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Thoracic Outlet Syndrome

 

Definition

Thoracic outlet is a passageway which the neuro-vascular bundle is passing through it from the chest to the arm, through this passageway three narrowing can be happened.

 The most proximal is called interscalene triangle, its borders are first rib inferiorly, anterior scalenus anteriorly, middle scalenus muscle posteriorly, pass through it the subclavian artery and brachial plexus.

The second passageway is called the costoclavicular triangle which is bordered anteriorly by the middle third of the clavicle, posteromedial by the first rib, and posterolateral by the upper border of the scapula. 

The last passageway is called the subcoracoid or sub-pectoralis minor space:  The borders of the thoraco-coraco-pectoral space include the coracoid process superiorly, the pec minor anteriorly, and ribs 2-4 posteriorly

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. Almost all cases of TOS (95-98%) affect the brachial plexus; the other 2-5% affecting the subclavian artery and vein. 

Causes

Congenital Factors:

  • Cervical rib

  • Prolonged transverse process

  • Anomalous muscles

  • Fibrous anomalies (transvers costal, cost costal)

  • Abnormalities of the insertion of the scalene muscles

  • Fibrous muscular bands

  • Exostosis of the first rib

  • Cervicodorsal scoliosis

  • Congenital uni- or bilateral elevated scapula

  • Location of the A. or V. Subclavian in relation to the M. scalene anterior

Acquired Conditions:

  • Postural factors

  • Dropped shoulder condition

  • Wrong work posture (standing or sitting without paying attention to the physiological curvature of the spine)

  • Heavy mammaries

  • Trauma

  • Clavicle fracture

  • Rib fracture

  • Hyperextension neck injury, whiplash

  • Repetitive stress injuries (repetitive injury most often form sitting at a keyboard for long hours)

Muscular Causes:

  • Hypertrophy of the scalene muscles

  • Decrease of the tonus of the M. trapezius, M. levator scapulae, M.rhomboids

  • Shortening of the scalene muscles, M. trapezius, M. levator scapulae, pectoral muscles

Clinical Presentation

Signs and symptoms of thoracic outlet syndrome vary from patient to patient due to the location of the nerve and/or vessel involvement. Symptoms range from mild pain and sensory changes to limb-threatening complications in severe cases.

Signs and symptoms are typically worse when the arm is abducted overhead and externally rotated with the head rotated to the same or the opposite side. As a result, activities such as overhead throwing, serving a tennis ball, painting a ceiling, driving, or typing may exacerbate symptoms.

Compressors* - a patient that experiences symptoms throughout the daytime while using prolonged postures resulting in increased tension or compression of the thoracic outlet. The most common aggravating postures are head forward with the shoulder girdles protracted and depressed or activities that involve working overhead with the arms elevated. These positions cause an increase in tension/compression (such as working overhead with elevated arms) that would result in an increase in tension or compression of the neurovascular bundle of the brachial plexus

Releasers* - Describes patients that often experience paranesthesia at night that often wakes them up. It is caused by a release of tension or compression to thoracic outlet, that restores the perineural blood supply to the brachial plexus, signaling a return of normal sensation. This is used as an indicator of a favorable outcome and resolution of symptoms.

Physical Examination

Observation

  1. Posture

  2. Cyanosis

  3. Oedema

  4. Paleness

  5. Atrophy

Palpation

  1. Temperature changes

  2. Supraclavicular fossa

  3. Scalene muscles (tenderness)

  4. Trapezius muscle (tenderness)

Neurological Screen

MMT & Flexibility of following muscles:

  1. Scalene

  2. Pectoralis major/minor

  3. Levator scapulae

  4. Sternocleidomastoid

  5. Serratus anterior

Special Tests

  • Elevated Arm Stress/ Roos test: the patient has arms at 90° abduction and the therapist puts downwards pressure on the scapula as the patient opens and closes the fingers. If the TOS symptoms are reproduced within 90 seconds, the test is positive.

  • Adson's: the patient is asked to rotate the head and elevate the chin toward the affected side. If the radial pulse on the side is absent or decreased then the test is positive, showing the vascular component of the neurovascular bundle is compressed by the scalene muscle or cervical rib.

  • Wright's: the patient’s arm is hyper abducted. If there is a decrease or absence of a pulse on one side then the test is positive, showing the axillary artery is compressed by the pectoralis minor muscle or coracoid process due to stretching of the neurovascular bundle.

  • Cyriax Release: the patient is seated or standing. The examiner stands behind the patient and grasps under the forearms, holding the elbows at 80 degrees of flexion with the forearms and wrists in neutral. The examiner leans the patient’s trunk posteriorly and passively elevated the shoulder girdle. This position is held for up to 3 minutes. The test is positive when paresthesia and/or numbness (release phenomenon) occurs, including reproduction of symptoms.

  • Supraclavicular Pressure: the patient is seated with the arms at the side. The examiner places his fingers on the upper trapezius and thumb on the anterior scalene muscle near the first rib. Then the examiner squeezes the fingers and thumb together for 30 seconds. If there is a reproduction of pain or paresthesia the test is positive, this addresses compromise to brachial plexus through scalene triangles.

  • Costoclavicular Maneuver: this test may be used for both neurological and vascular compromise. The patient brings his shoulders posteriorly and hyperflexes his chin. A decrease in symptoms means that the test is positive and that he neurogenic component of the neurovascular bundle is compressed.

  • Upper Limb Tension: These tests are designed to put stress on the neurological structures of the upper limb. The shoulder, elbow, forearm, wrist and fingers are kept in specific position to put stress on particular nerve (nerve bias) and further modification in position of each joint is done as "sensitizer".

  • Cervical Rotation Lateral Flexion: The test is performed with the patient in sitting. The cervical spine is passively and maximally rotated away from the side being tested. While maintaining this position, the spine is gently flexed as far as possible moving the ear toward the chest. A test is considered positive when the lateral flexion movement is blocked.

Investigation

  •  Electrophysiological studies

  •  Imaging studies

Treatment

  • Nonsteroidal anti-inflammatory drugs have been prescribed to reduce pain and inflammation.

  • Botulinum injections to the anterior and middle scalenus have also found to temporarily reduce pain and spasm from neurovascular compression, further research is needed because there are discrepancies in the literature. 

  • Surgical management of TOS should only be considered after conservative treatment has been proven ineffective.
    However, limb-threatening complications of vascular TOS have been indicated for surgical intervention.
    Surgery to treat thoracic outlet syndrome may be performed using several different approaches, including: transaxillary approach, supraclavicular approach and infraclavicular approach.

  • Transaxillary approach: The first rib forms the common denominator for all causes of nerve and artery compression in this region so that its removal generally improves symptoms. Surgeon makes an incision in the chest to access the first rib, divide the muscles in front of the rib and remove a portion of the first rib to relieve compression, without disturbing the nerves or blood vessels.

  • Supraclavicular approach has been advocated to perform first rib resection and scalenectomy, a safe and effective procedure, characterized by a shorter operative time and having a complication rate lower or comparable to that of transaxillary first rib resection.
    This approach repairs compressed blood vessels. The surgeon makes an incision just under the neck to expose the brachial plexus region. Then he looks for signs of trauma or muscles contributing to compression near the first rib. The first rib may be removed if necessary to relieve compression.

  • Infraclavicular approach: In this approach, the surgeon makes an incision under the collarbone and across the chest. This procedure may be used to treat compressed veins that require extensive repair.

  • Neurogenic TOS: Surgical decompression should be considered for those with true neurological signs or symptoms. These include weakness, wasting of the hand intrinsic muscles, and conduction velocity less than 60 m/sec. The first rib can be a major contributor to TOS. There is controversy, however, regarding the necessity of a complete resection to reduce the chance of reattachment of the scalenus, scar tissue development, or bony growth of the remaining tissue. In addition to the first rib, cervical ribs are removed, scalenectomies can be performed, and fibrous bands can be excised]. Terzis found that the supraclavicular approach to treatment to be an effective and precise surgical method

  • Arterial TOS: Decompression can include cervical and/or first rib removal and scalene muscle revision. The subclavian can then be inspected for degeneration, dilation, or aneurysm. Saphenous vein graft or synthetic prosthesis can then be used if necessary

  • Venous TOS: Thrombolytic therapy is the first line of treatment for these patients. Because of the risk of recurrence, many recommend removal of the first rib is necessary even when thrombolytic therapy completely opened the vein. The results of a study show that the infraclavicular approach is a safe and effective treatment for acute VTOS. They had no brachial plexus or phrenic nerve injuries.
    Angioplasty can then be used to treat those with venous stenosis

In venous or arterial TOS, medication can be administered to dissolve blood clots prior to thoracic outlet compression. It may also be to conduct a procedure to remove a clot from the vein or artery or repair the vein or artery prior to thoracic outlet decompression.

Some larger-chested women have sagging shoulders that increase pressure on the neurovascular structures in the thoracic outlet. A supportive bra with wide and posterior-crossing straps can help reduce tension. Extreme cases may resort to breast-reduction surgery to relieve TOS and other biomechanical problems.

 

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