Cyclical Vomiting Syndrome (CVS)
Cyclical Vomiting Syndrome (CVS) has been recognised for over 100 years, but we still know relatively little about the cause of the problem. There is increasing evidence that mitochondrial DNA mutations play a role in some people developing CVS.
CVS is characterised by recurrent, prolonged attacks of severe vomiting, nausea and lethargy, with no apparent cause. Vomiting persists at frequent intervals, 5-6 times per hour at the peak, for periods ranging from hours to 10 days or more. It most commonly lasts for between 1 and 4 days. The episodes are self-limiting and tend to be similar to each other in symptoms and duration. The sufferer is generally in good health between episodes.
There are no diagnostic clinical or laboratory tests for CVS itself, but when all specific conditions that could cause the symptoms have been eliminated by testing, doctors may classify the illness as Cyclical Vomiting Syndrome.
It is thought that anyone can potentially get CVS. CVS sufferers are more likely than average to have a family history of migraine, and/or travel sickness, but the association is not complete, and not all CVS sufferers have family histories of these problems.
A number of studies have been performed to estimate how common CVS is. Studies on school age children from Australia and Scotland have suggested that about 2% may be affected.
The onset of CVS can occur at any time. CVS most commonly develops between the age of 3-7 years and it can persist for periods of time ranging from months to decades. Although CVS is most commonly recognised in children, it is apparent that adult onset CVS is more common than was once thought. It affects males and females equally. As the name suggests, cyclic activity is often a feature of this condition. About 50% of sufferers show a strong regular pattern of vomiting episodes. The episodes may occur as often as several times a month or as little as several times a year. The frequency of episodes is relatively constant in any given individual, but varies between individuals.