Thoracic Outlet Syndrome PDF

Thoracic outlet syndrome By Dina Othman Shokri  Objectives At the end of this lecture, the student will be able to: I. Overview  Definition of TOS  Etiology , Classification of TOS II. Identify how to diagnosis TOS III. Know what are...

Thoracic outlet syndrome By Dina Othman Shokri  Objectives At the end of this lecture, the student will be able to: I. Overview  Definition of TOS  Etiology , Classification of TOS II. Identify how to diagnosis TOS III. Know what are the physical examination for TOS IV. What are the signs and symptoms for different types of TOS V. Know how to apply a successful patient management.  Thoracic outlet syndrome Thoracic outlet syndrome’ describes compression of the neurovascular structures as they exit through the thoracic outlet. The thoracic outlet is the anatomic space bordered by the first thoracic rib, the clavicle, and the superior border of the scapula (the clavicle anteriorly, the first thoracic rib posteriorly, the insertion of the pectoralis minor muscle onto the coracoid process of the scapula laterally, and the sternum medially). The thoracic outlet is marked by the anterior scalene muscle anteriorly, the middle scalene posteriorly, and The subclavian vasculature and brachial plexus—together termed the neurovascular bundle—pass from the scalene triangle into the costoclavicular space before exiting through the subcoracoid space. The thoracic outlet is both a confined and a dynamic space: compression of the neurovascular bundle resulting in the clinical syndrome generally termed thoracic outlet syndrome (TOS) may occur constantly or intermittently with movement of the neck, thorax, and arm This condition has emerged as one of the most controversial topics in musculoskeletal medicine and rehabilitation. This controversy extends to almost every aspect of the pathology including the definition, incidence, pathoanatomical contributions, diagnosis, and treatment. The pain and discomfort of TOS are generally attributed to the compression of the Subclavian vein, Subclavian artery, brachial plexus. The lowest trunk of the brachial plexus, which is made up of rami from the C8 and T1 nerve roots, is the most commonly compressed neural structure in TOS. These nerve roots provide sensation to the fourth and fifth fingers of the hand and motor innervation to the hand intrinsic muscles. TOS affects approximately 8% of the population and is 3-4 times as frequent in woman as in men between the age of 20 and 50 years (The mean age of people effected with TOS is 30s-40s; it is rarely seen in children). Females have less-developed muscles, a greater tendency for drooping shoulders owing to additional breast tissue, a narrowed thoracic outlet and an anatomical lower sternum, these factors change the angle between the scalene muscles and consequently cause a higher prevalence in women. Almost all cases of TOS (95-98%) affect the brachial plexus; the other 2-5% affecting vascular structures, such as the subclavian artery and vein. Possible 3 sites of compression of the vessels and nerves. Interscalene triangle Costoclavicular space Sub-coracoid tunnel or sub-pectoralis minor space Three spaces of the thoracic outlet.  Classification of thoracic outlet syndrome Vascular Thoracic Outlet Syndrome (vTOS): which represents approximately 3% of cases and compression is of the vascular structures (may be arterial or venous)) Neurological Thoracic Outlet Syndrome (nTOS): represents approximately 97% of cases and compression is of the neural structures of the brachial plexus. It may be divided into: True Neurological TOS (tTOS): is associated with true neurological deficits (mostly muscular atrophy). Disputed / non-specific / Symptomatic TOS (sTOS): is associated with symptoms of TOS, however, there are no objective neurological, electro- physical or radiological abnormalities. Causes Anatomical defects. Congenital may include an extra rib located above the first rib. Cervical ribs are present in approximately 0.5-0.6% of the population, 50-80% of which are bilateral, and 10-20% produce symptoms; the female to male ratio is 2:1. Cervical ribs and the fibromuscular bands connected to them are the cause of most neural compression. Fibrous bands are a more common cause of TOS than rib anomalies. Poor posture Dysfunctions or imbalances of the musculature of the neck and shoulder region. A common feature exhibited by individuals with TOS is a flexed head position, depressed and anteriorly shifted shoulder, and protracted scapula. This abnormal shoulder position, combined with 90° of abduction or flexion (as is commonly observed with those whose occupations require reaching, especially overhead, and repeated loading), could lead to a decrease in the costoclavicular space, increased friction of the neurovascular bundle in the subpectoral area. and a shortening of the sternocleidomastoid. The shortened sternocleidomastoid may cause the scalenes and pectoralis muscle groups to shorten, leading to improper head and neck alignment and postural dysfunction. The most commonly affected muscles in TOS Scalenes: When these muscles tighten, they pull on the first rib. These are accessory respiratory muscles, meaning they should help the diaphragm expand the rib cage while we breathe. If you have a bad habit of not efficiently using the diaphragm, then these muscles get overworked and will hypertrophy. Compression with movement of the scalene muscle. As the anterior scalene muscle goes from rest (A) to contracted (B), it pulls the first thoracic rib cranially and compresses the brachial plexus and subclavian within the costoclavicular space. Presence of a supernumerary cervical rib, as demonstrated in this figure, may constrict this space further. Pectoralis Minor. If this muscle is tight or shortened, it tilts the scapula forward, makes the scapula rotate downward, and promotes adduction of the shoulder which is a BIG problem for an overhead activity. Scapular stability. If the scapular muscle is weak as the Serratus Anterior and the Lower Trapezius. These muscles help posteriorly tilt the scapula while providing an upward rotational force to allow for appropriate positioning of the humeral head. If they are weak and the scapula is allowed to tip forward and rotate downward. Abnormal muscle mechanics at the pelvis. Pelvic alignment has been shown to affect posture, gait, and alignment of the axial skeleton (particularly the head and neck). If the axial skeleton is not aligned properly, stresses exerted on the body from exercise, occupational demands, or even from daily activities, may be distributed to other body segments and tissues that are not accustomed to adapting to these loads. For example, if the hip flexors (particularly the iliopsoas) are tight and the hip extensors are weak (particularly the glutes and hamstrings), the individual may exhibit an anterior pelvic tilt. In addition, abdominal muscles (e.g., Transverse abdominus) which normally generate a torque couple to resist the hip flexors, may be weak, thus causing lumbar vertebrae lordosis. This lordosis may induce thoracic vertebrae kyphosis, a common condition in those diagnosed with TOS. Trauma. This may involve macro-trauma, as in the case of an MVA (The scalene muscle could have been injured and scarred from a previous injury (whiplash), or microtrauma, as in the case of a muscle strain of the scapular stabilizers, resulting from repetitive overhead activities. The onset of symptoms related to a traumatic accident often is delayed. Trauma to the first rib or clavicle, and structural changes in the subclavian muscle or the costocoracoid ligament. Repetitive activity, such as typing on a computer, lifting things above head, as you would if you were stocking shelves. Athletes, such as baseball pitchers and swimmers, also can develop thoracic outlet syndrome from years of repetitive movements.