Cyclic Vomiting Syndrome and Cannabinoid Hyperemesis Syndrome

Cyclic vomiting syndrome (CVS) and cannabinoid hyperemesis syndrome (CHS) are related disorders characterized by stereotypical episodes of persistent, repetitive vomiting, separated by relatively asymptomatic periods. CVS and CHS often remain unrecognized for several years before patients are diagnosed, leading to extensive healthcare utilization and unnecessary diagnostic testing. Although the pathophysiology of CVS and CHS remains incompletely understood, convergent evidence points to a neurophysiological basis of these disorders. This chapter focuses on our current understanding of the contributing pathophysiological mechanisms in CVS and CHS, the clinical recognition of symptom patterns needed for diagnosis, and currently available therapeutic approaches.