Thoracic outlet syndrome

After undergoing bilateral breast reconstruction with latissimus dorsi flaps, a 34-year-old woman developed rightsided thoracic outlet syndrome. At operation, the latissimus dorsi flap was found to have formed a constrictive muscle sling that compressed the thoracic outlet. To the author's knowledge, thoracic outlet syndrome has not previously occurred under these circumstances.

Thoracic outlet syndrome was described over a century ago but was given its present name by Rob and Standeven[1] in 1958. Until recently, it has been poorly understood, and many sufferers have been told by their physician that their complaints were imaginary The syndrome can be related to numerous etiologic factors, all of which produce compression of the brachial plexus, the thoracic outlet's vascular structures, or both. In the following case, thoracic outlet syndrome was caused by a latissimus dorsi flap, used in breast reconstruction, which formed an excessively tight muscle sling. To the author's knowledge, this is the first time the syndrome has been encountered in this setting.

Case Report

A 34-year-old woman was admitted with symptoms of circulatory deficiency - paresthesias, hypothermia, pain, and cyanosis - aggravated by the use of her right upper extremity. Approximately three years earlier, she had undergone total bilateral subcutaneous mastectomies, owing to severe fibrocystic changes consistent with premalignant disease. She had a strong family history of cancer, and a maternal aunt had died of bilateral breast cancer.

The patient underwent multiple breast reconstructive procedures, some of which were complicated by sepsis, which necessitated debridement and intravenous antibiotic treatment. The subcutaneous mastectomies proved inadequate to allow further reconstruction; therefore, approximately one year after the original procedure, bilateral total mastectomies were performed, followed by latissimus dorsi flap reconstruction.

At the present admission, the patient complained of numbness of the fourth and fifth digits and of the medial aspect of the right arm; she also reported weakness and swelling, as well as frequent episodes of her arm "going to sleep." Vascular studies of the right arm were positive for thoracic outlet syndrome. With the limb at rest, the following pressures were measured: 111 mm Hg, arm; 113 mm Hg, forearm; and 105 mm Hg, index finger. Upon minimal abduction of the arm, the radial and ulnar pulses were obliterated. Adson's maneuver resulted in arterial compression, with no palpable pulse. There was a flow decrease upon hyperabduction of the arm; no pressure was detected. Electromyelography yielded normal results, but nerve conduction had decreased in comparison with a previous study. The right median nerve had a motor conduction velocity of 55.3 M/s (normal, 60.0 M/s), whereas the right ulnar nerve had a motor conduction velocity of 56.6 M/s (normal, 60.0 M/s) across the thoracic outlet and 52.6 M/s (normal, 55.0 M/s) across the elbow.

The patient was admitted for nipple reconstruction and surgical correction of her ischemic symptoms. At operation, the latissimus dorsi flap was found to have been created with undue tension; as a result, it formed a constrictive muscle sling that compressed the thoracic outlet. The muscle sling was released, and prophylactic transaxillary first rib resection was performed to insure that another operation would not be needed. Bilateral nipple reconstruction was also carried out. The patient recovered uneventfully, and postoperative vascular laboratory studies yielded normal results.

Discussion

Thoracic outlet syndrome denotes compression of the brachial plexus, the subclavian vessels, or both, accompanied by paresthesia, pain, numbness, and fatigue in the affected extremity. The chief contributing factors are bone abnormalities (fractured clavicle, cervical rib, or hypoplastic first rib), which are present in 30 percent of the cases;[2] in fact, the first rib is generally regarded as being the most important anatomic structure in the pathogenesis of thoracic outlet syndrome. Other potential contributing factors include tumors, poor posture, pendulous breasts, sagging shoulders, and muscular hypertrophy.

Because of their size, reliability, and long arc of rotation, latissimus dorsi flaps have long been preferred for reconstructing after radical mastectomy. To the author's knowledge, however, this is the first case of thoracic outlet syndrome attributable to breast reconstruction with such a flap. Plastic surgeons should keep this complication in mind when performing reconstructive procedures, and thoracic surgeons should be aware of it when treating thoracic outlet syndrome in women who have had these procedures.

References

[1] Rob CG, Standeven A. Arterial occlusion complicating thoracic outlet compression syndrome. Br Med J 1958; 2:709-12 [2] Daskalakis MK. Thoracic outlet compression syndrome: current concepts and surgical experience. Int Surg 1983; 68:337-44

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