Angiosome territories of the nerves of the upper limbs

The Role of Vascularized Nerve Grafting in Upper Extremity Reconstruction: A Systematic Review

Purpose

Vascularized nerve grafts (VNGs) have been proposed as encouraging alternatives to conventional nerve grafting; however, there is ongoing debate regarding the clinical advantages of the approach compared with standard grafting. This review aims to gather and analyze reported cases of upper extremity nerve repair using VNGs documented in the published literature.

Methods

In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed/MEDLINE, Embase, and Cochrane were searched. Inclusion criteria for this review included the following: (1) human subjects or cadaveric studies, (2) describing a vascularized nerve grafting procedure or suggesting a nerve and vascular supply for a potential vascularized nerve graft, and (3) upper extremity nerve repair in clinical studies.

Results

Data were extracted from 45 clinical studies. Of 535 patients, the most common injury pattern was root avulsion and rupture (88.7%). The most utilized VNG was the ulnar nerve (72.8%), followed by nerve to long head of triceps (8.8%) and sural nerve (8.2%); most common recipients were median (57.6%), axillary (12.5%), and musculocutaneous nerves (11.9%). Between patients who had medical research council scale scores, 69% had functional (M3 and above) motor and 72.7% sensory (S3<) recovery.

Conclusions

Vascularized nerve grafts can increase the odds of functional gain in challenging conditions such as large nerve gaps, nerve avulsions, ruptures, and scarred and irradiated beds. With the exception of well-known VNG options, literature on alternative VNGs is largely confined to case reports and series, with additional published cases, outcomes, and basic science research needed to establish the role of VNGs in nerve repair.

Clinical relevance

Our findings support the promise of VNGs for complex cases of nerve reconstruction. Evidence from published cases also indicates that VNGs enhance motor and sensory function recovery compared with traditional nerve grafting.

Anterior transposition of the radial nerve to achieve primary suture for its reconstruction: Anatomical feasibility study

INTRODUCTION

Radial nerve palsy after humeral shaft fractures is often associated with formation of a neuroma in continuity. The current standard of treatment is neuroma resection and nerve grafting with contentious results. Anterior transposition of the radial nerve may reduce the length of its path, allowing reconstruction by primary suture. The aim of this study was to determine the maximum length of radial nerve defect that can be treated by the anterior transposition to allow primary suture to be performed.

METHODS

We use 10 arms from five fresh cadavers. The radial nerve was dissected in the lateral inter-muscular septum and along the anterior aspect of the forearm. The radial nerve was transected at the level of the spiral groove and both stumps were than transposed anterior to the medial inter-muscular septum. The length of tension-free overlap that could be achieved was measured.

RESULTS

The average length of the overlap at zero degrees of elbow flexion was 10.00 ± 1.84 mm. Theoretically, this will allow a defect of 20 ± 3.69 mm SD to be treated by primary suture.

CONCLUSION

Our results suggest that anterior transposition can be used for radial nerve defects up to 2 cm; however, dissection of both stumps proved to be challenging.

Angiosomes of the Ulnar Nerve at the Elbow: A Cadaver Trial Using Contrast-Enhanced Ultrasound

Three major arteries supplying the ulnar nerve in the cubital tunnel are commonly known. However, their vascular territories (angiosomes) have not been described yet. Contrast-enhanced ultrasound was used to identify the angiosomes of posterior ulnar recurrent artery, inferior ulnar collateral artery and superior ulnar collateral artery in 20 fresh, non-frozen human body donors. The arteries were cannulated, and physiologic blood flow was simulated. Contrast agent was applied in each vessel in a randomized sequence, and the length of the contrast-enhancing ulnar nerve segment was measured by a radiologist blinded to the sequence. The angiosome of the posterior ulnar recurrent artery overlaps both other angiosomes. It fully covers the cubital tunnel in 63.6% of specimens. In addition, collateral flow via nerve and muscle branches of the arterial anastomotic network around the elbow (rete articulare cubiti) partly maintains the intra-neural blood flow in the absence of a vascular pedicle. The posterior ulnar recurrent artery is the dominant nutrient vessel of the ulnar nerve in the cubital tunnel. A potential watershed zone exists proximal to the Osborne ligament. Knowledge of these angiosomes may advance surgery of the ulnar nerve in the cubital tunnel.

Reconstruction of Foot and Ankle Defects Using Free Lateral Arm Flap: A Retrospective Review of Its Versatile Application

Background

Successful reconstruction of the feet and ankles remains challenging due to limited quantities of soft tissue and laxity. The free lateral arm flap (LAF) is an alternative to conventional flaps and has been widely used due to advancements in its flap characteristics. This study is aimed at utilizing the advantages of this flap to validate its increased applications for foot and ankle defects.

Methods

Twenty patients with various LAF types between May 2011 and May 2020 were enrolled. Clinical data was retrospectively collected, and defect sites were classified according to the subunit principle. We utilized various LAF types, such as LAFs with sensate, extended, osteomyocutaneous, or myocutaneous flaps, as necessary. A two-point discrimination test was performed, and results were statistically compared between flaps.

Results

Among the diverse etiologies of skin defects, chronic inflammation was the most common cause of defects. Various LAF types, including LAFs with fasciocutaneous, extended fasciocutaneous, musculocutaneous, and osteomyocutaneous flaps, were used. The versatility of free LAF helped successfully cover various defects in all cases. Results of the two-point discrimination test were statistically significant between groups.

Conclusions

Free LAF is a unique soft tissue free flap that is more versatile than other flaps, allowing flaps to be continuously modified and applied to various foot and ankle defects under different clinical conditions.

Vascularization of the lateral and medial antebrachial cutaneous nerves by cutaneous perforator arteries: An anatomical study

The forearm is an interesting donor site for non-vascularized nerve grafts, especially hand surgeons. Very few studies have described the use of the lateral and medial antebrachial cutaneous nerves (LABCN and MABCN, respectively) as vascularized nerve grafts (VNGs). The aim of this anatomical study was to analyze the characteristics and vascularization of these nerves to describe new potential donor sites for VNGs. Twelve forearms were dissected from fresh cadavers injected with red latex. The number of terminal branches, lengths, and proximal and distal diameters of both the LABCN and MABCN were studied. An anatomical description of the cutaneous perforator arteries from the radial and ulnar arteries that vascularized the nerve was also recorded: number of perforators, length, type of perforator (septo- or musculocutaneous), and location within the forearm (proximal, middle, and distal third). In over 80% of the specimens, the cutaneous perforator arteries from the radial and ulnar artery vascularized the LABCN and the MABCN, respectively. These arteries, found mostly in the proximal third of the forearm, had diameters >0.5mm. Most of them came from the radial and ulnar arteries (for LABCN and MABCN vascularization, respectively). In over 75% of the specimens, the nutrient arteries of both nerves also vascularized the superficial veins and the skin. We found that these nerves are vascularized by perforators arteries, which also participate in vein and skin vascularization. Altogether, this anatomical study shows that reconstructive surgeons could use new VNGs based on the perforator artery of the forearm.

Techniques for Imaging Vascular Supply of Peripheral Nerves

Few studies have been developed to map the vascular structures feeding peripheral nerves, with the majority using cadaveric models and inadequate sample sizes. Preliminary evidence, while limited, indicates that the mapping of these vessels may allow or preclude certain procedures in nerve reconstruction due to the location of essential arterial inflow to the vasa nervorum. This review evaluates the evidence regarding historical, current, and emerging techniques for visualizing these vascular structures in vivo and considers their potential application in peripheral nerve vasculature.

Propeller Flaps in the Upper Extremity: Arm and Forearm Reconstruction

The propeller flap is an island of skin that is raised on its pedicle (most commonly a single perforator) and can rotate 180 degrees to cover a soft tissue defect. Thanks to these features, the propeller flap brings reliable tissue from outside of the zone of injury while sparing the main vessels of the upper extremity. This technique limits the donor site to the same limb, captures skin characterized by having the same color and texture, does not necessarily need a microvascular anastomosis, and overall reduces the operating time and surgical cost. Our intent here is to present 27 cases with different soft tissue defects of the upper arm and forearm that have been successfully reconstructed using propeller flaps. The surgical technique, with emphasis on the anatomy of the upper arm, is described. In particular, use of a freestyle approach to customize a perforator-based propeller flap to cover defects from small to medium size is detailed. In our experience, the use of a perforator propeller flap in the upper extremity for resurfacing represents both a very reliable and aesthetically pleasant option.

Nerve vascularity in free vascularized nerve flaps

The blood supply of peripheral nerves consists of a complex internal vessels' network, feeding external vessels and the interlinking vasa nervorum. Patients with nerve damage may require nerve substitution. While the commonly performed avascular nerve grafts obtain vascularization only from random and slow inosculation into the vasa nervorum, their insufficient revascularization causes loss of the graft's potential due to central necrosis. This gets more relevant with the larger diameter of nerves injured. Examples for neurovascular flaps are the lateral femoral cutaneous nerve vascularized via the superficial circumflex iliac artery perforator (LFCN-SCIP) flap or the iliohypogastric nerve graft vascularized via the superficial inferior epigastric artery (SIEA). LFCN-SCIP shows a well concealed donor scar site with a maintained vascularization and a minor donor site morbidity. Therefore, the guaranteed axial nerve vascularity in LFCN-SCIP makes it a preferred autologous vascularized nerve therapy for peripheral nerve defects. A further option example is the anterior lateral thigh (ALT) flap with the LFCN.

Neural Perforasomes of the Upper Extremity

BACKGROUND

In the setting of the rapid advancement of integumentary vascular knowledge, the authors hypothesized that the extrinsic blood supply to the major peripheral nerves of the upper extremity could be categorized into discrete neural "perforasomes."

METHODS

Total limb perfusion of the arterial system was performed with gelatin-red lead oxide in cadaveric upper limbs. The perforating vessels to the radial, median, and ulnar nerves were identified, confirmed with fluoroscopy, and dissected. Distances to major anatomical landmarks of the upper extremity were measured. Additional cadaveric limbs' nerves were dissected and source arteries were selectively cannulated and injected to assess specific contribution to extrinsic nerve perfusion. The perfusion of each nerve was then calculated among all specimens.

RESULTS

The radial, median, and ulnar nerve perforators were mapped. The corresponding neural perforasomes were mapped. The distal portions of the superficial radial nerve and the posterior interosseous nerve demonstrated a lack of staining. Similarly, at the carpal tunnel and at the proximal 25 percent of the median nerve (corresponding to the pronator teres), the nerve lacked vascular staining. At the Guyon canal and the flexor carpi ulnaris, the ulnar nerve demonstrated a lack of vascular staining.

CONCLUSIONS

Peripheral nerves can be divided into neural perforasomes with limited overlap. The extrinsic perfusion of peripheral nerves is highly segmental. Absent stains within the nerves correspond to common sites of compression: carpal tunnel and pronator teres for the median nerve, supinator for the posterior interosseous nerve, and the Guyon canal and the flexor carpi ulnaris for the ulnar nerve.

Reconstruction of a 10-mm-long median nerve gap in an ischemic environment using autologous conduits with different patterns of blood supply: A comparative study in the rat

The aim of this study was to evaluate in the Wistar rat the efficacy of various autologous nerve conduits with various forms of blood supply in reconstructing a 10-mm-long gap in the median nerve (MN) under conditions of local ischemia. A 10-mm-long median nerve defect was created in the right arm. A loose silicone tube was placed around the nerve gap zone, in order to simulate a local ischemic environment. Rats were divided in the following experimental groups (each with 20 rats): the nerve Graft (NG) group, in which the excised MN segment was reattached; the conventional nerve flap (CNF) and the arterialized neurovenous flap (ANVF) groups in which the gap was bridged with homonymous median nerve flaps; the prefabricated nerve flap (PNF) group in which the gap was reconstructed with a fabricated flap created by leaving an arteriovenous fistula in contact with the sciatic nerve for 5 weeks; and the two control groups, Sham and Excision groups. In the latter group, the proximal stump of the MN nerve was ligated and no repair was performed. The rats were followed for 100 days. During this time, they did physiotherapy. Functional, electroneuromyographic and histological studies were performed. The CNF and ANVF groups presented better results than the NG group in the following assessments: grasping test, nociception, motor stimulation threshold, muscle weight, and histomorphometric evaluation. Radial deviation of the operated forepaw was more common in rats that presented worse results in the other outcome variables. Overall, CNFs and ANVFs produced a faster and more complete recovery than NGs in the reconstruction of a 10-mm-long median nerve gap in an ischemic environment in the Wistar rat. Although, results obtained with CNFs were in most cases were better than ANVFs, these differences were not statistically significant for most of the outcome variables.

Reconstruction of a long defect of the ulnar artery and nerve with an arterialized neurovenous free flap in a teenager: A case report and literature review

There is evidence that nerve flaps are superior to nerve grafts for bridging long nerve defects. Moreover, arterialized neurovenous flaps (ANVFs) have multiple potential advantages over traditional nerve flaps in this context. This paper describes a case of reconstruction of a long defect of the ulnar artery and nerve with an arterialized neurovenous free flap and presents a literature review on this subject. A 16‐year‐old boy sustained a stab wound injury to the medial aspect of the distal third of his right forearm. The patient was initially observed and treated at another institution where the patient was diagnosed with a flexor carpis ulnaris muscle and an ulnar artery section. The artery was ligated and the muscle was sutured. Four months later, the patient was referred to our institution with complaints of ulnar nerve damage, as well as hand pain and cold intolerance. Physical examination and ancillary tests supported the diagnosis of ulnar artery and nerve complete section. Surgery revealed an 8 cm hiatus of the ulnar artery and a 5 cm defect of the ulnar nerve. These gaps were bridged with a flow through ANVF containing the sural nerve and the lesser saphenous vein. The postoperative course was uneventful. Two years postoperatively, the patient had regained normal trophism and M5 strength in all previously paralyzed muscles according to the Medical Research Council Scale. Thermography revealed good perfusion in the right ulnar angiosome. The ANVF may be an expedite, safe and efficient option to reconstruct a long ulnar nerve and artery defect.

Angiosome-Based Allografts: Vascularized Composite Allotransplantation for Tailored Subunit Reconstruction with Volkmann Ischemic Contracture as a Case in Point

BACKGROUND

As we enter an age with new approaches to tissue reconstruction, the emphasis on the adage "like for like" has become even more relevant. This study illustrates the potential for several tailored vascularized composite allotransplantation reconstructive techniques and, in particular, for the management of Volkmann contracture.

METHODS

Twenty fresh cadaver dissections and 30 archival lead oxide radiographic studies were examined to (1) identify potential upper limb vascularized composite allotransplantation donor sites (i.e., elbow, forearm, and flexor tendon complex) and (2) demonstrate a "mock transplant" of the vascularized volar forearm allograft for a severe Volkmann ischemia defect. They were designed without skin to reduce antigenicity.

RESULTS

The elbow joint was supplied within the brachial angiosome and the flexor tendon complex of the flexor digitorum superficialis and flexor digitorum profundus by the superficial palmar arch of the ulnar angiosome. The forearm allograft of flexor muscles, median, ulnar, and anterior interosseous nerves, when harvested on the brachial vessels, was supplied within the radial, ulnar, and anterior interosseous angiosomes but could be based on the ulnar artery alone because of intramuscular connections with the other territories. A mock transplant was performed with a distal-to-proximal dissection of the allograft, facilitating the best and fastest technique.

CONCLUSIONS

This application of the angiosome concept highlights the anatomical feasibility of the volar forearm vascularized composite allotransplantation donor site focusing on a complex subunit problem in the upper limb-severe Volkmann ischemic contracture. It demonstrates the potential use and immunologic advantage of subdivided and modified nonskin variations of vascularized composite allotransplantation in reconstructive transplantation surgery.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Microanatomy of the brachial plexus roots and its clinical significance

PURPOSE

To provide the anatomical basis of brachial plexus roots for the diagnosis and treatment of brachial plexus root avulsion injury.

METHODS

The morphological features of brachial plexus roots were observed and measured on 15 cervicothoracic spine of adult cadavers. The relationship of brachial plexus nerve roots and the surrounding tissues also were observed, as well as the blood supply of anterior and posterior roots of the brachial plexus.

RESULTS

Origination of the nerve roots in the dorsal-ventral direction from the midline was fine-tuned at each level along the spinal cord. The minimum distance of the origin of the nerve root to midline was 2.2 mm at C ₅, while the maximum was 3.1 mm at T ₁. Inversely, the distance between the origin of the posterior root and the midline of the spinal cord gradually decreased, the maximum being 4.2 mm at C ₅ and minimum 2.7 mm at T ₁. Meanwhile, there was complicated fibrous connection among posterior roots of the brachial plexus. The C _5-6 nerve roots interlaced with tendons of the scalenus anterior and scalenus medius and fused with the transverse-radicular ligaments in the intervertebral foramina. However, these ligaments were not seen in C _7-8, and T ₁. The blood supply of the anterior and posterior roots of the brachial plexus was from the segmental branches of the vertebral artery, deep cervical artery and ascending cervical artery, with a mean outer diameter of 0.61 mm.

CONCLUSIONS

The systematic and comprehensive anatomic data of the brachial plexus roots provides the anatomical basis to diagnose and treat the brachial plexus root avulsion injury.

The angiosome territories of the spinal cord: exploring the issue of preoperative spinal angiography. Laboratory investigation

OBJECT

The angiosome concept has been the subject of extensive research by the senior author (G.I.T.), but its specific applicability to the spinal cord was hitherto unknown. The aim of this study was to see if the spinal cord vasculature followed the angiosome concept and to review the usefulness of preoperative spinal angiography in surgery for spinal disorders. Spinal cord infarction and permanent paraplegia may result from inadvertent interruption of the artery of Adamkiewicz. Spinal angiography, which may enable avoidance of this catastrophic complication, is still not commonly used.

METHODS

Two fresh cadavers were injected with a gelatin-lead oxide mixture for detailed comparative study of spinal cord vasculature. One cadaver had insignificant vascular disease, whereas the other had extensive aortic atherosclerosis, presenting a unique opportunity for study. After removal from each cadaver, radiographs of the spinal cords were obtained, then photographed, and the vascular territories of the cords were defined.

RESULTS

Four angiosome territories were defined: vertebral, subclavian, posterior intercostal, and lumbar. These vascular territories were joined longitudinally by true anastomotic channels along the anterior and posterior spinal cord. Anastomosis between the anterior and posterior vasculature was poor in the thoracolumbar region. The anterior cord relied on fewer feeder arteries than the posterior, and the anterior thoracolumbar cord depended on the artery of Adamkiewicz for its supply. In chronic aortic disease with intercostal artery occlusion at multiple levels, a rich collateral circulation supporting the spinal cord was found.

CONCLUSIONS

The arterial supply of the spinal cord follows the angiosome concept. The atherosclerotic specimen supports the suggestion that the blood supply is able to adapt to gradual vascular occlusion through development of a collateral circulation. Nevertheless, the spinal cord is susceptible to ischemia when faced with acute vascular occlusion. This includes inadvertent interruption of the artery of Adamkiewicz. The authors recommend the use of preoperative spinal angiography to prevent possible paraplegia in removal of thoracolumbar spinal tumors.