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UCLA Agi Hirshberg Center for Pancreatic Diseases

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Chronic Pancreatitis

Chronic Pancreatitis

Introduction

Chronic pancreatitis is an inflammatory disease of the pancreas characterized by destruction of its exocrine and endocrine tissue, and their replacement by fibrous scar. In the United States the majority of cases are caused by chronic alcoholism. The process is almost always progressive, even when patients stop drinking. Most of these individuals suffer chronic abdominal and back pain, and it is for this problem more than any other that they seek surgical help.

Etiology

Alcoholic Pancreatitis

In the United States, alcoholism causes about 75% of all cases of chronic pancreatitis. The disease may take one of several clinical forms. An episode of binge drinking may precipitate an attack typical of acute pancreatitis. This usually occurs in a patient who is a chronic alcoholic. Here the pancreas probably has already been permanently damaged by alcohol even though there might not be any other evidence of pancreatic disease (eg. pancreatic exocrine insufficiency, diabetes). The other clinical presentation also occurs in chronic alcoholics. These individuals have chronic abdominal and/or back pain, often with fatty stools (steatorrhea) and diabetes from pancreatic exocrine and endocrine insufficiency. Pancreatic calcifications occur in at least one third of patients. Weight loss is common since food often aggravates the pain and intake is voluntarily restricted. The usual age at onset is in the mid-thirties and men are affected more commonly than women.

Idiopathic Pancreatitis

Twenty to 30% of cases of chronic pancreatitis have no apparent cause. There is recent evidence that this form of the disease is more likely to be free of pain compared to the alcoholic variety (up to 50% painless vs 5%). Nevertheless pancreatic calcifications, and exocrine and endocrine insufficiency are common. It is to be anticipated that the number of cases labelled "idiopathic" will decrease as our understanding of the causes of the disease improves.

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Diagnosis

Clinical Manifestations: In 95% of patients with chronic pancreatitis, the principal symptom is abdominal pain. The intensity of the pain is often great. It has been described as cramping, boring, dull and aching in nature. It is usually located in the upper midportion of the abdomen, with radiation to either side under the rib margins. In more than half the cases, it also is felt in the back.

Variable weight loss occurs in 75% of patients with chronic pancreatitis. This is because food usually aggravates the pain, and intake is voluntarily restricted. Significant weight loss from malabsorption is less common. Even when malabsorption occurs, most patients who are able to eat maintain their weight by eating more.

Significant exocrine insufficiency does not occur until 90% of the secretory capacity of the pancreas is lost. This can be the result either of progressive parenchymal destruction or obstruction of the major ducts which prevents the pancreatic digestive enzymes from reaching the duodenum. In either case, it is a late development. The major consequences are steatorrhea and creatorrhea, excessive loss of fat and protein in the stools. Carbohydrate digestion is not impaired because amylase is also produced by the salivary glands. The patients may complain of bulky, offensive, fatty or oily stools.

About two thirds of patients with chronic pancreatitis have abnormal glucose tolerance and half of these have diabetes mellitus. In them, some degree of malabsorption is also present since exocrine and endocrine insufficiency usually develop in parallel. The diabetes is usually easily controlled with insulin, but hypoglycemia may be a problem in alcoholics with irregular eating habits.

Radiologic Features: In 30 to 50% of patients with chronic pancreatitis, plain x-rays of the abdomen reveal pancreatic calcifications. Indeed, when calcifications are present, the diagnosis of chronic pancreatitis is certain even if there is no clinical evidence of pancreatic disease.

With early chronic pancreatitis and even in some patients with advanced disease, ductal abnormalities demonstrated by ERCP may be minimal. However in the majority of patients with advanced disease, the main duct may be dilated up to one centimeter or more in diameter with intermittent points of obstruction. Strictures, cysts, and ductal calculi may be seen. The common bile duct is also opacified by this technique, and any distortion of its anatomy is evident. Chronic pancreatitis characteristically produces angulation of the distal common duct with a smooth, tapered narrowing of its intrapancreatic portion. Most patients with chronic pancreatitis who are being considered for surgical intervention should undergo some study which shows the anatomy of the ducts. This may influence a decision for surgery. For example, a patient with pain and a widely dilated duct may be a candidate for a pancreaticojejunostomy. If the duct were not dilated, pancreatic resection might be indicated instead.

CAT scans or MRI's also provide useful information about ductal anatomy, and an ERCP is often unnecessary. When the duct is grossly dilated, it usually can be seen running the length of the gland. Pseudocysts and cystic communications with the ductal system are evident. Biliary dilatation and the level of bile duct obstruction are defined clearly. CAT scans provide the most precise information about the size and configuration of the pancreas. This may be useful in decisions regarding possible pancreatic resection. For example, in a patient with pain and an enlarged head of the pancreas seen on CAT scan, a pancreaticoduodenectomy might be the best choice. Differential Diagnosis: Usually the diagnosis of chronic pancreatitis is straightforward. Most patients are chronic alcoholics with recurring episodes of abdominal pain, diabetes, weight loss, pancreatic calcifications and some evidence of malabsorption. Occasionally the distinction between chronic pancreatitis and pancreatic cancer may be difficult. This may occur when there is no previous history of pancreatitis, when the patient presents with jaundice and pain is not a prominent part of the picture, and when weight loss is significant. In such circumstances, operation may be necessary to make the diagnosis.

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Treatment of Pain

The medical management of pain in patients with chronic pancreatitis should include the cessation of all alcohol intake and cessation of smoking, if the patient is a smoker. Although it is difficult to predict the effect in an individual case, as many as 50% of patients experience some pain relief when they stop drinking. Pain relief may be more likely in those with early disease and relatively well preserved pancreatic function. In those with pain who already have severe pancreatic insufficiency, pain is likely to persist.

The indications for surgery for pain relief in these patients are impossible to state in precise terms. When the pain interferes substantially with the quality of life, surgery should be considered. Pertinent issues include obvious effects on health and well-being like weight loss and nutritional status, need for frequent hospitalization, inability to maintain employment, psychiatric manifestations (usually depression), deterioration of family life, and impending or actual narcotic addiction.

Operations to relieve pain in patients with chronic pancreatitis take one of two forms. The first are the so-called drainage operations which attempt to drain more adequately a dilated ductal system that is presumed to be obstructed. The second are the pancreatic resection operations which remove diseased pancreatic tissue, usually in situations where the pancreatic ducts are normal or narrowed in size. Sphincterotomy or sphincteroplasty of the sphincter of Oddi has no place in the treatment of pain in patients with this disease.

Drainage Operations (Pancreaticojejunostomy, Puestow Procedure): The main pancreatic duct has a normal diameter of approximately 4-5 mm in the head, 3-4 mm in the body, and 2-3 mm in the tail of the gland. When the diameter in the head and body increases to 7-8 mm or larger, a pancreaticojejunostomy is technically feasible and is likely to be effective in producing lasting pain relief. If the operation is done in a pancreas with a normal size duct, both short and long term results are poor, perhaps because the anastomosis strictures closed in most cases. Results: The operative mortality rate of longitudinal pancreaticojejunostomy averages about 4%, and the morbidity is minimal. Diabetes does not result from the operation; indeed, there is some evidence that exocrine and endocrine function may even improve slightly after pancreaticojejunostomy. Nevertheless, some patients will eventually require insulin since the destruction of the pancreas often continues. Pancreatic fistula is an uncommon complication of the operation, probably because the fibrous pancreas holds sutures quite well. Nevertheless, with a drain in place, it is not a serious complication and will almost certainly close spontaneously. Although pancreatic enzymes can now empty freely through the pancreaticojejunostomy, there is rarely any clinical improvement in the degree of malabsorption. Nevertheless, patients may gain weight because eating no longer produces pain, and they eat more.

Pain is relieved completely or substantially in 75-80% of patients for the first several years after the operation. Unfortunately it recurs in a considerable number of cases, so that by the time 5 years have passed, only about 60-70% still report good pain relief. In some patients recurrence of pain may be due to stenosis of the pancreaticojejunal anastomosis. Then reconstruction of the anastomosis may be beneficial. In the majority of cases, there is no apparent cause for the recurrence of pain, and other forms of treatment, including pancreatic resection, must be considered.

Recent experience suggests that drainage operations in patients with dilated ducts may be beneficial earlier in the course of the disease than has been the custom. The placement of pancreatic duct stents and efforts to remove pancreatic duct stones (ie endoscopic management of the disease) has been shown to be less effective and more expensive in the long run, compared to surgical drainage.

Pancreatic Resections (Pancreaticoduodenectomy, Pylorus Preserving Pancreaticoduodenectomy, Pancreatic Head Resection, 95% Pancreatectomy, Distal Pancreatectomy): Pancreatic resection should be considered for pain relief when the pancreatic duct is narrow or normal in diameter, when a previous pancreaticojejunostomy has failed, or when the pathologic changes in the pancreas particularly involve one part of the gland, and the rest is less diseased.

Pain is relieved in about 85% of the patients in the first several years after the operation. Unlike patients who have undergone longitudinal pancreaticojejunostomy, this initial good result is more likely to be permanent after resection. Thus after 5 years, about 80% of the survivors continue to experience relative freedom from pain compared to 60-70% in the drainage group. However, resection operations are more likely to produce diabetes.  Newer operations which combine drainage with limited resection (eg Frey or Beger procedures) may be best; they are more likely to produce permanent pain relief with the fewest side effects like diabetes.  Occasionally patients are best served by pancreatic resection with auto-islet transplantation.  All of these operations are available at UCLA.

Prognosis

In patients with alcoholic chronic pancreatitis, it is of interest to review mortality statistics unrelated to surgical intervention for complications of the disease. In general life expectancy is reduced by 10-15 years, and the mean age at death in several series was about 50 years. The principal causes of death include upper respiratory malignancies (most patients are heavy cigarette smokers), malnutrition, complications of diabetes, and suicide. Abuse of ethanol and/or drugs often is contributory. Recent studies reveal a 2-5 times increase in the incidence of pancreatic cancer in patients with chronic pancreatitis from a variety of causes.

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*Disclaimer
The condition information provided is not for self-diagnosis or self-treatment. Diagnostic testing and physician expertise are required for diagnosing your symptoms. Please check with your physician to determine what may be causing your symptoms and the treatment that is right for you.

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