neurological & vascular symptoms & signs in the upper limbs
produced by compression of the lower trunk of the brachial plexus & subclavian vessels between the clavicle & the most proximal rib
Anatomy
both the subclavian artery and the brachial plexus traverse between the anterior & middle scaleni muscles
base of the triangle is the 1st rib
even under N circumstances these NV structures bend acutely when the arm rest at the side
an extra rib (cervical rib) or fibrous equivalent, anomalous scalene muscle sharpens the angle
in some cases, thoracic outlet syndrome will be accentuated by recurrent anterior shoulder instability, and this may be the cause of the “dead arm syndrome”
Diagnosis
History
anomalies are all congenital
yet symptoms are rare before the age of 3O
with declining youth, the shoulders sag, increasing the bend of the NV bundle
indeed drooping shoulders alone may cause the syndrome
Clinical features
no general symptoms or neck symptoms
usually a female in her 30, may complain of
Symptoms
pain and/or paraesthesia in the ulnar forearm & hand
worse after household chores or after carrying shopping
weakness or clumsiness
excessive sweating, or blueness & coldness of the fingers
a female, the patient is often long-necked with sloping shoulders (like a Modigliani painting)
if a male, he is more likely to be thick-necked and muscular
Signs
lump (the abnormally elevated subclavian artery) may be palpable above the clavicle
pulsates, tender and pressure on it may increase symptoms
wasting of the interosseous and hypothenar muscles
weakness of the intrinsics
reflexes are usually normal
sensation may be diminished in the C8 and T1 distribution
vascular signs are uncommon
may be cyanosis and increased sweating
Special tests
used for pulse obliteration or provoke symptoms
Roos test
pulse fades when the arm is elevated to 90 degrees and externally rotated while the neck is turned to the opposite side
in another the same effect is produced by pulling the arm downwards and backwards while pushing the neck away
Neck and shoulder
movements are normal
excluding a diagnosis of cervical disc disease or musculo-tendinous cuff disorder
X-ray
may show a 'long' neck - i.e. the first thoracic vertebra stands clear in views of the cervical spine
occasionally a well-formed cervical rib, but more often just an enlargement of the transverse process of C7
CXR to rule out pancoast tumor
Differential diagnosis
Cervical spine lesions
In disc prolapse or spondylosis, pain is more vaguely distributed
neck movements are limited
in tuberculosis and secondary deposits the x-ray appearance is characteristic
Carpal tunnel syndrome
spina bifida occulta 30-70% with isthmic, 40% with dysplastic ~
many cases were wrongly called cervical rib syndrome
even when x-rays show a rib, the symptoms may still be due to median nerve compression in the carpal tunnel
nocturnal pain and its distribution are characteristic
Ulnar tunnel syndrome
symptoms and signs are sharply confined to the distribution of the ulnar nerve
the neck is unaffected
Pancoast syndrome
apical carcinoma of the bronchus may infiltrate the structures at the root of the neck, causing pain, numbness and weakness of the hand
hard mass may be palpable in the neck
x-ray of the chest shows a characteristic opacity
Spinal cord lesions
syringomyelia or other spinal cord lesions may cause wasting of the hand
other neurological features establish the diagnosis
Cuff lesions
with supraspinatus tendon lesions pain sometimes radiates to the arm and hand
shoulder movement is abnormal and painful
Treatment
Conservative
most patients managed
exercises to strengthen the shrugging muscles, postural training and instruction in ways of preventing shoulder droop or muscle fatigue
analgesics when necessary
Operative treatment
indicated
pain severe
muscle wasting is obvious
vascular disturbances
thoracic outlet is decompressed by removing the first rib (or the cervical rib)
best accomplished by the transaxillary approach, but care must be taken to prevent injury to the brachial plexus and subclavian vessels, or perforation of the pleura (Roos, 1966)