What symptom is most commonly associated with a patient diagnosed with thoracic outlet syndrome (TOS)?

The symptom most commonly associated with thoracic outlet syndrome (TOS) is shoulder weakness and vague pain. TOS occurs when the nerves or blood vessels in the thoracic outlet—the space between the collarbone and the first rib—are compressed. This compression can lead to a variety of symptoms, primarily affecting the upper body.

Shoulder weakness is a significant indicator of TOS, as it relates to the involvement of the brachial plexus, a network of nerves that innervates the arm and shoulder. Patients often report vague pain in the shoulder and arm that can be exacerbated by certain positions or activities, especially those requiring overhead movement.

On the other hand, while other symptoms such as numbness and tingling may occur in the extremities, especially the arms and hands as a result of nerve compression, these are not as central to TOS as the shoulder symptoms. Symptoms like numbness in the legs, severe headaches, or loss of balance are typically associated with other conditions and are not characteristic of TOS. Thus, the presence of shoulder weakness and vague pain is more indicative of thoracic outlet syndrome and aligns with the clinical presentation commonly observed in affected patients.