Endoscopic Release of the Brachial Plexus.

Publicado em: 2 de fevereiro de 2021 por Naeon
Publicações Científicas

Endoscopic Release of the Brachial Plexus.

Arthroscopy Techniques

Volume 9, Issue 10, October 2020, Pages e1565-e1569

https://www.sciencedirect.com/science/article/pii/S2212628720301663

Abstract

Thoracic outlet syndrome(TOS) is a debilitating condition, impairing the function of the upper limb, and can be  considered as an entrapment of neurovascular structures dedicated to the upper limb. Its open treatment uses large approaches and to this date just structures under the clavicle have been endoscopically approached. 

The purpose of this technical note is to describe an endoscopic all brachial plexus decompression of at all possible entrapment areas, between the neck and the arm. 

Introduction

Thoracic Outlet Syndromes(TOS)  is a debilitating condition, impairing the function of the upper limb, and can be  considered as an entrapment of neurovascular structures dedicated to the upper limb^1,2.

 The entrapment can be situated at different levels, between the neck and the arm, including the interscalenic triangle, the upper border of the first rib (by the rib itselt or a hypertrophic transverse cervical process with or without fibrous bands) the costo clavicular space, the retro coracoid, pectoralis minor and the penetration point of the neurovascular bundle at the level of the brachialis fascia¹. The exact location of the entrapment can be difficult to access as well as the etiology of the compression and the structures involved like brachial plexus, subclavicular vein and artery. 

The TOS pathophysiology is multifactorial, including anatomical variations, cervical rib, fibrous bands, anomalous muscles, joint hypermobility, or biomechanical dysfunctions of the neck and scapular girdle related to labor, post-traumatic or sports gesture³. On this scenario the bony compression by a narrowing space between the clavicle and the first rib or a cervical rib, that was previously considered the main entrapment cause, will be responsible for just 20-30% of the cases^1,2. 

TOS diagnosis remains difficult and controversial. No consensus have been reached to establish objective criteria proving the diagnose of TOS. Indeed it is mainly dynamic compression, therefore dynamic assessments seem to be more adapted, eventhough these assessments may be difficult or even present high rates of false negative results⁴.

Among the TOS types, the most common is the neurogenic(nTOS) one. Some of the clinical characteristics of the nTOS are pain, paraesthesia and weakness4.

The pain is usually neuropathic, affecting the posterior cervical area, trapezius and pectoral regions. It may also be felt on the entire upper limb. Weakness may also be described by these patients ^1,4,5.Reports of pain, weakness and paraesthesia associated with irritative maneuvers will strongly suggest the nTOS diagnosis4,6.

Complementary exams can be used, mainly to exclude other diagnoses (i.e roots compression at the cervical spine, peripheral nerve tumors, distal entrapment syndromes). One of the main situation that would suggest nTOS is the dynamic arterial subclavian duplex velocity assessment. This assessment compares the differences between the arterial subclavian flux in rest and during the stress maneuvers. The proximity between the brachial plexus and subclavian artery can provides one with an indirect suggest a brachial plexus entrapment^6-8. It can be useful even in patients with no vascular apparent compromise. Trained radiologists are also able to evaluate this entrapment by analysing the amont of fat tissue around the brachial plexus, and comparing its size between the resting and abduction and external rotation of the shoulder

The classical treatment for these patients is conservative^6,7, consisting on pharmacological measures, shoulder girdle rehabilitation and ergonomic readjustment for working or exercising^1,7. 

Surgery is indicated in cases refractory to the conservative treatment, after a long period of rehabilitation8. Surgical techniques should be directed to the structures that cause this entrapment. The most common procedures mention the resection of the cervical rib, scalenectomy and release of the pectoralis minor tendon next to the coracoid^7-10.

Endoscopic soft tissue decompression of the brachial plexus has been performed initially in cadaveric models¹¹. In vivo to this moment only subclavicular decompression of the brachial plexus was performed. The suprascapular space had been released so far through the trans trapezial portals, starting from a release of the suprascapular nerve, and moving proximaly to the interscalenic area, without performing any scalenectomy, nor exposing the phrenic, long thoracic and dorsal scapular nerves⁴.

The purpose of this technical note is to describe an endoscopic brachial plexus decompression on suffering from nTOS at all possible entrapment areas, between the neck and the arm. 

Surgical Technique

The procedure is performed in lateral decubitus under general anesthesia associated with interscalene plexus block. The upper limb – is set up with a traction allowing a positionning of the shoulder in anterior elevation, and slight abduction of respectively 30° and 15°.

 A standard bipolar radiofrequency was used, VAPR®(DePuy Synthes, Raynham, USA). Saline infusion is used, just by gravity through 4-way equipment with no pump.

Surgical Steps

The first step is the insertion of the video scope through the posterior portal for joint and subacromial space evaluation. In the bursal space, the lateral portal is done, followed by bursectomy. The coracoacromial ligament is identified and removed. The optic passes to the lateral portal, coracoid process and pectoralis minor tendon is identified. An anterioinferior portal is done in the axillary line, about 2 cm below the coracoid lateral to the conjoint tendon is done with the help of a needle under visualization control.

The coracoid is exposed using radiofrequency device through the anterioinferior portal, dissecting the space posterior to the pectoralis major, progressively moving medially until the pectoralis minor insertion can be visualized and released. The upper part of the pectoralis minor is exposed, along with the cords of the brachial plexus coming from a lateral and medial areas. Under visualization control, the medial portal is made, 5 cm medial to the anterioinferior portal.  The optic is moved to the anterioinferior portal(Fig. 1), then the radiofrequency device is inserted through the medial portal and is used to detach the pectoralis minor tendon, allowing the visualization of the terminal branch of the musculocutaneous nerve and the neurovascular bundle. 

At this step, three structures are visualized going from the brachial plexus towards the deltoid muscle: lateral pectoralis nerve, thoracoacromial artery branch and cephalic vein. If fibroses or adhesions are found they can be released in this region.

The costoclavicular space is then reached. Using the lateral pectoralis nerve as a landmark, the plane between the brachial plexus and the subclavian muscle is identified. Anatomical variations of the subclavian muscle or the presence of the pectoralis minimus muscle may entrap the plexus in this area. Radiofrequency myotomy of the subclavius muscle can be performed until the clavicle is reached(Fig. 2). Using the soft tissue shaver(Razek, São Carlos, Brazil) with no aspiration will increase muscle resection and increase the cervical space view. In some selected cases (distance between the plexus clavicle less than 1 cm), partial resection of the clavicle may also be performed by using a bony shaver.

Through this same portal, the optics advances proximally to the cervical region between the plexus and the clavicle. Using a blunt dissector, the first cervical portal is done, just above the clavicle, supraclavicular portal, over the brachial plexus (Fig. 3). A particular attention to the transverse cervical vessels, which are left in a more superficial plane is needed. Optic can be inserted through the medial portal and devices through the supracavicular portal. Identification of the upper plexus trunk, and emergence of the suprascapular nerve(Fig. 4) raising laterally and posteriorly towards the coracoid notch is done. At this anatomical location the suprascapular artery can cross the plexus over the upper trunk or between the upper and middle trunk. More inferiorly the dorsal scapular artery can be found at the level of the midle trunk.

Adhesions and/or a thickened fascia can be visualized between the scalene muscles and the brachial plexus. This fascia must be released, allowing visualization of the scalene muscles. Then suprascapular nerve neurolysis can also be performed at this point.

The cervical portal is made about 2.5 cm from the supraclavicular portal. and the radiofrequency device is inserted and used to increase the space around the entry point. Distance parameters may vary, but as usual, the portal is created under 

vizualisation control, with the aim to create access between the middle and anterior scalenes. The optics is moved to the supraclavicular portal. The release of the sheath to the scalene hiatus is continued using radiofrequency through the cervical portal(Fig. 5). Regarding the phrenic nerve which course is on the anterior border of the anterior scalene muscle, it is not easy nor necessary to visualize this nerve by endoscopy, however if visualized it needs to be protected.  The middle scalene is dissected(Fig. 6) and one can identifies the dorsal scapular nerve and/or the long thoracic nerve. They actually have a very similar origin, but their directions are different, the dorsal scapular nerve goes posteriorly and medially and the long thoracic nerve goes inferiorly, more anterior and above the first rib.

These nerves usually present an intramuscular path, the middle scalene myotomy can be done by direct visualization in order to release them. One can use the nerve stimulator in order to better understand which nerve is going to be released.

Subclavian artery can be visualized after the complete release of the anterior and middle scalenus muscles(Fig. 7)(Film. 1). Portals developed to this technique are as in the Fig. 8.

Thereafter revision of hemostasis and additional scalene myotomies may be performed with radiofrequency. A needle is positioned between the 2 cervical portals for infiltration of a betametasone, tramadol, tranexamic acid and magnesium sulfate solution.

The extubation requires additional care because sometimes infused fluid can compress the airways.

Rehabilitation

For neuropathic analgesia, drugs are administered according to the patient’s needs, including pregabalin, nortriptyline, vitamin C, prednisone, opioids and anti-inflammatory drugs. Ten days after surgery, the stitches are removed and the patient is able to remove the sling.

Tips and Tricks are in Table. 1, comparison with open surgery in Table. 2.

Discussion 

Endoscopic release of the brachial plexus as suggested in this technical note offers advantages compared to an open technique or to previoulsy described endoscopic techniques. It provides indeed a better visualization of the neurologic structures with magnification thanks to the arthroscope, almost equivalent to a microsope. It allows a three-level release, i.e. supraclavicular, retroclavicular in the costoclavicular outlet, and infraclavicular. It allows multiple level release without multiple approaches as required in case of an open scalenectomy and pectoralis minor tenotomy11, and thus less scar tissue formation since minimally invasive. 

Endoscopic techniques have been described before4 however they mainly managed retro clavicular and infra clavicular decompression. The supraclavicular decompression was addressed in those techniques though a different approach starting from the subacromial space, reaching the suprascapular nerve and the interscalenic area, up to the upper trunk, managing a local fibrous band section, and a neurolysis, but lacking two main aspects which are capital to the Thoracic outlet syndrome management: Scalenectomy, and exposition of the middle and inferior trunks. As described in the previous articles^4,12 safe approach of the middle and inferior trunks, and correct exposition of the subclavicular artery, phrenic, long thoracic, and dorsal scapular nerves was not achievable. Meanwhile, Garcia et al11, had described in 2012 an anatomical exposition of the previously cited structures, using a different technique and mainly a different surgical strategy. The procedure presented on this technical note has showed an improvement on the clinical scores which was greater than the previously published series4[JCGJ1] . It seems obvious that the release addressed on this technical note is more exhaustive, but the thorough release of the whole brachial plexus affords better clinical results. The main difference and benefit brought by this technique is the ability to perform a scalenectomy. The scalene muscles are clearly identified as compressors in this pathology. Scalenectomy is indeed a mandatory step of the open surgical procedure13. 

However, limitations can be raised. The first and most obvious one, is the importance of the learning curve. The interscalenic area is an anatomical region which must be well known before adventuring oneself around it endoscopically. Before performing the scalenectomy, the nerves and vessels around must be identified and preserved. When a doubt regarding the identification of those structures exists, the surgeon should never hesitate to convert to an open approach. It is therefore a technique that must be managed by surgeons trained into brachial plexus and peripheral nerve surgery.

The area is also sensible to pressure variation. Indeed a balance between low blood pressure, and high inflow pressure must be reached. The surgeon needs perfect bleeding management in order to obtain good visualization, and anesthesiologists must manage the blood and water inflow pressure in order to prevent neurological complications. Indeed, compressions can occur to the pneumogastric nerve, the carotid body but also to the spinal chord. 

Overall, this technique is clearly bringing many advantages to the management of neurogenic thoracic outlet syndromes, and we recommend that it becomes the reference technique compared to open techniques or previously described endoscopic techniques14. However, we acknowledge that it must be limited to neurogenic cases, and to cases where no anatomical variations or modifications3 is identified. It should not be applied to cases where symptomatic vascular compression occurs, and it is not a technique enabling first rib resection. As a matter of fact, we have not studied yet proved that the results obtained with neurogenic syndromes are applicable to vascular syndromes. At last, anatomical knowledge of the area by the surgeon, and ability to work in the region in open surgery as well as anesthesiology cooperation is mandatory.

References

1. Illig K, Donahue D, Duncan A, Freischlag J, Gelabert H, Johansen K, et al. Reporting standards of the society for vascular surgery for thoracic outlet syndrome. J Vasc Surg. 2016;64(3):e23-35.
2. Levine N, Rigby B. Thoracic outlet syndrome: biomechanical and exercise considerations. Healthcare. 2018; 6(2). piiE68.
3. Ferrante M, Ferrante N. The thoracic outlet syndromes: part 1. The arterial, venous, neurovascular, and disputed thoracic outlet syndromes. Muscle Nerve. 2017; 55(6):782-93.
4. Lafosse T, Hanneur M, Lafosse L. All-endoscopic brachial plexus complete neurolysis for idiopathic neurogenic thoracic outlet syndrome: surgical technique. Arthrosc Tech. 2017;6(4):e967-71. 
5. Kuhn J, Lebus G, Bible J. Thoracic outlet syndrome. J Am Acad Orth Surg. 2015; 23(4):222-32.
6.  Doneddu P, Coraci D, De Franco P, Paolasso I, Caliandro P, Padua L. Thoracic outlet syndrome: wide literature for few cases. Status of the art. Neurol Sci. 2016;38(3):383-8.
7.  Altobelli GG, Kudo T, Haas BT, Chandra FA, Moy JL, Ahn SS. Thoracic outlet syndrome: pattern of clinical success after operative decompression. J vasc surg. 2005; 42(1):122–8.
8. Chang DC, Rotellini-coltvet LA, Mukherjee D, De Leon R, Freischlag LA. Surgical intervention for thoracic outlet syndrome improves patient’s quality of life. J Vasc Surg. 2009;49(3):630–5
9. Soukiasian H, Shouhed D, Serna-Gallgos D, Mckenna R, Bairamian B, mckenna r. A video-assisted thoracoscopic approach to transaxillary first rib resection. Innovations (Phila). 2015; 10(1):21-6.
10.  Balderman J, Holzem K, Field B, Bottros M, Abuirqeba A, Vemuri C et al. Associations between clinical diagnostic criteria and pretreatment patient-reported outcomes measures in a prospective observational cohort of patients with neurogenic thoracic outlet syndrome. J Vasc Surg. 2017; 66(2):533-44.e.
11. Garcia JC, Mantovani G, Livernaux P. Brachial plexus endoscopy: feasibility study on cadavers. Chir Main. 2012; 31(1):7-12.
12. Lafosse T, Masmejean E, Bihel T, Lafosse L. Brachial plexus endoscopic dissection and correlation with open dissection. Chir Main. 2015; 34(6):286-93.
13. Cheng SWK, Reilly LM, Nelken NA, Ellis WV, Stoney RJ. Neurogenic thoracic outlet decompression: rationale for sparing the first rib. Cardiovasc Surg. 1995; 3(6):617–23.

14.Ferrante M, Ferrante N. The thoracic outlet syndromes: part 2. The arterial, venous, neurovascular, and disputed thoracic outlet syndromes. Muscle Nerve. 2017; 56(4):663-673.

Figure Legends

Fig.1: Scope through the anterioinferior portal: A) Fat over the Brachial Plexus, B) Released Pectoralis minor tendon

Fig. 2 Scope through the anterioinferior portal: A) Subclavius Muscle Released, B:Electrocautery device.

Fig. 3 Scope through the medial portal: A) Upper Trunk, B) Suprascapular artery.

Fig. 4 Scope through the medial portal: A) Suprascapular nerve, B Upper Trunk

Fig. 5 Scope through the supracavicular portal: A) Fribrous adhesion, B) Anterior Scalene Muscle

Fig. 6 Scope through the supracavicular portal: A) Scalene Muscle, B) Brachial Plexus

 Fig. 7 Scope through the supracavicular portal: A) Scalen Muscles Released, B) Subclavian Artery, C) Dorsal Scapular Artery.

Fig. 8 Special portals designed for the procedure: A) Anterioinferior, B) Medial, C) Supraclavicular, D) Cervical

Table Legends:

Table. 1 Tips and Tricks

Table. 2 Comparisson between Endoscopic and Open procecedures 

Film Legends

Endoscopic release of the Brachial plexus is a technical from NAEON Institute Sao Paulo-Brazil and Alps Surgery Institute/Clinique Générale d’Annecy-France.

After the Pectoralis Minor Release, the region of its cords and distal nerves is cleaned.

Dissection between the Pectoralis Minor and conjoined tendon is important and will expose the musculocutaneous nerve.

Here the musculocutaneous nerve is exposed.

Following key structures and the plexus one careful dissects this region until achieve the subclavius muscle’s fascia. 

The subclavius muscle’s fascia is opened and the muscle is exposed

All the muscle is released, and the clavicle is reached.

Just after the superior border of the clavicle the supraclavicular portal is made.

In the cervical direction a dissection of structures over the brachial plexus is done and the trunks of the brachial plexus are exposed.

Shaver with no aspiration can also be used.

Suprascapular nerve is visualized at the lateral border of the brachial plexus

Continuing dissection one can expose the suprascapular artery over the upper trunk

Anterior Scalenus muscle and fibrotic bands are reached.

The Anterior Scalenus muscle is carefully released.

The Middle Scalenus muscle have to be also released with special care because the Scapular Dorsal and Thoracic Long Nerves, released in this video were in the middle of this muscle.

Subclavian artery can be visualized, however it is not mandatory.

 [JCGJ1]Just confirm this is the correct paper