Surgical Case Study: 95 Percent Pancreatectomy to Treat Congenital Hyperinsulinism
St. Louis Children’s Hospital (SLCH) Physicians:
Patrick Dillon, MD, pediatric surgeon
Shawn Larson, MD, pediatric surgery fellow
Kathy Grange, MD, interim division director, genetics and genomic medicine
Abby Solomon Hollander, MD, interim division and clinical director, pediatric endocrinology and diabetes
Barbara Warner, MD, attending physician, NICU
Background: When Jimmy Hostetler was born on March 15, 2011, he was the fifth child (and fourth son) of Jeff and Janae Hostetler. The Hostetlers live north of Mount Vernon, Mo., near the town of Everton. Jimmy was born with hyperinsulinism, which was first treated by the small community hospital at which he was born and then at an NICU in Springfield, Mo. He was transferred to SLCH on March 27, 2011.
“Basically, both of the hospitals were waiting for Jimmy’s hyperinsulinism to declare itself—was it transient hyperinsulinism that could be treated with oral medication and correct itself over time, or was it the more severe and less common congenital hyperinsulinism caused by genetic defects?” says Dr. Hollander. “We suspected the latter, since a family history and plotting of their family tree revealed that both the Hostetlers had a background of congenital hyperinsulinism in their families. Genetic testing confirmed the diagnosis in Jimmy.”
Although the incidence of congenital hyperinsulinism is estimated to be one in 50,000 births in most populations, it occurs more frequently in the Hostetlers’ Mennonite community. In fact, within days of Jimmy’s admittance to SLCH’s NICU, he was joined by the baby of a relative of the Hostetlers’ with the same diagnosis.
“We know that early in infancy a child is extremely susceptible to permanent brain damage if they have any period of time of very low blood sugars,” says Dr. Hollander. “For that reason, our immediate focus for patients with congenital hyperinsulinism is maintaining their blood sugar in a good range so that damage doesn’t occur. We maintain the blood sugars through oral and tube feedings of breast milk or infant formula and intravenous dextrose, and drugs such as octreotide.”
She adds, “We know from the start that with this variety of hyperinsulinism we are not going to be able to manage without some type of surgery. Then it’s a matter of figuring out what is the most appropriate type for the individual patient.”
That determination is made through genetic mutation analysis to discover whether patients have the focal or diffuse form of the disorder.
“The focal form of the disease is easier to treat because only the affected portion of the pancreas needs to be removed. What area of the pancreas to remove is determined by a PET scan using a unique isotope that pinpoints the abnormal cells,” says Dr. Dillon. “In the diffuse form, the entire pancreas is affected, so the surgical solution is to remove 95 percent or greater of the organ to help reduce the amount of insulin being secreted.”
Dr. Dillon estimates that following a 95 percent pancreatectomy for diffuse disease, approximately 25 percent of patients are able to stop all medications. For the remaining patients, about 50 percent will continue to need some type of medication to manage their sugars, and the remaining 25 percent will need additional surgery to remove another small portion of their pancreas.
“Twenty years ago, the only treatment for congenital hyperinsulinism was a ‘one size fits all’ approach, meaning surgeons would remove the entire pancreas and then babies would have diabetes,” says Dr. Hollander. “Now we recognize there are some patients with focal disease for whom surgery can result in a cure, and we know that allowing a bit of the pancreas to remain prevents patients from becoming diabetic and from having the nutritional problems of someone without a pancreas.”
The surgical challenge and approach: A 95 percent pancreatectomy involves removing the tail, body and a portion of the head of the pancreas called the uncinate process. The surgery’s difficulty comes from the pancreas’ location in a highly protected area of the body, surrounded by vital organs and systems that need to be maintained. Among the procedure’s challenges is preserving the blood supply to the spleen, whose vessels are located underneath the pancreas. “This is particularly important in newborns and young children since the spleen plays an important role in protecting them from certain bacterial infections,” says Dr. Dillon.
Further challenges include identifying and avoiding the bile duct, which courses through the head of the pancreas and into the duodenum, as well as identifying and protecting the superior mesenteric vein and artery, the large vessels going to the gastrointestinal tract.
“During both Jimmy and his baby relative’s surgery, we were able to protect and maintain the functions of all these systems,” says Dr. Dillon. “It’s a challenging operation on an organ about the size of your index finger.”
The outcome: For babies with diffuse congenital hyperinsulinism, the goal of surgery is not always a cure but rather an improvement in the amount of insulin being secreted in order to better maintain blood sugars over 60 mg/dL. Jimmy’s insulin now is better regulated, although he continues to receive octreotide and a combination of oral and gastrostomy tube (g-tube) feedings. According to his mom, Jimmy is a “smiley, happy” baby who is rarely fussy and sleeps well.
“A real key to these patients doing well is parents who are willing to be diligent around the clock, being aware of his feedings and his blood sugars. If something went wrong with his g-tube, he would be at immediate risk, so it is a testament to his parents that he is doing so well,” says Dr. Hollander.
As Jimmy grows older, there is a risk that the abnormal beta cells causing his pancreas to produce too much insulin may become damaged, causing him to develop diabetes. The focus now, however, is to continue maintaining his blood sugars in a good range.
For more information about our surgical services, contact Children’s Direct at 800.678.HELP (4357).
