INDICATIONS/CONTRAINDICATIONS

Vascular reconstruction techniques are required in the management of patients with thoracic outlet syndrome (TOS) when a vascular injury has occurred to either the subclavian vein or artery. Neurogenic TOS (NTOS) accounts for between 90% and 95% of clinical cases and is caused by compression or irritation of the brachial plexus. The remainder of cases is venous TOS (VTOS), which results from stenosis of the subclavian vein. Arterial TOS (ATOS) only occurs when compression of the subclavian artery results in arterial thrombosis and/or an aneurysm formation. This is very uncommon and accounts for less than 1% of all cases.

VTOS frequently presents with symptoms of upper extremity swelling with or without skin discoloration. Patients may report a heavy sensation or a feeling of “pressure” in the upper extremity. For suspected cases of VTOS, the initial management is immediate anticoagulation with subcutaneous low–molecular-weight or intravenous heparin. Venous ultrasound studies are often used in the initial diagnosis, but the high degree of false-negative studies limits its usefulness. A contrast venogram has much greater diagnostic accuracy and a therapeutic capability as well. Catheter-delivered chemical thrombolysis, and possibly mechanical thrombectomy may be used, the author’s preference is to avoid balloon venoplasty at the initial presentation. If balloon venoplasty is felt to be necessary, limiting this to an 8 mm or less balloon is preferable. The use of intravascular stents as a management for VTOS should be strictly avoided.

Some cases of VTOS may be treated nonoperatively. Patients who present in their mid-30s or older, have minimal or no narrowing of the subclavian vein after lytic therapy and remain asymptomatic may be treated with 3 to 6 months of anticoagulation and observed. This is a fairly small percentage of patients presenting with VTOS. The majority of patients will require surgical thoracic outlet decompression with or without vein reconstruction.

Patients with ATOS from a subclavian or axillosubclavian artery aneurysm represent an absolute indication for surgery, even if asymptomatic at the time of presentation.

PREOPERATIVE PLANNING

The surgical treatment of TOS requiring vascular reconstruction involves resection of the first thoracic rib through a supraclavicular or paraclavicular (combined supra- and infraclavicular) approach. The surgeon and the assistant would benefit from the use of surgical telescopes and a headlight to improve visualization. During the procedure, the degree of retraction on the spinal nerves, phrenic nerve, and brachial plexus trunks must be minimized to avoid a nerve traction injury. The author uses bipolar cautery for much of the procedure to avoid transmitting electrical current to the nerves in this area.

SURGERY

Positioning

General anesthesia is administered and the patient is intubated with the endotracheal tube taped to the side of the patient’s mouth opposite to the side of the procedure. The use of neuromuscular blocking agents is avoided following intubation so an electrical nerve stimulator can be used to assist in identifying and confirming the function of nerves.

The patient is placed in a modified semi-Fowler position with the head on a padded roll, rotated 45 degrees away from the operative side. Both arms are tucked to the side if possible. Otherwise, the operative side arm is tucked to the patient’s side and an arm board is placed on the nonoperative side as far down on the bed as possible to allow the assistant to stand close to the table. A roll of gauze is placed into the patient’s hands for padding. The operative-side shoulder is elevated off of the bed by placing a stack of folded surgical towels behind the shoulder to pivot the shoulder and lateral clavicle anteriorly and open the costoclavicular space. The field is draped so that a sternotomy can be performed in the unlikely event that additional exposure is needed.

Supraclavicular Exposure

A 5 cm long incision is made beginning at the lateral border of the sternocleidomastoid muscle (SCM). The incision extends laterally 1 to 2 cm above the clavicle. The subcutaneous tissue and platysma muscle are divided, and flaps are raised under this muscle with electrocautery. A Weitlaner retractor is placed below the level of the platysma and the scalene fat pad is mobilized off of the lateral border of the SCM using electrocautery. Small sensory nerve branches and anterior jugular veins are identified running approximately perpendicular to the incision. These structures are identified and mobilized laterally without tension. Another self-retaining retractor can be placed between the lateral wound edge and the SCM muscle to retract it medially. The scalene fat pad is now mobilized laterally. The omohyoid muscle is identified running approximately parallel to the incision. This is encircled with a vessel loop to allow for its retraction. Deep to the omohyoid muscle will lie the anterior scalene muscle.

Dissection through the deep part of the fat pad is done with bipolar cautery to protect the phrenic nerve and brachial plexus. The suprascapular and transverse cervical arteries are identified and preserved. They typically run parallel to the incision, with the suprascapular artery below the level of the incision, and the transverse cervical artery above it. The dissection continues with bipolar cautery until the scalene muscle is identified deep and slightly medial to the lateral edge of the SCM muscle. Mobilization of the scalene fat pad continues from medial to lateral exposing the upper and middle trunks of the brachial plexus, as well as the subclavian artery. The lower trunk is deeper to these structures, and not usually identified at this point. The suprascapular artery is dissected off of the scalene fat pad laterally to complete the mobilization. A 2-0 silk traction suture is placed on the tip of the fat pad, which is retracted laterally.

The phrenic nerve is then identified on the surface of the anterior scalene muscle running from lateral to medial. A nerve stimulator (current setting 0.5 to 1 mA, frequency setting 30 Hz) is used to confirm the location and function of the nerve. The areolar plane between the surface of the scalene muscle and the phrenic nerve is developed, and tissue adjacent to the nerve is grasped and gently retracted to mobilize the nerve medially. Occasionally, an accessory phrenic nerve branch located at the lateral edge of the anterior scalene muscle is preserved if present. Near the cephalad portion of the scalene muscle, the phrenic nerve receives a contribution from the C5 spinal nerve, which limits the degree that the phrenic nerve can be mobilized. After mobilization, the nerve stimulator is used to confirm intact phrenic nerve function. Once the phrenic nerve is mobilized off of the anterior surface of the scalene muscle, the plane along the medial border of the muscle is developed using bipolar cautery. The subclavian artery is identified medially, and the dissection around the anterior scalene is continued down to the scalene tubercle of the first rib. A Richardson or Cloward retractor placed below the clavicle facilitates exposure. There may be muscle fibers running between the anterior and middle scalene muscles that must be divided to facilitate mobilization of the brachial plexus trunks.

The lower portion of the anterior scalene muscle is partially divided medially and laterally directly on the scalene tubercle exposing part of the first rib. The central part of the muscle is preserved at this time to facilitate the division of the cephalad portion of the anterior scalene muscle. The scalene muscle is then divided with bipolar cautery as far cephalad as possible while protecting the phrenic nerve and its C5 spinal nerve. Once the cephalad border of the muscle is divided, the remaining muscle attachments to the first rib are divided and the muscle is removed.

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