Recurrent abdominal pain and vomiting

2. Which is the most likely diagnosis at this point?

• Narcotic bowel syndrome
• Opioid withdrawal
• Crohn disease
• Chronic pancreatitis
• Chronic mesenteric ischemia
• Cannabinoid hyperemesis

Narcotic bowel syndrome

Narcotic bowel syndrome is the most likely diagnosis. Grunkemeier et al¹⁶ described it as chronic or frequently recurring abdominal pain that is treated with narcotics, either chronically or acutely with high doses, and that includes all the following features¹⁶:

• The pain worsens or resolves incompletely with continued or increasing doses of narcotics
• The pain markedly worsens when the narcotic dose is decreased, and decreases when the drug is reinstituted (the “soarand-crash” effect)
• The frequency, duration, and intensity of the pain episodes gradually increase
• The nature of the pain and its intensity are not explained by a current or previous gastrointestinal diagnosis.¹⁶

This syndrome is common in patients who receive high doses of narcotics for postoperative pain or for other, nonmalignant causes of pain. Patients eventually become dependent on the drugs but are not aware that chronic use activates and facilitates areas in the brain that enhance the perception of pain.¹⁶ A study of a rat model of narcotic bowel syndrome¹⁷ showed that morphine-induced hyperalgesia depends on central sensitization involving the activation of spinal microglia. This eventually results in concomitant peripheral sensitization involving the colonic mucosal neuroimmune system, and also in central or peripheral activation of opioid kappa-receptors by dynorphin release.¹⁷

Patients tend to present with chronic or intermittent colicky abdominal pain that requires escalating doses of narcotics. Eventually, they develop tachyphylaxis and shortened pain-free periods and will require even higher doses of narcotics. This ultimately enhances the perception of pain and worsens opioid bowel symptoms, causing a vicious circle of pain and more narcotic use.¹⁶

Laboratory tests are usually normal, and imaging may show only ileus. Gastric emptying may be delayed in patients who have either narcotic bowel syndrome or gastroparesis, but since abdominal pain from narcotic bowel syndrome is a result of central and visceral hypersensitivity, these patients perceive more severe abdominal pain than patients with gastroparesis alone.

Opioid withdrawal

Symptoms of opioid withdrawal may appear as soon as 6 to 24 hours after cessation of the opioid in patients known to be dependent on opioids. These patients present with crampy abdominal pain with nausea.¹⁸ Other symptoms include agitation, rhinorrhea, lacrimation, excessive yawning, arthralgias, papillary dilation, and piloerection.¹⁸

Our patient did not have the typical signs of opioid withdrawal.

Crohn disease

Crohn disease is a multisystem disorder with specific clinical and pathologic features. It is characterized by focal, asymmetric, transmural, and occasionally granulomatous inflammation primarily affecting the gastrointestinal tract.¹⁹ Characteristic symptoms include abdominal pain, chronic diarrhea with or without rectal bleeding, and weight loss. Extraintestinal signs may include anemia and inflammatory changes in the eyes, skin, and joints. The diagnosis is based on endoscopic, radiographic, and pathologic findings.¹⁹

Our patient did not have diarrhea or signs of Crohn disease on CT, endoscopy, or histology.

Chronic pancreatitis

Chronic pancreatitis involves progressive inflammatory changes resulting in permanent structural damage to the pancreas and subsequent exocrine and endocrine dysfunction.²⁰ Patients have epigastric abdominal pain that often radiates to the back²⁰; it is associated with eating and is partly relieved with leaning forward. Symptoms of pancreatic insufficiency such as fat malabsorption (resulting in steatorrhea and fat-soluble vitamin deficiency) and diabetes are common. Calcifications within the pancreas on CT suggest chronic pancreatitis.²⁰ Serum lipase and amylase levels may be normal or slightly elevated.²⁰

Our patient’s abdominal pain was not typical of pancreatitis. He had no signs or symptoms of pancreatic insufficiency and no calcifications within the pancreas.

Chronic mesenteric ischemia

Chronic mesenteric ischemia (“intestinal angina”) is caused by a reduction in intestinal blood flow as a result of occlusion, vasospasm, or hypoperfusion of the mesenteric vasculature.²¹ It is commonly seen in patients who smoke or who have atherosclerotic vascular disease. These patients have chronic dull or crampy abdominal pain that usually occurs within 1 hour after eating.²¹ To avoid pain, patients avoid eating, resulting in weight loss.²¹ CT angiography with multi-detector CT is as effective as angiography (the gold standard) in depicting splanchnic arterial anatomy.²²

Our patient is young and has no known risk factors for atherosclerosis such as smoking. His abdominal pain is more intermittent than chronic and is not associated with eating.

Cannabinoid hyperemesis

Cannabinoid hyperemesis should be considered in patients with long-term cannabis use presenting with cyclic vomiting, abdominal pain, compulsive use of hot showers, and improvement of symptoms with cannabis cessation.²³ Although cannabinoids have been recognized for their antiemetic effects, long-term use may eventually cause autonomic instability and disturbances in the hypothalamic-pituitary-adrenal axis, resulting in cyclic vomiting and thermoregulatory impairment.²³

Although our patient presented with multiple episodes of vomiting and abdominal pain, he denied using marijuana, he tested negative for tetrahydrocannabinol, and he did not associate any relief of his symptoms with hot baths.

CASE CONTINUED

Our patient receives intravenous hydration, antiemetics, and a narcotic in tapering intravenous doses, and his symptoms gradually improve. He is discharged from the hospital. However, a few weeks later he is readmitted with the same symptoms of abdominal pain and nausea.