Median arcuate ligament (Dunbar) syndrome: Laparoscopic management and clinical outcomes of a single centre.

BACKGROUND: Median arcuate ligament syndrome (MALS) is a condition characterised by chronic abdominal symptoms associated with median arcuate ligament (MAL) compression of the coeliac artery. AIM: In this observational study, we aimed to evaluate the outcomes of laparoscopic treatment in patients with MALS.
MATERIALS AND METHODS: The data of ten patients with MALS who were subjected to laparoscopic sectioning of the MAL were retrospectively reviewed. The following data were evaluated: age, gender, clinical and diagnostic test findings, American Society of Anaesthesiologists score, operative findings and complications and mortality, hospital stay duration and hospital readmission. The diagnosis of MALS was established by computed tomography (CT) angiography.
RESULTS: Six (60%) of ten patients with MALS were female and four (40%) were male. The mean age was 42.4 ± 12.3. The main symptoms were epigastric pain (100%) and weight loss (60%). CT angiography showed high-grade stenosis of the anterior wall of the proximal coeliac trunk and post-stenotic dilation caused by extrinsic compression of the MAL. Surgical procedure was uneventful in all patients. Operating time was 155.5 min (120-200) and intra-operative blood loss was 150 ml (100-250). Length of stay was 3.1 day (2-9), with no mortality. The post-operative complications developed in two female patients. One of them developed ileus and the other patient developed pulmonary thromboembolism. At 6-month follow-up, all patients were asymptomatic.
CONCLUSION: Laparoscopic decompression is an effective treatment for MALS and can provide symptomatic relief. This method may be the preferred modality of treatment in view of its lack of morbidity and good results.

INTRODUCTION

Median arcuate ligament syndrome (MALS), also named Dunbar syndrome or coeliac axis compression syndrome, is due to compression of the coeliac axis and/or coeliac ganglion by the median arcuate ligament (MAL) of the diaphragm. It was first described by Harjola in 1963 who reported resolution of postprandial upper abdominal and epigastric pain in a patient following surgical decompression of the coeliac axis due to a fibrous coeliac ganglion.[1] Physical examination is usually normal. Radiographic evidence of external compression of the coeliac artery is needed to confirm the diagnosis. Although the incidence of MALS is unknown, case and series reports have increased in the last years, possibly due to the widespread use of imaging examinations such as computed tomography (CT) angiography and magnetic resonance.[2] Patients with MALS are often middle-aged thin females. It may cause various clinical symptoms such as postprandial epigastric pain, weight loss, nausea, vomiting and abdominal bruit.[3] Its diagnosis may be difficult and very often delayed. MALS remains controversial in terms of the pathophysiologic origin of the symptoms, diagnosis and optimal treatment and management. Until recently, there has been some reluctance to consider intervention with revascularisation or ligament release. Within the latest decade, minimally invasive techniques, including laparoscopic release of the MAL, have shown promising results.[45] Herein, we present the clinical outcomes of laparoscopic treatment of patients with MALS in our clinic.

MATERIALS AND METHODS

This study included data from ten patients with MALS who were subjected to laparoscopic sectioning of the MAL at Dicle University School of Medicine, Department of General Surgery, between the dates of January 2015 and December 2019. The patients described in this series all presented with typical symptoms of the MALS. They underwent an extensive pre-operative workup to exclude other more common causes for their symptoms. Typically, most of our patients had a relatively long duration of symptoms and had undergone multiple investigations elsewhere before a diagnosis was finally made. Only one of the patients had a history of abdominal (liver hydatid cyst) surgery. No patient had a documented psychiatric history.

The following data were obtained: age, gender, clinical and diagnostic test findings, American Society of Anaesthesiologists (ASA) score, operative findings and complications, post-operative complications and mortality, hospital stay duration and hospital readmission. Data were obtained retrospectively from our hospital electronic medical records and study protocols. The diagnosis of MALS was confirmed in all patients by CT angiography [Figures 1a, b and 2]. Other causes of abdominal pain were excluded with extensive medical evaluation including laboratory tests, electrocardiogram, abdominal ultrasonography, upper gastrointestinal endoscopy and/or colonoscopy. We did not perform an extensive dissection of the neural plexus around the coeliac trunk, and the fact that all of our patients had good symptomatic relief suggests that release of the compressed vessel is the key component. The study was performed in accordance with the Helsinki Declaration.

Figure 1

Pre-operative axial and sagittal computed tomography angiography image of the patient (a and b), stenosis at the origin of the coeliac trunk (red arrow) (b), post-operative axial and sagittal computed tomography angiography image of the patient (c and d)

Figure 2

Three-dimensional sagittal reconstructed image of a patient diagnosed with median arcuate ligament syndrome, showing the severe stenosis at the origin of the coeliac trunk (white arrow)

Anatomy

The MAL is a tough fibrous arch connecting the right and left crura of the diaphragm at the level of the aortic hiatus (T12-L1). It traverses anterior to the aorta and is usually cranial to the coeliac artery. The position of the MAL and the origin of the coeliac artery vary between individuals. A relatively cranial origin of the coeliac artery or caudal insertion of the MAL can lead to extrinsic compression of the proximal coeliac artery.[6]

Surgical technique

Under general anaesthesia, the patient was replaced by supine position in reverse Trendelenburg position with the legs abducted and supported on cushioned spreader bars. The surgeon stood between the patient's legs. A temporary nasogastric tube was inserted. Thromboembolism prophylaxis with enoxaparin sodium 40 mg was administered subcutaneously at the anaesthesia induction in patients ≥40 years old and in patients with a history of previous thromboembolism. The operation was performed through five trocars inserted in the upper abdomen. A camera port was inserted on the midline at about 5 cm above the umbilicus. Four additional trocars were inserted under direct vision into the right and left subcostal areas, left flank and subxiphoid position.

A retractor was inserted into the subxiphoid trocar to elevate the left lobe of the liver medially, and the stomach was retracted to the patient's left side with a Babcock clamp. After gastrohepatic ligament sectioning, the common hepatic artery and the left gastric artery were dissected and isolated with a vessel loop for retraction. The arteries were followed to the origin of the coeliac trunk. There was no need to dissect the splenic artery. The right crus was dissected [Figure 3a], and the MAL was identified and divided by energy device and/or a hook cautery [Figure 3b]. The anterior surface of the aorta was exposed for about 3 cm. The coeliac trunk was completely skeletonised [Figure 3c]. All fibrotic tissues overlying the coeliac axis were resected [Figure 3d]. Undue dissection of the oesophagus hiatus was not performed in order to avoid post-operative gastro-oesophageal reflux. Intraoperative ultrasonography was not employed to assess coeliac artery flow after decompression.

Figure 3

Dissection of the diaphragmatic crus (a), dissection of the median arcuate ligament (yellow arrow), view of the coeliac artery (white arrow) (b), releasing the coeliac artery (c), laparoscopic view showing visualisation of the aorta (white arrow) and decompression of the coeliac artery after dividing the median arcuate ligament (yellow arrow) (d)

Follow-up

Patients returned for ambulatory follow-up on the 10th day and 1, 3 and 6 months after operation. Follow-up was extended as needed. Control CT was performed at the 3rd post-operative month [Figure 1c and d].

Statistical analysis

The statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS version 21.0, SPSS Inc., Chicago, IL, USA) computer programme. Descriptive statistics were expressed as the mean and standard deviation (SD) for numerical variables and as numbers and percentages for categorical variables.

RESULTS

There were six (60%) women and four (40%) men aged from 19 to 65 years, with a mean age of 42.4 ± 12.3 years (mean ± SD). Clinical manifestations lasted from 8 months to 2 years. Intermittent epigastric pain was referred by all patients. Four (40%) patients complained that the pain was postprandial and relieved with fasting. Six (60%) patients had a weight loss of 4–9 kg, with a mean of 5.6 ± 1.4 kg. On physical examination, all patients had epigastric tenderness; there was no defence or rebound. Demographic and clinical characteristics of patients are shown in Table 1.

Table 1

Demographic and clinical characteristics of patients

	n (%)
Number age (years) mean	10 (19-65) 42.4±12.3
Gender
Female	6
Male	4
Clinical presentation
Epigastric pain	10 (100)
Weight loss	6 (60)
Postprandial pain	4 (40)
ASA score
I	2 (20)
II	5 (50)
III	3 (30)
CT angiography coeliac trunk
High-grade stenosis	10 (100)
Post-stenotic dilatation	10 (100)

ASA: American Society of Anaesthesiologists, CT: Computed tomography

The diagnosis of MALS was confirmed in all patients by CT angiography that showed high-grade stenosis of the anterior wall of the proximal coeliac trunk caused by extrinsic compression of the MAL. Compression was more intense on expiration. Post-stenotic dilation was also observed in all patients. Two patients (20%) were ASA I, 5 ASA II (50%) and 3 ASA III (30%). Surgical procedure was uneventful in all patients. Operative time ranged from 120 to 200 min, with a mean of 155.5 min. Only one of the patients had a history of abdominal (liver hydatid cyst) surgery. Conversion to open operation occurred only in this patient due to intra-abdominal adhesions. No operative complication was recorded. Intraoperative blood loss was 150 ml (100–250). Length of stay was 3.1 day (2–9). The post-operative complications developed in two female patients. One of them developed ileus and the other patient developed pulmonary thromboembolism. Medical treatment was applied to these patients. At 6-month follow-up, all patients were asymptomatic. Two patients referred with episodes of mild abdominal pain in the first 2 months, but they became asymptomatic afterwards. All six patients who referred weight loss before the operation recovered most of the weight. CT angiography obtained at that time was normal, with no coeliac axis stenosis.

DISCUSSION

The MAL is a band of fibrous tissue that joins the left and right crura of the diaphragm to form the anterior surface of the aortic hiatus at the level of the 12th thoracic vertebra. The MAL usually comes into contact with the aorta above the origin of the coeliac axis. However, in some individuals, this ligament may be abnormally low and passes in front of the coeliac axis, causing its compression, which is named MALS.[7]

The pathogenesis of MALS has been usually related to ischaemia, but some authors have proposed a connection between the symptoms and compression of the coeliac ganglion and plexus. These aspects could explain the variability in the published results regarding different treatment modalities. Coeliac denervation and neurolysis also play a role in the relieving of pain in MALS along with the relief of mechanical pressure. Initial symptoms appear when flow through the lumen of the CT diminishes to 50%–75% and severe symptoms appear at 75%–90% of stenosis. With critical stenoses (over 90% of lumen reduction), full-blown MALS is observed.[8] Increased demand for blood flow through a compressed coeliac artery leads to foregut ischaemia, resulting in epigastric pain, although compensatory increased flow through the collateral vessels usually prevents the development of ischaemia. These collaterals include the network of vessels from the superior mesenteric artery and an extensive array of vessels that communicate with the gastric and splenic vasculature. Although the ischaemic pathophysiology of MALS is widely accepted, there is a debate whether neuropathic mechanisms are also involved. Irritation of sympathetic pain fibres and/or splanchnic vasoconstriction and ischaemia, including overstimulation of the coeliac ganglion to cause chronic pain, has been suggested in these patients. Hence, the actual pathophysiology of MALS is likely multifactorial including compressive effects on the CT and surrounding neurogenic structures (ischaemic and neurogenic). The constriction and chronic irritation of the coeliac plexus seem to be responsible for the many vegetative symptoms such as tachycardia, fainting, dizziness, diarrhoea and sweating. Sustained compression of the CT may lead to changes in vascular layers such as intimal hyperplasia, proliferation of elastic fibres in the media and disarray of the adventitia. Some authors suggest that the interruption of sympathetic nerve fibres in the section of the arcuate ligament can help relieve abdominal pain, because the perivascular sympathetic and denervation of the coeliac ganglion reduce vasospasm, increasing flow.[1]

The diagnosis of MALS may be difficult. Typical symptoms of MALS include recurring epigastric pain, mainly postprandial, nausea, vomiting, weight loss and reduced appetite. However, an expressive number of patients with MALS do not have these typical symptoms.[9] In our series, six (60%) patients had weight loss, and four (40%) patients complained that the pain was postprandial. In addition, the typical symptoms may mimic other diseases such as peptic ulcer and cholelithiasis. Therefore, complete medical evaluation, including laboratory examinations, CT angiography, endoscopy and ultrasonography, should be performed to exclude other medical conditions.[10]

The treatment of MALS consists of releasing the compression of the coeliac axis by sectioning the MAL. The objective is to restore adequate blood flow through the compressed coeliac trunk artery.[11] Several authors have confirmed that adequate selection of patients is the most important factor to improve surgical treatment outcome. However, selecting patients who are likely to benefit from surgery is a challenge.[12]

Surgical treatment may be performed through laparotomy, laparoscopy or robotic-assisted laparoscopy.[13] Since the first release of the coeliac axis through laparoscopy by Roayaie et al.[14] in 2000, this access became the standard treatment of MALS. Laparoscopic treatment of MALS compared with open operation has several advantages including less morbidity, less post-operative pain, less blood loss, less adhesions, shorter recovery period, faster return to normal activities and better cosmetic results.[15] Robotic-assisted approach has also been successfully employed to treat MALS. However, due to cost limitation, the experience is still limited, and its use has been restricted to fewer medical centres.[16]

Sustained symptom relief has been reported in 80%–100% of patients with MALS who underwent surgical decompression, depending on several factors including patients' selection and severity of coeliac trunk stenosis.[1718] Roseborough[19] reported subjective improvement of symptoms in 14 (93%) of 15 patients treated laparoscopically, with a mean follow-up period of 44.2 months. The following clinical factors may indicate better prognosis: postprandial abdominal pain, age between 40 and 60 years, weight loss >20 pounds and absence of history of mental illness or alcohol abuse.

Percutaneous transluminal angioplasty/stent constitutes a useful adjunct procedure in patients with residual symptoms and/or stenosis after operative intervention. Endovascular therapies serve another major role in the management of MALS, in cases with splanchnic aneurysms, typically described in the pancreaticoduodenal arcade but also described in the gastroepiploic arteries. They can arise because of increased collateral flow dynamics or a post-stenotic dilatation.[12] In our centre, we could not apply endovascular techniques due to the lack of an experienced team.

Some authors have suggested that addition of neurolysis is also fundamental to treat the pain associated with MALS. It has been hypothesised that the pain may also have a neuropathic component due to a chronic compression and/or overstimulation of the coeliac ganglion. Neurolysis with complete excision of the coeliac nerve plexus may correct the neuropathic component of the pathogenesis of the syndrome.[20] Given neurogenic involvement in MALS, Sultan et al.[12] contended that the abdominal nerve plexus could be routinely removed in addition to release of the ligament.

In a literature review, Jimenez et al.[21] analysed post-operative outcome of 400 patients subjected to surgical treatment of MALS between 1963 and 2012. Eighty-five per cent (339/400) of patients had immediate post-operative relief of symptoms and 6.5% (26/279) had symptom recurrence. The incidence of complications was 11.6% for laparoscopic approach and 6.5% for open surgery. The most common complications of laparoscopic approach were bleeding and pneumothorax and of open surgery were thrombophlebitis, gastro-oesophageal reflux and stroke. Laparoscopy conversion to open surgery occurred in 11 of 121 (9.1%) patients due to bleeding. There were no procedure-related deaths in both approaches.

Gastro-oesophageal reflux disease may develop after surgical treatment of MALS, either after open surgery or laparoscopic approach. This is possibly due to inadvertent dissection of the oesophageal hiatus. In case of opening of the oesophageal hiatus, it should be properly closed.[22] Severe complications such as ruptured pseudoaneurysm of the inferior pancreaticoduodenal artery have also been reported.[2324] In our study, one of the patients developed ileus and the other patients developed pulmonary thromboembolism after surgery.

There have been reported some other case reports and several small series of patients who underwent laparoscopic division of the MAL.[252627] In the largest of these, Tulloch et al.[28] published a retrospective review of outcomes in patients with the MALS and compared laparoscopic versus open coeliac ganglionectomy over a 10-year period. In this study, ten patients were treated laparoscopically, and two of these required conversions to an open procedure. The median time to return to a normal diet and the average hospital stay were significantly shorter in those treated laparoscopically compared with patients who had an open procedure. The median hospital stay was 2 days and the postoperative morbidity was similar to other reported studies in laparoscopically treated group.[29] In our study, four patients had moderate nausea and abdominal pain during the first 48 h postoperatively, but fortunately, these symptoms resolved spontaneously.

One of the most important limitations in this small series observational study was the absence of a control group. Although we achieved success with laparoscopic methods in the treatment of MALS in our study, larger case series were needed in order to present the definitive results.

CONCLUSION

MALS is a rare entity. Given its less invasive nature, laparoscopic decompression of the MAL can provide an important approach where the risk of surgery and cosmetic impairment are significant. Based on the literature and our experience, laparoscopy is a highly useful tool in the treatment of MALS and constitutes the preferred treatment modality actually. Nevertheless, more studies comparing modalities of treatment are required.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.