Radial Artery Occlusion Impairs Median Nerve Perfusion—A Study Using Microvascular Imaging in Healthy Volunteers

<b>Background/Objectives:</b> The transradial approach is widely used for vascular access in many disciplines. Radial artery occlusion (RAO) is a frequent sequel, and hand/arm pain affects 7.8% of patients. We aimed to elucidate whether RAO or ulnar artery occlusion (UAO) causes impaired neural blood flow and, thus, if symptoms may be attributable to claudication or nerve damage. <b>Methods:</b> Forty healthy volunteers (73% female), with a mean age of 38 years and without clinical or sonographic signs of carpal tunnel syndrome, were included. All underwent a standardized ultrasound examination (Aplio i800 and i22LH8 linear transducer, Canon Medical Systems) of the forearm, investigating the median nerve and its intraneural blood flow as well as the vascular status of the limb. The radial and ulnar arteries were then sequentially compressed, while changes to intraneural blood flow were noted. Thereafter, the (reverse) Barbeau test and the (inverse) modified Allen Test (MAT) were performed. <b>Results:</b> Simulated RAO and UAO halted intraneural blood flow in 65% and 62.5% of individuals, respectively. A total of 32.5% of participants reported discomfort in the hand/arm. Absent flow during occlusion was found at a significantly higher rate in symptomatic individuals. MAT and inverse MAT were abnormal (>10 s) in 17.5% and 7.5% of patients. Barbeau and reverse Barbeau produced type D results in 15% and 20%, respectively. <b>Conclusions:</b> Both simulated RAO and UAO caused the cessation of intraneural blood flow of the median nerve in two-thirds of participants, and a large proportion reported symptoms. MAT and Barbeau tests did not seem to be useful in predicting impaired neural blood flow.