Causes Of CVS

Causes of CVS #CyclicVomitingSyndrome

The exact cause of cyclic vomiting syndrome is unknown. Although nausea and vomiting are the main features of cyclic vomiting syndrome, researchers now believe that the primary organ affected is the brain and that the symptoms of the disorder develop due to abnormalities in the normal interaction between the brain and the gut (brain-gut disorder).

Although the specific cause of cyclic vomiting syndrome is unknown, likely there are several causes. Researchers have noted a relationship between cyclic vomiting syndrome and migraines, and some theorize that cyclic vomiting syndrome may be a migraine variant. Many children with cyclic vomiting syndrome have a family history of migraines or develop migraines when they get older. Cyclic vomiting syndrome may be referred to as a type of “abdominal migraine” and the terms are sometimes used interchangeably. An abdominal migraine is a migraine variant in which there are recurrent episodes of abdominal pain. Vomiting may or may not accompany an abdominal migraine.

Additional factors that may be associated with the development of cyclic vomiting syndrome include dysfunction of the autonomic nervous system. The autonomic nervous system is the portion of the nervous system that controls or regulates certain involuntary body functions including heart rate, blood pressure, sweating, the production and release of certain hormones, and bowel and bladder control. Autonomic disturbances are common during episodes, including fever, tachycardia, high blood pressure and urinary retention (blockage). Vomiting itself is an autonomic disturbance. Autonomic or “functional” disturbances can also occur between episodes, such as reflex sympathetic dystrophy (a chronic pain condition), syncope (fainting), and disorders of gastrointestinal motility. The latter are particular common, and can include gastroesophageal reflux (GERD, explained below), delayed gastric emptying (resulting in bloating during meals), irritable bowel and/or constipation.

Additional conditions sometimes seen in individuals with cyclic vomiting syndrome include depression, anxiety, attention deficit hyperactivity disorder (ADHD), seizures, autistic spectrum disorders and learning disabilities.

Some research indicates that the dysfunction in the body’s response to stress may contribute or trigger episodes of cyclic vomiting syndrome. Affected individuals may experience altered release of corticotrophin-releasing factor (CRF) from the hypothalamus, the portion of the brain that controls the production and release of certain hormones. CRF is a stress hormone that stimulates the adrenal cortex, which controls the body’s response to stress. Some research has indicated that CRF may cause vomiting.

Researchers have also learned that, in most cases, blood and urine testing reveal signs of abnormal energy metabolism. In many of those cases, changes (mutations) of genetic material found in the DNA of mitochondria (mtDNA) play a role in the development of cyclic vomiting syndrome. Mitochondria, which are found by the thousands in the cells of the body, particularly in muscle and nerve tissue, produce the vast majority of energy that is required for the function of biological processes. As opposed to the genetic instructions of cellular chromosomes (nuclear DNA), which are found within the nucleus of each cell, mitochondrial genetic instructions are found outside of the nucleus of the cell. The exact role such mutations play in the development of cyclic vomiting syndrome is unknown.

Mutations affecting the genetic instructions for mitochondria (mtDNA) are inherited from the mother. MtDNA found in sperm cells typically is destroyed following fertilization. As a result, all human mtDNA comes from the mother. An affected mother will pass the mutation(s) on to all her children, but only her daughters will pass the mutation(s) on to their children. As a result, family members related entirely through women carry the same mtDNA genetic sequence. In half or more of CVS families, those relatives often suffer themselves from dysautonomic or functional-related symptoms, especially chronic pain (including migraine), bowel disorders, and depression.

The exact way the abovementioned factors and additional, as yet unidentified, factors interact to cause cyclic vomiting syndrome is unknown. Research is ongoing to determine the cause and underlying mechanisms that result in cyclic vomiting syndrome.