Definition
Symptoms & signs due to compression of brachial plexus & /or subclavian vessels at root of neck
Epidemiology
80% 30-50 years
F:M = 2:1
Incidence
Uncommon
Anatomy
Thoracic Outlet forms communication at root of neck
- for passage of nerves and vessels from mediastinum to axilla
- vein is anterior to Scalenus Anterior
Boundaries
Anterior: Scalaneus Anterior
Posterior: Scalaneus Medius
Floor: First Rib
Roof: Prevertebral fascia & clavicle
Aetiology
Bony / muscular / ligamentous compression of neurovascular bundle at Thoracic Outlet
Bony
1. Cervical Rib
- 5 / 1000
- only 10% of cervical ribs are symptomatic
- 10% of TOS have cervical rib
Varies from
- enlarged TP
- complete developed with cartilage uniting it to cartilage of 1st thoracic rib
2. 1st Thoracic Rib
- abnormal curve
- increased size or shape
3. Clavicle
- posterior fracture callus
- abnormal shape / malunion
Musculo-ligamentous
Most important cause
1. Fibrous Band
Cervical rib joined to 1st rib by congenital fibrous band
- elevates lower part of brachial plexus
- makes it more susceptible to scissor compression by clavicle from above
- 9 variants recognised
2. Scalenus Muscles
Abnormal insertion
Decreased size of cleft between S Anterior & S Medius
Other
Trauma
- Precipitates condition in 2/3
Posture
- shoulder sags with middle age
- hyperabduction in sleep
- scapular winging secondary to trapezius palsy
Occupational
- hyperabduction of shoulders (painters, welders)
- pressure (backpacks, soldiers)
Classification
1. Neurogenic
Compression of brachial plexus alone
- usually lower trunk C8,T1
- most common 95%
2. Vascular
Compression of subclavian blood vessels alone
- usually vein obstruction
- occasionally arterial insufficiency
- rare 2%
3. Combined
Compression of both nerves & vessels
- rare 3%
Symptoms
2° compression of Plexus > Vessels
Pain
- intermittent
- suprascapular area and neck
- may be whole arm
- more common medial arm & ulnar forearm
- radiates to neck
Worse after activity
- overhead
- carrying heavy weight
Paraesthesia
- C8 & T1 (mainly ulnar nerve distribution)
- may be whole arm
Weakness
- most noticeable is grip
Venous
- duskiness & cyanosis of hand
Arterial
- cold, pale hand & forearm
- Raynaud's
Signs
Pain from percussion or constant thumb pressure in supraclavicular region over plexus
Listen for bruit / compare arm BP
Sensation
- decreased in C8 / T1 distribution
Power
- decreased especially grip strength
1. Elevated Arm Stress Test (EAST)
- shoulder abducted 90° & ER
- elbows at 90°
- hands clasped / unclasped for 3min
- positive if symptoms reproduced or arms drop 2° pain & weakness
2. Adson Manoeuvre
- head toward side tested, neck extended
- arm by side
- palpate radial pulse of extended arm
- patient inhales deeply
- positive test if decrease or obliteration in pulse with concomitant reproduction of symptoms
3. Wright's Manoeuvre
- head turned away from tested arm, neck extended
- arm abducted and ER
- breath in
- loss of pulse or reproduction of symptoms
- highly sensitive
Xray neck / CXR
Cervical rib
Clavicle fracture
CT
MRI
May show fibrous band
- exclude cord pathology
Angiogram
Must do with arms abducted and by side
- will show compression of subclavian vein
NCS
- unhelpful as symptoms intermittent
- stimulus cannot be placed proximal to site of compression or irritation
- exclude CTS / cubital tunnel Syndrome
DDx
Cervical Disc (C8/T1) / spinal cord lesion
Ulna nerve entrapment
Shoulder pathology
Pancoast tumour
MS
Management
Non-operative
Explanation & reassurance
- shoulder girdle exercises
- posture improvement
- analgesia
Operative
Indications
10% of patients
- intolerable pain
- significant loss of function
- significant arterial or venous symptoms
Options
Resection of cervical rib
Scalenectomy
Resection first rib
Clavicular osteotomy
Complications
Chest
- pneumothorax
- empyema
Nerve injury
- phrenic nerve
- T1
Vessel injury
Recurrence of symptoms