Does esophageal function vary at the striated and smooth muscle segments in functional chest pain?

OBJECTIVE: Hypersensitivity of the esophageal wall may contribute to the pathogenesis of functional chest pain. Whether the hypersensitivity is more uniformly distributed along the esophageal wall or is segmental is not known. METHODS: Graded balloon distentions were performed randomly at the smooth muscle as well as at the striated muscle portions of the esophagus in 20 patients with functional chest pain and in 15 healthy volunteers, using impedance planimetry. Sensory thresholds and cross-sectional area were examined in relation to the esophageal wall tension, and the results were compared between two levels as well as the two groups of subjects. RESULTS: During balloon distention, 17 (85%) patients reported typical chest pain, 11 (55%) at both levels, four (20%) at the smooth muscle level, and two (10%) at the striated muscle level only. The sensory thresholds for perception, discomfort, or pain were lower in patients than in controls (p < 0.05). The cross-sectional area and the esophageal wall stiffness at the smooth muscle level were lower than those obtained at the striated muscle level both in controls and in patients (p < 0.01). The wall tension at which moderate discomfort and pain were reported was lower in patients than controls (p < 0.05). CONCLUSIONS: Although in most patients the esophagus is uniformly hypersensitive, in some either the smooth muscle or the striated muscle segment can be hypersensitive. If considering balloon distention at only one level, we recommend balloon placement at 10 cm above the lower esophageal sphincter because of a higher yield of hypersensitivity.