In early 2010, actress Chandra Wilson's teenage daughter, Sarina McFarlane, began experiencing never-ending bouts of nausea. Every month the queasiness escalated to the point that, for days, McFarlane could not stop vomiting.
Like clockwork, the vomiting stopped and nausea eased a bit. But when a new month started, the vomiting cycle returned.
The case sounded like an episode straight out of "Grey's Anatomy," where Wilson plays Dr. Miranda Bailey. Wilson said for a year, her daughter's doctors were baffled by the condition.
"She had every kind of scan you could think of, you know, upper GI's and CT scans, and delayed gastric emptying tests, and you know, blood work constantly," Wilson told ABC's local Philadelphia affiliate, WPVI.
After excluding a host of other possible diagnoses, Wilson said her daughter was diagnosed with cyclic vomiting syndrome, or CVS, a neurological disorder characterized by a series of prolonged attacks of severe nausea and vomiting, with no apparent cause.
CVS is also known as abdominal migraines because symptoms usually begin with severe abdominal pain or a migraine headache, followed by episodes of vomiting that can last for hours or even days.
Once an episode is over, the sufferer inexplicably returns to normal health, often with no remnants of the disease.
For most people, vomiting can be a source of relief from an unsettled stomach. But for those who suffer from CVS, initial vomiting only triggers a cycle of more vomiting.
While a definite cause is unknown, some researchers point to a variety of neurological conditions that may be related to CVS. Many experts say CVS may be one variation of a migraine.
"The gut contains a large amount of serotonin, perhaps more than the brain itself, so that represents a curious linkage between migraine, which also involves dynamics with serotonin," said Dr. Joel Saper, founder and director of the Michigan Headache and Neurological Institute.
According to researchers, for some, an intense headache or a condition known as an abdominal migraine may signal the onset of a vomiting episode. And many diagnosed with CVS have shown a family history of migraine headaches.
"The direction research is headed, we'd say it's highly likely that there is genetic connection between migraines and CVS," said Kathleen Adams, president and co-founder of the Cyclic Vomiting Syndrome Association.
Adam says the association's scientific board is working to change the CVS's diagnostic code from its current classification as a gastrointestinal illness to a form of migraine.
While the actual number of cases is unknown because of sparse research on the syndrome, estimates indicate that CVS may not be as rare as many believe. Rather, according to the Cyclic Vomiting Syndrome Association, more often it is misdiagnosed. Surveys that have been conducted on the condition suggest that as many as 2 percent of children worldwide may suffer from CVS.
Initially identified as a pediatric disease and believed that children would outgrow the disorder, researchers now say it can persist into adulthood and even appear in adults for the first time.
Natalie Robertson's most distinct memory of her first week as a freshman at Chico State University in California was enduring daylong episodes of uncontrollable vomiting.