Chronic Pancreatitis

Overview

Chronic pancreatitis is characterised by recurrent or persistent abdominal pain arising from the pancreas. The inflammatory process results in irreversible destruction and fibrosis of the pancreas. Often associated with exocrine or endocrine pancreatic insufficiency.

Pancreas anatomy and physiology

Pancreatic anatomy

Pancreas extends retroperitoneally across posterior abdominal wall. It means “All (pan) Flesh (Kreas)”. The pancreas consists of the following parts:

• Head
• Neck
• Body
• Tail

The head is encircled by duodenum and tail in contact with spleen. Pancreas has a poorly developed capsule & therefore adjacent structures (common bile duct, duodenum, splenic vein, transverse colon) are commonly involved in inflammatory process.

Blood Supply

• Pancreatic branches of the splenic artery
• Superior pancreaticoduodenal artery
• Inferior pancreaticoduodenal artery

Venous drainage

• Drains with the splenic vein → Superior Mesenteric → Portal vein

Nerve invervation

• Parasympathetic → Vagus nerve → Stimulates pancreatic juice secretion
• Sympathetic

Lymphatic drainage

• Head and Neck → Pancreticoduodenal nodes →
• Body and Tail → Pancreaticosplenic nodes →

Embryology

• Fusion of the ventral and doral outpounchings of forgut

Pancreatic physiology exocrine (98%) & endocrine (2%) functions

Exocrine: Pancreatic acinar cells produce digestive enzymes, which are stored in secretory granules. The Pancreatic exocrine secretion is regulated by cephalic, gastric & intestinal stimuli. Acinar cells secrete pancreatic juice made up the enzymes:

• Amylase → Carbohydrate digestion
• Lipase → Lipid digestion after bile has emulsified the fat
• Proteases (MANY!) → Protein digestion

Exocrine section is stimulated by:

• Vagus nerve
• Secretin (hormone)
• Cholecystokinin

Endocrine: Islets of Langerhans – clusters of hormone-producing cells secreted directly into circulation. Endocrine cells of the pancreas:

• Beta cells → Insulin
• Alpha cells → Glucagon
• D cells → Somatostatin.

Aetiology and Risk Factors

Aetiology

• Recurrent acute pancreatitis of any cause, especially alcohol
• Secondary to pancreatic ductal obstruction
  • Pancreatic head cyst, tumours
  • Cystic fibrosis
• Associated with autoimmune disease (primary biliary cirrhosis, primary sclerosing cholangitis)

Risk Factors

Pathophysiology

Pathological features

• The process may affect the whole or part of the gland
• The head tends to be the most severely involved part in chronic alcoholic pancreatitis
• Features of acute pancreatitis may be present (fat necrosis, haemorrhage and/or oedema)
• Chronic inflammatory changes include atropy, duct dilation, microcalcification and intraductal stone formation with cystic changes secondary to ductal occlusion.

Clinical Manifestation

Clinical Presentation of chronic pancreatitis is similar to acute pancreatitis but less severe. This include epigastric pain that may radiate to the back, nausea and vomiting. Patients may present to ED and require opiates. Pain is worse with food and alcohol. Exocrine features of chronic pancreatitis include weight loss and malnutrition (due to malabsorption of macromolecules) and also steatorrhea (due to fat malabsorption).

Diagnosis

• Pancreatic cancer
• Acute pancreatitis
• Gallstone disease
• Peptic ulcer disease
• Mesenteric Ischemia
• Triple A (AAA)
• Myocardial infarction
• Irritable bowel syndrome
• Nephrolithiasis (kidney stones)

Investigations

• Abdominal – X-ray may show pancreatic calcification
• Abdominal ultrasound – may show cystic changes and duct dilatation within the pancreas.
• Bloods – glucose (to assess pancreatic exocrine function) and serum amylase/lipase (which tend to be normal in chronic pancreatitis)
• Pancreatic CT scan
• ECRP

Treatment

Management involve prevention of cause/progressive damage by stoping alcohol and smoking. Encourage diet rich in antioxidant. Controlling symptoms and complication involve dietary modification (low fat), pancreatic enzyme supplements, analgesia (may require opiates), insulin (for diabetes if develops). Surgical management includes percutaneous or endoscopic drainage to drain excess fluid in the pancreas that is causing obstruction. Pancreaticduodenectomy is performed to remove possible causes and complications.

Complications and Prognosis

Resectional surgery is associated with increasing risk of exocrine and endocrine pancreatic failure and high risk of complications

Complications

• Pseuodocyst
• Obstruction
• Fistula
• Infections
• Portal hypertension
• Diabetes Mellitus
• Pancreatic calcification
• Opiod addiction

Prognosis

• Generally, pain decreases or disappears over time, regardless of aetiology
• Ten-year survival after diagnosis is 20% to 30% lower than the general population.

References

UpToDate
Best Practice
Oxford Handbook of Clinical Medicine
Oxford Handbook of Clinical Surgery