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Thoracic outlet syndrome (TOS) is a broad term that refers to
compression of the neurovascular structures in the area just
above the first rib and behind the clavicle.
The brachial plexus (95%), subclavian vein (4%), and subclavian
artery (1%) are affected.
two basic types of TOCS and four subtypes
The two basic types are vascular and neurogenic.
The vascular type is further divided into arterial and
The neurogenic type has been subdivided into "true“
neurogenic and non specific
Neurogenic TOS accounts for more than 90%
of all TOS cases, whereas vascular TOS
constitutes 3% to 4% of all cases.
Most TOS cases are seen in adults between the ages of 20 and 50 years.
Vascular TOS is seen equally in nonathletic men and women,
but neurogenic TOS is three to four times more likely to occur in women than in men.
the most important of these passageways is the interscalene triangle,
which is also the most proximal.
this triangle is bordered by
the anterior scalene muscle anteriorly,
the middle scalene muscle posteriorly,
and the first rib inferiorly.
this area become smaller with certain provocative maneuvers.
anomalous structures, such as fibrous bands, cervical ribs, and
anomalous muscles, may constrict this triangle further.
contains the vast majority of neurovascular compression cases
It is crossed by
Subclavian artery (which occupies the floor of space)
Three trunks of brachial plexus (upper, middle & lower)
Subclavian vein runs beneath the anterior scalene muscle and doesn’t cross
the costoclavicular triangle, bordered
anteriorly by the middle third of the clavicle,
posteromedially by the first rib,
posterolaterally by the upper border of the scapula.
Contains subclavian artery, vein & 3 cords of brachial plexus
The retropectoralis space lies inferior to the coracoid process beneath the
pectoralis minor tendon.
Same except the cord divides into 5 terminal branches
Cervical rib-usually arises from the seventh cervical
vertebra. and rarely c6.Usually symmetrical on two sides,
sometimes assymetrical and rarely unilateral. more
common in females. It is relationship of neurovascular
bundle structure with cervical rib that may cause
Fisrt thoracic rib – a first thoracic rib can cause
compression if it is unusually high, large or irregularly
A deformed thoracic outlet as a result of sloping shoulders ,scoliosis and
fracture of first rib can also compress the neurovascular structures
against the first rib.
Clavicle – clavicle along with subclavius muscle forms the
anterior wall of cevicoaxillary passage.
normally clavicle is curved forwards in its medial 2/3.congenital
flattening or malunion cause narrowing of this passage and compression
Congenital malformations- associated conditions
Klippel feil syndrome
Scalenus anterior – hypertrophy of the muscle due to shouldr descent ,
spasm of the muscle due to mild irritation of brachial plexus holds the
first rib higher and thus cause narrowing of scalenic hiatus
Scalenus medius- hypertrophy , spasm and abnormal insertion on first
rib or its fusion with anticus can cause narrowing of scalenic hiatus
Pectoralis minor- persons working with the arms hyperabducted or sleeping
with the arms over the head develop paresthesia as a result of compression of
neurovascular bundle by pectoralis minor and coracoids
Tight omohyoid muscle- this is important in long necked people causing
compression of brachial plexus,as it may run diagonally across brachial plexus
Congenital fibromuscular bands are noted in as many as 80% of patients with
Trauma or repetitive activities
Motor vehicle accident hyperextension injury, with subsequent fibrosis and scarring
Effort vein thrombosis (ie, spontaneous thrombosis of the axillary veins following
vigorous arm exertion)
Playing a musical instrument: Musicians can be particularly susceptible owing to
their need to maintain the shoulder in abduction or extension for long periods
Neurologic symptoms occur in 95% of cases. The lower 2 nerve roots of the
brachial plexus, C8 and T1, are most commonly (90%) involved, producing
pain and paresthesias in the ulnar nerve distribution.
The second most common anatomic pattern involves the upper 3 nerve roots
of the brachial plexus, C5, C6, and C7, with symptoms referred to the neck,
ear, upper chest, upper back, and outer arm in the radial nerve distribution.
Pain, particularly in the medial aspect of the arm, forearm, and the ring and small digits
Paresthesias, often nocturnal, awakening the patient with pain or numbness
Raynaud phenomenon, hand coldness, and color changes may also be seen, usually due to an
overactive sympathetic nervous system as opposed to ischemia.
Most have a history of neck trauma preceding their symptoms, most commonly from auto
accidents and repetitive stress at work.
Often in young adults with a history of vigorous arm activity
Symptoms usually develop spontaneously from arterial emboli
Easily fatigued arms and hand
Pain, often in younger men and often preceded by excessive activity in the
Swelling of the arm
Paresthesias in the fingers and hand (may be secondary to swelling as opposed to
Superficial vein distensions
Paget schroetter syndrome
Neurogenic TOS is classically associated
with certain provocative tests,
venous collaterals in left anterior chest in a patient with
subclavian thrombosis (Paget-
Cervical radiography - May demonstrate a skeletal abnormality
Cervical or first rib: This is usually associated with the arterial form of TOS but also
can be a predisposition to developing the neurologic form following neck trauma.
Color flow duplex scanning for suspected vascular thoracic outlet syndrome (TOS)
Evidence of peripheral emboli in the upper extremity
Suspected subclavian stenosis or aneurysm (eg, bruit or abnormal supraclavicular pulsation)
Blood pressure differential greater than 20 mm Hg
Obliteration of radial pulse during EAST
Persistent or intermittent edema of the hand or arm
Peripheral unilateral cyanosis
Prominent venous pattern over the arm, shoulder, or chest
Nerve conduction evaluation via root stimulation and F wave is the best direct approach to evaluation of
Cervical myelogram, CT scan, or MRI may be appropriate for patients suspected
of having cervical disk disease or spinal cord disease.
In majotiy of pts conservative management will effect in improvement or
complete relief of symptoms
Initial management consists of
Exercise programme directed towards improving posture,strengthening
shoulder muscles and avoiding hyperabduction
The goal of self stretching is to relieve compression in the thoracic cavity,
reduce blood vessel and nerve impingement, and realign the bones, muscles,
ligaments, and tendons causing the problem.
Moving shoulders forward (hunching) then back to neutral, followed by extending
them back (arching) then back to neutral, followed by lifting shoulders then back
Tilting and extending neck opposite to the side of injury while keeping the
injured arm down or wrapped around the back.
Injected into a joint or muscle, cortisone can help relief and lower
Short for Botulinum Toxin A, Botox binds nerve endings and prevents the
release of neurotransmitters that activate muscles. A small amount of Botox
injected into the tight or spastic muscles (usually one or all three scalenes)
found in TOS sufferers often provides months of relief while the muscle is
Pectoralis minor tenotomy
Ideal for removal of a cervical rib or a fibrous remanant and allows inspection
Idael for venous and arterial obstruction
Video assisted thorasic surgery
First rib resection