Saturday, April 14, 2007

Transduodenal Sphincteroplasty

What is the sphincter of Oddi?
The sphincter of Oddi refers to the smooth muscle that surrounds the end portion of the common bile duct and pancreatic duct. This muscle relaxes during a meal to allow bile and pancreatic juice to flow into the intestine. What is sphincter of Oddi dysfunction?
Sphincter of Oddi dysfunction refers to the medical condition that results from the inability of the sphincter to contract and relax in a normal fashion. This may cause obstruction of bile flow resulting in biliary pain and obstruction to the flow of pancreatic juice, which can lead to pancreatitis.

What causes sphincter of Oddi dysfunction?
The cause of sphincter of Oddi dysfunction is unknown. Several theories have been proposed including the presence of microlithiasis (microscopic stones in the bile) and duodenal inflammation. What are the symptoms of sphincter of Oddi dysfunction?
The symptoms of sphincter of Oddi dysfunction include recurrent attacks of upper right quadrant or epigastric abdominal pain. This pain is usually non-colicky and steady. The pain may be aggravated by meals, particularly fatty foods. Opiates may also worsen symptoms. Patients may present with a recurrence or persistence of pain after gallbladder removal.

Who is affected by sphincter of Oddi dysfunction?
Sphincter of Oddi dysfunction is usually seen in female patients who have had their gallbladders removed. Typically, patients range in age from 30–50 years.

How is sphincter of Oddi diagnosed?
Noninvasive tests include: (1) a blood test to measure liver and pancreatic enzymes; and (2) radiographic tests: quantitative Hepatobiliary scintigraphy in which a radioactive isotope is injected into the bloodstream, and the uptake and clearance of the isotope from the liver and biliary tract are measured. Endoscopic retrograde cholangiopancreatography (ERCP) is an endoscopic procedure used in diagnosis. During ERCP, an endoscope is inserted into the mouth and advanced to the duodenum to the opening of the bile and pancreatic ducts. Contrast is injected and measurements of ductal diameter and biliary and/or pancreatic drainage times are made. Sphincter of Oddi manometry is the gold standard to diagnose sphincter of Oddi dysfunction. It may be performed at the time of ERCP and measures pressures using a triple lumen catheter and water perfusion. High pressures are indicative of sphincter dysfunction.

Can sphincter of Oddi be treated and if so, how?
Medical therapy may be considered in the initial treatment plans. This includes a low-fat diet, antispasmodics, non-addictive analgesics, nifedipine, and nitroglycerin. Usually the side effects of these drugs limit their usefulness, and none of the drugs are specific to the sphincter of Oddi. More invasive treatment modalities include: endoscopic injection of botulinum toxin into the sphincter, and endoscopic or surgical ablation of the sphincter of Oddi.

What is the cause of recurrent symptoms?
Recurrent symptoms usually occur if there is scarring of the incision made during endoscopic sphincterotomy or surgical sphincteroplasty.

What is the long-term outcome of sphincterotomy or sphincteroplasty?
Long-term relief of pain in patients who have undergone endoscopic or surgical procedures for sphincter of Oddi dysfunction may be demonstrated in up to 70% of patients.

Overview The goal of treatment is to reduce sphincter of Oddi pressure, thereby improving drainage of biliary and pancreatic secretions into the duodenum. This may be accomplished through medical, endoscopic, or surgical therapy.

Medical Therapy Medical therapy for sphincter of Oddi dysfunction is an attractive approach mainly because it is noninvasive (as compared with endoscopic or surgical therapy), thereby avoiding the occasionally severe complications of sphincterotomy. Because the sphincter of Oddi is composed of smooth muscle, it is reasonable to assume that drugs that relax smooth muscle may be effective in patients with sphincter of Oddi dyskinesia and not in patients with papillary stenosis. Agents such as calcium channel blockers and long-acting nitrates have been shown to reduce sphincter of Oddi basal pressure and improve symptoms. However, there are several drawbacks to medical therapy. First, side effects may be seen in up to one-third of patients. Second, a response rate of only about 75% is expected in patients with the spastic-type of sphincter of Oddi dysfunction. Third, medical therapy utilizing muscle-relaxing agents is not expected to be effective in the patient with papillary stenosis.

Transduodenal Sphincteroplasty
Surgical Therapy Surgical treatment consists of transduodenal (through the duodenum) sphincteroplasty with or without transampullary septectomy (surgically removal of the septum through the Ampullary)

Figure 13. Surgical technique for transduodenal sphincteroplasty.

Figure 14. Surgical technique for transduodenal sphincteroplasty with transampullary septoplasty.

This procedure has shown long-term benefit in follow-up at 1–2 years in uncontrolled trials.

There are no randomized trials comparing surgical sphincteroplasty with endoscopic sphincterotomy.

Endoscopic Therapy
Endoscopic Sphincterotomy
Endoscopic sphincterotomy is the current standard of therapy for sphincter of Oddi dysfunction

(Figure 16). Controlled studies document the short-term and long-term efficacy of endoscopic sphincterotomy with relatively low morbidity (untoward effects as a result of medical intervention or disease) and mortality (the number of given deaths over a given time or place) rates. The presence of an elevated basal sphincter pressure appears to predict good benefit from sphincter ablating (surgical removal, especially by cutting) procedures. In appropriate situations, benefits of endoscopic sphincterotomy are greater than 90%, with good results in long-term follow-up. Because of the high complication rate of pancreatitis after endoscopic sphincterotomy for sphincter of Oddi dysfunction, prophylactic (preventing the spread of disease, or an agent that prevents th spread of disease) short-term pancreatic stenting (stent - A slender hollow tube inserted into the body to revlieve a blockage. For example, a blockage in a bile duct can cause a patient to become jaundiced. In such cases, flow of bile can be reestablished by placing a stent into the duct through the area of blockage.) is recommended, and often yields good results.

Other Endoscopic Therapy
Endoscopic balloon dilation (dilation refers to the expansion of an opening by use of a dilator, for example, a balloon during endoscopy. This also refers to the expansion of an organ or a vessel.) and stenting, in an attempt to preserve sphincter function, have not been found to be effective in reducing sphincter of Oddi pressure or symptoms. This technique is also associated with unacceptably high complication rates.

Endoscopic technique for Botulinum toxin (Botox) injection.
Recent success has been reported using botulinum toxin (Botox) injections to reduce sphincter of Oddi pressure and to improve bile flow dynamics

(Figure 17).
This technique, pioneered at the Johns Hopkins Hospital, has shown promise both as a diagnostic and therapeutic modality. The mechanism of action of Botox occurs at the nerve endings within the sphincteric muscle. Botox inhibits the release of acetylcholine (a neurotransmitter), preventing the contraction of the muscle.
Figure 17. Mechanism of action of botulinum toxin.

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