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 7th 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