• 8
    Jan
  • Sphincter of Oddi function and dysfunction: SO DYSFUNCTION Clinical features

SO dysfunction has been known by many names in the past, including biliary dyskinesia, biliary spasm, biliary dyssynergia, papillary stenosis, papillitis, odditis and postcholecystectomy syndrome. There are two main clinical conditions that relate to what portion of the sphincter mal­functions. The more common problem is biliary SO dysfunc­tion. Patients with dysfunction of the pancreatic portion of the sphincter usually include patients with idiopathic recur­rent pancreatitis. Pancreatic pain without pancreatitis has also been suggested, but the definition of discrete pancreatic pain without clear pancreatitis is unclear.

Patients with biliary SO dysfunction are typically females (females to males seven to one) in their mid-40s and usually present five to seven years after having undergone cholecys- tectomy for cholelithiasis. Acute attacks can be associ­ated with severe pain, as in patients with true biliary colic. However, apart from localized tenderness, signs of periton- ism or fever are not present. The pain is situated in the epi­gastrium or right upper quadrant, often radiates into the back, and may be associated with nausea and vomiting. The pain generally occurs in episodes lasting up to several hours or until relieved by analgesics. Initial treatment of patients presenting with the above clinical symptoms is directed at relieving the pain, usually achieved by the administration of a systemic analgesic or buscopan. Pethidine (meperidine) is thought to be the most appropriate analgesic in patients with suspected SO dysfunction. These pain episodes may occur at intervals of weeks or months. Some patients also describe discomfort in the upper abdomen that is more frequent and may occur every day. The attacks of pain can occur after fatty meals and are often nocturnal. Patients may complain of sen­sitivity to codeine and other opiates, but this is nonspecific. Indeed, the first episode of pain may have been experienced following opiate medication, usually for an unrelated proce­dure. SO dysfunction is commonly associated with work ab­senteeism and health care use. One study found that patients over-report nongastroenterological somatic complaints (ie, somatization disorder) and childhood sexual abuse, suggesting a role for broad psychiatric assessment and treatment of some patients with SO dysfunction.

The true extent of biliary SO dysfunction is difficult to know. In a study conducted over 30 years ago, 23.5% of close to 2000 patients complained of mild biliary type pain two to nine years following cholecystectomy. In a more re­cent study, 6.4% of postcholecystectomy patients complained of biliary pain for which no other cause could be found. Fifteen of the 29 patients agreed to undergo SO manometry; two of the 15 patients (14%) had abnormal manometry. Overall, the study suggested that after cholecys- tectomy, approximately 1% of patients will have SO dys­function.

TABLE 1 Sphincter of Oddi manometric pressures

Normal

Median range

Abnormal

Basal pressure (mmHg)

15

3-35

>40

Amplitude (mmHg)

135

95-195

>300

Frequency (n/min)

4

2-6

>7

Sequences

Antegrade (%)

80

12-100

Simultaneous (%)

13

0-50

Retrograde (%)

9

0-50

>50

Cholecystokinin 20 ng/kg

Inhibits

Contracts

The pancreatic form of the disorder is seen in patients who have often been diagnosed with idiopathic recurrent pancrea­titis in which no cause for the pancreatitis is apparent. These patients frequently have manometric abnormalities.

TABLE 2 Sphincter of Oddi dysfunction manometric criteria

Stenosis
Basal pressure >40 mmHg Dyskinesia Frequency >7/min Intermittent rise in basal pressure
Retrograde contractions >50% Paradoxical cholecystokinin-octapeptide response

Whether patients with intact gallbladders have SO dys­function is a matter of some debate. In a study of patients with intact gallbladders and idiopathic recurrent biliary type pain, SO manometry and gallbladder emptying studies were performed. Seventy per cent of these patients had an abnormal gallbladder ejection and/or SO manometry, but these abnormalities were independent of one another. In es­sence, this means that SO dysfunction can exist in the presence of an intact gallbladder, and gallbladder dyskinesia can occur with normal SO function. However, when assessing a patient with biliary type pain, the majority of clinicians act on an abnormal gallbladder ejection fraction by per­forming cholecystectomy and await the results of the surgery before considering investigating the SO.
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