Dr. David Fleisher, an associate professor of children's health at the University of Missouri who has treated Robinson and more than 400 other patients with CVS, said he understands why many with the disorder are met with skepticism from others -- doctors included. The primary reason, he said, is that many physicians may not have heard of the disease.
"With functional disorders like CVS, the only way to diagnose it is to get a patient's history of symptoms," said Fleisher. "Not many physicians know the clinical pattern of CVS, so it's hard for patients to get the recognition or care they need."
CVS is often mistaken for other disorders including urinary tract infection, appendicitis and brain tumors seen in MRI scans, Fleisher wrote in a 1993 article in the Journal of Pediatric Gastroenterology and Nutrition.
In a 2002 issue of Contemporary Pediatrics, Dr. B.U.K. Li, director of the Cyclic Vomiting Program at Children's Hospital in Milwaukee, Wis., and one of the world's leading experts on CVS, blamed the on-again, off-again symptoms for difficulties in understanding the disease.
"Between episodes, the child with CVS is asymptomatic and appears so normal that the history of repetitive bouts of relentless vomiting and dehydration can be difficult to believe," he wrote.
According to Fleisher, some behaviors by individuals with CVS during an episode may also mislead doctors.
Bussey said when her daughter has nothing left in her stomach to vomit, she drinks water to induce vomiting, which can make her feel better, which, according to Fleisher, is an action some doctors may interpret as bulimia. Otherwise, the violent reflux and bile may cause her daughter to burn her esophagus and stomach lining, Bussey said.
At times, an attack can send Robertson into a state of conscious coma. Robertson can understand what is going on around her, but is unable to respond to others.
"Their mental state is altered so they can hear what others are saying, but they are unable to answer," said Fleisher. "So commonly it can be seen as a symptom of drug abuse or being drunk."
Currently there are no diagnostic tests for CVS. Though medications are available to alleviate the pain experienced during a vomiting episode, there is no standard treatment for the condition.
According to Fleisher, sometimes the only way physicians can control CVS symptoms during an attack is to sedate the patient.
"Emotions promote nausea and CVS," said Fleisher. "When doctors put them to sleep, the vomiting stops immediately and they are numb to their misery."
While a definite cause is unknown, some researchers point to a variety of neurological conditions that may be related to CVS.
Many researchers say CVS may be one variation of a migraine. 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.
"I don't think that any researcher is ready to say that there is a definitive genetic connection between migraines and CVS," said Kathleen Adams, president and co-founder of the Cyclic Vomiting Syndrome Association. "However, almost all of the literature has significantly shown that CVS may be a migraine variant."