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Thoracic outlet syndromes

Hugh A. Gelabert and Erdogan Atasoy

A VASCULAR APPROACH

Introduction

A renewed interest in thoracic outlet syndrome (TOS) has been evident with an increased number of publications in the recent literature. Advances in standardization of diagnostic criteria and evaluation, advances in surgical technique, as well as formulation of treatment algorithms have resulted in improved results of treatment.

History

Initial reports of aberrant cervicobrachial findings date to the Greek physician Galen (Aelius Galenus, ca. 129-ca. 200) and the Renaissance anatomist Andreas Vesalius (15141564), who described the presence of cervical ribs. There was more modern recognition by the anatomist François-Joseph Hunauld (1701-1742), who reported the association of cervical ribs with upper extremity symptoms.

Sir Astley Cooper (1768-1841) is credited with describing symptoms resulting from arterial vascular compression due to a cervical rib. ¹

Spontaneous venous thrombosis of the axillary and subclavian veins was described independently by the English surgeon Sir James Paget (1814-1899) and the Austrian internist Leopold von Schrötter (1837-1908). The term “Paget-Schroetter syndrome” was coined by the English surgeon Edward Stuart Hughes in 1948 in an effort to aggregate disparate reports of spontaneous upper extremity venous thrombosis.

The term “thoracic outlet syndrome” was coined by Peet in 1956. ² This recognized the common denominator of anatomical compression at the thoracic outlet as the mechanism resulting in the variety of presentations that had previously been separately enumerated: scalenus anticus syndrome, costoclavicular syndrome, backpack palsy, and neurovascular compression syndromes. The first rib was recognized as the fulcrum against which the brachial plexus, subclavian artery, and subclavian vein were compressed.

The surgical approaches to first rib resection then followed. O. T. Clagett in 1962 described the use of posterior high thoracoplasty for first rib resection. ³ David. B. Roos published the initial description of transaxillary first rib resection in 1966, ⁴ and Robert. J. Sanders described the supraclavicular resection of a first rib in 1985. ⁵

Principles and justification

PREOPERATIVE ASSESSMENT

Clinical diagnosis

The clinical diagnosis of neurogenic TOS is based on the presence of core symptoms of pain or paresthesias extending from the base of the neck to the hand. These symptoms are frequently exacerbated by overhead or forward use of arms in tasks such as driving or typing. Physical examination is characterized by sensitivity to palpation or percussion over the brachial plexus at Erb’s point. Additional examination findings may include loss of the radial pulse with arm abduction, fatigue or symptom reproduction with overhead stress testing, or upper extremity limb tensioning.

Vascular presentations most commonly include thrombotic events. In the venous system, this includes thrombosis of the subclavian vein with secondary pain, swelling, and cyanosis of the limb. On the arterial side, the presentation ranges from digital ischemia from repeated microembolization to major artery thrombotic occlusion and limb threat.

Testing

The diagnosis of TOS has diverged along vascular and neurological lines. Neurological diagnosis has relied principally on physical examination and clinical judgment along with nerve conduction studies and response to anterior scalene muscle blocks.

Nerve conduction testing has evolved from the initial measurement of conduction velocities to the more recent use of somatosensory evoked potentials across the thoracic outlet and median antebrachial cutaneous sensory nerve amplitudes. These remain limited in their sensitivity and specificity. Image or electrophysiologically guided anterior scalene muscle block with local anesthetic remains the most sensitive and specific test with which to diagnose neurogenic TOS.

Imaging for the diagnosis of thrombotic vascular presentations of TOS has relied on catheter-based arteriography and venography to identify areas of compression and occlusion of arteries and veins. The concomitant use of thrombolysis allows rapid, nonsurgical dissolution of thrombus. At the same time, this allows identification of the site of compression or other pathology within either the venous or arterial system.

More recent use of magnetic resonance imaging (MRI) and computed tomography angiogram (CTA) allow for diagnosis of compression in non-occluded vessels. MRI has been used extensively in the diagnosis of both occluded vessel and neurogenic TOS, identifying features such as edema of the brachial plexus cords and displacement of the brachial plexus by various compressive elements.

Initial management and indications for surgical intervention

Initial management of neurogenic TOS relies on physical therapy and risk-factor modification (most commonly workplace ergonomic assessment and correction). This is often supplemented with medication to manage pain. If this fails to relieve symptoms, scalene muscle block testing is used to provide relief of symptoms and to confirm the diagnosis. Surgical decompression is then the best alternative to achieve symptomatic relief when the conservative management has failed.

Vascular presentations are managed with anticoagulation and thrombolysis. Arterial thrombosis may be effectively relieved by surgical thrombectomy. This is followed by diagnostic angiography and surgical decompression. Surgical decompression of the thoracic outlet is necessary for all vascular presentations where TOS compression of the subclavian vessels is confirmed.

Choice of surgical approach

Transaxillary first rib resection is very effective in decompressing the thoracic outlet for the neurogenic, arterial, and venous presentations of TOS. In vascular cases that require reconstruction of the subclavian vessels, separate supraclavicular and infraclavicular incisions are needed. This is usually not necessary for those who present with venous occlusion but is more commonly required in arterial presentations, which often include the finding of aneurismal dilatation of the artery. Venous occlusion may most often be managed with balloon angioplasty following rib resection.

The supraclavicular rib resection allows for effective decompression of neurogenic TOS. It is limited in that the anterior portion of the first rib is not reliably removed via this approach. For this reason, the paraclavicular (supraand infraclavicular incisions) approach has been adopted for vascular presentations. ⁶ In this operation, a secondary incision is made beneath the clavicle to allow removal of the most anterior portion of the first rib.

The posterior high thoracoplasty approach has proven most useful for the resection of a residual posterior rib segment in patients who present with recurrent or persistent neurogenic symptoms. ⁷

Operations

FIRST RIB RESECTION: TRANSAXILLARY APPROACH

Conceptual approach

The transaxillary approach allows for resection of the entire first rib (“cartilage to cartilage”) with minimal need for distraction of the brachial plexus and minimal risk to the phrenic and long thoracic nerves.

In essence, the operation requires identification and division of three muscles: the subclavius, the anterior scalene, and the middle scalene. The rib is divided in its midportion to allow distraction of the anterior and posterior segments to facilitate dissection.

Execution

The patient is placed in lateral decubitus with the intended surgical side up. An axillary roll, bean bag, and pillows are used for padding and support. The index limb (hand, arm, shoulder, axilla, and chest wall) is prepped and draped into the field. The limb is abducted away from the chest by a surgical assistant or a mechanical arm holder.

The incision is placed inferiorly in the axilla, purposely trying to avoid axillary contents, extending from the lateral border of the pectoralis major to the lateral border of the latissimus dorsi. (See Figure 5.1a .)

The incision is carried down onto the chest wall. Once in the areolar plane of the chest wall, the dissection is carried up to the apex of the axilla with the use of a Kitner dissector. In the course of this dissection, the intercostal brachial cutaneous nerve is often encountered. We attempt to preserve this by gently retracting or mobilizing by partially dividing entrapping intercostal muscles in the second interspace.

On reaching the apex of the axilla, the subclavian vein is identified. In front of this lies the subclavius muscle ligament attaching onto the first rib. Behind the vein lies the anterior scalene muscle. These are dissected free of surrounding tissue using a Kitner dissector. The anterior scalene muscle is divided over a right angle. The subclavius muscle tendon is elevated over a tonsil clamp and divided.

A Haight-Alexander periosteal elevator is used to remove intercostal muscle from the lateral margin of the rib. The goal of this dissection is to remove the rib along with its periosteum to prevent regrowth of bone.

This dissection is carried out anteriorly toward the sternum and posteriorly toward the transverse process at the base of the first rib. The same elevator is used to dissect the pleura away from the inferior aspect of the first rib. Finally, the elevator may be used to remove the lateral aspect of the middle scalene muscle from the dorsal surface of the rib. It is not used to remove the more medial portion of the middle scalene muscle, as this would potentially jeopardize the lower trunks of the brachial plexus.

The medial portion of the middle scalene muscle is dissected away from the brachial plexus with a right-angle clamp. It can then be elevated with the right-angle clamp and divided with scissors.

At this point, the brachial plexus, subclavian artery, and vein should be clearly evident as well as the first rib. A rightangle clamp is passed beneath the rib and rotated so that the tip of the clamp is on the medial aspect of the rib and can be used to sweep away any remnant attachments.

A Roos nerve root protector is placed between the inner aspect of the rib and the neurovascular structures to protect these, while Bethune rib shears are used to transect the rib in its midportion.

The Bethune rib shears may again be used to transect the rib anteriorly near the costochondral junction. (See Figure 5.1b .)

Using the periosteal elevator, the posterior remnant of the first rib is cleared of remaining middle scalene muscle. The rib may then be grasped with a rongeur and excised back to the articulation with the transverse process. To avoid injury, it is important to clearly visualize the T1 nerve root as it lies inferior to the rib. (See Figure 5.1c .)

An alternative method of removing the posterior rib segment is to use the small box rongeur to grasp the rib and twist the rib to disarticulate it. This separates the rib from the transverse process and allows removal. Typically, a small residual portion remains and may be removed with a narrow Dale rongeur. (See Figure 5.1d .)

Following removal of the rib, the last portion of the case requires examination of the brachial plexus, subclavian artery, and subclavian vein to assess for any residual fibrous bands, which may contribute to compression. If identified, these should be removed.

A catheter is placed for intra-incision infusion of local anesthetic. The incision is normally closed over a 10 Fr round fluted drain.

FIRST RIB RESECTION: SUPRACLAVICULAR APPROACH

Conceptual approach

The supraclavicular approach has the advantage of being familiar to most vascular surgeons. The position of the patient is similar to that which is considered a neutral body position with a direct anterior to posterior approach.

The operation essentially requires resection of two muscles (anterior and middle scalene) and removal of the posterior aspect of the first rib. The phrenic and long thoracic nerves are prominently displayed and must be protected. The operation requires gently retracting the brachial plexus in order to expose the middle scalene. For these reasons, nerve injuries are of concern and occur with a significantly greater incidence following the conceptual approach than following the transaxillary approach.

The supraclavicular exposure does not allow for resection of the anterior aspect of the first rib. Accordingly, in instances of venous TOS, an additional infraclavicular incision is also required.

Execution

The patient is positioned supine with a folded sheet beneath the shoulder to reduce traction of the brachial plexus (see Figure 5.2a ).

The incision begins at the lateral margin of the sternocleidomastoid muscle about 2 cm above the clavicle and extends transversely, directed posteriorly.

A subplatysmal flap is elevated and beneath this the scalene fat pad is encountered.

The fat pad is mobilized away from the lateral margin of the internal jugular vein. Care is taken to identify and seal any leak of lymph fluid that may occur.

As the scalene fat pad is reflected laterally, the anterior surface of the anterior scalene muscle is revealed. It is normally covered by layers of connective tissue. Within these layers is the phrenic nerve. The phrenic nerve will course from the superior lateral margin of the scalene muscle toward the inferior medial aspect of the muscle. A nerve stimulator helps confirm the identity of the nerve. Attention should be paid to identifying and preserving an accessory branch of the phrenic nerve, which occasionally arises from the C5 nerve root. (See Figure 5.2b .)

The margins of the anterior scalene muscle are dissected with a Kitner dissector and the insertion of the muscle onto the first rib is identified. The muscle should be transected as close to its insertion as possible. It is then mobilized by grasping the cut edge and gently retracting cephalad. Care is taken to protect the phrenic nerve from distraction. Once retracted, the anterior scalene muscle is divided at its upper attachment and removed. (See Figure 5.2c .)

Next, the middle scalene muscle is identified posterior to the C5 nerve root and upper border of the brachial plexus. It is dissected away from the brachial plexus with blunt dissection. Attention is paid to identifying the long thoracic nerve as it arises from the brachial plexus (C5, C6) and dives into the middle scalene muscle. The nerve is protected as the muscle is divided with scissors or the Harmonic scalpel. (See Figure 5.2d .)

The muscle is resected down to the first rib. At this point, the intercostal muscle is dissected away from the rib with a periosteal elevator. This dissection is carried beneath the rib up to the point where the brachial plexus crosses the first rib and then continued with finger dissection to the point beneath the subclavian artery. Similarly, the pleura is separated from the lower surface of the rib with finger dissection.

The posterior aspect of the rib is then divided within 1 cm of the transverse process using a Schumacher bone cutter or Raney rongeur. This allows mobilization of the rib and may facilitate further dissection of the intercostal muscles and pleura away from the rib. (See Figure 5.2e .)

Finally, the rib is divided anteriorly beneath the subclavian artery using a Dale rongeur.

The resected rib segment is then extracted while taking care not to injure the surrounding nerve structures. At the same time, the remaining attachments are divided. (See Figure 5.2f .)

In patients with venous symptoms (i.e., arm swelling, congestion, venous compression, or blood clot), an additional incision inferior to the clavicle is required to allow resection of the most anterior portion of the first rib and the subclavius muscle.

The wound is closed in layers. A 10 Fr fluted drain is placed in the bed of the incision. The scalene fat pad is sutured to the lateral border of the sternocleidomastoid to return it to its normal position and to pad the brachial plexus. The platysma is closed with absorbable suture, as is the skin.

FIRST RIB RESECTION: POSTERIOR APPROACH

Conceptual approach

The posterior approach to the resection of a first rib is most useful for the removal of a long residual rib segment following prior transaxillary or supraclavicular operation. It has the advantages of avoiding the reoperative planes of the prior surgery and allowing direct access to the residual rib segment. It has the disadvantage of requiring division of the trapezius and rhomboid muscles—where many patients find a nidus of pain and muscular spasm.

Execution

The patient is placed in lateral decubitus with an axillary roll, padded on bean bag and pillows. The arm rests on a Mayo stand or arm support. (See Figure 5.3a.)

The incision is centered over the T1 vertebral body, midway between the scapula and vertebral body. Dissection is carried down to the muscle layer where the trapezius and rhomboid muscles are divided. (See Figure 5.3a.)

The posterior superior serratus muscle is resected and the sacrospinalis is retracted. This allows identification of the first rib stump. (See Figure 5.3b.)

The stump of the first rib is dissected free of intercostal muscle with a narrow periosteal elevator or cautery. Once separated from the surrounding muscle and tissue, the rib remnant may be resected with a rongeur or transected using a rib shear. It is important to observe and protect the T1 nerve root during this process.

The T1 nerve root is identified with a nerve stimulator. Once identified, neurolysis is performed by carefully clearing the nerve of investing scar tissue using magnification and micro scissors. With cephalad extension of the incision, neurolysis may be performed on the C7 and C8 nerve roots as well. (See Figure 5.3c.)

If sympathectomy is to be performed at the same time, the incision is extended caudad to allow exposure of the second rib. The rib is separated from the intercostal muscles and a 2 cm segment is resected (head and neck). (See Figure 5.3d.)

This allows mobilization of the pleura and exposure of the sympathetic chain (see Figure 5.3e ).

The lower third of the stellate ganglion is divided (T1) sharply. The T1, T2, and T3 ganglia are removed sharply and branches are clipped (see Figure 5.3f ).

Wound closure is accomplished by approximating the muscle layers with interrupted figure-eight absorbable sutures. A 10 Fr round fluted drain is placed at the bed of the incision. Skin is closed with skin clips.

Outcome

The result of surgical decompression for neurogenic TOS is greatly influenced by patient selection. Excellent surgeons will experience disappointing outcomes in poorly selected patients. A standardized protocol for evaluation and preparation of patients is essential.

Adjunctive use of video-endoscopy, fiber optic lights, and mechanical wound and limb retractors allows better visualization and safer execution of the surgery. Use of Seprafilm to reduce adhesions is done routinely. Assistance with pain management, psychological support, and physical therapy help from a care team improves outcomes.

The results of surgery for the vascular presentations of TOS are usually excellent. The prompt restoration of patency is essential to improving outcomes. If thrombolysis or thrombectomy is not performed promptly (within 7 to 10 days) restoration of vascular patency and resolution of symptoms are far less likely.

AN ALTERNATIVE APPROACH

Definition

Thoracic outlet compression syndrome (TOCS) is characterized by compression of the important neurovascular structures in the thoracic outlet, resulting in a complex of signs and symptoms of the upper extremity, shoulder girdle region, upper chest, and neck and head areas. These symptoms and signs include upper extremity pain, numbness, tingling, weakness, and other manifestations such as coldness, vasomotor, and sometimes nail-shape changes and swelling in the hands and fingers. Structures compressed include the brachial plexus (most common) and the subclavian vein and artery (less common). The compression is usually caused by either some congenital or acquired changes in the soft and osseous tissues located in this region, which result in the occurrence of some narrowing in this area and symptoms that follow.

It is now well known that at least 40%-50% of TOCS cases have associated distal nerve compression symptoms, such as cubital tunnel; carpal tunnel; pronator teres; and, less often, radial tunnel compression. These associated findings have been attributed to disturbance of the antegrade axonal transportation, causing the neural sheath and distal nerve to become more vulnerable to compression. However, when a combined procedure is indicated and correctly performed, it results in total decompression of the neurovascular structures, creating a larger space for their passage and less chance of recurrence.

Anatomy

Anatomically, there are three locations within the thoracic outlet region that are responsible for the development of compression of the neurovascular structures: (1) the interscalene triangular space; (2) the costoclavicular space; and, less commonly, (3) the subpectoralis minor space (see Figure 5.4 ).

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