Rumination is an unperceived somatic response to food ingestion that disrupts abdominal accommodation, researchers report in the January issue of Clinical Gastroenterology and Hepatology. They go on to show that it can be corrected by biofeedback-guided control of abdomino-thoracic muscular activity.
Rumination syndrome is characterized by effortless recurrent regurgitation of recently ingested food into the mouth, followed by expulsion or re-chewing and swallowing. It is a minor social inconvenience but can lead to nutritional deficiencies.
The regurgitation is believed to result from a sudden increase in intra-gastric and intra-esophageal pressures that propel a retrograde flow of contents into the esophagus. However, little is known about the activities of the abdomino-thoracic muscles that mediate rumination, or whether these can be controlled.
Elizabeth Barba et al investigated whether rumination is controllable and can be reversed by behavioral treatment in a prospective study of 28 patients. Their rumination syndrome was diagnosed based on intestinal manometry, which detected abdominal compression associated with regurgitation.
In the study, patients were trained to modulate abdomino-thoracic muscle activity under visual control of electromyographic recordings (EMG; see figure).
Recordings were made after challenge meals, before training (baseline), and during 3 treatment sessions. Rumination events were measured with questionnaires given each day for 10 days before training, immediately after training, and at 1, 3, and 6 months after training.
Barba et al found that by the end of the first treatment session, EMG activities of the intercostals, upper rectus, lower rectus, and internal oblique were significantly lower than at the beginning of the session.
By the end of the 3 sessions, patients had effectively learned to reduce intercostal activity by 50% and anterior wall muscle activity by 30%. They had reported about 27 regurgitation episodes/day at the beginning of the study—these were reduced to about 8 episodes/day immediately after treatment. Regurgitation episodes decreased further, to about 4 episodes/day 6 months after training.
How does rumination syndrome develop? Barba et al explain that the abdomen and thorax are separate compartments of the abdomino-thoracic cavity—the diaphragm serves as a dynamic boundary that allows changes in one compartment to have an immediate effect on the other. Gastric content is regurgitated by a coordinated abdomino-thoracic maneuver that involves sudden contraction of the intercostal muscles (thoracic suction), along with a contraction of the anterior abdominal muscles, (abdominal compression). The diaphragm facilitates the creation of a common cavity phenomenon between the abdomen and thorax by allowing upward displacement of gastric content.
Interestingly, the abdomino-thoracic maneuver that mediates rumination is usually unnoticed by the patients themselves—maybe because the fine coordination of the thoracic suction, abdominal push, and hiatal opening requires a relatively brief and mild action. Barba et al say it is not clear how ruminators learned this apparently useless response to feeding, but rumination is classified as a psychiatric disorder.
However, ruminators also have a high background tone of the abdominal and intercostal muscles that can be corrected by biofeedback training. Barba et al point out that in contrast to other functional gut disorders, defined by subjective symptoms, rumination has an objective mechanical basis and requires cognitive intervention to achieve sustained remission.
They propose that their therapy might be simplified with use of manometry or even hand-guided learning of diaphragmatic breathing.