Thoracic Outlet Syndrome (TOS) is a condition that arises from the compression of nerves or blood vessels in the narrow space located between your collarbone and first rib, known as the thoracic outlet. This compression can lead to a variety of symptoms, and in some instances, it may contribute to feelings of shortness of breath.
What is Thoracic Outlet Syndrome?
The thoracic outlet, situated just below the collarbone and above the first rib, serves as a passageway for the subclavian artery, subclavian vein, and the brachial plexus nerves as they travel from the neck to the arm. When these structures are compressed by bones, muscles, or fibrous bands in this area, it can lead to various symptoms.
There are three primary classifications of TOS, determined by the specific structures that are compressed. Neurogenic TOS, the most common type, involves the compression of the brachial plexus nerves. Venous TOS occurs when the subclavian vein is compressed, while arterial TOS, the least common type, involves compression of the subclavian artery.
How TOS Can Lead to Shortness of Breath
Thoracic Outlet Syndrome can contribute to the sensation of shortness of breath through several interconnected mechanisms. Compression of nerves, particularly those associated with respiratory function, can play a role. The phrenic nerve, which originates from the cervical spine, innervates the diaphragm, the primary muscle involved in breathing. Irritation or dysfunction of nerves, including those of the brachial plexus, can indirectly impact the muscles responsible for chest expansion.
Chronic pain and muscle guarding in the neck, shoulders, and chest, common with TOS, can also restrict the natural movement of the rib cage and diaphragm. The scalene muscles in the neck, which can be affected in neurogenic TOS, assist in breathing, and their persistent spasm or tightness can limit full chest expansion. This physical restriction can make it difficult to take a deep breath, leading to a feeling of breathlessness.
Referred pain is another mechanism where nerve compression can be perceived as breathing difficulty. Pain originating from compressed nerves in the thoracic outlet can radiate to the chest area, mimicking cardiac or respiratory issues. The brain may interpret this pain as an internal problem affecting the lungs or heart, leading to a sensation of shortness of breath even when the respiratory system itself is functioning adequately.
Living with chronic pain and discomfort, often experienced by individuals with TOS, can also elevate anxiety and stress levels. Increased anxiety can trigger hyperventilation, a rapid and shallow breathing pattern that directly manifests as shortness of breath or a feeling of not getting enough air. This psychological component can create a feedback loop, where physical symptoms exacerbate anxiety, which in turn worsens perceived breathing difficulties. While less direct, severe vascular compression, such as swelling from venous TOS, can cause significant distress that is perceived as breathing difficulty.
Other Indicators of Thoracic Outlet Syndrome
TOS often presents with other symptoms affecting the upper extremities. Individuals frequently experience numbness, tingling, or weakness in the arm, hand, or fingers. These sensations can worsen with overhead activities or at night. Pain is a common indicator, often felt in the neck, shoulder, arm, or hand, and may be described as an ache. The arm may also tire quickly during activity, and grip strength can weaken. In cases of venous TOS, swelling or a bluish discoloration of the arm or hand is noticeable. A feeling of heaviness in the arm is also reported.
Diagnosis and Management of TOS
Diagnosing Thoracic Outlet Syndrome can be complex due to its varied symptoms, which can overlap with other conditions. A healthcare provider typically begins with a thorough medical history and physical examination, including provocative tests that involve specific arm and neck movements to try and reproduce symptoms. Imaging studies, such as X-rays, MRI, or MRA, may be used to rule out other conditions or identify anatomical abnormalities like an extra rib. Nerve conduction studies or electromyography can also assess nerve function.
Treatment for TOS usually begins with conservative approaches. Physical therapy is a primary first-line treatment, focusing on posture correction, strengthening exercises, and stretching to alleviate pressure on nerves and blood vessels. Medications, including anti-inflammatory drugs or muscle relaxants, may be prescribed to manage pain and discomfort. Lifestyle modifications, such as avoiding activities that worsen symptoms and maintaining good posture, are also important. Surgical intervention, such as removing a portion of the first rib or certain muscles, is typically considered for severe cases where conservative treatments have not provided sufficient relief, particularly for vascular compression or persistent neurological symptoms.