1: What is CVS?

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What is CVS?


Cyclic vomiting syndrome, or cyclical vomiting syndrome, (CVS) is a chronic functional condition of unknown cause characterized by recurring attacks of intense nausea, vomiting, and sometimes abdominal pain, headaches, or migraines and prostration with no apparent cause. CVS typically develops during childhood but it may persist into adult life. Vomiting occurs at frequent intervals for hours or days. The episodes tend to be similar to each other in symptoms and duration and are self-limited with return of normal health between episodes.


The four phases of CVS


The illness has four phases:

1. The inter-episode phase,during which the patient is relatively symptom free.

2. The prodrome phase, which begins when the patient senses an oncoming episode.

3. The emetic phase, characterized by intense, persistent nausea, severe vomiting, and other symptoms.

4. The recovery phasebegins with the subsidence of nausea and ends when hunger, tolerance of oral intake, and vigor return to normal.


Historical perspective


Cyclic vomiting syndrome (CVS) was first described in French literature in 1806 by Dr. W. Heberden, and in English literature in 1882 by Dr. Samuel Gee. Dr. Gee reported a series of patients, all of whom were children ranging in age from infancy to nine years. Many of his observations continue to be used as diagnostic criteria for CVS. Existing pathophysiologic evidence points towards CVS as a brain-gut disorder involving neuroendocrine pathways in genetically predisposed individuals. In the 1990s, renewed interest in CVS led to international conferences in 1994 and 1998.


Who gets CVS?


The onset of CVS may occur at any time, but most commonly develops between the ages of 3-7 years. It may persist for periods of time ranging from months to decades. Although CVS is most commonly recognized in children, it is apparent that adult onset CVS is more common than was once thought. Females are affected slightly more than males.

CVS sufferers are more likely than average to have a family history of migraine and/or travel sickness, but not all CVS sufferers have family histories of these problems.





Episodes may begin at any time, but most commonly occur during the night or early morning. There is relentless nausea with repeated bouts of vomiting or retching. The vomiting has been described as the most intense kind of nausea a human can experience. The person is pale and listless. They may experience intense abdominal pain and less often headache, low-grade fever and diarrhea. Prolonged vomiting may cause mild bleeding due to irritation of the esophagus. The symptoms are frightening to the person and family and may be life-threatening if delayed treatment leads to dehydration. CVS is very different from the normal vomiting. The most obvious thing is that the vomiting doesn’t stop. Only bacillus cereus food poisoning matches this high intensity of emesis in CVS.


Attacks tend to be stereotypical, in that a patient’s attacks tend to be similar each time, although attacks vary from person to person. 50% of CVS suffers experience the same progression and character of attack with every episode. Laboratory tests often reveal a persistent presence of lactic acid in the blood.

During CVS, these symptoms occur


Severe and constant, unremitting nausea

Occurs in 76% of patients and is usually the most distressing symptom. It is unrelenting and completely unrelieved by vomiting, disappearing only when the episode is over. The vomiting has been described as the most intense kind of nausea a human can experience.


Repeated vomiting and retching, often violently, peaking at up to 5-6 times per hour or more

Vomiting typically begins during the night or early morning. It peaks in the first hour and is particularly severe, occurring up to 13 times an hour, and is accompanied by retching. The emesis is often projectile (50%), containing bile (76%), mucous (72%), or blood (32%).


Pallor, often extreme paleness of the skin


Low-grade fever

Fevers have been reported in about 25% of cases.



Headaches have been reported in about 25% of cases.


Abdominal pain

Pain around the belly button or epigastric pain is present in 80% of patients and may be severe enough to mimic an acute abdomen. Dr. David R. Fleisher has identified three types of functional abdominal pain that may affect CVS patients: Irritable Bowel Syndrome, abdominal migraines and abdominal pain that are symptom of panic.



About 30% of patients have loose stools near the onset of the cyclic vomiting episodes, and some have severe diarrhea during the vomiting phase.


Lethargy or unresponsiveness/conscious coma

Patients describe being in a state of confusion and exhaustion during the episode, with no control over their body’s reactions.  Patients still hear and know what is going around them but struggle to be able to respond. This has been named a «conscious coma».




«Perplexing» or unusual behaviours

Many of the behavioral disturbances that may be observed are designed to lessen the nausea (e.g. fetal positioning, social withdrawal, compulsive drinking, turning off lights). The intense distress experienced by patients during the emetic phase of CVS may prompt behaviors that are in some cases mistaken to be psychotic or bulimic. Many patients who are normally pleasant and cooperative may become irritable, demanding and unable to think clearly or give an accurate history.


Excessive salivation, and/or spitting

Nausea increases salivation, but patients may be unwilling to swallow their saliva as this causes retching. They may dribble, spit or hold their saliva in their mouths, making speech difficult.


Extreme thirst

Thirst is often intense even though taking fluids results almost immediately in vomiting.



Dehydration and electrolyte imbalance may be severe during the vomiting phase, with about 60% requiring intravenous rehydration.


Vomiting blood

Many patients develop hematemesis from either peptic esophagitis or a Mallory-Weiss tear.




Eye problems




Pathologic bathing behavior (prolonged hot baths or showers).

Many patients experience symptom relief when they take hot baths or showers.

Several case reports implicate marijuana as a cause of intractable vomiting with prolonged hot baths or showers considered pathognomonic of «cannabinoid hyperemesis syndrome (CHS),» and this symptom has been used to distinguish CHS from CVS. Venkatesan and colleagues of the Medical College of Wisconsin conducted an internet survey among 514 CVS patients from members of the Cyclic Vomiting Syndrome Association USA in 2014, and  sought to examine the relationship between marijuana use and CVS.

The study showed that marijuana use is associated with hot showers, but even though the frequency of prolonged hot baths or showers is higher among patients using marijuana, this phenomenon of this behavior was also seen in CVS patients who denied any use of it, and they concluded that this kind of bathing should not be interpreted as being pathognomonic of marijuana use


Seek Help for Signs or Symptoms of Severe Dehydration

People who have any signs or symptoms of severe dehydration should call or see a healthcare provider right away:

·        excessive thirst

·        dark-colored urine

·        infrequent urination

·        lethargy, dizziness, or faintness

·        dry skin

Infants, children, older adults, and people with weak immune systems have the greatest chance of becoming dehydrated. People should watch for the following signs and symptoms of dehydration in infants, young children, and people who are unable to communicate their symptoms:

·        dry mouth and tongue

·        lack of tears when crying

·        infants with no wet diapers for 3 hours or more

·        infants with a sunken soft spot

·        unusually cranky or drowsy behavior

·        sunken eyes or cheeks

·        fever

If left untreated, severe dehydration can cause serious health problems, such as organ damage, shock, or coma—a sleeplike state in which a person is not conscious.

How frequently do the episodes occur?


As the name suggests, cyclic activity is often a feature of this condition. Episode frequency is relatively constant for any given individual, but varies between individuals. Vomiting occurs at frequent intervals for hours or days. A patient may suffer from 1 to 70 episodes per year with an average of 12 episodes a year. Patients with uncomplicated CVS are asymptomatic between episodes; attacks have an “on-off ” pattern. About half of all sufferers show a strong regular pattern of vomiting episodes.