CELIAC PLEXUS NEUROLYSIS (CPN)
Originally described in 1914, modern CPN may be performed percutaneously, at the time of laparotomy, or under the direction of endoscopic ultrasound (EUS) (7). Alcohol is typically injected into the plexus but it may also be injected into the ganglia proper. Although steroid injections have been described for CPN, they are more commonly used for pain associated with chronic pancreatitis than for pain with pancreatic cancer.
Historically, percutaneous and surgical neurolysis was considered the mainstay treatment. Percutaneous CPN is generally approached posteriorly with imaging guidance, while surgical neurolysis, which was originally performed during staging laparotomy, has been replaced by laparoscopy (4,8). Over time, however, both treatments seem to have yielded to the EUS approach. EUS CPN offers several advantages over radiologic and surgical techniques, including enhanced needle precision, the ability to inject the neurolytic agent into a larger area, and the ability to perform CPN at the time of tumor biopsy and staging (9). Regardless of which technique is chosen, alcohol is injected bilaterally into the peri-aortic fat pad at the level of celiac artery and diaphragmatic hiatus.
EUS-guided CPN is currently the most common technique used today. Consistent with other endoscopic procedures, traditional preoperative questioning and positioning is performed. Next, adequate hydration is ensured and anticoagulants are held as indicated. Pulse oximetry and non-invasive blood pressure monitoring are obtained while the patient is sedated and recovering. Antibiotics are administered for those on proton pump inhibitors due to the risk of post-operative abscess from bacterial overgrowth of the upper GI tract. EUS may be performed using linear-array endosonographic imaging by way of a GF-UC30P (Olympus Corporation, Center Valley, PA, USA), GF UC140P-AL5, or GF UC 160 PAT8 (Pentax Precision Instruments, Orangeburg, NY, USA).
Visualization of the celiac plexus is best seen from the posterior lesser curve of the stomach. The aorta is seen longitudinally, and the first arterial branch below the diaphragm is identified (Figure 1). With experience, the celiac plexus and ganglia can be readily identified. Traditionally, a 22-guage needle is advanced through the scope after being purged of air in anticipation of injection. There are larger specialty needles for CPN, including needles with multiple side-holes, to allow for a larger injection field (EUSN-20-CPN: Cook Endoscopy, Winston-Salem, NC, USA). The needle is advanced near the lateral anterior aorta, flushed, and aspirated. For CPN in pancreatic cancer patients, 10 mL (0.25%) of bupivacaine is injected, followed by 10 mL of dehydrated (98%) alcohol. The needle is then flushed and directed to the contralateral side of the aorta where the injection sequence is repeated. Impediments to visualization include lymphadenopathy or direct tumor encasement of the plexus and/or ganglia. In these cases, unilateral injection may be the only possibility, which could result in an associated decrease in efficacy (10). This procedure typically takes well under an hour. Afterwards, the patient is monitored and then discharged home in the absence of unstable vital signs as appropriate.
Multiple studies have compared CPN to medical pain management. In 1995, Eisenberg et al. reported pain relief in 90% of their patients at 3 months from CPN, with a majority of those having significant relief until death (11). Lillemoe et al. and Wong et al. both reported pain control beyond 6 months to be common (8,12). In 2004, JAMA published a randomized control trial (RCT) that compared patients who underwent percutaneous CPN using a posterior approach with patients given systemic analgesic medications (12). Their results showed a significant difference in pain scores between the two groups, with the CPN patients reporting less severe pain (14% vs. 40%; P=0.005). This same study, however, did not show CPN to improve patient quality of life or survival. In 2007, Yan et al. performed a meta-analysis of five randomized trials comparing CPN to medical management (13). A significant difference was found between groups in visual analog scores and opioid usage, the results favored CPN. A second meta-analysis of nine RCT’s performed by Puli et al. in 2009, showed an 80% decrease in pain with CPN compared to non-interventional management (14). In a RCT by Wyse et al. , patients were randomized to CPN had significantly less pain than those who did not have intra-operative neurolysis (15).
Predictive factors for failure of CPN include direct tumor invasion of the plexus and unilateral injection (10). To date, there have been no head-to-head comparisons between CPN techniques. As a result, endoscopic, percutaneous, and surgical approaches to CPN are considered equally effective.