that acute-on-chronic aortoiliac artery occlusion developed. Only a small amount of the thrombus in the left iliac arteries was retrieved at the time of surgery because the left iliac arteries were previously occluded. The right common iliac artery showed dilatation with atherosclerotic changes, and the occlusion of the right common iliac artery might induce an acute aorto-right iliac artery occlusion. However, we believe that simultaneous occlusions of the aorto-right iliac arteries and the right femoral artery occurred, rather than occlusion of the aorto-right iliac arteries prior to occlusion of the right femoral artery, because an abundant thrombus was obtained from the aorto-right iliac arteries and the thrombus was as fresh as the thrombus from the infrainguinal arteries. Consequently, we assume that the left iliac artery was previously occluded, and occlusions of the aorto-right iliac artery and right femoral artery followed. Babu et al. reported that the cause of sudden thrombosis in patients with atherosclerotic occlusive disease was precipitated by a low-flow state or by cardiac decompensation [8]. The patient did not have chronic heart failure, and no blood test values showed clear evidence of hypoperfusion. However, we assume that he was dehydrated because the weather was hot and he had a high temperature of 37.5 °C on admission. The patient also was at risk for heatstroke due to infrequent water intake related to chronic paralysis. Dehydration may have contributed to the development of AAO.

In the present case, ischemic pain in the abdomen or limbs was not obvious because of the sensory deficit, and emergence of paresthesia or paralysis from spinal ischemia could not be evaluated because of the preexisting motor or sensory deficits. The left lower extremity showed little ischemic change due to the collaterals induced by the atherosclerotic lesion. Thereafter, only objective symptoms of acute limb ischemia in the right lower extremity, such as pallor, poikilothermia, and pulselessness, were indicative of the diagnosis of AAO. Since subjective symptoms were absent, the absolute time of onset of aortic occlusion was not established. However, the staff in a facility for the handicapped checked his condition on the previous night, and the onset of ischemia was considered to be within 12 h.

The ultrasound scan suggested that the hypoechoic thrombus in the distal right external iliac artery was fresh. On preoperative CT, the thrombus looked homogeneous in density from the aorta to the right external iliac artery. Therefore, we assumed that the occlusion of the aorta and iliac arteries was acute rather than chronic. We supposed that absence of subjective symptoms might mask the severity of AAO. Because patients with AAO have had poor prognosis without surgical treatment [8–10], we opted for surgical treatment. Surgical alternatives for AAO include simple thromboembolectomy, axillofemoral bypass, aortofemoral bypass, and thrombolytic therapy [8]. In the axillofemoral bypass, the risk of graft occlusion was expected to be higher in the patient who lived a sedentary lifestyle compared with the ambulatory individual. The patient with SCI had decrease in the respiratory capacity due to COPD and was not in a good general status for aortofemoral bypass. The effect of thrombolytic therapy was unclear in patients with a massive thrombus. Meanwhile, thromboembolectomy is often associated with difficulty in restoring complete perfusion in patients with in situ thrombosis [9] and poses risks of embolism, dissection, or rupture. If the thromboembolectomy was unsuccessful, we were considering proceeding to an axillofemoral bypass, as other authors stated [9, 10]. However, the simple thromboembolectomy established adequate blood flow.

For the treatment of limb ischemia, the degrees of sensory loss and muscle weakness are useful in diagnosing ischemia that requires emergency surgical treatment [12, 13]. Paralysis is an important indicator of limb viability; limb ischemia with paralysis is considered irreversible, and amputation is necessary. We could not evaluate ischemic motor or sensory dysfunction in the lower extremities because of the preexisting neurological deficit. The onset of ischemia was considered to be within 12 h, but the absolute time was unknown. However, limb ischemia was considered reversible because the venous Doppler signal was audible on the right pedal; the limb ischemia was classified as category IIb on the basis of the clinical categories of acute limb ischemia [12, 13]. Primary amputation was considered acceptable because of the chronic quadriplegia, but simultaneous thromboembolectomy for the infrainguinal arteries and AAO was less invasive than primary amputation. Complete limb revascularization was attempted and achieved by simultaneous thromboembolectomy.

A good outcome was achieved despite the lethal condition in the present case. We considered using continuous hemodiafiltration for ischemia reperfusion syndrome if serum potassium ion concentrations increased drastically, but no postoperative complications developed. The patient’s CPK levels showed significant change after revascularization, but those levels did not exceed normal limits. We believe that CPK and Cr levels were low because the patient had loss of muscle mass due to chronic paralysis, which would make loss of the muscle an advantage in avoiding ischemia reperfusion syndrome.