Novel sensory trigger for gastrocolonic response

Gastrocolonic response (GCR) is a physiologic increase in motor activity of the colon following meal ingestion. The presence of GCR, in colonic manometry (CM) studies, is used as a marker of normal colonic motor activity. Our aim was to investigate whether GCR could be induced by sensory stimulation (visual or olfactory) prior to food ingestion, and to describe the characteristics of patients with this response.

We prospectively marked time of meal presence and initiation on CM tracings of patients with idiopathic constipation. We reviewed electronic medical records and normal CM studies. Presence of sensory GCR was defined as an increase by at least 25% of the baseline motility index (MI) after exposure to meal, prior to food ingestion. Manometry characteristics of patients with a sensory GCR response were compared to those without.

Eighty-nine patients, (47% females, median age 9 years) met the inclusion criteria. Forty-seven (52.8%) patients had a positive sensory GCR. This cohort had a higher proportion of postprandial GCR (93.6% vs. 76.2%, p-value = 0.02) and lower fasting MI (2.08 mm Hg vs. 3.54 mm Hg, p < 0.01). Thirteen (14.6%) patients who had no postprandial GCR had higher baseline MI (median of 3.69 vs. 2.46 mm Hg, p < 0.05).

Visualizing or smelling food resulted in a significant increase in baseline MI in more than 50% of patients. Our findings propose a novel, alternate pathway that can induce GCR. This central sensory pathway may have clinical relevance in the diagnosis and management of patients with colonic dysmotility.