Rumination syndrome, also known as merycism, is a chronic motility disorder characterized by the effortless regurgitation of most meals following consumption. This condition is distinct from the psychological
concept of rumination, which involves obsessive negative thinking. In rumination syndrome, the regurgitation is due to the involuntary contraction of muscles around the abdomen. Unlike typical vomiting, there is no retching, nausea, heartburn, odor, or abdominal pain associated with the regurgitation, and the regurgitated food remains undigested. Historically, this disorder was primarily documented in infants, young children, and individuals with cognitive disabilities, with prevalence as high as 10% in institutionalized patients with various mental disabilities. However, it is increasingly being diagnosed in otherwise healthy adolescents and adults, despite a general lack of awareness among doctors, patients, and the public.
Understanding the Symptoms and Presentation
The hallmark symptom of rumination syndrome is the repetitive regurgitation of undigested food after a meal. This can manifest in various ways; in some individuals, the regurgitation is small and occurs over a long period, allowing for rechewing and re-swallowing. In others, it can be bilious and brief, requiring expulsion. While some experience symptoms only after certain meals, most individuals with the syndrome have episodes following any ingestion, from a single bite to a large meal. However, some long-term patients may identify a few food or drink items that do not trigger a response.
Crucially, the regurgitation is typically described as effortless and unforced, lacking the nausea that often precedes typical vomiting. The undigested food also lacks the bitter taste and odor associated with stomach acid and bile. Symptoms can begin anywhere from immediately after ingestion to two hours later, though the more common range is between thirty seconds and one hour after completing a meal. Symptoms tend to cease once the regurgitated contents become acidic. Other common symptoms reported in daily life include abdominal pain (38.1%), lack of fecal production or constipation (21.1%), nausea (17.0%), diarrhea (8.2%), bloating (4.1%), and dental decay (3.4%). These additional symptoms are not necessarily prevalent during regurgitation episodes and can occur at any time. Weight loss is frequently observed (42.2%), with an average loss of 9.6 kilograms, particularly in cases where the disorder has gone undiagnosed for an extended period, often due to associated nutritional deficiencies. Depression has also been linked with rumination syndrome, though its specific effects on the syndrome are not fully understood. Acid erosion of teeth and halitosis (bad breath) can also be features of the condition.
Exploring Causes and Pathophysiology
The exact cause of rumination syndrome remains unknown, but studies have identified correlations between hypothesized causes and patient histories. In infants and the cognitively impaired, the disorder has often been attributed to over- or under-stimulation from caregivers, leading the individual to seek self-gratification or self-stimulus. In all populations, it has also been linked to a bout of illness, a period of recent stress, or changes in medication. For adults and adolescents, hypothesized causes generally fall into two categories: habit-induced and trauma-induced.
Habit-induced cases often involve individuals with a history of bulimia nervosa or intentional regurgitation (such as professional regurgitators). What might initially be self-induced behavior can form a subconscious habit that continues outside the individual's control. Trauma-induced cases describe an emotional or physical injury, such as recent surgery, psychological distress, concussions, or family deaths, which preceded the onset of rumination, sometimes by several months. The pathophysiology of rumination syndrome is also poorly understood, with several theories attempting to explain the mechanisms behind the regurgitation. One widely documented mechanism suggests that food ingestion causes gastric distention, followed by abdominal compression and the simultaneous relaxation of the lower esophageal sphincter (LES). This creates a common cavity between the stomach and the oropharynx, allowing partially digested material to return to the mouth. Explanations for LES relaxation include a learned voluntary relaxation (common in those with or who had bulimia), relaxation due to intra-abdominal pressure, or an adaptation of the belch reflex, where swallowing air immediately before regurgitation activates the belching reflex, triggering LES relaxation. Patients often describe a feeling similar to the onset of a belch preceding rumination.
Diagnosis, Misdiagnosis, and Treatment Approaches
Diagnosis of rumination syndrome is non-invasive and primarily based on a thorough patient history. Costly and invasive studies like gastroduodenal manometry and esophageal pH testing are often unnecessary and can even lead to misdiagnosis. Diagnostic criteria include consistent regurgitation of recently ingested food for at least six weeks within the past twelve months, with symptoms beginning within 30 minutes of meal completion and ceasing within 90 minutes or when the regurgitated matter becomes acidic. The symptoms must not be due to a mechanical obstruction and should not respond to standard treatments for gastroesophageal reflux disease. In adults, the absence of classical or structural gastrointestinal diseases supports the diagnosis. Supportive criteria include regurgitant that is not sour or acidic, generally odorless, effortless, or preceded by a belching sensation, and the absence of retching, nausea, or heartburn.
Patients often visit an average of five physicians over 2.75 years before receiving a correct diagnosis, highlighting the lack of awareness. Rumination syndrome is frequently misdiagnosed, particularly as bulimia nervosa or gastroparesis. While there may be a connection between rumination and bulimia, rumination is not self-inflicted, and patients with rumination syndrome often cannot control the reflex, unlike those with bulimia who intentionally induce vomiting. Gastroparesis, another common misdiagnosis, involves vomiting (not regurgitation) of undigested food several hours after a meal, preceded by nausea and retching, and with a bitter or sour taste. Rumination syndrome is classified as a gastroduodenal disorder. In healthy adolescents and adults without mental disabilities, it is considered a motility disorder rather than an eating disorder, as patients typically have no control over its occurrence and no history of eating disorders.
Currently, there is no known cure for rumination syndrome, and medications like proton pump inhibitors have shown little to no effect. Treatment approaches differ for infants and adults with cognitive disabilities compared to those of typical intelligence. For infants and cognitively impaired adults, behavioral and mild aversion training have shown improvement in most cases. Aversion training involves associating ruminating behavior with negative results and rewarding good behavior, often by placing a sour or bitter taste on the tongue when ruminating behaviors begin. For patients of normal intelligence, rumination is not intentional, and treatment focuses on habit reversal using diaphragmatic breathing to counter the urge to regurgitate. This technique, which involves breathing using the diaphragm before and during the typical rumination period, physically prevents the abdominal contractions needed to expel stomach contents. Supportive therapy and diaphragmatic breathing have shown improvement in 56% of cases and total cessation of symptoms in an additional 30% in one study of adolescent patients. Patients who successfully use this technique often experience an immediate improvement in health. However, individuals with a history of bulimia or intentional vomiting may have a reduced chance of improvement due to reinforced behavior. The technique is not used with infants or young children due to the complex timing and concentration required, though most infants outgrow the disorder within a year or with aversion training.
