Thoracic outlet syndrome part 1: Clinical manifestations, differentiation and treatment pathways

doi:10.1016/j.math.2009.08.007

Manual Therapy

Volume 14, Issue 6, December 2009, Pages 586-595

https://doi.org/10.1016/j.math.2009.08.007 Get rights and content

Abstract

Thoracic outlet syndrome (TOS) is a challenging condition to diagnose correctly and manage appropriately. This is the result of a number of factors including the multifaceted contribution to the syndrome, the limitations of current clinical diagnostic tests, the insufficient recognition of the sub-types of TOS and the dearth of research into the optimal treatment approach. This masterclass identifies the subtypes of TOS, highlights the possible factors that contribute to the condition and outlines the clinical examination required to diagnose the presence of TOS.

Introduction

Opinions in the literature about thoracic outlet syndrome (TOS) vary in the extreme, swaying from the belief that it is the most underrated, overlooked and misdiagnosed peripheral nerve compression in the upper extremity (Shukla and Carlton, 1996, Sheth and Belzberg, 2001) to questioning whether it exists (Wilbourn, 1990). These varying beliefs highlight the need for the clinician to be rigorous in their clinical assessment so that patients are not misdiagnosed and are appropriately managed. Unfortunately the diagnosis of TOS remains essentially clinical and is often one of exclusion with no investigation being a specific predictor. This may be attributed, in part, to the fact that TOS is considered to be a collection of quite diverse syndromes rather than a single entity (Yanaka et al., 2004). Consequently, this also results in TOS being one of the most difficult upper limb conditions to manage.

The aim of this paper (Part 1) is to clarify the nomenclature, classification, varying clinical presentations and assessment techniques so that the reader may attempt to assess and differentially diagnose patients presenting with TOS. The second paper (Part 2) will outline specific rehabilitation approaches used by the authors to treat one sub-type of TOS.

Section snippets

Definition

A broad definition of TOS is a symptom complex characterized by pain, paresthesia, weakness and discomfort in the upper limb which is aggravated by elevation of the arms or by exaggerated movements of the head and neck (Lindgren and Oksala, 1995).

Anatomical considerations

The pain and discomfort of TOS are generally attributed to the compression of the subclavian vein, subclavian artery and the lower trunk of the brachial plexus as they pass through the thoracic outlet (Cooke, 2003, Samarasam et al., 2004, Barkhordarian, 2007).

Three sites of compression of the vessels and nerves are possible (Fig. 1). The lower roots of the brachial plexus may be compressed as they exit from the thoracic cavity and rise up over the first rib (or a cervical rib or band when

Classification and pathophysiology

TOS is often categorized into two specific clinical entities: Vascular TOS (vTOS) and Neurological TOS (nTOS) (Atasoy, 1996, Rayan, 1998, Sharp et al., 2001). vTOS can be divided into arterial and venous TOS syndromes due to compression or angulation of either the subclavian or axillary artery or vein (Rayan, 1998, Davidovic et al., 2003). Usually it is caused by a structural lesion, either a cervical rib or another bony anomaly (Rayan, 1998). Arterial involvement is more common than venous

Incidence

The incidence of TOS is reported to be approximately 8% of the population (Davidovic et al., 2003), is extremely rare in children (Cagli et al., 2006), and affects females more than males (between 4:1 and 2:1 ratios) (Gockel et al., 1994, Davidovic et al., 2003, Demondion et al., 2003, Degeorges et al., 2004). In particular, tnTOS is typically found in young women (van Es, 2001).

According to Davidovic et al. (2003), 98% of all patients with TOS fall into the nTOS category and only 2% have vTOS.

Etiology

Bony pathology or soft tissue alterations are commonly attributed to the etiology of TOS. Numerous causes have been cited in the literature ranging from congenital abnormalities (anomalies of the transverse process of seventh cervical vertebra, cervical rib, first rib, enlarged scalene tubercle, scalene muscles, costoclavicular ligaments, subclavius or pectoralis minor) to traumatic in origin (such as a motor vehicle accident or sporting incident) (Gruber, 1952, Makhoul and Machleder, 1992,

Diagnosis

Diagnosis of TOS is clinical and based on a detailed history, subjective and objective examination of neurovascular and musculoskeletal systems of the neck, shoulder, arm and hands (Roos, 1982, Novak et al., 1995). Frequently a multitude of further investigations are required, many of which in the case of sTOS may indeed prove to be negative (Barkhordarian, 2007). The literature laments that there is no one test or investigation that consistently proves the diagnosis of TOS. Given that TOS

Differential diagnosis

The first step in the differential diagnosis of TOS is to separate it from other painful conditions of the upper extremity and neck. Other pathologies may mimic TOS or have some clinical overlap (Table 2). It should be taken into account that co-existence of pathology can occur. Upton and McComas (1973) introduced the ‘double crush’ hypothesis, stating that a proximal level of compression could cause more distal sites along the nerve to be more susceptible to compression (Mackinnon, 1994). This

Treatment

Treatment strategies for TOS, particularly with regard to surgical intervention, remain highly controversial. The available literature does not provide strong support either for or against surgery or conservative management (Degeorges et al., 2004). The sub-type of TOS to some extent determines the appropriate treatment pathway. Part 2 of this article will comprehensively outline conservative management.

vTOS generally requires surgical treatment and surgery usually involves decompression of the

Conclusion

To diagnose TOS is a difficult process that requires time and effort. Given that the etiology of TOS is multifactorial and the signs and symptoms so varied, it would appear logical that physical therapy can successfully be employed in the optimal management of TOS patients (both conservative and surgical).

There is a need for the development of a systemized approach to conservative management for TOS (refer to Part 2). If a better objective framework can be established this could facilitate

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