Thoracic Outlet Syndrome (TOS) is a complex and sometimes difficult condition to identify and treat. Thoracic outlet syndrome occurs with compromise of the nerves and blood vessels passing from the neck into the arm through a region known as the “thoracic outlet”. Entrapment of this neurovascular bundle can lead to both neurological symptoms (numbness and burning of the entire hand) and vascular symptoms (coolness and discoloration of the hand).
A majority of thoracic outlet patients will have neurological signs and symptoms. Signs of TOS include changes in sensation across multiple dermatomes or changes in the radial pulse with different positions of provocation; these respective symptoms help differentiate between neurological and vascular entrapment.
Regardless of the symptom differentiation, the cause of thoracic outlet syndrome should be classified as a structural or functional origin in order to provide an appropriate intervention. Conservative treatment is recommended for all types of TOS and surgery is only indicated if conservative approaches fail.
A paper in the journal Manual Therapy, described an interesting approach to conservative management of thoracic outlet syndrome: look at the scapula! Because the thoracic outlet passes underneath the clavicle and coracoid (a possible location for entrapment), the position and control of scapular movement may be a missing link’ in thoracic outlet rehabilitation.
The authors, Watson and colleagues, noted that most neurologic-type TOS patients present with depressed scapula, both at rest as well as during shoulder abduction and flexion. Lifting the arm with insufficient upward rotation, scapular winging, and anterior tilt of the scapula may reduce clearance of the thoracic outlet. Interestingly, this pattern of dynamic scapular dysfunction is associated with muscle imbalance: tightness of the upper trapezius, levator scapula, and pectoralis minor with weakness of the serratus anterior, lower trapezius, and rhomboids. This pattern is also commonly seen in shoulder impingement and instability. Watson et al. suggested the upper trapezius might be prone to weakness in thoracic outlet syndrome; however, no EMG evidence exists in thoracic outlet syndrome patients to substantiate this relationship.
The authors proposed a rehabilitation program for thoracic outlet syndrome focusing on scapular position and control, beginning in lower ranges of abduction and progressing to higher levels of elevation. Patients begin with scapular setting drills and progress to lower levels of abduction (30, 45, and 90 degrees) and flexion below 90 degrees. Patients then progress to maintaining upward rotation and elevation with synchronous activation of the trapezus and serratus muscles.
The authors note that this approach is based on their clinical approach with only anecdotal evidence of success. Further research is needed to validate this treatment approach, but it serves as a great suggestion for conservative management of thoracic outlet syndrome.
REFERENCE: Watson LA, Pizzari T, Balster S. Thoracic outlet syndrome part 2: conservative management of thoracic outlet. Man Ther. 2010 Aug;15(4):305-14.
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