Long-Term Outcome of Patients with Postoperative Refractory Diarrhea After Tailored Nerve Plexus Dissection Around the Major Visceral Arteries During Pancreatoduodenectomy for Pancreatic Cancer
Executive Summary
This briefing examines the long-term outcomes and clinical implications of tailored nerve plexus dissection around the superior mesenteric artery (SMA) and celiac artery (CA) during pancreatoduodenectomy (PD) for pancreatic ductal adenocarcinoma (PDAC). While aggressive dissection of these plexuses—often necessary for achieving R0 resection in borderline resectable cases—increases the incidence of postoperative refractory diarrhea, the condition is typically manageable and tends to resolve over time. Crucially, the data indicates that patients who experience this diarrhea have a significantly lower rate of local recurrence, suggesting that aggressive nerve dissection is a justifiable trade-off for superior local disease control.
Key Takeaways:
Diarrhea Incidence: 39.0% of patients developed refractory diarrhea (requiring opioid antidiarrheals for ≥ 6 months), strongly correlated with Level 3 (LV3) nerve plexus dissection.
Anatomic Drivers: Dissection around the SMA (plSMA) has a greater impact on diarrhea than dissection around the CA (plCA).
Oncological Benefit: The diarrhea group showed a significantly lower local recurrence rate (14.1%) compared to the non-diarrhea group (26.2%).
Long-Term Recovery: Postoperative nutritional status (pre-albumin) typically recovers within two years, and over 60% of patients are able to discontinue opioid antidiarrheals within three years of surgery.
Surgical Methodology and Nerve Plexus Classification
The study evaluated 200 consecutive patients undergoing subtotal stomach-preserving pancreatoduodenectomy (SSPPD) for PDAC. A standard lymphadenectomy was performed, with the level of nerve plexus dissection tailored based on preoperative CT scans and the distance between the tumor and major arteries.
Dissection Level Definitions
The degree of dissection around the plSMA and plCA was categorized into three levels:
Level 1 (LV1): Simple resection without lymph node (LN) or nerve plexus dissection (not applied in PDAC surgery).
Level 2 (LV2): En bloc resection of LNs along the artery while preserving the nerve plexus.
Level 3 (LV3): En bloc dissection of regional LNs and the nerve plexus close to cancer invasion, involving hemi-circumferential or more extended dissection of the plSMA or plCA.
The Artery-First Approach
An artery-first approach was utilized to judge resectability, maximize resection margins to the SMA, and reduce blood loss. This allowed for systematic mesopancreas dissection and strict adjustment of the nerve plexus dissection level.
Analysis of Postoperative Refractory Diarrhea
Postoperative refractory diarrhea was defined as a condition requiring opioid antidiarrheal drugs (such as opium tincture) at six months post-surgery.
Impact of Dissection Site and Depth
The study found that the frequency of diarrhea was directly linked to the extent of nerve plexus removal:
Key Findings on Diarrhea Etiology
SMA Dominance: SMA LV3 dissection had a significantly greater impact on diarrhea than CA LV3 dissection.
Circumferential Impact: 100% of patients who underwent whole circumferential dissection of the plSMA developed diarrhea. In contrast, one-third of patients with circumferential CA LV3 dissection did not develop diarrhea if the SMA was limited to LV2.
Pharmacological Management: Initial treatment involved non-opioid drugs (albumin tannate or natural aluminum silicate). If these failed, opioid antidiarrheals (0.3 ml of opium tincture before meals) were used to achieve a goal of three or fewer solid/soft stools per day.
Oncological Outcomes and Local Disease Control
A critical finding of the study is the inverse relationship between postoperative diarrhea (resulting from aggressive surgery) and cancer recurrence.
Recurrence and Survival Metrics
Despite the diarrhea group containing a higher proportion of Borderline Resectable Artery (BR-A) cases (32.0% vs. 13.1%, P=0.001), their oncological outcomes were favorable in several areas:
Local Recurrence: Significantly lower in the diarrhea group (14.1%) compared to the non-diarrhea group (26.2%, P=0.036).
R0 Resection Rate: Comparable between groups (85.8% for diarrhea vs. 78.6% for non-diarrhea).
Overall Survival (OS): Comparable (Median Survival Time: 30.0 months for diarrhea vs. 33.4 months for non-diarrhea).
Recurrence-Free Survival (RFS): Comparable (16.1 months for diarrhea vs. 19.6 months for non-diarrhea).
Clinical Significance
The lower local recurrence rate in the diarrhea group suggests that the aggressive nerve plexus dissection (LV3) required to achieve local control in BR-A PDAC is effective. The comparable survival rates—despite the diarrhea group having more advanced arterial involvement—further justify this surgical approach.
Long-Term Nutritional Status and Recovery
Concerns regarding the long-term morbidity of refractory diarrhea were addressed through a longitudinal analysis of patient nutrition and medication dependence.
Nutritional Recovery
While the diarrhea group showed lower pre-albumin levels at discharge compared to the non-diarrhea group, these levels stabilized over time:
Pre-albumin at discharge: 11.9 g/dL (diarrhea) vs. 16.5 g/dL (non-diarrhea).
Pre-albumin at 2 years: 19.7 mg/dL (diarrhea) vs. 19.8 mg/dL (non-diarrhea).
Weight Loss: There were no significant differences in body weight loss between the two groups at two years post-operation.
Discontinuation of Medication
The data indicates that intestinal function and the regulation of peristalsis recover over time:
At 2 Years: 42.5% of patients with diarrhea were able to stop using opioid antidiarrheal drugs.
At 3 Years: 61.3% of patients with diarrhea were able to discontinue opioid antidiarrheals.
Conclusion
The study concludes that although aggressive dissection of the nerve plexus around the SMA and CA increases the frequency of postoperative diarrhea, this symptom is controllable and often temporary. Given the significant reduction in local recurrence rates, particularly in borderline resectable artery (BR-A) cases, LV3 dissection is justified as a means to achieve R0 resection and local disease control in PDAC patients. The long-term recovery of nutritional markers and the high rate of medication discontinuation by year three suggest that the functional impact on gastrointestinal quality of life is not a permanent deterrent to radical surgery.
