Paralysis: a rare presentation of abdominal aortic aneurysm thrombosis

Case Reports

CJEM 2005;7(6):420-422

Abstract

Résumé

Introduction

Acute thrombosis of the abdominal aortic aneurysm (AAA) is rare and usually presents with vascular compromise of the lower limbs. A unique case of AAA thrombosis that presented with acute paralysis of a limb is discussed. This variant in clinical presentation can be attributed to ischemia of the spinal cord before complete occlusion of the aorta.

A brief review of the vascular anatomy of the spinal cord, focusing on the artery of Adamkiewicz, will help with recognition of such cases in the future. Clinical presentation, mechanisms and management of AAA thrombosis are reviewed.

Case report

An 85-year-old woman with a past history of hypertension, hypercholesterolemia and previous epistaxis is discharged from the emergency department after cauterization and nasal packing for recurrent epistaxis. She returns after an abrupt onset of paralysis and numbness in her left leg while in the vehicle en route home. "She cannot get out of the car." The patient also complains of back pain that radiates into the left buttock. Her blood pressure is 214/114 mm Hg and her pulse is 85 beats/min. Findings are restricted to the left leg, where there is hypotonia, decreased deep tendon reflexes and a sensory level deficit at L1 for pain, touch, proprioception and vibration. Her femoral and dorsalis pedis pulses are equal bilaterally. She has no other neurologic deficit.

A unenhanced CT of the head is normal. Lumbar CT without contrast reveals no significant disc bulging or central spinal narrowing, but does identify an infrarenal abdominal aortic aneurysm of 4–4.5 cm, with some intraluminal thrombus.

On returning from CT scan, the patient's clinical appearance has deteriorated. Both legs are paralyzed with sensory level deficits at L1. They appear mottled and cold with no palpable dorsalis pedis pulses. A clinical diagnosis of acute AAA with paralysis due to spinal cord ischemia is made.

The patient is urgently transferred to a tertiary centre for management by a vascular surgeon. She is not administered anticoagulants, due to the previous history of severe epistaxis and to an inability to exclude an aortic dissection at this stage. At the tertiary centre, an emergent CT scan with contrast reveals an infrarenal, 3.8-cm AAA, with a large acute thrombus causing almost complete occlusion of the lumen. The occlusive thrombus extends inferiorly into the iliac arteries. The patient undergoes emergency revascularization, but her paralysis does not resolve postoperatively. Her recovery is complicated by a stroke, and she dies without leaving the hospital.

Discussion

Acute paralysis of the lower extremities before vascular compromise is an extremely rare presentation of AAA thrombosis.^1–3 The anatomy of spinal vascular supply can explain this presentation (Fig. 1).⁴ The artery of Adamkiewicz, or arteria radicularis magna (ARM), is the main blood supply to the inferior spinal cord and has a variable origin from level T9 to L3⁵ but has been found to originate as low as L5.⁶ Abdominal aortic aneurysm thrombosis can occlude the origin of this artery, resulting in acute spinal ischemia.^1,7 In our case, this spinal ischemia and paralysis occurred before the complete occlusion of the AAA, explaining the unusual presentation. In all cases of abdominal aorta surgery preoperative investigations to determine the (variable) origin of the artery of Adamkiewicz are necessary. Identifying its site of origin reduces the incidence of spinal cord injury and operative time during the repair of thoracoabdominal or descending aorta aneurysms.⁸

The usual presentation of AAA thrombosis is that of abrupt vascular compromise of the lower extremities, with absent distal pulses (68%), pain (45.7%) involving lower extremities, coolness (31.4%), numbness (34.3%) and mottled skin below the umbilicus (42.9%) being the most frequent findings.^1,7 Both hypertension and hypotension have been noted.1 Some motor disturbance is found in 22.9% of these cases.⁷

The reported incidence of thrombosis of abdominal aneurysms is 0.6%–1.8%7 with only 51 cases of AAA thrombosis reported in the literature.1–3 Unlike AAA rupture, the risk of developing an AAA thrombosis is independent of the size of the aneurysm.^7,9 The differential diagnosis for AAA thrombosis includes aortic dissection and AAA rupture. Abdominal pain is more indicative of AAA rupture, and AAA thrombosis usually has severe lower limb pain.⁷ Hypertension can be associated with both AAA thrombosis and aortic dissection, and an initial presentation of paralysis has also been documented with aortic dissection.¹⁰ Usually chest or upper back pain will be expected with aortic dissection in addition to the paralysis.

Abdominal aortic aneurysm thrombosis can occur due to several mechanisms. In our case the positional change, when the lady got into the car, could have dislodged a large mural thrombus leading to occlusion. Alternatively the external pressure, while sitting in the vehicle, could have lead to a low flow state leading to thrombosis of the AAA. Other mechanisms for AAA thrombosis include:

• iliac artery occlusion with proximal propagation of the thrombus;⁷
• thromboembolism of cardiac origin;⁷
• hypercoagulable states;¹
• intraplaque hemorrhage;⁹ and
• direct trauma: the Heimlich manoeuvre has been associated with 3 cases of AAA occlusion.¹¹

Immediate heparinization is required to prevent further extension of the thrombus and additional vascular occlusion. Hopefully this will prevent renal artery involvement and renal failure.^1,7 Expedient surgery can decrease mortality and morbidity. Prolonged lower extremity ischemia may result in compartment syndrome, amputation, reperfusion syndrome and death.¹ Inline aortic reconstruction is deemed the optimal treatment,¹ but axillobifemoral bypass is an acceptable alternative, especially in high risk patients.¹ The mortality of AAA thrombosis is 45%–50%.⁷

Conclusion

Abdominal aortic aneurysm thrombosis is a rare condition that usually presents with vascular compromise of the lower extremities. In unique circumstances, AAA thrombosis can present with neurologic signs, such as paralysis, that can distract diagnostic attention away from the vascular catastrophe in progress. An awareness of this clinical variant and an understanding of the vascular supply to the spinal cord can lead to earlier diagnosis.

References

1. Suliman AS, Raffetto JD, Seidman CS, Menzoian JO. Acute thrombosis of abdominal aortic aneurysms: review of two cases and review of the literature. Vasc Endovascular Surg 2003;37:71-5.
2. Bolduc ME, Clayson S, Madras PN. Acute aortic thrombosis presenting as painless paraplegia. J Cardiovasc Surg (Torino) 1989;30:506-8.
3. Fairhead JF, Phillips D, Handa A. Embolic spinal cord infarction as presentation of abdominal aortic aneurysm. J R Soc Med 2005;98:59-60.
4. Goetz GC, editor. Textbook of clinical neurology. 2nd ed. St. Louis (MO): WB Saunders; 2003.
5. Lo D, Vallee JN, Spelle L, Cormier E, Saillant G, Rancurel G, et al. Unusual origin of the artery of adamkiewicz from the fourth lumbar artery. Neuroradiology 2002;44:153-7.
6. Biglioli P, Roberto M, Cannata A, Parolari A, Fumero A, Grillo F, et al. Upper and lower spinal cord blood supply: the continuity of the anterior spinal artery and the relevance of the lumbar arteries. J Thorac Cardiovasc Surg 2004;127:1188-92.
7. Hirose H, Takagi M, Hashiyada H, Miyagawa N, Yamada T, Tada S, et al. Acute occlusion of an abdominal aortic aneurysm: case report and review of the literature. Angiology 2000;51:515-23.
8. Hachiro Y, Kawaharada N, Morishita K, Kukada J, Fujisawa Y, Kurimtoto Y. Thoracoabdominal aortic aneurysm repair after detection of the adamkiewicz artery by magnetic resonance angiography: a way to shorten operating time and improve outcome. Kyobu Geka Japanese J Thorac Surg 2004;57(4):280-3.
9. Shnacker A, Witz M, Lehmann JM. Acute thrombosis of an aortic aneurysm. J Cardiovasc Surg (Torino) 2001;42:111-3.
10. Beach C, Manthey D. Painless acute aortic dissection presenting as left lower extremity numbness. Am J Emerg Med 1998;16:49-51.
11. Ayerdi J, Gupta SK, Sampson LN, Deshmukh N. Acute abdominal aortic thrombosis following the Heimlich maneuver. Cardiovasc Surg 2002;10:154-6.