An electromyographic biofeedback program significantly improved abdominothoracic muscle control and abdominal distension compared with placebo in a randomized trial of patients fulfilling Rome III criteria for functional intestinal disorders.
Sensations of abdominal distension improved by 56% with biofeedback (standard deviation, 1%) versus 13% (SD, 8%) with placebo, wrote Elizabeth Barba, MD, of University Hospital Vall d’Hebron in Barcelona, and her associates. The study was published in the December issue of Clinical Gastroenterology and Hepatology (doi:). Biofeedback also led to a doubling of anterior wall muscle activity (101%; SD, 10%) compared with a 4% (SD, 2%) improvement with placebo. Finally, biofeedback lowered intercostal muscle activity by a mean of 45% (SD, 3%) compared with 5% (SD, 2%) with placebo (all P values less than .001).
“Biofeedback in this trial was applied using a complex technique that provided effective guidance to patients and allowed close control of the mechanistic effects of the intervention on postural tone,” the researchers noted. “Having proved the [efficacy] of this treatment, the next steps are to develop and then to properly validate a simpler technique for widespread application.”
Episodic abdominal distension is a primary reason for visiting gastroenterology clinics. Patients typically experience an objective, visible increase in girth with no detectable cause, although they often have irritable bowel syndrome, functional dyspepsia, or both. Past work has linked abdominal distension with increased diaphragmatic tone and ventral protrusion and decreased muscle tone of the abdominal wall, the researchers noted.
Therefore, they developed an electromyography (EMG) biofeedback program to help patients learn to correct abdominothoracic muscular dystony. The trial comprised 48 patients (47 women and 1 man) ranging in age from 21 to 74 years. During each 30-minute session, patients sat upright in a quiet room while EMG recorded the activity of the intercostal muscles, anterior abdominal wall (external oblique, upper rectus, lower rectus, and internal oblique muscles), and diaphragm. Patients reported their sensation of abdominal distension on a visual rating scale ranging from 0 (no distension) to 6 (extreme distension). Those in the intervention group watched the EMG readout and were taught to reduce their intercostal and diaphragm activity while increasing the activity of the anterior abdominal muscles. Three training sessions occurred over 10 days and patients performed similar exercises at home for 5 minutes before each meal. Patients in the placebo group underwent the same instrumental interventions but did not watch the EMG recording, received no instructions about muscle control, and were given oral simethicone.
Symptoms associated with abdominal distension lessened by 57% (SD, 9%) in the biofeedback group and by 23% (4%) in the placebo group (P = .02). Treatment outcomes did not vary based on symptoms and there were no adverse effects of treatment, the researchers said. Furthermore, 19 patients in the placebo group who did not improve underwent biofeedback training and experienced benefits similar to those of the original intervention group. Sensations of abdominal distension and associated symptoms improved significantly immediately after biofeedback compared with baseline and continued to improve significantly over 6 months of follow-up.
The researchers described the complexity of the intervention, which, they acknowledged, would need to be simplified before it could be deployed widely. They measured the activity of the external oblique, upper rectus, lower rectus, and internal oblique muscles with bipolar leads, and recorded intercostal muscle activity by placing a monopolar electrode at the second intercostal space on the right midclavicular line, with a ground electrode over the central sternum. To verify correct placement, they recorded EMG responses to a Valsalva maneuver and a deep inhalation. They measured diaphragmatic activity by mounting electrodes on a polyvinyl tube, performing nasal intubation, and positioning the electrodes across the diaphragmatic hiatus under fluoroscopic control.
Funders included the Spanish Ministry of Economy and Competitiveness and the Instituto de Salud Carlos III. The researchers reported having no conflicts of interest.