Thoracic Outlet Syndrome due to a Cervical Rib

Cervical Rib Producing Thoracic Outlet Syndrome

A Cervical Rib is a rib arising from the 7th Cervical Vertebra. The charecteristic radiological feature of the a cervival vertebra is its transverse process which is directed downwards and laterally.

Whereas the transverse process of a Thoracic vertebra is directed upwards and laterally.This is the most important identification feature of a cervical rib in a plain radiograph.

The clincal manifestations of a cervical rib is called Thoracic Outlet Syndrome.

Thoracic outlet syndrome is neurovascular symptoms in the upper extremities due to pressure on the nerves and vessels in the thoracic outlet area.

What is meant by the Thoracic Outlet?

Thoracic Outlet is bounded

Anteriorly- Upper border of Manubrium Sterni

Laterally- First Rib on each side

Posteriorly- Superior srface of body of first thoracic vertebra

Antero posterior Diameter of the Thoracic Outlet is 5cm and the Transverse  Diameter 10cm.

The specific structures compressed are the Nerves of the Branchial plexus , Subclavian Artery or Subclavian Vein.

Aetiological Factors of Thoracic Outlet Syndrome

·Cervical Rib

·Congenital Fibrous Band Between First Rib & C7

·Abnormal Fusion of Scalene Muscles at the Insertion Site

·Clavicular Fracture Callus/ Traumatic

·Exostosis of First Rib/ Neoplastic

·Narrowing of Costo Clavicular Space

·Compression by Pectoralis minor Tendon

·Long Transverse process of C7

·Poor posture, ie Drooping Shoulders –Psychological     Depression  has to be ruled out.

·Repetitive activities, causing enlargement of the Scalenus    anterior muscle ( Lateral           Flexion     of Cervical Spine)

  Hence this type of Thoracic outlet syndrome is more common in Swimmers & Volley ball players.

·Post Sternotomy ( Pneumonectomy/ ASD Closure )

·Obesity/ Recent Weight Gain  causes – Narrowing of the Thoracic outlet.

 

Cervical Rib

·Arises from 7^th Cervical vertebra

·Present in 0.5% of individuals

·May be Unilateral/ Bilateral

·Commoner on the Right Side

Types of Cervical Rib

1.     Complete Cervical Rib

2.     Cervical rib ending in a bony mass

3.     Cervical rib tapering as a Fibrous band ( Not visible in a Plain Radiograph )

4.     Complete Fibrous Band – No Radiological Finding

Clinical Features of Thoracic Outlet Syndrome

Upper Extremity

Arterial-  Numbness, Tingling & Weakness of Arms & Hands

Venous -  Swelling of Hand & Fingers, Pain

Neurological - Pain & Parasthesia over Ulnar / Median nerve distribution,Weakness & Coldness of the Hands, Tiredness& Heaviness on elevation of Arms.

Chest – Angina Like Pain/ Shoulder pain

Vertebral Artery Involvement- Dizziness/ Headache/Syncope

Note : In patients with Normal Coronary Angiogram & Normal Esophageal Function  having  Persistent Chest Pain Consider the possibility  of TOS

Clinical Signs of TOS

1.Difference in Pulse in both upperlimbs

2.Atrophy of  Thenar/Hypothenar  eminence

3.Brittle Nails / Focal Ulcers/Gangrene

4.The White Hand Sign –pallor of hand due to  Arterial TOS

5.Oedema of Hands – Venous TOS or Paget-Schroetter Syndrome or Effort Thrombosis.

Diagnostic Triad of Thoracic Outlet Syndrome or Selmonosky Triad 

1.     Tenderness in the Supraclavicular  Area

2.     Abduction & Adduction weakness of 4&5 fingers C8 - T1

3.     Pallor / Parasthesia on elevation of the Limb

Clinical Tests for Thoracic Outlet Syndrome

· Hyper abduction Manoeuvre- When arm is hyperabducted to 180°, neurovascular bundle components are compressed by the pectoralis minor tendon, leading to disappearance of radial pulse.

· Costoclavicular Compression   Manoeuvre- By keeping  the shoulders in backward and downward position as in exaggerated military position, causes reduction in costo clavicular space  and compression of subclavian artery leading to disappearance of radial pulse.

· The Elevated Arm Test or  Roose Test- Arm abducted at 90 degree with external rotation of the shoulder. Opening & closing of hands done rapidly for 3 minutes. A normal individual can do this  without any difficulty. In TOS patient develops pain and parasthesia of fore arm muscles and fingers.

Clinical Investigations for Thoracic Outlet Syndrome

1. Plain Radiograph of Neck

2.MRI Scan

3.Nerve Conduction Velocity Study

Differential Diagnosis of Thoracic Outlet Syndrome

1.     Cervical Spondylosis

2.     Cervical Disc Prolapse

3.     Cervical Cord Compression

4.     Carpel Tunnel Syndrome

5.     Raynaud’s disease / Pancoast Tumour of Lung

Treatment of Thoracic Outlet Syndrome- Conservative

1.     Maintain a Proper posture

2.     Weight Reduction ( Obesity predisposes to TOS )

3.     Physiotherapy- Exercise to strengthen the  Shoulder girdle to prevent drooping.

4.     Stop any repetitive activity or work for prolonged period

Indications of Surgical Intervention in Thoracic Outlet Syndrome

1.     Failure of Conservative Management for 6 months

2.     Progression of the Neurological Symptoms

3.     Occlusion of Subclavian Artery

4.     Thrombosis of Subclavian/ Axilliary vein

Surgical Excision of the Cervical Rib or Scalenotomy Operation

— 

Anterior Approach

Posterior Approach

Trans Axillary Approach

    

Important Operative Surgery Steps

Lateral Supra Clavicular Incision

Platysma& Deep fascia incised

Sternomastoid  retracted medially

Phrenic nerve is identified over the Scalenus anterior muscle

Scalenus anterior muscle is divided at its insertion to first rib after safeguarding the Phrenic nerve

Cervical rib is divided along with the Periosteum to prevent recurrence.

  

Complications of the Surgery for Cervical Rib

1.     Phrenic nerve injury

2.     Injury to Brachial plexus

3.     Injury to Subclavian artery and vein

4.     Pneumothorax