Arterial complications of the thoracic outlet syndrome.

Chithra, R (2013) Arterial complications of the thoracic outlet syndrome. Masters thesis, Madras Medical College, Chennai.


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INTRODUCTION : Thoracic outlet syndrome (TOS) describes a spectrum of symptoms and signs related to the passage of key anatomical structures through a narrow aperture on their way to the distal upper extremity. TOS results from compression of the neurovascular bundle in thoracic outlet area and the three components of the bundle in the thoracic outlet area are the brachial plexus, subclavian vein, and subclavian artery (SCA). Thus, there are three types of TOS, depending on which structure is compressed: neurogenic (nTOS), venous (vTOS), and arterial (aTOS). The commonest form of TOS is neurogenic type. The arterial TOS forms less than 1% of cases, but the morbidity and mortality is severe that warrants immediate attention and management. The common etiology for aTOS is the presence of bony abnormalities. Cervical rib is found in approximately 0.5% of the general population and it contributes to the compressive neurovascular symptoms of the thoracic outlet. The symptoms of aTOS are caused by emboli arising from subclavian artery pathology, like intimal damage, stenosis, poststenotic dilatation or aneurysm. The commonest etiology is presence of cervical rib. Other causes include anomalous first rib, post-traumatic callous formation in the clavicle, bony prominence or tumours in the clavicle, and rarely congenital fibrous band. The syndrome is caused by the anatomical narrowing caused by the cervical rib or anomalous first rib eliminating the space under the subclavian artery. This external compression results in repeated trauma in the intima of subclavian artery, resulting in subclavian stenosis, thrombosis, aneurysm formation with mural thrombus and distal embolisation. AIMS AND OBJECTIVES : The aim of this study was to review our operative experience and to assess the symptomatic outcome of patients with arterial thoracic outlet syndrome who underwent decompression of the thoracic outlet. 1. To study the patient factors and their symptoms, 2. To analyze the type and site(s) of artery lesion, 3. To analyze the causative compressive agents, 4. To analyze the methods of surgical exposure and methods of decompression, 5. To study the techniques for repairing arterial lesions at the thoracic outlet, 6. To analyze the post operative outcome. CONCLUSIONS : Arterial complications due to compression at thoracic outlet are uncommon, comprising only less than one percent. But, it can result in significant morbidity and long term disability. Early recognition and surgical decompression provides favourable outcome in majority of patients. Two unanticipated results in this study are (1) higher incidence in males and (2) left side cervical rib predominance. Arterial thoracic outlet syndrome is usually associated with bony component, and as cervical ribs are more common in females, the assumption is that females are more commonly associated with aTOS. This may be a wrong notion and in aTOS it may be that it is equal in both sexes. And also, this syndrome is the result of two factors added together: one is the anatomical narrowing and another is continuous trauma, causing changes in the muscle type. So, males being prone to repeated trauma, they are at higher risk in developing aTOS. Study at a larger scale is needed to confirm this. Left sided predominance in this study cannot be considered significant, considering the size of the study. In most patients, presence of cervical rib does not mean aTOS. In early stages of arterial compression, patient is usually asymptomatic, and the disease progresses silently. Only when, there is a distal embolism causing ischemic changes, this condition is diagnosed. If patients could be diagnosed before arterial changes occur, even at the stage of minimal post stenotic dilatation, just by decompressing thoracic outlet without any arterial repair, changes can be reversed. Mild symptoms, especially unilateral Reynaud syndrome needs further investigation to rule out thoracic outlet arterial compression. Supraclavicular approach to tackle both bony component and arterial lesion is the best option in aTOS. Removal of the compressing bony component only without first rib removal is not affected the subjective and objective improvements in our patients. Resection of first rib is not necessary in our view. The results in our patients confirm the effectiveness of only removing the agent of compression. The choice of arterial repair depends on the condition of the artery. No arterial intervention in simple dilatation and resection and anastomosis when there is aneurismal dilatation. This approach has minimal complications and maximum benefit. Distal embolectomy should be considered in all cases of acute limb ischemia, depending on the duration of occlusion and condition of the distal run-off vessels and collaterals. In conclusion, this study confirms that when thromboembolic complications are present, surgery is indicated in all aTOS cases. However earlier diagnosis before thromboembolism should be the goal. We also conclude that supraclavicular approach and cervical rib excision without first rib excision is an effective procedure.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Arterial complications ; thoracic outlet syndrome.
Subjects: MEDICAL > Vascular Surgery
Depositing User: Kambaraman B
Date Deposited: 24 Jul 2017 03:01
Last Modified: 24 Jul 2017 03:01

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