<unk> , or merycism, is a chronic motility disorder characterized by effortless regurgitation of most meals following consumption, due to the involuntary contraction of the muscles around the abdomen. There is no retching, nausea, heartburn, odour, or abdominal pain associated with the regurgitation, as there is with typical vomiting, and the regurgitated food is undigested. The disorder has been historically documented as affecting only infants, young children, and people with cognitive disabilities (the prevalence is as high as 10% in institutionalized patients with various mental disabilities). It is increasingly being diagnosed in a greater number of otherwise healthy adolescents and adults, though there is a lack of awareness of the condition by doctors, patients and the general public.<unk>  presents itself in a variety of ways, with especially high contrast existing between the presentation of the typical adult sufferer without a mental disability and the presentation of an infant and/or mentally impaired sufferer. Like related gastrointestinal disorders,<unk>  can adversely affect normal functioning and the social lives of individuals. It has been linked with depression. Little comprehensive data regarding<unk>  in otherwise healthy individuals exists because most sufferers are private about their illness and are often misdiagnosed due to the number of symptoms and the clinical similarities between<unk>  and other disorders of the stomach and esophagus, such as gastroparesis and bulimia nervosa. These symptoms include the acid-induced erosion of the esophagus and enamel, halitosis, malnutrition, severe weight loss and an unquenchable appetite. Individuals may begin regurgitating within a minute following ingestion, and the full cycle of ingestion and regurgitation can mimic the binging and purging of bulimia. Diagnosis of<unk>  is non-invasive and based on a history of the individual. Treatment is promising, with upwards of 85% of individuals responding positively to treatment, including infants and the mentally disabled.
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Sympathicolysis
Shark attack
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