B54. Surgery for chronic pancreatitis.
Chronic pancreatitis is characterised by chronic inflammation of the pancreas with replacement of normal parenchyme by fibrotic scar tissue, which causes chronic abdominal pain and pancreatic insufficiency. It is an ongoing, progressive pathologic response to pancreatic injury. In most cases, chronic pancreatitis is caused by having multiple episodes of acute pancreatitis. The disease progresses gradually from a single episode of acute pancreatitis to relapsing episodes of acute pancreatitis to chronic pancreatitis.
Etiology
In the western world, alcohol-related pancreatitis is the most common cause. Notably, a considerable alcohol intake is necessary to cause chronic pancreatitis, an average of five units daily for five years or more. However, in a significant proportion of cases remain idiopathic.
The causes of chronic pancreatitis are classified using a system termed TIGAR-O, which is also an acronym.
- Toxic-metabolic factors
- Alcohol abuse
- Tobacco smoking
- Hypertriglyceridaemia
- Idiopathic
- Genetic (hereditary pancreatitis, cystic fibrosis)
- Autoimmune
- Recurring acute pancreatitis
- Obstructive chronic pancreatitis
- Tumour of papilla of Vater
- Duct sclerosis
- Ductal stones
Clinical features
Abdominal pain in the epigastric region which radiates to the back and nausea/vomiting are the most common symptoms.
Diagnosis and evaluation
Contrast CT or MRCP will show pancreatic atrophy and parenchymal calcification. If other investigations are not diagnostic, pancreatic functional diagnostics may be used. The most likely underlying cause of the chronic pancreatitis must be sought, based on history of exposure to risk factors, lab tests, and possibly genetic testing. Unlike in acute pancreatitis, amylase and lipase are rarely elevated.
Functional diagnostics of pancreatic insufficiency
Direct pancreatic functional testing
IV administration of pancreas-stimulating hormones (secretin or cholecystokinin) stimulates the secretion of pancreatic juice. This fluid can be collected by an oroduodenal tube or an upper endoscope and measured. A bicarbonate concentration of this fluid of < 80 mEq/L is diagnostic of exocrine pancreatic insufficiency.
Direct tests are more sensitive than indirect tests, but also more expensive and difficult to perform.
Indirect pancreatic functional testing
Measuring the amount of elastase in the stool can be used for diagnosis of exocrine pancreatic insufficiency. Impaired glucose tolerance or diabetes mellitus may be due to endocrine pancreatic insufficiency. Increased content of lipids in the stool may indicate lipase deficiency due to pancreatic insufficiency.
Treatment
Treatment for chronic pancreatitis unfortunately is not curative. Patients should avoid risk factors like smoking and alcohol, and they should consume low-fat, small meals. Painkillers are often necessary for chronic abdominal pain.
Coeliac ganglion block is an option for refractory pain. A permanent coeliac ganglion block (coeliac plexus neurolysis) can be used for pain management in case pharmacological therapy is insufficient. This involves radiographically guided puncture of the coeliac ganglion, followed by installation of ethanol, which destroys the nerve tissue permanently. Injection of a local anaesthetic instead produces temporary pain relief
Patients with diagnosed exocrine pancreatic insufficiency require pancreatic enzyme supplementation, which is to be taken with foods.
Surgery is indicated for:
- Intractable abdominal pain (most common indication for surgery)
- Complications
- Pseudocyst > 5 cm
- Bile duct stenosis
- Duodenal stenosis
- Internal pancreatic fistula
- Suspicion of malignancy
The management differs based on whether the pancreatic duct is dilated or not, as this dilation indicates whether increased intraductal pressure is a contributing cause of the complaints or not. A dilated duct is an obstructed duct (due to stone or stricture), which requires drainage.
Surgical procedures involve resection of the pancreatic parenchyme, drainage of the pancreatic duct, or a combination of both.
Surgery for chronic pancreatitis with not-dilated pancreatic duct
Coeliac plexus block with bupivacaine gives pain relief for 3 – 6 months, after which it may be repeated.
Partial surgical pancreatectomy of fibrotic and poorly drained parenchyme may also be performed, although these are rarely necessary. These surgeries are the same as those performed for pancreatic malignancy, including Whipple operation or distal pancreatectomy. If the whole parenchyme is diffusely involved, a total pancreatectomy may be performed, which is followed by islet cell autotransplantation to reduce the risk for diabetes mellitus.
Surgery for chronic pancreatitis with dilated pancreatic duct
Endoscopic (ERCP) therapy is the first choice for treatment of dilated pancreatic ducts. If this is insufficient, surgery may be performed. Both modalities can treat any stones or strictures.
Surgical options include the Frey operation and the Beger operation. These are different forms of pancreatic head resections. If the chronic pancreatisis causes biliary tract obstruction and jaundice, pancreatic head resection can be combined with a biliodigestive anastomosis.
The Frey procedure is a duodenum-preserving resection of the pancreatic head combined with longitudinal opening of the dilated pancreatic duct. A Roux-limb is anastomosed to the resected head and opened pancreatic duct as a longitudinal pancreatojejunostomy, which drains the pancreatic duct into the jejunum.
The Berne modification of the Beger procedure is another duodenum-preserving pancreatic head resection. A crater-shaped resection is made of the pancreatic head, after which a Roux-limb is anastomosed to it.
Complications
Complications of loss of pancreatic function can cause pancreoprivic diabetes mellitus, maldigestion and malabsorption, osteoporosis, and steatorrhoea.