Scapulothoracic Abnormal Motion (STAM)

Patients with STAM may be diagnosed more specifically with one of the following conditions. Treatment at NewYork-Presbyterian begins with non-surgical measures including pain management with oral medication and/or injections, and physical therapy to stretch tight muscles in the chest and shoulder.

Surgical options are reserved for patients who do not achieve symptom relief with conservative management.

Pectoralis minor syndrome – This is characterized by pain and restricted movement in the shoulder caused by excessive tightness in the pectoralis minor, which is the small muscle in the front of the chest. Tightness in the muscle may be caused by hyperactivity, an increase in muscle mass, and/or an anatomical variant. Pectoralis minor syndrome can also occur after shoulder replacement surgery with pain in the front of the shoulder. Patients with this syndrome tend to have less abnormal movement of the shoulder than those with other STAM diagnoses.

In the absence of other problems in the shoulder, pectoralis minor syndrome that does not respond to nonoperative treatment can be addressed with a minimally invasive surgery that releases the tendon arthroscopically.

Functional or Structural STAM

STAM may have either a structural or functional cause. This distinction is important since it helps to guide treatment. In both types of STAM, scapular winging is seen.

Functional STAM occurs when the muscles that support the shoulder are otherwise healthy but are “out of sync” resulting in an imbalance of the muscles around the scapula.  

Patients with functional STAM can often be successfully treated with a minimally invasive procedure to release the tight pectoralis minor muscle. In some cases, the surgeon will also anchor the scapula to the chest to normalize movement.

Structural STAM refers to a problem within the muscles that support the shoulder. These muscles may be paralyzed after an injury to either the muscle itself or to the nerves that transmit nerve signals from the spinal cord.

Individuals with structural STAM may require a tendon transfer to the scapula to balance the muscles that are no longer functioning correctly.

Thoracic Outlet Syndrome (TOS) – The thoracic outlet refers to the space between the neck and the shoulder that forms a passageway for a bundle of nerves and blood vessels (called the brachial plexus) that serve the surrounding areas. In patients with TOS, when the affected arm is raised, this area narrows, compressing the nerves and blood vessels. This can produce symptoms that may include pain, numbness or tingling in hand, and a flushing sensation in the arm. 

Neurogenic TOS (relating specifically to the nerves) is the most common type of this disorder. There is growing evidence that STAM caused by a tight pectoralis minor muscle pulling the scapula down and out of alignment is a significant factor in the development of this condition.  Overdevelopment of the large muscles on the side of the neck can also lead to neurogenic TOS.

When medication and physical therapy do not provide relief for neurogenic TOS caused by a tight pectoralis muscle, orthopedic surgeons can arthroscopically release the tendon in front of the shoulder. This minimally invasive procedure opens the constricted area. Any excess tissue in the area that is contributing to pressure on the brachial plexus is removed at the same time.

Other causes of TOS include the presence of an extra rib; or a tumor or cyst in the thoracic outlet. Venous TOS is diagnosed when a blood clot forms in one of the neck veins.

Snapping Scapula Syndrome – Patients with this condition usually experience pain at the side of the scapula closest to the spine. The syndrome develops when the area between the scapula and the ribs becomes abnormally narrow and inflamed.  Often, this is due to the scapula being pulled out of correct alignment by a tight pectoralis minor muscle. Inflammation of the bursa (a fluid-filled cushion that rests between the bones) follows, leading to the snapping sensation and sound patients experience when moving the affected arm, caused by the bone “catching” on the bursa. 

Treatment for snapping scapula syndrome starts with medication and physical therapy. If pain and snapping continue, a minimally invasive procedure can correct the imbalance between the tight pectoralis minor muscle and the scapula. The surgeon also removes any tissue under the scapula and inflammation that is contributing to the patient’s symptoms. This relatively new arthroscopic surgery has a shorter recovery time compared with older surgical techniques.