The word rumination is derived from the Latin word ruminare, which means to chew the cud. Rumination is the voluntary or involuntary regurgitation and rechewing of partially digested food that is either reswallowed or expelled. This regurgitation appears effortless, may be preceded by a belching sensation, and typically does not involve retching or nausea.
In rumination, the regurgitant does not taste sour or bitter. The behavior must exist for at least 1 month, with evidence of normal functioning prior to onset. Rumination occurs within a few minutes postprandial and may last 1-2 hours. Though frequency may vary, rumination typically occurs daily and may persist for many months or years.
While the pathophysiology of rumination remains unclear, a proposed mechanism suggests that gastric distention with food is followed by abdominal compression and relaxation of the lower esophageal sphincter; these actions allow stomach contents to be regurgitated and rechewed and then swallowed or expelled.
Several mechanisms for the relaxation of the lower esophageal sphincter have been offered, including (1) learned voluntary relaxation, (2) simultaneous relaxation with increased intra-abdominal pressure, and (3) an adaptation of the belch reflex (eg, swallowing air produces gastric distention that activates a vagal reflex to relax the lower esophageal sphincter transiently during belching). Rumination may cause the following:
- Weight loss
- Growth failure
- Electrolyte imbalance
- Gastric disorders
- Upper respiratory distress
- Dental problems
- In the US: No systematic studies have reported the prevalence of rumination; most of the information about this disorder is derived from small case series or single case reports. Rumination disorder has been reported in children and adults with mental retardation as well as in infants, children, and adults of normal intelligence. Among those with otherwise normal intelligence and development, rumination is most common in infants. The prevalence in adults of normal intellectual functioning is unknown because of the secretive nature of the condition and because physicians lack awareness of rumination among this population.
Rumination is more common in individuals with severe and profound mental retardation than in those with mild or moderate mental retardation. Prevalence rates of 6-10% have been reported among the institutionalized population of individuals with mental retardation.
- Internationally: Rumination has been reported and researched in other countries (eg, Italy, Netherlands); however, frequency of occurrences in other countries is unclear.
Rumination is estimated to be the primary cause of death in 5-10% of individuals who ruminate. Mortality rates of 12-50% have been reported for institutionalized infants and older individuals.
Rumination occurs in both males and females. A male predominance has been reported by 1 case series, although this finding may not be definitive.
Rumination onset in otherwise normally developing infants typically occurs during the first year of life; onset usually manifests at age 3-6 months. Rumination often remits spontaneously.
- For individuals with severe and profound mental retardation, onset of rumination may occur at any age; average age of onset is age 6 years.
- Rumination among adolescents and adults of normal intelligence is gaining increased recognition.