Dunbar syndrome
Celiac artery compression syndrome, also known as median arcuate ligament syndrome, Dunbar syndrome, or Harjola-Marable syndrome, is a rare condition characterized by upper abdominal pain in the setting of compression of the celiac trunk by the diaphragmatic crurae.
Although well-recognized as a clinical entity, there remains some controversy regarding this condition due to the relatively high prevalence of celiac artery narrowing in asymptomatic patients and autopsy studies .
Epidemiology
- more common in females (4:1 female/male ratio)
- average age 30-50 years old
- thought to be more common in thin patients
Clinical presentation
- chronic abdominal pain, especially postprandial
- can be relived by positional changes, e.g. standing position
- can be aggravated by supine position
- nausea/vomiting
- weight loss
Pathology
The median arcuate ligament is the fibrous arch that unites the diaphragmatic crura forming the anterior arc of the aortic hiatus. The celiac trunk is a major branch of the abdominal aorta, originating anteriorly near the level of the diaphragm and usually in close proximity to the median arcuate ligament.
There is considerable variation in positioning of both the celiac trunk and the diaphragm . In some, the ligament is positioned more inferiorly relative to the celiac artery, resulting in compression. The degree of compression typically varies with respiration, most accentuated during end-expiration when the two structures move closer together.
The etiology of abdominal pain is hypothesized to be ischemic, due to impaired flow secondary to compression. Alternatively, the contribution of a neuropathic component related to the effect on the celiac plexus has been proposed .
Radiographic features
It is important to note that narrowing of the celiac trunk at the diaphragm is non-specific and most commonly seen in asymptomatic patients. As always, imaging findings should be correlated with the clinical history.
Recognized imaging features of celiac artery compression include:
- focal narrowing of the superior aspect of the proximal celiac trunk forming a hooked or "J" appearance
- post-stenotic dilatation or evidence of collateral formation
- absence of associated atherosclerosis
The phase of respiration often has a significant impact on the degree of celiac narrowing. Most commonly, the celiac arterial narrowing is accentuated during end-expiration and lessens during end-inspiration. It has therefore been recommended to image during end-inspiration to lessen the chance of detecting clinically insignificant narrowing (false positive) .
Ultrasound
Doppler ultrasound can be a useful noninvasive diagnostic tool. In young adults, a peak systolic velocity over the compressed segment of the celiac artery of greater than 200 cm/s in the mid position between inspiration and expiration has a reported sensitivity and specificity of 75% and 89%, respectively, in detecting stenosis of 70% or greater .
CT
CT angiography and conventional angiography are considered to be the gold standard imaging modalities for detection of the proximal celiac stenosis with classic hooking configuration.
Additional features that may be appreciated include post-stenotic dilatation, prominent collaterals, such as the gastroduodenal and common hepatic arteries, and thickening of the median arcuate ligament. A thickness of the median arcuate ligament of greater than 4 mm is considered abnormal .
Treatment and prognosis
Symptomatic patients are treated with surgical decompression. This is usually performed laparoscopically by dividing the median arcuate ligament.
History and etymology
The clinical entity was described in 1963 by P T Harjola, a Finnish surgeon who performed the first median arcuate ligament release . A larger case series of 15 patients was published in the American Journal of Roentgenology in 1965 by the radiologist J David Dunbar and surgeon Samuel Marable, both from Ohio, USA .
Differential diagnosis
- normal anatomic variant: mild or moderately narrowed appearance of the celiac trunk at the diaphragm is common, and severe (>80% stenosis) may be asymptomatic
- celiac artery atherosclerosis: more likely to present with luminal irregularity, lacking the classic "J" or hooked appearance of the stenosis, and in older patients with other areas of atherosclerosis
See also
Siehe auch:
- Arteria-mesenterica-superior-Syndrom
- Truncus coeliacus
- Hiatus aorticus
- vaskuläre Kompressionssyndrome
- Kompressionssyndrome
- diaphragmatic crurae
und weiter:
Assoziationen und Differentialdiagnosen zu Truncus-coeliacus-Kompressionssyndrom:
