Safety and efficacy of EUS-guided celiac plexus block in the evaluation of patients with median arcuate ligament syndrome anatomy for possible surgery

After institutional review board approval of the study was obtained on March 24, 2022 (IRB 84927), a retrospective chart review was conducted of all patients with postprandial abdominal pain and celiac artery compression anatomy who underwent EUS-guided CPB between 2014 and 2022. Data on EUS-guided CPB available from January 2015 to December 2021 were included in the analysis. The median follow-up time from the initial EUS-guided CPB was 14 months (range, 6-40 months). The patient with the unsuccessful CPB was lost to follow-up. Most of the procedures (n = 11) were performed between June 2019 and December 2021 by 5 different EUS-trained endoscopists. The single EUS procedure performed in 2015 did not result in a CPB because of inability to visualize the celiac nerve plexus. EUS performed before 2020 used the Olympus GF-UC140 linear echoendoscope (Olympus America, Center Valley, Penn, USA), and those performed after 2020 utilized the Olympus GF-UCT180 curved linear echoendoscope (Olympus America). The procedure was performed with the use of propofol anesthesia without opiates. All endoscopists identified the celiac plexus and celiac ganglia in a standard fashion, using the take-off of the celiac trunk from the anterior aspect of the aorta as the anatomic landmark (Fig. 2A). Color Doppler imaging was used to identify vascular structures. CPB was performed through a transgastric approach with a single injection in the area of the celiac nerve plexus (Fig. 2B) by use of a mixture of .25% bupivacaine and triamcinolone (40 mg/mL). The volume and concentration varied among the endoscopists; 10 mL .25% bupivacaine and 1 mL triamcinolone were used most frequently. Most patients had several previously diagnosed comorbidities; notably Ehlers-Danlos syndrome (EDS) and/or postural orthostatic tachycardia syndrome (POTS) was present in 5 of 12 patients (Table 1). All patients had evidence of compression of the celiac artery by the MAL (MAL anatomy) visualized on duplex US, CT, or MR imaging, or a combination thereof. All patients experienced abdominal pain, and most had other associated symptoms. These symptoms most commonly included nausea/vomiting and bloating/fullness. Response to EUS-guided CPB was defined as patient-reported subjective improvement in abdominal pain and ability to eat with no to minimal pain after the CPB. Response to surgery was defined as patient-reported improvement in pain, increased oral intake, and satisfaction with surgery. Patients were classified as experiencing “improvement” if they reported improvement in pain, ability to eat, and satisfaction with surgery and “partial improvement” if they reported some improvement in those symptoms.

Twelve patients (10 women, median age 24.5 years [range, 19-62 years]) with postprandial abdominal pain were evaluated in the Stanford Digestive Health Clinic. During their evaluation, they were found to have celiac compression or MALS anatomy. To help determine whether the abdominal pain was related to MALS, patients were recommended to undergo a diagnostic CPB. Patients were offered EUS-guided CPB or referral to anesthesia pain for CT-guided CPB. We report on the 12 patients who underwent EUS-CPB. During the same time period, there were 12 additional patients with suspected MALS who were under the care of anesthesia pain and underwent CT-guided CBP. Of those patients who underwent EUS-CPB, 11 underwent successful CPB, and 1 procedure was aborted because of inability to visualize the celiac plexus. Of the patients who underwent successful CPB, 9 of 11 (82%) patients responded with improvement in symptoms. The results did not differ by endoscopist or CPB injection technique. No adverse events were reported during any of the performed CPB procedures. The duration of improvement in symptoms was variable, ranging from 7 hours to 3 months, with a median duration of 7 days. Of 9 responders, 8 went on to have MAL release surgery. In patients who underwent MAL release surgery, 7 of 8 (88%) reported at least partial improvement in symptoms, and 1 patient experienced no change in symptoms. The responses to CPB and MAL release are summarized in Table 1. Of the 2 nonresponders to EUS-guided CPB, 1 patient was later suspected of having superior mesenteric artery syndrome in addition to several other previously diagnosed conditions that included EDS/POTS and gastroparesis, which may have contributed to the original symptoms and lack of response to CPB. The second nonresponding patient ultimately received a diagnosis of suspected functional dyspepsia and visceral hypersensitivity with potentially overlapping irritable bowel syndrome-mixed (IBS-M).

Similar results were seen in patients who underwent CT-guided CPB. Of those, 11 nerve blocks were completed and 1 was aborted because of inability to visualize the celiac ganglion. Nine (82%) patients who underwent CT-guided CPB reported improvement in symptoms after the block. Of those, 8 underwent MAL release surgery, with 89% partial improvement in postprandial abdominal pain.

CPB is most often used for the treatment of pancreatic cancer–related pain; however, the technique has expanded in utility to non–cancer-related pain, including chronic pancreatitis and MALS. Whereas clear diagnostic guidelines for the evaluation of MALS are lacking, imaging studies to aid in diagnosis have included mesenteric duplex US, CT angiography, MR angiography, gastric tonometry, and mesenteric arteriography. However, a symptomatic response to CPB has increasingly been used to evaluate potential surgical candidates for MAL release, both in adults^{,,,  ,}  and in children. Among the most common symptoms reported in MALS are abdominal pain in 94%, nausea and vomiting in 55.6%, weight loss in 50%, and abdominal bloating in 39% of cases. In our study, 88% of patients who responded to CPB ultimately also had a favorable response to MAL release surgery with at least partial improvement in symptoms. The reason for partial instead of complete improvement in symptoms may include the heavy burden of comorbid GI and extraintestinal conditions in this cohort, including gastroparesis, SIBO, POTS, and EDS. In many cases, postprandial pain significantly improved , but symptoms like nausea, vomiting, and bloating remained less responsive to both CPB and MAL release surgery. This is consistent with a prior study showing that abdominal pain was most responsive to CPB, with 83% of patients reporting decreased abdominal pain after CPB whereas nausea and vomiting each decreased in approximately 69% of patients. Whether these less responsive symptoms of nausea/vomiting and bloating/fullness were primarily caused by MALS itself or by other comorbid conditions such as gastroparesis or small intestinal bacterial overgrowth (SIBO) is difficult to delineate, given the overlap of symptoms in these conditions. Likewise, existing preliminary findings suggest patients that with dysautonomia diagnoses or connective tissue disorders may have worse outcomes. In our study, almost half (5/12) of patients carried a diagnosis of EDS and/or POTS. There does appear to be an overlap between MALS with POTS and EDS, suggesting a possible shared pathophysiology. However, the prevalence of MALS in patients with POTS or EDS has not been well described in large series. In a series of 11 patients who underwent MAL release surgery, Huynh et al reported EDS in 18%, POTS in 27%, and gastroparesis in 71%. Celiac artery compression was reported in >50% of the 93 patients with POTS who underwent celiac artery Doppler ultrasound; however, this study did not report on whether those patients had GI symptoms suggestive of MALS. Previous studies have reported a MALS prevalence of 2% to 5% in patients with POTS and symptom response rates to surgery that are lower than those in patients without comorbid dysautonomia. However, overall, a positive response to CPB appears to predict a favorable response to surgical intervention. Surgical intervention in prior studies has reported success rates of 70% to 80% of cases without a preceding unified diagnostic process. Symptomatic recurrences have been described in ≤36% of patients after successful MAL release surgery. The only factor identified with risk of recurrence was preoperative American Society of Anesthesiologists class III or higher. Of those patients with recurrent symptoms who underwent follow-up imaging, celiac compression was present in only 50%. This further supports the hypothesis that the cause of MALS is neurogenic rather than vascular in origin. It is possible that routine evaluation with CPB preoperatively may further improve the response rate.

Traditionally, CPB and neurolysis have been performed under CT guidance through the back. However, an EUS-guided anterior approach was introduced in 1996 and is regarded as a relatively safer approach. Owing to the rare nature of the condition and the lack of large randomized trials, it is not known whether there is a difference in efficacy between CT-guided and EUS-guided approaches. In our study, EUS-guided CPB was successfully completed in 11 of 12 (92%) of patients, with 9 of 11 (82%) patients reporting symptomatic improvement, whereas a prior study reported that 7 of 10 (70%) patients achieved symptom improvement after CT-guided celiac or splanchnic block. CPB regardless of approach has relatively few serious adverse events. The more serious adverse events may include neurologic events and pneumothorax, but these have mainly been reported in posterior percutaneous approaches in 1% of patients. Even more rare are vascular injuries and retroperitoneal bleeding. Mild and generally self-limiting adverse events related to EUS-guided CPB can occur in ≤30% of cases. These most commonly include diarrhea (7%), increase in abdominal pain (2%-4%), and hypotension (4%). Serious adverse events are rare, and typically in <1% of cases may include bleeding or infections. Overall, the safety profile of EUS-guided CPB has been deemed favorable, and this case series further supports the safety of EUS-guided CPB in MALS. In all of the 12 patients undergoing EUS-guided CPB in the current study, no procedural adverse events were reported. In 1 patient, self-limited postprandial diarrhea occurred for several weeks until spontaneous resolution.

The present study suggests that EUS-guided CPB is a safe approach to evaluating patients with MALS anatomy for possible surgery, and the study adds to the evidence supporting the utility of CPB response as a predictor of symptom improvement after MAL release surgery. Ideally, larger randomized controlled trials could be used to confirm the benefit of preoperative celiac block, both for diagnosis of MALS and prediction of symptom response to MAL release surgery. However, given the already demonstrated utility in patient evaluation for surgery and the safety of the procedure, EUS-guided CPB could be considered an option in the diagnosis and treatment algorithm for patients suspected of having MALS who are undergoing evaluation for surgical intervention, especially when CT-guided CPB is not available or is contraindicated because of spinal abnormalities.

Funded through the Colleen and Robert D. Haas Fund as part of the San Francisco Foundation.