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Abstract

marijuana, cannabinoid hyperemesis syndrome: marijuana, cannabinoid hyperemesis syndromeFigureFigureFigureA 28-year-old man presented to the ED with diffuse abdominal pain, nausea, and more than 15 episodes of non-bilious, non-bloody emesis over the previous 48 hours. His pain was worst in the morning, but improved after a hot shower. Of note, the patient had used products similar to this on a daily basis. (Photo.) This was his fourth visit to the ED for abdominal pain over the past year. Previous visits have included an extensive workup, including unremarkable abdominal CTs, labs, and upper endoscopy. What is the most appropriate diagnosis, and what are the treatment options? Find the diagnosis and case discussion on p. 16. Diagnosis: Cannabinoid Hyperemesis Syndrome Cannabinoid hyperemesis syndrome (CHS) is characterized by cyclic episodes of moderate to severe diffuse abdominal pain, nausea, and emesis in patients endorsing frequent marijuana use. Many patients present repeatedly, and undergo multiple rounds of costly, nondiagnostic tests. The diagnosis of CHS is becoming increasingly common, and is likely due to an increase in the THC content of marijuana, the prevalence of marijuana use, and the availability of commercial marijuana. Shifts in laws and stigma about marijuana use may also be influencing the frequency with which patients report marijuana use to physicians. CHS can be separated into three phases: prodromal, hyperemetic, and recovery. The prodromal phase may last months to years, and involves low-level abdominal discomfort from frequent marijuana use. The hyperemetic phase typically lasts up to 48 hours, and involves intense episodes of non-bilious, non-bloody emesis, sometimes more than five times per hour. Episodes occur cyclically at an interval of weeks to months, and asymptomatic periods may or may not involve marijuana use. (Curr Drug Abuse Rev 2011;4[4]:241.) The pathophysiology of CHS is still an active area of investigation, but may involve CB1 receptors in the gastrointestinal tract and central nervous system. (Pharmaceuticals [Basel] 2010;3[7]:2163.) Initial use of marijuana may provide a therapeutic effect to the patient with decreased nausea and abdominal pain, while chronic use eventually tips the scale toward nausea, pain, and emesis. The recovery phase, which almost invariably coincides with marijuana cessation, is characterized chiefly by a lack of hyperemetic episodes. Confidently diagnosing CHS can be challenging. Excluding the diagnosis of cyclic vomiting syndrome is difficult because both conditions involve cyclic episodes of abdominal pain, nausea, and emesis. Some studies indicated that the only way to discriminate between the syndromes is whether marijuana cessation causes remission. (Ger Med Sci 2017;15:Doc06.) CHS is also more often associated with frequent marijuana use and symptomatic relief via hot showers. (Curr Drug Abuse Rev 2011;4[4]:241.) Up to 92 percent of patients diagnosed with CHS endorse symptomatic relief when taking hot showers. (J Med Toxicol 2017;13[1]:71.) It is important in the ED to exclude acute diagnoses such as pancreatitis, bowel obstruction, or cholecystitis while not repeating prior negative workups. Chronic diagnoses, such as irritable bowel syndrome, Crohn's, or celiac should be investigated by the primary care physician. Treatment in the ED consists primarily of IV fluids and antiemetic medications. Haloperidol (5-10 mg IV) may be beneficial because of the dopamine antagonism and interactions between CB1 and dopamine pathways. (Am J Ther 2017;24[1]:e64.) Recent research suggests that capsaicin creams applied in the ED can also provide quick symptomatic relief. A suggested mechanism of action involves TRPV1 receptors in nociceptive pathways. (Clin Toxicol [Phila] 2017;55[8]:908.) No long-term pharmacologic interventions have been shown to reduce the intensity or frequency of episodes, and cessation of marijuana use is the only intervention that has consistently demonstrated efficacy. (J Med Toxicol 2017;13[1]:71.) Broaching the topic of marijuana as a causative agent while the patient is in the ED is challenging. Many patients resist the idea that marijuana use may be causing their symptoms. Discussion of CHS should be reserved for the end of the visit when symptoms have significantly resolved. It is useful to engage the patient in a conversation on the paradoxical causative role of marijuana. Admitting that cannabis can provide nausea relief in many situations and elaborating on CHS may help reduce resistance to the diagnosis. Engaging patients in the idea that marijuana, like many other medications and remedies, may have side effects is also useful. These conversations help reduce return visits, which are common for CHS patients. This patient received treatment in the ED with IV normal saline and haloperidol with significant improvement. After engaging him in a thoughtful discussion about his cannabis use, he acknowledged that cannabis may have side effects in some patients and agreed to a trial of cannabis cessation to see if his symptoms would resolve.