Dorsal Scapular Artery Variations and Relationship to the Brachial Plexus, and a Related Thoracic Outlet Syndrome Case

The dominance of dorsal scapular artery as the blood supply to muscles of the back in the absence of two primary vessels: a cadaveric case report

PURPOSE

Understanding of rare or unknown anatomical variations of the vasculature of the neck is critical to reduce the risk of complications during surgeries and other invasive procedures in the neck and shoulder regions.

METHODS

Bilateral dissection of the neck and muscles of the back of an 87-year-old Caucasian male donor was performed to demonstrate the origin, course and termination of the arteries that arise in the neck.

RESULTS

Several anatomical variations were noted on the right side of the neck of the donor body - (i) only inferior thyroid and ascending cervical arteries originated from the thyrocervical trunk (TCT), from the first part of the subclavian artery (SA), whereas the transverse cervical (TCA) and suprascapular (SSA) arteries were entirely absent, (ii) Dorsal scapular artery (DSA) emerged normally from the third part of the SA. However, after supplying the rhomboids and levator scapulae muscles, DSA provided two additional branches to the trapezius muscle and a branch to the supraspinatus muscle. Interestingly, the branches to the trapezius muscle from the DSA were the only sources of blood supply to the muscle.

CONCLUSION

We report a unique anatomical variation involving the absence of the TCA and SSA from the TCT. The unilateral absence of these major vessels and the branches of DSA supplying the trapezius and supraspinatus muscles have not been reported previously in the literature in a single case report. This case study may provide useful information for head and neck reconstruction and shoulder repair surgeries.

Rare Superior and Middle Trunk Fusion Accompanied by Altered Division Rearrangement Results in a Unique Brachial Plexus Variant: A Case Report

During routine dissections of cadavers as part of the medical curriculum, we identified a rare unilateral variation in the brachial plexus on the right side of a female body donor. This variation consisted of four unusual changes to the regular pattering of nerve bundles and the dorsal scapular artery permeating the complex neural network. The variation included contributions of root C4 to the plexus by a root C4/C5 anastomosis, a rare fusion of the superior and middle trunks to a 'superomiddle' trunk, a preliminary, proximal branching of the suprascapular nerve off the C5 root. We further observed an accessory 'medial anterior division' branching off the fused upper and middle trunks merging with the anterior division of the inferior trunk forming the medial cord. The latter event potentially introduced nerve fibers from C5 to C7, which are absent in common patterns. We aim to relate these observations to previous categorizations and quantifications of brachial plexus patterns. We believe that the combination of different variations in this case resulted in a unique pattern. Since this observation was made in the dissection class, we further aim to raise awareness among medical students and anatomical instructors for the likelihood of variations to textbook patterns. This will hopefully foster an appreciation of uniqueness and individuality in the interaction with future patients demonstrating that proper preparation prior to surgical interventions is always a necessary prerequisite.

Changes in blood flow in the dorsal scapular artery and relationship to shoulder joint function in rotator cuff tears

Background

One of the pain-related factors in rotator cuff tears (RCTs) is abnormal scapular motion, which is thought to be related to the levator scapulae muscle activation. Additionally, attention has recently focused on the peak systolic velocity (PSV) as one of the causes of pain, but blood flow outside of the vessels supplying the rotator cuff has not been clarified. This study aimed to determine the difference in PSV in the dorsal scapular artery (DSA), which is the vessel that supplies the levator scapulae muscles, and the association between PSV and pain and shoulder function in patients with RCTs between the tear and nontear sides.

Methods

This study included 31 patients with RCTs with tear and nontear sides. Magnetic resonance imaging and radiographic examinations included Cofield classification, Goutallier classification, thickening of the coracohumeral ligament, and measurement of the acromiohumeral interval. Clinical evaluation included an automatic range of motion (ROM) for flexion, abduction, and external rotation (ER), a visual analog scale, and the Shoulder36. PSV was evaluated using ultrasound pulsed Doppler mode to assess PSV of DSA. The PSV of DSA on the first rib was drawn in the medial aspect of the suprascapular angle in the long axis, and the maximum PSV waveform was measured three times. The average value was used for further analysis.

Results

The PSV in the DSA was significantly higher (P = .04, 95% confidence interval: 0.2-7.6) on the tear (22.6 ± 7.4 cm/s) than the nontear sides (18.9 ± 6.9 cm/s). In addition, a significant negative correlation (r = -0.46, P = .0087) was found between PSV in DSA and ER on the tear side.

Conclusion

This study revealed a significantly increased PSV in the DSA on the tear side in RCTs and negatively correlated with ER ROM. The results suggest that increased PSV in the DSA may contribute to ER ROM limitation in the glenohumeral joint.

Origin variations and brachial plexus relationship of the dorsal scapular artery

The dorsal scapular artery can either be a direct branch of the subclavian artery or a branch of the transverse cervical artery. Origin variation is related to its relationship with the brachial plexus. Anatomical dissection was performed on 79 sides of 41 formalin-embalmed cadavers in Taiwan. The origin of the dorsal scapular artery and the variations of its brachial plexus relationship were scrutinized and analyzed. Results showed that the dorsal scapular artery originated most frequently from the transverse cervical artery (48%), followed by the direct branch from the third part (25%) and the second part (22%) of the subclavian artery and from the axillary artery (5%). Only 3% of the dorsal scapular artery passed through the brachial plexus if its origin was the transverse cervical artery. However, 100% and 75% of the dorsal scapular artery passed through the brachial plexus when they were direct branches of the second and the third part of the subclavian artery, respectively. Suprascapular arteries were also found to pass through the brachial plexus when they were direct branches from the subclavian artery, but all passed over or under the brachial plexus if they originated from the thyrocervical trunk or transverse cervical artery. Variations in the origin and course of arteries around the brachial plexus are of immense value not only to the basic anatomical knowledge but also to clinical practices such as supraclavicular brachial plexus block and head and neck reconstruction with pedicled or free flaps.

Delayed diagnosis of dorsal scapular artery pseudoaneurysm following blunt chest trauma

Pseudoaneurysm is a well-recognised form of vascular injury following blunt trauma. Its diagnosis is often delayed due to late manifestation of signs and symptoms. Nonetheless, complications of pseudoaneurysm can be severe and even fatal. A 60-year-old man presented to our tertiary trauma centre with blunt chest trauma. His treatment was initially focused on the left clavicular fracture. He was eventually diagnosed with a dorsal scapular artery pseudoaneurysm and a large chest wall haematoma on computed tomography on his third hospital admission in two weeks. This pseudoaneurysm was treated with endovascular embolisation. This article highlights the value of meticulous clinical examination as well as judicious use of biochemistry and imaging in trauma management.

Intertruncal approach to the supraclavicular brachial plexus, current controversies and technical update: a daring discourse

We propose a new approach to local anesthetic injection for the supraclavicular brachial plexus block: an intertruncal approach by which local anesthetic is deposited in the two adipose tissue planes between the upper and middle and the middle and lower trunks. We present sonographic and microscopic images to illustrate the relevant anatomy. This approach offers potential advantages over the ‘corner pocket’ technique in that it results in consistent local anesthetic spread to the three plexus trunks and the needle endpoint lies farther away from the pleural surface which is important for the prevention of pneumothorax. It also offers an advantage over the ‘intracluster’ approach as it purposefully avoids intraneural injection respecting the integrity of the epineurium of individual trunks. Comparative studies are required to confirm that these anatomic and technical advantages result in improved outcomes.

MR imaging features of presumed retroclavicular and periscapular intermuscular vascular plexi - An observational, anatomic study

OBJECTIVE

To describe MR imaging features of presumed vascular plexi in the periscapular (PSC) and retroclavicular (RC) locations.

MATERIALS/METHODS

443 consecutive MR studies performed as "brachial plexus" protocol (axialT1-W and sagittal STIR) were reviewed for presence, size and characteristics of PSC and RC plexi.

RESULTS

Presumed PSC and RC vascular plexi were present in 10%. Both plexi more commonly occurred on the left side. Percutaneous biopsy (n = 1) yielded no vascular neoplasm.

CONCLUSION

RC and PSC vascular plexi are commonly encountered on routine brachial plexus MR imaging and may represent variant vascular networks, as they are frequently found on the contralateral asymptomatic side.

Neurogenic Thoracic Outlet Syndrome Caused by Vascular Compression of the Brachial Plexus: A Report of Two Cases

Thoracic outlet syndrome (TOS) is caused by compression of the brachial plexus and/or subclavian vessels as they pass through the cervicothoracobrachial region, exiting the chest. There are three main types of TOS: neurogenic TOS, arterial TOS, and venous TOS. Neurogenic TOS accounts for approximately 95% of all cases, and it is usually caused by physical trauma (posttraumatic etiology), chronic repetitive motion (functional etiology), or bone or muscle anomalies (congenital etiology). We present two cases in which neurogenic TOS was elicited by vascular compression of the inferior portion of the brachial plexus.

Phrenic nerve decompression for the management of unilateral diaphragmatic paralysis - preoperative evaluation and operative technique

Background:

Unilateral diaphragmatic paralysis (UDP) can be a very disabling, typically causing shortness of breath and reduced exercise tolerance. We present a case of a surgical decompression of the phrenic nerve of a patient who presented with UDP, which occurred following cervical spine surgery.

Methods:

The workup for the etiology of UDP demonstrated paradoxical movement on “sniff test” and notably impaired pulmonary function tests. Seven months following the onset of the UDP, he underwent a surgical decompression of the phrenic nerve at the level of the anterior scalene.

Results:

He noted rapid symptomatic improvement following surgery and reversal of the above noted objective findings was documented. At his 4-year follow-up, he had complete resolution of his clinical symptoms. Repeated physiologic testing of his respiratory function had shown a complete reversal of his UDP.

Conclusions:

Anatomical compression of the phrenic nerve by redundant neck vasculature should be considered in the differential diagnosis of UDP. Here we demonstrated the techniques in workup and surgical management, with both subjective and objective evidence of success.