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Thoracic Outlet decompression- supraclavicular first rib resection

    Overview

    Learn the Thoracic Outlet decompression/ supraclavicular first rib resection surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Thoracic Outlet decompression/ supraclavicular first rib resection surgical procedure.
    The thoracic outlet lies at the apex of the thorax and is traversed by the subclavian vessels and brachial plexus as they enter the upper extremity. It can be divided, conceptually, into three spaces from proximal to distal: the scalene triangle, costo-clavicular space and sub-pectoral space (lying under pectoralis minor). Thoracic outlet syndrome (TOS) is the result of compression of one or more of the neuromuscular structures at this site and is classified according to the structure being compressed as: neurogenic, arterial and venous. Neurogenic TOS remains by far the most common of these.
    Clear consensus on diagnosis and treatment is still lacking. It is generally agreed that for most individuals with a diagnosis of neurogenic TOS the emphasis is on physiotherapy. Surgery is reserved for individuals who fail to respond to conservative measures. With careful patient selection surgery can be effective.

    Indications

    An understanding of the aetiology of TOS remains incomplete. The presence of cervical ribs was first described by Galen and historically, these extra ribs were the first recognised cause of TOS. These may be present in 0.5 to 1.0% of people. Additional ‘ribs’ vary from a small exostosis arising from the transverse process of the seventh cervical vertebra to a complete rib, which attaches anteriorly to the first rib and either can cause compression. However, the majority of individuals with cervical ribs are not symptomatic. Several other anomalies at the thoracic outlet have been implicated in TOS, in particular, variations in the anatomy of the scalene triangle. An intimate understanding of the anatomy of this space is of particular importance for surgeons performing surgery in this area. The triangle is formed by the anterior and middle scalene muscles and the upper border of the first rib and anomalies of the first rib and scalene muscles have been described. An overlapping of the insertions of the scalene muscles onto the first rib, such that the two muscles form a ‘U’ or ‘V’ shape sling which compresses the inferior plexus and artery. Accessory scalene muscles are described as are multiple types of fascial bands. Occasionally, an acquired space occupying lesion can lead to a compressive pathology e.g. Pancoast tumour, malunited clavicle fracture or fracture callous. However, the most common causes of compression probably arise as a result of secondary postural changes which can arise as a result of trauma but may also arise through obesity or changes in physical activity.
    Neurogenic TOS is thought to arise as a combination of congenital anatomical predisposition and trauma. Poor posture of the neck, shoulders and upper back can be related to trauma. Injury incites a postural change resulting in secondary muscle imbalance which leads to pain, swelling and further abnormal posture. A negative cycle that promotes the syndrome results. If the poor posture is maintained scarring and fibrosis in muscle and peri-neural tissue becomes established and can lead to nerve compression.
    Neurogenic TOS accounts for the majority of cases. Diagnosis is clinical and can be challenging with a lack of clear consensus on the condition. Symptoms are notoriously varied with differing degrees of neck, shoulder arm and hand symptoms and often no clear objective signs. Onset of symptoms often follows trauma, the so called ‘whiplash’ injury associated with road traffic accidents is a common inciting cause. Pain, parasthesia and colour changes with activity and arm elevation are usual but non-specific. It is important to distinguish alternative sources of symptoms, in particular, cervical spine disease and peripheral compressive neuropathies.
    A number of clinical tests have been described to diagnose TOS, although none have particularly good specificity. Hyperabduction and abduction of the shoulder combined with external rotation (ABER) are frequently deployed as provocative manoeuvres. A decrease or loss of the radial pulse has been interpreted as a positive sign, but many non-symptomatic individuals may demonstrate similar pulse volume changes. Reproduction of symptoms in symptomatic individuals is probably a more useful indicator. In Adson’s test the patient’s neck is extended and turned to the affected side and in this position a deep breath is taken and held. Again, a loss of radial pulse is interpreted as a positive sign. Roos test uses the ABER position combined with opening and closing of the hands maintained for up to three-minutes. Replication of symptoms is a positive test. Tenderness over the first rib in the posterior triangle of the neck is a useful sign, it can demonstrate increased sensitivity over the plexus and be compared to the contralateral side. Similarly, a Tinel’s test can be performed in this area. Both palpation and percussion over the nerve may produce parasthesia distally and the cutaneous territory that that Tinel’s radiates to can give an indication as to the part of the plexus that is being compressed.
    Plain radiographs satisfactorily show ossified cervical ribs and may show modelling deformities of the clavicle. The availability of high definition MRI scan has meant that it is possible to visualise anatomical anomalies such as non-ossified ribs, fibrous bands and accessory muscles. The sensitivity of such investigations is still not known. Additionally, TOS is a dynamic condition and the optimal protocol of dynamic imaging has yet to be defined. Currently, the mainstay of imaging is to rule out space occupying lesions and cervical spine disease. Arterial and venous TOS are more straightforward to diagnose with duplex ultrasound and/or angiography. Electrodiagnostic tests are valuable to rule out more peripheral sites of compression neuropathy (carpal tunnel and cubital tunnel syndrome). Sensory changes occasional will be seen in the medial antebrachial cutaneous nerve in patients with inferior brachial plexopathy from compression but EMG & NCS are typically normal in patients with TOS.
    Management of TOS is best established in a multidisciplinary setting. The majority of cases of neurogenic TOS are treated with appropriate physiotherapy. Therapy aims to restore proper muscle balance and posture. Only cases which fail to respond to a committed course of therapy for six-months are considered for surgical treatment. Surgical treatment involves the identification and resection of compressive elements, including cervical ribs, the scalene muscles, first rib and fibrous bands. Supraclavicular and transaxillary approaches to first rib excision have both been described.

    Setup

    The patient is placed in a beach-chair position, the head up posture helps to minimise venous engorgement. The head should be secured in a head-ring with the neck extended and head turned away from the operative side. A small sandbag is placed under the scapula to help extend the posterior triangle of the neck. The arm is left free to allow the shoulder to be abducted and rotated during the operation, this is necessary to assess for dynamic compression points in different positions of the shoulder. The arm is left free to allow different muscle groups to be examined during nerve stimulation.
    Intra-operative nerve stimulation is utilised to aid nerve identification, so systemic muscle paralysing agents should ideally be avoided or alternatively a short acting agent is used at induction alone. Disposable nerve stimulators specifically designed for intra-operative use are commercially available. An alternative, which is preferred by the author, is to use the type of peripheral nerve stimulator utilised for nerve localisation during regional anaesthetic blockade. This style of stimulator allows for small currents to be applied precisely using the stimulator needle. The device is earthed to the patient via an ECG ‘dot’ and the lead is placed in an arthroscopy drape so that it can be included in the sterile filed. Loupe magnification and bipolar diathermy is advised.

    Operation

    A head up posture helps to minimise venous engorgement and extends the posterior triangle of the neck. Ensure the head is secured in a head-ring with the neck extended and head turned away from the operative side. The arm is left free to allow the shoulder to be abducted and rotated during the operation in order to assess for dynamic compression points. Adhesive tapes or drapes are used to shut-off the limb and allow movement of the extremity. The entire arm is kept visible to allow for inspection of different muscle groups when nerve stimulation is being employed

    The surface landmarks for the posterior triangle of the neck are marked:
    Sternocleidomastoid (SCM), Trapezius (T) and Clavicle (C). The skin incision will be at the base of the triangle.

    The incision is made parallel to and a finger breadth above the clavicle.
    The platysma is split and the supraclavicular nerves deep to it are identified.

    Wherever possible the supraclavicular nerves are preserved to decrease the risk of scar sensitivity. An external neurolysis aids in mobilising the nerves out of the operative field.

    In younger, well-muscled individuals, division of the clavicular head of the sternocleidomastoid (SCM) affords better anterior exposure. Dissection is carried deeper in the plane between the external jugular vein (EJV) and the SCM.

    The omohyoid is an important landmark and lies superficial to the supraclavicular fat-pad overlying the upper trunk of the brachial plexus. Omohyoid can be satisfactorily retracted out of the way, avoid dividing the muscle which will cause further fibrosis.

    The fat pad is incised at it’s inferior aspect just above the clavicle, careful homeostasis with bipolar diathermy is required as numerous small vessels traverse this space. The fat pad can then be lifted superiorly to expose the scalene triangle. Preserve the fat pad as best as possible so that it can be replaced at closure as a protective layer over the neurovascular structures.

    The anterior scalene muscle is identified and the phrenic nerve is seen on it’s anterior surface. This is confirmed with diaphragmatic contraction with nerve stimulation. Remember to alert your anaesthetist to the fact that you are stimulating the diaphragm as it will be detected on the capnogram. A current of 0.1mA is sufficient to generate clinically detectable diaphragm contraction. Once the phrenic nerve has been identified care is taken to avoid injury to this important nerve.
    *phrenic nerve

    The neuromuscular structures are delineated. Soft rubber sloops are placed and used to apply gentle retraction. The upper trunk is the first and most lateral structure seen in the interscalene space. The supra scapular nerve arises from it’s lateral aspect and this helps confirm the upper trunk correctly. If in doubt stimulation of the upper trunk can be performed, deltoid, biceps and shoulder external rotation confirms upper trunk stimulation:
    Upper trunk (UT) and subclavian artery (SCA)

    The scalenius anterior is demonstrated here. A scalentomy is performed releasing the muscle as it attaches to the superior aspect of the first rib. Bipolar diathermy is useful to cut and coagulate the muscle producing the minimum of bleeding.

    SA – Scalenus anterior

    The middle and lower trunks are also slooped (yellow sloop). By moving the trunks anteriorly the middle scalene muscle can be delineated. The long thoracic nerve most commonly passes behind this muscle but can pass through the substance of the muscle, it should be identified with nerve stimulation and then protected.

    The scalenius medius has a broad footprint of attachment onto the first rib. The muscle is released off of the bone to expose the superior aspect of the rib. The orientation of the rib will now be appreciated, the rib is almost vertical in the coronal plane with a posterior-superior to anterior-inferior lie.

    Sub-periosteal dissection is then continued until the superior surface of the body of the rib is exposed. The rib exposure is completed on the undersurface of the rib. The parietal pleura is attached to the inner aspect of the rib and there is a risk of pleural tear. Sharp periosteal elevators allow a clean, accurate dissection in the sub-periosteal plane and minimises the risk of pleural tear.

    The rib is cut posteriorly at the the neck-body junction and anteriorly close to the cost0-chondral junction. The posterior rib is approached lateral to the plexus, retracting the plexus medially. The anterior rib is approached on the medial side of the subclavian artery, in the interval between the artery and vein. This part of the operation carries the highest risk of inadvertent injury to the neurovascular structures and pleura. The rib needs to be removed in a precise controlled manner. With limited access conventional rib cutters tend to be too large and tend to ‘tear’ the rib from it’s bed. The author prefers to use a selection of up and down cutting Kerrison rongeurs for the bone cuts. The rongeur resects small 3-4mm portions of bone, and so to cut the width of the rib takes 4-5 bites. Sectioning the rib in this manner is both precise and safe, each application of the rongeur is done under direct vision to achieve the desired cut. The rib cuts are orientated to leave squared ends rather than oblique spikes. With the bone cuts completed the rib can now be rotated. Any residual intercostal muscle attached to the undersurface of the rib can now be released with sharp dissection. Once the rib is entirely free of attachment it can be safely removed.

    Residual bone ends are checked for impingement and trimmed and smoothed as required. The arm is moved through a full range of movement, there should be no residual entrapment of the plexus and vessels.

    Prior to closure the pleura is examined for any significant tears. Moderate sized pleural tears are obvious and repaired. As an adjunct the thoracic outlet is filled with saline and a Valsalva manoeuvre performed to examine for any positive pressure air leakage into the pleural space. Significant pneumothoraces are rare after first rib excision, but if there is concern then an intercostal drain should be placed and connected to an underwater seal. Subsequently drains can be removed at 48 hours.

    The fat pad and omohyoid are replaced as cover for the neuromuscular structures. An epidural catheter is played adjacent to the plexus and is instilled with levobupivicaine for pain relief.

    The wound is closed with an absorbable sub-cuticular suture and the arm is supported in a sling.

    Post Operative

    Patients are observed in hospital overnight. The following day gentle mobilisation is started as pain allows, and formal physiotherapy is commenced 2 weeks after surgery.
    The aim of post operative physiotherapy is to promote gliding of the neurovascular structures within the surgical bed to mitigate against the effects of post surgical fibrosis. This is in addition to the ongoing physiotherapy that patients with TOS will have been instructed in pre-operatively. Emphasis on restoration and maintenance of proper muscle balance and posture will have been instituted prior to surgery and it is key that this is continued post operatively.

    Recommended Reading

    Diagnosis and treatment of TOS is challenging. Patients have usually suffered from chronic symptoms and the diagnosis has often been previously overlooked. A multidisciplinary approach is essential with physiotherapy forming the cornerstone of assessment and treatment. Novak and Mackninnon, reported improvement in 25 out of 42 individuals with a minimum of 6 months of physiotherapy.
    Surgery can be very effective when proper patient selection is emphasised and significant improvement in quality of life can be achieved. Chang et al used the Dissability of Arm, Shoulder and Hand and Short Form -12 instruments to assess quality of life as an outcome, following supraclavicular first rib excision for neurogenic and venous TOS and showed significant improvements.
    Persistent symptoms following surgery are usually associated with incorrect diagnosis. Recurrent symptoms following surgery are not common but may be due to excessive scar formation. Atasoy, has reviewed over 700 surgical patients treated at a specialist hand surgery unit over a twenty year period, and emphasises the importance of post operative exercises starting on the first day after surgery.

    References:
    Novak, C.B., Collins, E.D. and Mackinnon, S.E., 1995. Outcome following conservative management of thoracic outlet syndrome. Journal of Hand Surgery, 20(4), pp.542-548.
    Chang, D.C., Rotellini-Coltvet, L.A., Mukherjee, D., De Leon, R. and Freischlag, J.A., 2009. Surgical intervention for thoracic outlet syndrome improves patient’s quality of life. Journal of vascular surgery, 49(3), pp.630-637.
    Atasoy, E., 2010. A hand surgeon’s further experience with thoracic outlet compression syndrome. The Journal of hand surgery, 35(9), pp.1528-1538.

    Reference

    • orthoracle.com

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