Imminent rupture of infected aortic aneurysm presenting as lower
back pain in an older patient: A case report
Satoshi Takashima, Tadatsugu Morimoto, Takaomi Kobayashi, Hirohito
Hirata, Tomohito Yoshihara, Masatsugu Tsukamoto, Masaaki
Mawatari
1 Department of Orthopedic Surgery, Faculty of
Medicine, Saga University.
Corresponding author: Tadatsugu Morimoto
Mailing address: Department of Orthopedic Surgery, Faculty of Medicine,
Saga University, 5-1- 1 Nabeshima, Saga, Japan
Tel: +81-95-234-2343
Fax: +81-95-234-2059
E-mail:sakiyuki0830@gmail.com
Conflict of Interest: The authors declare that they have no competing
interests to declare.
【Cover letter】
Editor-in-Chief
Clinical case reports
Dear Editor:
I wish to submit a case report for publication in Clinical Case Reports,
titled “Imminent rupture of infected aortic aneurysm presenting as
lower back pain in an older patient: A case report.” This paper was
co-authored by Tadatsugu Morimoto, Hirohito Hirata, Masatsugu Tsukamoto,
Takaomi Kobayashi, Tomohito Yoshihara, and Masaaki Mawatari.
This paper presents the clinical case of an elderly male patient who
presented to our hospital with complaints of lower back pain and an
infected aortic aneurysm at the time of his initial visit. The patient
had poorly controlled type II diabetes mellitus. He presented to our
hospital with back pain and numbness in the left lower extremity, which
had increased gradually. Further examination revealed an infectious
aortic aneurysm, and the patient was referred to the cardiovascular
surgery department. We believe that this case makes a significant
contribution to the literature because infective aortic aneurysms are
rare and are expected to increase in the future due to an increase in
the number of compromised hosts.
Furthermore, we believe that there are lessons to be learned from the
clinical course of our patient and that this paper will be of interest
to the readers of your journal. We hope that the takeaway message will
serve as a reminder to physicians regarding consideration of diagnosis
of infectious aneurysms when patients present with lower back pain. A
delayed diagnosis can have serious consequences and may lead to
unsatisfactory clinical outcomes. We hope that the information provided
in this report will aid in early detection and treatment of this
disease.
This manuscript has not been published or presented elsewhere in part or
in entirety, and is not under consideration by another journal. We have
read and understood your journal’s policies and believe that neither the
manuscript nor the study violates any of these policies. The authors
declare no conflicts of interest.
Thank you for your consideration. I look forward to hearing from you.
Sincerely,
Satoshi Takashima
Department of Orthopedic Surgery, Faculty of Medicine, Saga University,
5-1-1 Nabeshima, Saga, Japan
Tel: +81-95-234-2343
Fax: +81-95-234-2059
E-mail: stmh1156@gmail.com
【Manuscript】
Keywords: Infected abdominal aortic aneurysm, lower back pain,
misdiagnosis
●Introduction:
Infected abdominal aortic aneurysm (IAAA) is a rare but potentially
fatal sequela of infectious inflammatory disease of the aortic wall.
However, it is rather an under-recognized disease. The incidence of IAAA
has increased in the recent years due to the aging population and
increasing number of immunocompromised hosts1. Early
diagnosis and management of IAAA can improve the prognosis and survival.
However, the diagnosis of IAAA is sometimes challenging in the early
stages due to its varied clinical presentation, such as lower back
pain2.
Herein, we report the case of an older patient in whom a differential
diagnosis of spinal degenerative disease was considered due to symptoms
such as lower back pain, lower extremity pain, and numbness. However,
the patient was ultimately diagnosed with IAAA.
Case history and examination:
A 63-year-old male patient presented to the orthopedic outpatient clinic
with complaints of back pain and left leg numbness, which had gradually
increased over the past month. The patient had a history of diabetes
mellitus (DM), hypertension, and dyslipidemia, but had self-interrupted
his medications. No other significant medical history was elicited by
the patient.
Physical examination revealed lower back pain and the patient was able
to walk without experiencing any neurological deficits. He experienced
swelling and local heat in the left lower limb without any erythematous
changes or cold sensations in the right leg. The left dorsalis pedis
artery was palpable; however, the right dorsal foot artery was poorly
palpable.
Investigations were performed to localize the source. His laboratory
data showed marked elevation of white blood cells (26.9 × 103/L) and
C-reactive protein (17.96 mg/dL; normal range < 0.3 mg/dL),
along with increased glycosylated hemoglobin (HbA1c) value (9.4%;
normal range < 6.0%), Aspartate Aminotransferase (155 U/L;
normal range <30 U/L), alanine transaminase (ALT) (93 U/L;
normal range < 42 U/L), and gamma-glutamyltransferase (437
U/L; normal range < 64 U/L) levels were also markedly elevated
indicating severe infection, DM and liver dysfunction. Fever, back pain,
and elevated C-reactive protein levels were suggestive of pyogenic
spondylitis. Therefore, lumbar spine radiography and Magnetic Resonance
Imaging (MRI) examination were performed. However, lumbar spine
radiography and MRI revealed no findings suggestive of pyogenic
spondylitis (Figure 1). Based on these results, hepatobiliary system
disease was suspected and a medicine specialist was consulted. The
patient was admitted due to the suspicion of liver abscess, and
underwent detailed examination and treatment.
Differential diagnosis, investigation, and treatment
Contrast-enhanced abdominal computed tomography (CT) revealed a
pseudoaneurysm in the descending aorta. The surrounding soft tissues
showed a small amount of gas in the L3/4 intervertebral space and above
and below them, suggesting a left psoas abscess and L3/4 vertebral
spondylodiscitis (Figure 2). On reviewing the radiograph and MRI, we
realized that we had missed the imminent rupture of an infected
abdominal aortic aneurysm (IAAA) (Figure 1). Blood cultures were
positive for Gram-negative rods, and the microorganism was identified as
Escherichia coli. Based on these findings, the patient was ultimately
diagnosed with a left psoas abscess and septic shock secondary to IAAA.
Ceftriaxone (CTRX) (2.0 g) was administered every 12 h. Pazufloxacin
(PZFX) (1.0 g) was added every 12 h to allow tissue penetration. After
the initiation of antibiotic therapy, no worsening tendency was
observed. Antimicrobial susceptibility testing revealed that the isolate
was susceptible to cefazolin (CEZ) at the minimal inhibitory
concentrationvalue. Therefore, 2.0 g of CTRX being administered every 12
h was replaced with 1.0 g of CEZ every 6 h.
●Outcome and follow-up
Four days later, fever and back pain worsened again. Subsequent
antibiotic treatment was continued, and the fever stabilized. Laboratory
data showed an improvement in white blood cell count (14.5 ×
103/L) and C-reactive protein levels (3.56 mg/dL;
normal range < 0.3 mg/dL). However, CT revealed a ruptured
IAAA despite the patient being fully alert. An emergency surgery was
performed (Figure 3). The patient underwent aorto-right external iliac
bypass, femoro-femoral bypass, enterectomy, and colostomy. He was
managed in the Intensive Care Unit post-surgery, but was in a state of
circulatory failure since the end of the surgery. The patient was
confirmed dead on the fourth postoperative day.
●Discussion:
IAAA was first described by Osler in 1885 as an aneurysm caused by a
bacterial embolus from infective endocarditis3. The
concept has since been broadened to include all aneurysms caused by
infections along with those caused by the addition of infection to an
existing aneurysm4. IAAA is rare, accounting for
0.7%-3% of all aortic aneurysms, and is difficult to treat. The
hospital mortality rate of patients with infected aortic aneurysms is
high, ranging between 5-44%5,6. In the past,
bacteremia from infective endocarditis and infective emboli were the
main sources of infection. However, with the increasing prevalence of
atherosclerosis and medically induced arterial injury (catheters and
surgery) associated with aging and an increasing number of easily
infected hosts such as those with diabetes, malignancy, and collagen
disease, the incidence of IAAA has been reported to
increase7.
Correct and early medical examination and treatment are essential
because IAAA is characterized by a faster rate of
enlargement8 and a higher frequency of rupture due to
its multifocal nature9, in comparison to abdominal
aortic aneurysm (AAA). However, while AAA is often accompanied by severe
symptoms, such as abdominal pain, impaired consciousness, and abnormal
blood pressure, most cases of IAAA rupture are confined to the
retroperitoneum, and rupture into the abdominal cavity is extremely
rare10. Back pain is often the main symptom in IAAA
rather than abdominal pain11. There have been a few
cases of IAAA wherein physicians and spine surgeons engaged in lower
back pain treatment, and a correct diagnosis was not reached. Therefore,
physicians and spine surgeons should be aware of the possibility of IAAA
when the patient complains of persistent back pain even after the
administration of treatment for symptomatic relief. According to reports
by various authors, rupture or impending rupture of an AAA should be
suspected when (1) the patient is a middle-aged or older male with a
history of an abdominal mass; (2) the pain is severe, with a definite
onset time and a component of lateral abdominal pain; (3) there is no
tenderness in the lumbar spine or surrounding soft tissues and no
neurological symptoms; (4) the iliopsoas muscle shadow is abnormal on
radiography; and (5) a beating mass is detected in the
abdomen9. Palpation of the abdominal mass is
recommended in patients with atypical lower back
pain9.
The present case involved an older male patient who did not present with
lumbar spinal tenderness or neurological symptoms. Remarkably, an
abdominal examination was not conducted; therefore, the presence of an
abdominal mass was not initially established. Regrettably, the
possibility of IAAA, which could have been a potential diagnosis, was
not initially considered. In addition, as in the present case, missed
imaging findings can also be problematic. IAAA is difficult to diagnose
because the main symptom is fever, and the patient presents with a
variety of symptoms, including thoracoabdominal pain and back pain,
depending on the location of the aneurysm12. IAAAs are
easily overlooked when fever is not the primary symptom. Blood
investigations showing signs of infection, such as increased white blood
cell counts and elevated C-reactive protein levels, along with positive
blood cultures and the presence of soft tissue infiltration around the
aorta, as shown on CT or magnetic resonance angiography (MRA), may lead
to a diagnosis of IAAA. IAAA does not present with serious symptoms in
the early stages, and back pain is the main complaint in 44% cases;
therefore, orthopedicians are likely to be involved. However, in cases
of lower back pain without the primary complaint of fever, abdominal
examinations and blood investigations are rarely performed, and
orthopedic surgeons tend to focus only on their area of expertise in
diagnostic imaging13,14. Focusing on the spine and
spinal cord, without paying attention to the soft tissues that appear in
the imaging, can lead to overlooking serious diseases such as IAAA. In
the present case, the diagnosis was made on the same day as the patient
was suspected of a serious disease and internal medicine and radiology
department was consulted, although it had been missed at the time of the
initial visit. It should be noted that physicians treating lower back
pain tend to look at the ABC (Alignment, Bone, Cartilage) but miss the
soft tissues15. It is necessary to review images from
the edges to ensure that entities such as aortic disease, neoplastic
lesions of the spine, and hip disease are not missed during this
process.
●Consent:
Written informed consent for the publication of this case report
(including photographs, case progress, and data) was obtained from the
patient’s relatives.
【Author Contributions】
ST and TM designed and outlined the main conceptual ideas. TY and TK
collected the data. MT, MT, and HH. aided in the interpretation of the
results and worked on the manuscript. MM supervised this study. ST wrote
the manuscript with the support of MT, M.T, and HH. All the authors
discussed the results and commented on the manuscript.
【Funding Information】
No funds, grants, or other support was received.
【COI statement】
The authors declare that they have no conflicts of interest.
【Data availability statement】
Data sharing is not applicable to this article as no datasets were
generated or analyzed in the current study.
【ORCID】
Satoshi Takashima: 0009-0009-5013-5812.
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【Figure/Table】
Figure 1
Radiographic and Magnetic resonance imaging (MRI) of the lumbar spine
before treatment.
Lumbar spine radiograph and (B) MRI showing no findings suggestive of
discitis or vertebral body destructive lesions at the time of the
initial examination. We observed the presence of an imminent rupture
of the infected abdominal aortic aneurysm (white arrow) on
reexamination.