Our study focusing on the Taiwanese population revealed that the DSA originated from the TCA (48%) more often than from the second and the third parts of the subclavian artery combined (47%). This is similar to results with a higher percentage of DSA originating from the TCA found in studies in Japan (55.7%)5 and Thailand (69%)6. Contrary to studies in Asia, DSAs were reported to originate more frequently from the subclavian artery in the United States (61.2% in2, 74.6% in3, and 71% in8). Earlier studies from France, Germany, Italy, Hungary, Switzerland, and Spain also showed that the DSA originated predominantly from the subclavian artery4. Although it is not clear whether the differences in DSA origin is related to race, it is important for physicians to be informed of these variations when performing procedures in their respective regions.
Although the overall percentages of DSA passing through the brachial plexus was only 44% in the Taiwanese population, 100% and 75% of the DSAs were found passing through the brachial plexus when they originated directly from the second and the third parts of the subclavian artery, respectively. Limited studies investigating the relationships between the DSA and brachial plexus also reported similar results, with > 90% of the DSA passing through the brachial plexus when they were direct branches from the subclavian artery2,6. The close apposition of the subclavian artery and brachial plexus could be the reason for the high incidence of DSA passing through the brachial plexus.
The presence of vessels within the brachial plexus may pose a risk to health. Arterial compression of the brachial plexus might result in pain or related thoracic outlet syndrome. Verenna et al.8 reported a patient diagnosed with thoracic outlet syndrome, and symptoms were not relieved until the DSA, which was a direct branch from the subclavian artery and passed through the brachial plexus, was surgically ligated. Therefore, in case of upper extremity radiating pain or paresthesia with obvious proximal etiology, the possibility of a vascular compression of the brachial plexus should be considered8. Moreover, the presence of vessels within the brachial plexus may affect the safety and efficacy of brachial plexus blockade7. Vascular puncture-related complications may threaten the safety of the patients; however, sonographic assessment can significantly reduce such complications9. Nambyiah et al.10 had successfully identified arteries within the brachial plexus in > 90% of subjects using a portable ultrasound device.
In addition to DSA, the suprascapular artery was also found passing through the brachial plexus in our study. The overall percentage for the suprascapular arteries passing through the brachial plexus was 33%, similar to results found in France (28%)11. However, 100% and 92% of the suprascapular arteries were found within the brachial plexus when they were direct branches from the subclavian or axillary arteries, respectively. Moreover, 15 sides of the brachial plexus examined in our study had both the DSA and suprascapular artery passing through brachial plexus, which may pose higher risks for neurovascular complications around this region.
Variations in the origin and course of arteries around the brachial plexus are of immense value to surgeons, angiographists, and anatomists. For example, the pedicled DSA flaps are widely used for reconstruction of head, neck, and upper back defects12,13. Sufficient perfusion in the distal region determined the flap survival rates and therefore the outcome of the surgery. In this study, we showed that DSAs and the suprascapular artery originating directly from the subclavian artery had high percentages running through the brachial plexus, which were reported to impede needle approaches and may cause technical difficulties or complications in supraclavicular blocks7,14. Although there is no information about whether the perfusions of arteries were affected when they passed through the brachial plexus, we believe it would be beneficial and important to acquire this information for clinical evaluation.