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PANCREATIC SURGERY IN INFANTS AND CHILDREN
Kishore Adyanthaya*, Amrish Vaidya**,Vrishali Patil***
*Associate Honorary; **Assistant Honorary; ***Registrar, Dept. of Paediatric Surgery; BHIMS, Mumbai 400 020.
INTRODUCTIONPancreatic disease in children is relatively rare. Congenital malformation like annular pancreas may present early in life but pancreas divisum is difficult to diagnose unless surgeon has a deep suspicion of the condition. Any child with unexplained recurrent abdominal pain should be investigated for diseases of pancreas. Because of better imaging facility more and more cases are detected. The clinical picture in acute pancreatitis may range from mild transient self limiting abdominal discomfort to fulminant, rapidly deteriorating discomfort that is complicated by multi organ failure with a fatal outcome within hours or days. Pancreatic malignancy is rare in childhood.
CONGENITAL ANOMALIES
With the exception of pancreas divisum, congenital abnormalities of pancreas like annular pancreas, aplasia, hypoplasia, dysplasia, heterotropic pancreas are rare. Pancreatic anomalies are suspected early in life if infant presents with high intestinal obstruction, neonatal hyperglycaemia, failure to thrive and maldigestion.
Annular Pancreas
This is a comparatively rare anomaly. [1-3] It consists of a flat band of pancreatic tissue encircling the second part of duodenum. It results from failure of migration of ventral pancreatic analage to the dorsal aspect of duodenum. [3] Annular pancreas is classified into neonatal type and adult variety.4 50% present in paediatric age group, 86% of whom present in neonatal period. [5] The cases which present during neonatal period usually have intrinsic duodenal lesion like atresia or stenosis. Several congenital malformations are associated with annular pancreas including Downs syndrome, malrotation, duodenal obstruction, cardiac anomalies, Meckels, anorectal malformation, spinal defects and cryptorchidism. [5] New born presents with symptoms of acute or sub acute duodenal obstruction. Plain radiograph will demonstrate classic "double bubble", diagnostic of duodenal obstruction. Definitive diagnosis can only be made on laparotomy. Surgical approach is a bypass operation preferably a duodeno-duodenostomy or a duodeno-jejunostomy. Division of annular pancreas is not recommended because risk of damage to major duct. Adult variety is usually asymptomatic. It may be incidental finding on laparotomy or at autopsy. Epigastric discomfort, vomiting, haematemesis may be the presenting symptom. Barium meal examination eccentric narrowing of duodenum, focal effacement of mucosal pattern or localized medial retraction of descending segment are characteristic of annular pancreas. [6]
Pancreas Divisum
Normally the duct of Wirsung fuses with dorsal pancreatic duct and becomes the major out flow tract for the pancreas. The minor papilla communicate with dorsal pancreas with duct of Satorini, which is very small. Pancreas divisum is the result of a failure of the ducts of the embryologic dorsal and ventral pancreas to fuse in-utero, resulting in drainage of the bulk of pancreatic juice via the duct of Santorini through the relatively small minor papilla. The associated anatomic or functional stenosis, at the minor papilla may account for increased incidence of acute or recurrent pancreatitis in these patients who lack alternate pancreatic outflow. Pancreas divisum is common anomaly found in 10% of individuals at autopsy. [7] , [8] In children investigated for unexplained recurrent pancreatitis the incidence of pancreatitis may be significantly high - upto 25%. [9-11] most of the patients with pancreas divisum never develop any symptoms. They are diagnosed on investigating case of unexplained recurrent abdominal pain or case of pancreatitis. Pancreas divisum can be considered as cause of abdominal pain when patient has recurrent attacks of abdominal pain associated with elevated serum amylase or when the patient has recurrent pain suggestive of pancreatic source but amylase has never been elevated and no other source for abdominal pain is found. [12-15] When pancreas divisum causes symptoms it’s because of stenosis at minor papilla. The flow of pancreatic juice within the dorsal duct is impeded resulting in ductal hypertension which causes the symptoms. Pancreas divisum is suspected on ERCP when duct of Wirsung fails to be visualized or is rudimentary after injection of major papilla of Vater. Then an attempt should be made to find and cannulate the minor papilla. If minor papilla can be cannulated, ERCP will demonstrate that duct of santorini is the dominant duct and it extends the entire length of body and tail of the pancreas.
The primary goal of treatment is to establish adequate drainage of duct of Santorini. The drainage can be adequately achieved by minor papilla sphincteroplasty.16-20 Endoscopic minor papilla sphincterotomy, balloon dilatation and stenting of duct of Santorini has been tried with variable success.14 But if chronic pancreatitis has developed and in the presence of dilated duct with multiple stenoses, a longitudinal pancreatico-jejunostomy should be done. [21] , [22]
Hyperinsulinism or Nesidioblastosis
Nesidioblastosis is a disease of pancreas in which there is diffuse b cell and islet hyper plasia, associated with foetal type budding from pancreatic ducts and disruption of cell ratio and cell to cell contact within the exocrine pancreas. [23] Hypoglycaemia in new born can lead to permanent brain damage so prompt evaluation and treatment is essential. In neonatal hyperinsulinism, the serum insulin does not respond to a fall in blood glucose level and insulin levels inappropriately elevated in presence of hypoglycaemia. The disregulation of insulin storage and release is the principal lesion in this disorder. It’s the most common cause of persistent neonatal hypoglycaemia and 50% of neonates with persistent hypoglycaemia have hyperinsulinism. [24] Other causes of persistent hypoglycaemia are endocrinal and due to inborn errors of metabolism. Signs and symptoms are hypotonia, irritability, abnormal reflexes and convulsions and coma. The severe forms manifest immediately after birth and milder forms the patients may be asymptomatic until stressed.
Diagnosis is based on following criteria
a)Inappropriately raised insulin leveling relation to blood glucose level taken at various times postprandially and during fasting (Insulin level greater than 10mU/ml associated with simultaneous glucose level less than 50 mg/dl).
b)Glucose infusion rate greater than 10 mg/kg/min require to maintain blood glucose level above 35 mg/dl in absence of glucosuria.
c)Low levels of plasma free fatty acids and ketone bodies during hypoglycaemia.
d)Glycaemic response to glucagon despite hypoglycaemia.
Work up of child with suspected hypoglycaemia of pancreatic origin is complex. After ruling out endocrine deficiencies such as adrenal insufficiency, panhypopituitarism, isolated growth hormone deficiency, hypothyroidism, congenitaladrenal hyperplasia by the physical findings and hormone assay. Metabolic or ketotic hypoglycaemia can be ruled out by presence of ketone bodies and ketonuria. Ketonuria is absent in hyperinsulinism because insulin inhibits lipolysis and hence production of keton bodies.
Medical treatment consists of providing adequate glucose to prevent hypoglycaemia by infusing intravenously 10 to 20% glucose. Frequent feedings are needed to provide constant input of glucose. Diazoxide is mainstay in medical therapy. [25] It inhibits glucose-stimulated insulin secretion. Octreotide inhibits insulin release, and is useful for short time therapy before surgery. [26] , [27] Surgical treatment is indicated when infant remains dependent upon intravenous glucose inspite of diazoxide and chlorthiazide, which potentiates the action of diazoxide. [28] During surgery blood glucose level should be monitored. The entire pancreas should be felt for reddish brown nodular adenomas, if found should be subjected to frozen section. If no localized lesions are found biopsies should be taken from head, body, and tail of pancreas. A near total pancreatectomy is done leaving a thin rim of pancreas along the duodenum and common bile duct. Ectopic pancreatic tissue should be looked for and excised.
PANCREATITIS
Pancreatitis is inflammation of pancreas; which can result from number of causes and can be either acute or chronic. Pancreatitis is uncommon during childhood, but is being recognized with increasing frequency. It represents a diagnostic and therapeutic challenge and should be considered in every case of unexplained acute or recurrent abdominal pain.
Acute pancreatitis
The most common cause of acute pancreatitis in children are systemic infection, trauma, congenital malformation of pancreatic or bile ducts or drugs. [29] , [30] Less common causes are metabolic disorders and familial pancreatitis. About a third of cases of pancreatitis are related to disorders of the biliary or pancreatic ducts with choledochal cyst being most common. Anomalous pancreatico-biliary duct junction (ABPDJ) with its long common channel permits reflux of bile into the pancreatic duct. [31] , [32] APBDJ not associated with choledochal cyst is drawing special attention because most of these develop recurrent abdominal pain due to pancreatitis. [33-35] Pancreas divisum and stenosis of the ampulla are also associated with pancreatitis. [36-40] Several viral infections are known to cause acute pancreatitis : mumps, coxsackie, epstein-barr, cytomegalo virus. [41-43] Pancreatitis is also seen after immunization with live attenuated mumps, measles and rubella vaccine. [44] Obstruction to pancreatic duct by ascariasis lumbricoides has been reported to cause pancreatitis. Blunt injury to abdomen may cause acute symptoms or a delayed sub-acute presentation if trauma is less severe. Use of certain immuno suppressive drugs can be associated with pancreatitis. Other drugs which can cause pancreatitis include azothiaprine, mercaptopurin, a asperginase, thiazide, valproic acid and organophosphorus insecticides. Cholelithiasis occurs in association with pancreatitis in less than 5% of children. Many children with pancreatitis who did not have any associated cause were termed idiopathic pancreatitis, but recently when carefully investigating these children with ERCP and MRCP many children had detectable anatomic abnormality such as pancreas divisum or pancreaticobiliary malunion. [38-40]
The most common complaint is upper abdominal or peri umbilical pain. The typical radiation of the pain to the back observed in adults is missing in 60-90% of children. [45] , [46] Pain is associated with anorexia, nausea and vomiting. Pain is constant and worsens on feeding. There is tenderness in the epigastrium. In severe disease child is irritable and assumes a flexed position. Abdomen may be distended with guarding and rigidity. Severe haemorrhagic pancreatitis develop bluish discolouration around the umbilicus (Cullen’s sign), or on the flanks (Grey-Turners sign). In very severe cases child may present with shock, respiratory distress or multi organ failure or unexplained jaundice or ascites. When necrosis, abscess or psudocyst develops he may present with mass in the epigastrium.
Serum amylase is the widely used test in acute pancreatitis. It may be normal in first 24 hours and peaks between 24 and 72 hours and in uncomplicated cases remains elevated for 2 to 5 days. Its sensitivity in paediatric cases is less than adults and 40% of pancreatitis in children show normal level. Serum lipase levels are usually elevated in pancreatitis and remains elevated for longer time than amylase. Chest and abdominal radiography which while not diagnostic of pancreatitis may help to rule out other entities in differential diagnosis. Localized ileus, pancreatic calcification, gall stones may be seen. Ultra sonography is the most useful investigation and may show increased pancreatic size and decreased echogenicity. It may also show peripancreatic fluid collection. Contrast enhanced dynamic CT scan is the imaging modality of choice; it shows the size, texture of inflamed pancreas, peripancreatic fluid collection, abscess, pseudocyst, ductal dilatation, calcification and perfusion defects of the pancreas to differentiate interstitial pancreatitis from necrotising pancreatitis. [47-49] MRCP has no added advantage over CT scan.
Treatment of acute pancreatitis is largely supportive. The primary goals are to minimize the causative factors if any and to provide supportive care. Children with acute pancreatitis are deprived of oral intake. Nasogastric suction is introduced if there is ileus with vomiting and distension. Fluid resuscitation is started to prevent hypovolaemia due to third space loss and vomiting. Full monitoring of CVP, intake and output, blood gases, serum electrolytes, creatinine, calcium, glucose and lipid profile done. Parenteral analgesics using either narcotic or NSAID should be started even in mild pancreatitis because pain can be extreme. Measures to put the pancreas to rest such as H2 blockers, atropine, calcitonin, glucagons and stomatostatin have not shown to change course of disease. Recent studies have shown that some antibiotics like cefuroxime, ciprofloxacin and imipenem cross blood pancreatic barrier and are found in high level in pancreas and within the necrotic pancreatic tissue. [50] , [51] It has been shown that in severe acute pancreatitis, it can reduce the incidence of septic complications. [52] , [53] Total parenteral nutrition is indicated if extended period of fasting is anticipated. Refeeding can be started when pain and tenderness is reduced, initially with carbohydrates.
Complications include respiratory failure, shock, renal failure, disseminated intravascular coagulation - which indicate that the patient has severe pancreatitis. During the first two weeks of the illness, sterile or infected pancreatic and peripancreatic necrosis can be observed. The two can be distinguished by USG or CT guided fine needle aspiration. [54] Late complications develop after second week of illness and include pseudocyst and abscess formation. [55] These inflammatory masses develop in about 15% of children. Surgery is indicated if diagnosis is in doubt, if patient develops infected necrosis or in sterile necrotising pancreatitis, if patient deteriorates in spite of adequate medical management or if there is pancreatic abscess or the patient develops a pseudocyst. Infected pancreatic necrosis needs debridement and multiple drainage of lesser sac. Most of pseudocysts resolve spontaneously. If pseudocyst does not resolve in six weeks or if it’s larger than six centimeters surgery is indicated.
Pseudocyst
Pancreatic pseudocyst are contained collection of fluid rich in pancreatic enzymes. They are not lined by epithelium. The most common site is in lesser sac behind the stomach. They occur in 20% of cases of acute or chronic pancreatitis. Mostcommon cause of pseudocyst in children is after trauma or infection. [56] It may or may not communicate with the pancreatic duct system. The fluid is usually clear with some debris and amylase level is always > 50,000 somogyi units, 57 most pseudocysts resolve over a course of six weeks, particularly associated with acute pancreatitis. Pseudocyst that persists beyond six weeks, those larger than six centimeters and those associated with chronic pancreatitis are less likely to resolve spontaneously. Rupture, infection and haemorrhage are the complications that can occur in a pseudocyst. For many years the standard treatment is laparotomy and internal drainage of the cyst into the gastrointestinal tract. CT guided percutaneous cysto gastrostomy and endoscopic cysto gastrostomy are the newer methods of drainage.
NEOPLASM
Pancreatic neoplasm are rare in infants and children. They can be cystic or solid and benign or malignant and may or may not be harmonically active. Only 150 cases are reported in English literature. Cystic tumours are cystadenoma, cystadenocarcinoma, mucin cystadenoma and carcinoma or teratoma. Most endocrinologically active originate in the islet cells, b cells secrete insulin, g cells secrete gastrin. Glucagonomas and somatostatinomas are not seen in children. Ultrasonography, CT scan, arteriography and transhepatic portal vein sampling helping localizing the tumour. Insulinomas are most common tumours and usually are benign, solitary that occurs in children older than 4 years of age.[58-60] Plasma insulin to blood glucose ratio greater than 1.0 is diagnostic (< 0.4 is normal). [58] Most of the tumours can be enucleated as they are well encapsulated. Per operative USG helps in identifying obscure lesions. If tumour is not identified a distal pancreatectomy with careful sectioning of the gland is advised. [61] Gastrinoma is the second commonly reported hormonal tumour. The tumour is usually malignant, multi centric and metastatic at discovery. Children usually present with recurrent episodes of peptic ulceration. The serum gastrin level is elevated. Although total gasrectomy was the only mode of treatment, H2 blockers and omeprazole has changed direction of treatment. But children will require life long medication. Surgical resection which should be aggressive, especially if solitary lesion is found. Total gastrectomy still may be required if medical management fails or those with residual tumour or with metastases. [61]
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