J Al-Koteesh, Y Masannat*, N V M James, U Sharaf
Prince Philip Hospital, Llanelli; *Leeds General Infirmary, Leeds
Correspondence to: Dr Jamal Al-Koteesh, Consultant Radiology, Prince Philip Hospital, Llanelli, SA14 8QF Wales Tel: +44 (0) 01554 783259 Fax: +44 (0) 1554 783150 Email: jakturk50@yahoo.co.uk
SMJ 2005 50(3): 122-123
Abstract
Abdominal aortic aneurysm (AAA) is one of the important differential diagnoses of back pain which is often missed. Chronic contained rupture is a rare event that can cause diagnostic difficulties, presenting in different ways such as back pain, neuropathy or groin mass. We are presenting a case of 46-year-old man who presented with history of recurrent low back pain radiating to his left leg, associated with sensory deficit in the left thigh. His complaint proved to be resulting from chronic contained AAA leak.
Key words: Chronic, contained, rupture, aortic, aneurysm
Introduction
Patients presenting with ruptured AAA often have abdominal pain associated with hypotension and pulsatile abdominal mass. But patients having chronic rupture of AAA might have a long history of less apparent clinical signs. This condition is usually misdiagnosed as back pain, or crural neuropathy. This report describes our experience with a patient who had a chronic contained AAA rupture that was treated as musculoskeletal back pain for few months before reaching the correct diagnosis.
Case report
A 46-year-old male presented with back pain following a fall. The pain was in the lower back, severe, radiating to the left lower limb and groin. It increased by movement and was not relieved by simple oral analgesia. He had some numbness in the upper part of the left thigh with no other sensory loss. No history of bowel or urinary problems and no abdominal complaints. He has had similar attacks for the past year, and was awaiting MRI scan to rule out disc prolapse arranged by his General Practitioner. The patient was known to have protein S deficiency on warfarin; otherwise he was fit and healthy.
On examination he was haemodynamically stable, with normal respiratory and cardiovascular examinations. Back examination revealed paravertebral muscle spasm, and straight leg raise was 30 degrees on both sides. Decreased movement was noted in the left lower limb especially at the hip and knee joints, but sensation and power were intact in both lower limbs. His initial bloods were normal except for his INR which was 3.9. He was admitted for pain relief and observation overnight. Lumbo-sacral spine X-rays (Fig 1) showed large soft tissue mass overlying the spine from L1 to L4, with erosions of the anterior aspects of L2-L3 vertebra on the lateral views, raising the suspicion of retroperitoneal pathology. MRI of the lumbar spine showed no evidence of significant disc prolapse, but there was a large mass with signal void in front of the lumbar spine. Abdominal MRI (Fig 2) showed 12 cm infra-renal AAA with a defect in its left lateral wall leading to a 6cm left para-vertebral mass, with high signal intensity, displacing the psoas muscle and eroding the left lateral side of L2 and L3 vertebral bodies. Laparatomy confirmed the ruptured AAA which was repaired with a straight wooven dacron graft. Post operatively the patient subsequently developed ischemic changes of both lower limbs for which he underwent bilateral femoral Embolectomies. Renal function deteriorated and the patient developed pulmonary edema. Patient deteriorated rapidly and subsequently died.
Discussion
Contained retroperitoneal rupture is a rare complication of AAA, but it has been recognised since Szilagyi initially described it in the sixties of the last century.1 Two criteria should be present to diagnose the condition, which are; visual confirmation of perforation of AAA and haematoma contained by either fibrotic tissue or retroperitoneal organs. Two important determining factors to developing chronic rupture are, the rate of hemorrhage and the resistance from adjacent tissue.2
Incidence of this condition varies between published papers. Ando et al3 found four cases among 149 patients who required repair of an infrarenal AAA making the incidence 2.7%. In another study five out of 411 patients operated for AAA (1.2%) were found to have contained rupture.4 On the other hand Jones et al found seven cases out of 20 (35 %) which were evaluated by CT scan preoperatively.5
Chronic rupture has been associated with mis-diagnosis. It has been reported to present as back pain, lumbar neuropathy2,3,6,7 spinal cord compression,8 strangulated inguinal hernia, inguino-scrotal mass.9 obstructive jaundice10 and metastatic cancer.11 It also has been reported to occur at the site of previous graft repair of AAA.12 Presentation depends on the site of rupture, and on the pressure effect exerted by the haematoma on the adjacent structures. Haematoma from chronic rupture lying on the psoas muscle will cause irritation of the femoral nerve and present as femoral neuropathy, because the femoral nerve arises from 2nd, 3rd and 4th lumbar nerves, which pass through the psoas muscle.7 That would explain the sensory deficit that our patient had in the area of the upper left thigh anteriorly.
This patient suffered from low back pain for nearly one year. In the literature, symptoms progress over days, weeks or even months, and periods of survival up to several months has been reported.2,5 Vertebral body erosions have been reported as a complication of chronic AAA rupture.7,11,12 which was also noted in our patient. The important factors that contributed to the late diagnosis in our patient is his young age (46 years), the absence of other risk factors for AAA and the long history of the presenting complaint. Once the diagnosis is made, surgery should be done urgently.5,6 The operative risk in chronic rupture is the same as for elective surgery if it is done urgently after full assessment, hydration and preparation for the operation, but if it is done as an emergency the mortality is high.2,5
In conclusion chronic rupture is an important subset of ruptured AAA, which is usually compounded by late diagnosis. High index of suspicion is needed to diagnose this condition as it has different modes of presentation.
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