Can the change of vasomotor activity in irritable bowel syndrome patients be detected via color Doppler ultrasound?

Background: Irritable bowel syndrome (IBS) is one of the most frequently referred conditions to the gastrointestinal outpatient clinic. The pathophysiology of IBS has not been determined with certainty. Visceral hypersensitivity is indicated as one of the pathophysiologies. The sympathetic nervous system is primarily in charge of controlling the arteries, and its effect is vasospasm in the medium and large arteries, resulting in decreased blood flow.

Aim: To demonstrate, using Doppler evaluation of the brachial artery, that sympathetic activity impairs vasomotor performance due to autonomic neuropathy, which we believe is associated with IBS.

Methods: There were 58 participants in the study. The control group consisted of 29 healthy patients, while the remaining 29 patients had been diagnosed with IBS. Patients who met the Rome IV criteria and had IBS were included in the study. People with known polyneuropathy or non-IBS chronic conditions that can progress were excluded from the trial, as were those with essential hypertension, diabetes mellitus, cardiovascular disease, or peripheral arterial disease, and patients diagnosed with anxiety or depression. Those with moderate to severe carpal tunnel syndrome or a median nerve lesion due to trauma were also excluded from the trial. A Doppler probe was used to measure the baseline diameter and flow rates of the brachial artery from 2 cm superior to the antecubital fossa. The Doppler probe remained stationary throughout the experiment, allowing for continuous measurements. Then, to activate the sympathetic fibers, an electrical stimulus for 5 s with an intensity of 10 mA and a frequency of 1 Hz was applied to the median nerve at the wrist level via the bipolar stimulus electrode. The artery diameter and flow rates were measured again immediately following the fifth stimulus.

Results: In healthy persons with no history of chronic illness, there was a statistically significant decrease in flow rate after stimulation (P < 0.001). In addition, stimulation resulted in a statistically significant reduction in the diameter of the brachial artery (P < 0.001). Patients diagnosed with IBS had statistically significant vasodilation and an increase in flow rate.

Conclusion: Sympathetic stimulation causes a reduction in vascular diameter and blood flow, whereas it has the reverse effect on IBS patients. In investigating the involvement of autonomic neuropathy in the development of IBS, significant changes in brachial artery Doppler parameters were observed before and after stimulation of the median nerve with low-current sensory stimulation. This method is thought to be more user-friendly and comfortable than other methods described in the literature.