Cyclic vomiting syndrome

Affected people may vomit or retch 6–12 times per hour, and an episode may last from a few hours to over three weeks and in some cases months, with a median episode duration of 41 hours. Stomach acid, bile and, if the vomiting is severe, blood may be vomited. Some with the condition drink water to reduce the irritation of bile and acid on the esophagus during emesis. Between episodes, the affected person is usually healthy but can be in a state of fatigue or experience muscle pain. In approximately half of cases, the attacks, or episodes, occur in a time-related manner. Each attack is stereotypical; that is, in any given person, the timing, frequency, and severity of attacks is similar. Some affected people experience episodes that progressively worsen when left untreated, occurring more frequently with reduced symptom-free phases. Episodes may happen every few days, every few weeks or every few months, for some happening at common uniform times, typically mornings. Some people also have a strong urge to bathe in warm or cold water. In fact, many people with CVS experience a compulsion to be submerged in hot water, and end up taking several baths during the duration of an episode. For some the psychological compulsion to be in hot water is so extreme that they cannot stop themselves from taking very long baths in near scalding hot water several times per day. For some of these people, they may have just finished taking a lengthy bath in extremely hot water and immediately feel this compulsion again and end up taking another bath right after drying off. Some people with the condition experience insomnia, diarrhea (GI complications), hot and cold flashes, and excessive sweating before an episode. Some report that they experience a restless sensation or stinging pain along the spine, hands, and feet followed by weakness in both legs. Some of these symptoms may be due to dehydration or hypokalemia from excessive vomiting, rather than the underlying cause of CVS. ==Genetics==

There is no known genetic pathogenesis for CVS. Recent studies suggest many affected individuals have a family history of related conditions, such as migraines, psychiatric disorders and gastrointestinal disorders. Inheritance is thought to be maternal, a possible genetic mitochondrial inheritance. Adolescents show higher possible mitochondrial inheritance and maternal inheritance than found in adults. Single base-pair and DNA rearrangements in the mitochondrial DNA (mtDNA) have been associated with these traits. ==Diagnosis==

The cause of CVS has not been determined and there are no specific diagnostic tests for CVS. Several other medical conditions, such as cannabinoid hyperemesis syndrome (CHS) or ureteropelvic junction (UPJ) obstruction, can present the same symptoms, and the differential diagnosis for CVS is very wide. An estimated 12% of people fitting the criteria for CVS have specific and possibly serious gastrointestinal, renal, neurological, or metabolic disease. If all other possible causes have been ruled out, a diagnosis of CVS using Rome criteria by a physician may be appropriate. ==Treatment==

Treatment for cyclic vomiting syndrome depends on the evident phase of the disorder and the symptoms reported. Episodes that are associated with migraines may respond to treatments effective for abdominal migraines. Prophylactic migraine medications, such as topiramate and amitriptyline, have seen recent success in treatment for the prodrome and vomiting phases, reducing the duration, severity, and frequency of episodes. Patients with non-migraine-associated CVS may be less responsive to migraine medications and have been proposed to have a distinct subtype of CVS. Therapeutic treatment for the prodromal phase, characterized by the anticipation of an episode, consists of sumatriptan (nasal or oral) an anti-migraine medication, anti-inflammatory drugs to reduce abdominal pain, and possible anti-emetic drugs. These options may be helpful in preventing an episode or reducing the severity of an attack. The most common therapeutic strategies for those already in the vomiting phase are maintenance of salt balance by appropriate intravenous fluids. Sedation via high dose intravenous benzodiazepines, typically lorazepam, has been shown to shorten the length of emergency department stays for some patients. Having vomited for a long period prior to attending a hospital, patients are typically severely dehydrated. For a number of patients, potent anti-emetic drugs such as ondansetron (Zofran) or granisetron (Kytril), and dronabinol (Marinol) may be helpful in either preventing an attack, aborting an attack, or reducing the severity of an attack. Many patients seek comfort during episodes by taking prolonged showers and baths typically quite hot. The use of a heating pad may also help reduce abdominal pain. Intravenous Haloperidol may be an effective treatment. ==Prognosis==

Fitzpatrick et al. (2007) identified 41 children with CVS. The mean age of the sample was 6 years at the onset of the syndrome, 8 years at first diagnosis, and 13 years at follow-up. As many as 39% of the children had resolution of symptoms immediately or within weeks of the diagnosis. Vomiting had resolved at the time of follow-up in 61% of the sample. Many children, including those in the remitted group, continued to have somatic symptoms such as headaches (in 42%) and abdominal pain (in 37%). Most children who have this disorder miss on average 24 school days a year. ==Epidemiology==

The average age at onset is 3–7 years, with described cases as young as 6 days and as old as 73 years. Typical delay in diagnosis from onset of symptoms is 3 years. Two studies on childhood CVS suggest nearly 2% of school-age children may have CVS. ==History==

Cyclic vomiting syndrome was first described in France by Swiss physician Henri Clermond Lombard and first described in the English language by pediatrician Samuel Gee in 1882. It has been suggested that Charles Darwin's adult illnesses may have been due to this syndrome. Darwin's illness had features seen in patients with cyclic vomiting, in particular his susceptibility to seasickness when onboard HMS Beagle, episodes being brought on by pleasurable events, and his periods of extreme lethargy dating back to his university student days. However in Darwin's case it is argued that his vomiting was due to an inherited mitochondrial disorder. ==See also==