Clinical Diagnosis of TOS

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How does your doctor diagnose TOS?

After your doctor asks about your signs and symptoms, he or she may suspect the diagnosis of TOS. In that case, he or she will likely perform a specialized physical examination. The type of examination will change, depending on the type of TOS that the doctor suspects. 

Clinical Diagnosis of Thoracic Outlet Syndrome

Clinical diagnosis of neurogenic TOS

Clinical diagnosis of venous TOS

Clinical diagnosis of arterial TOS

Clinical Diagnosis of Neurogenic TOS

Similar to the clinical diagnosis in many other musculoskeletal conditions, doctors try to confirm the diagnosis and to understand the causative factors. Doctors use clinical tests intended to demonstrate compression or tension on the brachial plexus when moving the neck or arms. Unfortunately, no clinical test for neurogenic TOS is specific or accurate in confirming the diagnosis. The combination of several tests, along with a high index of suspicion on the doctor’s part, can increase the likelihood of an accurate diagnosis of neurogenic TOS. In particular, the Roos test and the upper limb neural tension test are more likely to increase confidence in the diagnosis. No clinical test can demonstrate the underlying causative mechanism in most cases.

Clinical Diagnosis of Venous TOS

A large deep venous blood clot causes venous TOS. This clot causes several secondary changes, including arm swelling and color changes. Doctors can easily detect these secondary changes, but almost always are unable to clinically prove a blood clot. A doctor would see the swelling and color changes of the arm, and would look for evidence of new collateral veins of the upper chest and shoulder. However, in most cases, the clinical examination is obvious at first glance, and the doctor would immediately order imaging tests to prove a deep venous blood clot.

Clinical Diagnosis of Arterial TOS

Arterial TOS includes arterial pathology, usually aneurysm or stenosis. These changes often present with large arterial blood clot, or smaller distal arterial blood clot fragments. Patients with large proximal blood clots usually present in dramatic fashion. Doctors would promptly diagnose these patients with acute loss of blood flow, which is a surgical emergency. In those patients without large clots, doctors would look for aneurysm or stenosis in the thoracic outlet, and signs of small clots distally. These doctors would then order imaging tests to assess the arteries and look for the source of blood clots.

Clinical Diagnosis of TOS

How does my doctor examine me for TOS?

Are clinical tests effective in TOS?

Can multiple types of TOS occur in the same patient?

Yes, one patient can have multiple types of TOS at the same time. As shown above, the artery, vein, and brachial plexus pass through each thoracic outlet together. Furthermore, the mechanism of compression is similar for all types of TOS. Thus, a patient can have compression of 1, 2, or all 3 of these vital structures. In fact, many patients with neurogenic TOS have significant compression of the subclavian vein, but without a blood clot. Since this compression impairs venous drainage of the arm, swelling or edema of the arm can result. As a result, compression of the brachial plexus is magnified. In that case, treatment to relieve the venous compression helps relieve compression on the brachial plexus.

It is often difficult for a physician to distinguish these multiple compression effects. Therefore, modern imaging quite often provides this important additional information prior to treatment.