Chronic

P.R. RAMASAMY, D. FOX, G. NARENDRA, L. CARNIE and R. WATURA
Frenchay Hospital, Bristol, UK

Chronic contained rupture of aortic aneurysm is a rare event which can cause diagnostic difficulties. It can present as high lumbar neuropathy, hence, chronic contained rupture should be borne in mind while examining patients with back pain. Delayed diagnosis and delayed surgical repair of the ruptured aneurysm can compromise the final results. The outcome of urgent repair of a chronic contained leak is equivalent to that of elective aneurysm repairs.

Rupture of an abdominal aortic aneurysm usually presents acutely, the cardinal features being abdominal pain, pulsatile abdominal mass and hypovolaemia. The diagnosis is often made clinically, but may be aided by ultrasound, computerised tomography (CT) and/or magnetic resonance imaging (MRI). Chronic contained rupture of an abdominal aortic aneurysm is a well-described but rare occurrence, which may present with various symptoms causing diagnostic difficulties.

A 67-year-old man presented with an 8-week history of severe left sided thigh pain and moderate back pain. He had no bladder or bowel symptoms. Respiratory and cardiac examination was unremarkable. The initial abdominal examination was reported as normal. Neurological examination revealed weakness of left hip flexion and left knee extension, loss of left knee jerk and decreased sensation in the left L2-3 dermatomal distribution. The rest of the neurological examination was normal.

Haematological and biochemical investigations were normal apart from a serum albumin of 18 g/l. Plain radiographs of the lumbar spine were unhelpful (Figure 1). An MRI scan of the lumbosacral spine demonstrated erosion of the anterior aspect of the 4th lumbar vertebral body on the left side with a paraspinal mass compressing the higher lumbar nerve roots. There was no evidence of disc pathology or metastases (Figure 2). An MRI scan of the abdomen showed a 6 cm infra-renal aortic aneurysm which was continuous with the paraspinal mass (Figures 3 and 4) Contrast-enhanced CT of the abdomen and a CT -guided biopsy of the suspected left psoas haematoma was performed (Figure 5). Histological examination showed findings consistent with an organised haematoma. There was no evidence of malignancy.

The patient underwent an urgent surgical repair of the aortic aneurysm. The post-operative recovery was uneventful.

Figure 1: Lateral lumbar spine radiograph, showing minor illdefinition of the superior end-plate of L3 vertebral body with anterior osteophyte

Acute rupture of an abdominal aortic aneurysm is a surgical emergency with an operative mortality as high as 60%.3 A chronic contained leak of an abdominal aneurysm is possible if the rupture occurs into a confined anatomical space with subsequent tamponade of the haemorrhage. Clinical presentation may then be delayed for up to several months.3 Symptoms usually relate to pressure effects from the haematoma. Most patients complain of some back or abdominal pain, but pain may be completely absent.^1,4 There are reported cases in the literature of chronic aortic rupture masquerading as a psoas abscess, renal colic, obstructive jaundice due to compression of the common bile duct and as a groin hernia.^1,2 There are several reported cases presenting with a high lumbar neuropathy. This occurs because the fibres of the femoral nerve pass around the psoas muscle and may be compressed by the haematoma.

Both CT and MRI can make the diagnosis of a chronic contained rupture.^1,5,6 As many of these patients present with back pain, with or without symptoms of a lumbar neuropathy, MRI will often be the initial investigation. The field of view of an MRI scan of the lumbar spine may be limited. The scrutiny of the aorta and paravertebral tissues on the ‘scout’ image is important if the diagnosis is not to be missed. Biopsy of the paravertebral mass may be necessary if the diagnosis remains in doubt.

Once the diagnosis of a chronic contained leak is made, surgery should be performed as an urgent procedure, because the literature suggests that most contained leaks will eventually rupture.3 Urgent repair in a stable patient has an operative survival similar to that of elective repair .³

Chronic contained rupture of an abdominal aortic aneurysm is a rare but life-threatening cause of a lumbar neuropathy, with or without back pain. A high index of suspicion is necessary to avoid delays in the diagnosis. The aorta should always be scrutinised on MRI scans of the lumbar spine.

Figure 2: Sagittal midline lumbar spine MRI (T2-weighted spin echo), showing abnormal high signal in L3 vertebral body, but no evidence of intervertebral disc disease

Figure 3: Coronal MRI abdomen (T1-weighted spin echo), showing a left paravertebral mass displacing the psoas muscle and eroding the adjacent vertebral body, which is of abnormally low signal

Figure 4: Axial MRI abdomen (Fat suppressed T2 weighted spin echo), showing 7cm aortic aneurysm which has ruptured into the left psoas muscle. There are multiple layers of varying signal within the haematoma, representing different stages of organisation

Figure 5: Axial contrast-enhanced CT abdomen, showing the aortic aneurysm, contained haematoma, and erosion of the adjacent lumbar vertebral body

1. Larsson EM, Heiling M and Holtas S. Aortic pathology revealed by MRI in patients with clinical suspicion of spinal disease. Neuroradiology 1993; 35: 499-502
2. Rosenthal D, Clark MD, Stanton PE, et al. Chronic contained rupture of abdominal aortic aneurysm. Is it real? J Cardiovasc Surg 1986; 27: 723-4
3. Jones CS, Reilly MK, Dalsing MC, et al. Chronic contained rupture of abdominal aneurysms. Arch Surg 1986; 121: 542-6
4. Higgins R, Peitzman AB, Reidy M, et al. Chronic contained rupture of an abdominal aortic aneurysm presenting as a lower extremity neuropathy. Ann Emerg Med 988; 17:284-7
5. Clayton MJ, Walsh JW and Brewer WH. Contained rupture of abdominal aortic aneurysms: sonographic and CT diagnosis. AJR Am J Roentgenol 1982; 138: 154-6
6. Petasnick JP. Radiologic evaluation of aortic dissection. Radiology 1991; 180: 297-305

Copyright date: 27th March 2001
Correspondence: P.R. Ramasamy, House 3, Staff Residences, Weston Hospital, Weston Super-Mare, BS23 4TQ, UK

Chronic contained leak of abdominal aortic aneurysm presenting as lumbar neuropathy