Thoracic oudet syndrome was described over a century ago but was given its present name by Rob and Standeven1 in 1958. Until recendy, 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 oudet s vascular structures, or both. In the following case, thoracic oudet syndrome was caused by a latissimus dorsi flap, used in breast reconstruction, which formed an excessively tight muscle sling. To the authors knowledge, this is the first time the syndrome has been encountered in this setting.
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 oudet 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. Adsons 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 oudet and 52.6 M/s (normal, 55.0 M/s) across the elbow.
Figure 1. By acting like a muscular sling, the latissimus dorsi flap compressed the thoracic outlet and produced symptoms of circulatory insufficiency.
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 oudet (Fig 1). 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.