Striated Muscle Contractility and Distal Esophageal Distensibility Define Novel Subtypes of Functional Dysphagia

Functional dysphagia (FD) is a common condition that significantly affects quality of life. Although esophageal hypersensitivity is believed to contribute to FD pathogenesis, recent evidence suggests that reduced esophageal distension may play a role. This cross-sectional study aimed to explore the mechanisms underlying FD in terms of esophageal distension during primary peristalsis.

Twenty-five patients with FD and 25 healthy participants were enrolled. All participants were assessed using high-resolution manometry with distension-contraction plots (DCPs) of peristalsis and "barium onigigography (BOG) with obstruction level (OL) system," a recently developed method. OL was graded 0 to 4, with OL0 indicating normal bolus transit and OL4 representing the most impaired bolus transit.

DCPs revealed 2 subtypes of FD: FD with preserved esophageal distension (FD-pED), resembling conventionally recognized FD, and FD with reduced esophageal distension (FD-rED), categorized as an esophageal motility disorder. Based on BOG, 10 of 11 patients with FD-pED exhibited OL0. Conversely, 13 of 14 patients with FD-rED exhibited OL1 to OL2 (ie, impaired bolus transit). Contractility of the striated muscle region was significantly lower in the FD-rED group than in the FD-pED and healthy groups. The amplitude of striated muscle contractility was an important determinant of distal esophageal distensibility.

A new subtype of FD, termed FD-rED, is proposed. Reduced contraction in the striated muscle region may contribute to reduced esophageal distension in the FD-rED. Focusing on the striated muscle region may provide a promising approach for developing new diagnoses and treatments for FD-rED.