The Incidence of Thoracic Outlet Syndrome

Background

Thoracic outlet syndrome (TOS) refers to a constellation of compressive problems that occur at the thoracic outlet. TOS has been recognized since the 19th century, and the “modern” era of treatment, especially for neurogenic TOS, dates from at least the 1970s. Despite this, however, the incidence and prevalence of these syndromes are almost completely unknown. To attempt to answer this fundamental question, we established a prospective database of all patients who presented to our clinic with a diagnosis of potential TOS, as described below.

Methods

We established a database of all patients referred to our clinic from July 1, 2014 to May 2018. All subjective data, the tentative diagnosis, and plan at the time of the office visit were prospectively recorded. For patients with neurogenic TOS (NTOS), a standardized workup sheet was used based on the Society for Vascular Surgery's recently published reporting standards document. For patients with venous TOS (VTOS), diagnosis was made by clinical examination and ultrasound, and for those with arterial TOS (ATOS), by clinical examination, ultrasound, and cross-sectional imaging when needed.

Results

From July 1, 2014, to May 1, 2018, 526 patients were referred to our institution with a diagnosis of possible TOS. Of these, 432 (82%) were referred with symptoms suggestive of NTOS, 84 (16%) with symptoms suggestive of VTOS, and 10 (2%) with findings and/or symptoms suggestive of ATOS. NTOS: After evaluation as per the algorithm previously mentioned, 234 patients (54%) were judged high suspicion for NTOS, 126 (30%) moderate suspicion, and 72 (17%) low suspicion; 360 (83%) of those originally referred were felt to potentially have NTOS. Of the 84 patients with VTOS, 25 (30%) presented with acute Paget-Schroetter syndrome, 41 (48%) with subacute or chronic occlusion, and 18 (21%) with McCleery's syndrome. Finally, 8 of the 10 limbs had true ATOS; of these, 6 (75%) underwent decompression and repair and 2 (25%) endovascular intervention only. Based on referral assumptions and population density in our area, the incidence of NTOS seems to be between 2 and 3 cases per 100,000 people per year and that of VTOS between 0.5 and 1 per 100,000 people per year, ATOS being sporadic. The ratio of those with decent suspicion for NTOS and VTOS, respectively, is about 80:20, whereas that of those undergoing surgical decompression is about 75:25.

Conclusions

The rates of NTOS and VTOS, as aforementioned, are approximately 25 and 8 per year in a metropolitan area of 1,000,000, respectively. Although a rare disease, these numbers are not insignificant, although are much lower than prior estimates.

Introduction

Thoracic outlet syndrome (TOS) refers to a constellation of compressive problems that occur at the thoracic outlet. Although overlap exists, three separate types of thoracic outlet syndrome are described: compression of the nerves (brachial plexus) at the scalene triangle and/or retropectoral space produces neurogenic thoracic outlet syndrome (NTOS), compression of the vein at the anterior costoclavicular junction produces venous thoracic outlet syndrome (VTOS), and compression of the artery by the first or cervical rib leading to organic damage to it produces arterial thoracic outlet syndrome (ATOS).¹ In addition, patients with ipsilateral arteriovenous access can develop a form of VTOS, likely because of the high flow created through the vulnerable vein in this situation.²

TOS has been recognized since the 19th century, and the “modern” era of treatment, especially for NTOS, dates from at least the 1970s. Despite this, however, the incidence and prevalence of these syndromes are almost completely unknown. To be fair, several factors contribute to this, including the very subjective nature of the problem and resultant lack of consensus as to diagnosis, poor physician awareness and thus recognition, and the very fuzzy line between physiologic brachial plexus compression and the true syndrome. Several authors have attempted to determine incidence and prevalence, and identify the ratio between each disorder, but such reports either rely on very old, suspect data and opinion,³ or are analyses of operative cases only based on sampling data.^4,5 To attempt to answer this fundamental question, we established a prospective database of all patients who presented to our clinic with a diagnosis of potential TOS, as described below.