Recurrent abdominal pain and vomiting
A 32-year-old man presents to the emergency department with excruciating abdominal pain associated with multiple episodes of vomiting for the past 2 days. He reports no fevers, headaches, diarrhea, constipation, hematochezia, melena, musculoskeletal symptoms, or weight loss. His abdominal pain is generalized and crampy. It does not radiate and has no precipitating factors. The pain is relieved only with intravenous narcotics.
He does not smoke, drink alcohol, or use illicit drugs. He has no known drug or food allergies. He says that his current condition causes him emotional stress that affects his performance at work.
About a year ago, after a complicated surgical procedure, he needed chronic high-dose narcotics. A few months later, he developed multiple bouts of abdominal pain and vomiting that required hospital visits. He now takes oral oxycodone 10–15 mg every 4–6 hours.
On admission, his vital signs are stable, but he is in excruciating pain. He is alert and oriented to person, place, and time. His sclera are anicteric, and the pupils are equal, round, and reactive to light. Lung and heart examinations are normal. The abdomen is soft and nondistended but tender in all four quadrants without guarding; the liver and spleen are not palpable, and no abdominal masses are detected. He has no skin rash, joint swelling or tenderness, or peripheral edema. The neurologic examination is normal. Computed tomography (CT) of the abdomen with contrast shows no signs of bowel obstruction, pancreatic calcifications or edema, cholecystitis, or hepatobiliary disease. Results of initial laboratory testing are shown in Table 1.
1. Based on the information available, which is the least likely cause of his symptoms?
- Acute pancreatitis
- Cyclic vomiting syndrome
- Acute intermittent porphyria
- Gastroparesis
Acute pancreatitis
Acute pancreatitis is the least likely cause of his symptoms. It is commonly caused by gallstones, alcohol, hypertriglyceridemia, and certain drugs.1 The associated abdominal pain is usually epigastric, radiates to the back, and is accompanied by nausea or vomiting, or both. The onset of pain is sudden and rapidly increases in severity within 30 minutes. CT shows enlargement of the pancreas with diffuse edema, heterogeneity of pancreatic parenchyma, peripancreatic stranding, and peripancreatic fluid collections.1 The diagnosis is based on two of the following three criteria: abdominal pain characteristic of acute pancreatitis; a serum amylase or lipase concentration three or more times the upper limit of normal; and characteristic findings of acute pancreatitis on CT.1
Cyclic vomiting syndrome
Cyclic vomiting syndrome is thought to be caused by episodic dysautonomia, mitochondrial DNA mutations, and hypothalamic emetic response oversensitivity,2–4 but the exact pathogenesis is unknown. The syndrome has been strongly linked to migraine and to the chronic excessive use of cannabinoids.5–9 The Rome III diagnostic criteria10 are the following: the vomiting episodes are stereotypical, ie, they are acute and last for less than 1 week; the patient has had three or more episodes in the previous year; and the patient has no nausea or vomiting between episodes. The patient must meet all three criteria. A history of migraine or a family history of migraine further supports the diagnosis.
Acute intermittent porphyria
Acute intermittent porphyria is characterized by neurovisceral symptoms such as convulsions, paresis, autonomic dysfunction, constipation, and diarrhea that result from the overproduction of porphyrin precursors and deficiency of porphobilinogen deaminase.11
Most patients have poorly localized, severe, steady abdominal pain that develops over hours to days and that may persist for days to weeks.11 Since the pain is neuropathic, abdominal tenderness is usually minimal during an acute attack. Other clues include signs of ileus, such as constipation, nausea, abdominal distention, or decreased bowel sounds; bladder dysfunction, eg, urinary retention, incontinence, or dysuria; reddish-brown urine; and sensory neuropathy of the chest, back, and extremities.11 Blistering skin lesions are usually not seen. The presence of porphobilinogen in the urine confirms the diagnosis.11
Gastroparesis
Gastroparesis is a result of discoordination between the sympathetic and parasympathetic nervous systems, neurons, and smooth muscles within the stomach, causing a decrease in gastric motility. Common causes are diabetes,12 scleroderma,13 and neurologic disorders.14 It can also be iatrogenic,15 resulting from visceral nerve injury and drug treatment with narcotics, calcium channel blockers, muscarinic cholinergic antagonists, or certain antidepressants. Symptoms are related to gastric stasis, ie, abdominal pain from gastric distention, bloating, vomiting, and early satiety.15 Abdominal pain may worsen after eating, and vomitus usually consists of recently ingested food. These patients may have abdominal distension or tenderness and succussion splash. After excluding possible mechanical obstruction, a gastric-emptying study may be necessary to make the diagnosis.15
CASE CONTINUED
A serum and urine drug screen in our patient is positive only for opioids. Urine measures of delta-aminolevulinic acid and porphobilinogen are normal. CT angiography of the abdomen shows no signs of mesenteric vascular occlusion. Esophagogastroduodenoscopy shows antral gastritis, but the esophagus and duodenum appear normal, and colonoscopy is normal as well. Histologic study of biopsy specimens obtained during endoscopy is unrevealing. A gastric-emptying study shows delayed emptying. The patient’s abdominal pain and vomiting persist with the initial dose of intravenous narcotic but resolve with escalating doses. When asked, the patient denies an excessive need for hot baths.
