Thoracic Outlet Syndrome Flashcards
What is TOS?
Constellation of symptoms that occur from compression of the neurovascular bundle
What is usual age of onset?
20-50
Is there a sex predominance? Why?
70% are female
likely because 70% of cervical rib happen in women
Which form of TOS is most common? Least common?
nTOS 95%
aTOS <1%
What injuries cause nTOS?
hyperextension injury, whiplash, repetitive stress injury, falls
What are anatomical predisposing factors for nTOS? (3)
Cervical rib
Congenital band
Scalene triangle muscle variations
What are the histopathological findings in nTOS? (4)
Predominance of Type I muscle fibers (slow twitch)
Endomysial fibrosis (thickened tissue around individual muscle finer)
2fold increase in CT
Mitochondrial abnormalities
What is the usual composition of type I and II muscle fibbers?
usually 50% each but become 80% in nTOS
What are symptoms of nTOS? (5)
Extremity pain
paresthesia
weakness + neck pain and occipital headache
raynaud’s
CP for pec minor syndrome
Why remove the first rib in nTOS?
Prevents lower trunk of plexus from getting fixed to the rib with scarring
How does a neck injury cause nTOS?
Underlying narrowed scalene triangle
Asympto until neck trauma tears scalene muscle
Swelling and bleeding result in swelling, scarring and compression
How many patients with nTOS have a predisposing neck injury?
>80%
What is the double crush syndrome?
get distal neurapathy from proximal axonal injury
What is the treatment for nTOS?
Conservative therapy is physical therapy for 4-6weeks
If fails then surgical approach
What are findings of nTOS on CT/MRI?
negative findings support diagnosis of nTOS
What can findings be on EMG for nTOS?
usually negative
What is necessary for diagnosis of nTOS?
Physical findings
What is the path of the phrenic nerve?
lateral border of scalene, passes lateral to medial as it descends along anterior surface of the scalene, then passes behind the subclavian into the mediastinum
What is the path of the long thoracic nerve?
passes through the belly of the middle scalene where the components form a single nerve
what does the long thoracic nerve supply? what happens if you injure the nerve?
serratus anterior, winged scapula
what proportion of patients have abnormal scalene anatomy?
2/3
What syndrome can develop in long-standing severe nTOS?
complex regional pain syndrome type I
What are symptoms of CRPS-I
persistent vasospasm, disuse edema, extreme hypersensitivity
What investigations to do for nTOS?
CXR, CT/MRI, EMG
What can you do to see if patient will respond to surgical decompression?
Scalene muscle block
What are some differential diagnoses for nTOS?
Carpel tunnel syndrome, ulnar nerver compression, rotator cuff tendonitis, cervical spine strain, fibromyositis, cervical disk disease, cervical arthritis, brachial plexus injury
What are advantages/disadvantages for transaxillary approach for nTOS?
cosmetic incision, adequate to remove first rib
incomplete exposure of scalene triangle, limited for vascular reconstruction
What are advantages/disadvantage of supraclavicular approach?
wider exposure, compete resection of scalene muscles, direct visualization of nerve roots, vascular reconstruction
first rib resection may need additional incision
What are complications after decompression for nTOS?
pneumothorax 10%
phrenic 10% (usually asymptote)
other nerve injuries
lymph leak
similar for either approach
What is the adson test for aTOS?
Adson’s sign is the loss of the radial pulse in the arm by rotating head to the ipsilateral side with extended neck following deep inspiration. for nTOS
Many false positives
90 degree abduction in external rotation hold for 3 mins. This will elicit symptoms usually within 60s
What is the elveys test for nTOS?
for nTOS
Arms out then flex hand then tilt head contra to illicit symptoms.. negative test usually can rule out nTOS and a positive usually indicates compression along the nerve
how many patients have cervical rib in nTOS?
5%, gen pop 1.5%
What bony abnormalities does aTOS have?
cervical ribs 63%, anomalous 1st rib?, fibrocart band 10%
What segment of the subcalvian is usually compressed?
thrid segment and get post-stenotic dilation
What are the symptoms in aTOS?
hand schema from micro emboli most common manifestation
exertional pain, raynauds, retrograde extension of thrombus rare but can cause stroke
what is the pe in aTOS?
Bilateral BP, bruits in supraclavicular fossa, bruit with shoulder abduction or overhead, papable cervical rib, pulsatile supraclavicular mass, splinter hemorrages, digital ischemia
What maneuvers to diagnose aTOS?
adson Take long deep breath elevate chin and trun head to affected side with patient seated upright with arms resting on knees. Positive result occurs with ablation of radial pulse
Abduction-external rotation (elevated arm stress)
Externally rotates and abducts arms greater then 90 degrees
Devel of hand pain or paresthesias within 60 is positive result
This is diagnostic for nTOS
What will NIVS show in aTOS?
Duplex
High peak velocities, aneuryms, intimal disruption
Clavicle may interfer
Arm abduction to 130 while imaging costoclavicular space is most discriminating technique
what is the rate of bilat aTOS?
10-25%
what is treatment for aTOS?
no role for medical
anticoag role unknown
What are the three components of surgical treatment in aTOS?
relieve arterial compression
remove cervical rib, first rib and scalene to avoid recurrence
Remove source of emboli
aneurysm, thrombus
restore distal circulation
what is the classification for anatomical findings of aTOS?
Scher
0 asympto no tx
I stenosis with mini post stenotic dilations. no intimal disruptio. needs decompression of TO
II aneurysm with intimal damage and mural thrombus. decompression of TO with subclavian artery reconstruction
III distal embolization from subclavian pathology. needs thrombolysis or thrombectomy, decompression, vascular reconstruction`
Why do we remove first rib in a TOS?
allows neruvasc bundle to relax downward
common insertion fro fibromuscula structures
What surgical approaches for aTOS?
transax not adequate for vascular reconstruction
supraclavicular
what are outcomes of surgical repair of aTOS?
90% symptom relief
bypass patency 90-100%
no mortality
What are complications for aTOS?
pneumo, hem, chylous leak, brachial plexopathy, vascular injury, injury to phrenic or long thoracic
cervical sympathetic chain injury uncommon but can give horners
What is vTOS?
thrombosis or severe narrowing of subclav-ax vein secondary to extrinsic compression
effort thromosis as usually young healthy individiauls who engage in repetitive shoulder motion
What elements contribute to vTOS compression?
first rib, clavicle with associated subclavius muscle and fibrous costocoracoid ligament , anterior scalene and tubercle
alternating inflammation, perivenous fibrosis, endothelial injury, stasis, thrombosis
may have no abnormality of structure or may have anomalies of ant scalene, subclavius, pec minor, scalenus minimus, bony abnormalities of clavicle, rib and ligementous abnorm of costocoracoid ligament
what is mean ge of onset for vTOS?
32
What is the order of common to least common TOS?
n
v
a
What are the clinical features of vTOS?
Upper arm edema hallmark (93%)with subclavian vein thrombosis
Can be accompanied by pain and cyanosis (77%)
Edema usually involves shoulrder and is non pitting
Dilated superficial veins neck chest wal
Pain described as aching, stabbing or tight
Worse with exertion
Ahing with exeriese 66%
Venous hypertension and worsening of smptoms
What are rare but bad complications of vTOS?
Bad complications include PE <12% and phlegmasia cerulea dolens
What investigations for vTOS?
B mode Low sensitivity high specificity for thrombosus
Color flow increased sensitivy 80-100% and specificity 80-100%
Venography
how do you perform venography?
Gold standard
Puncture basilic vein
Cephalic may not be adequate as it often drains directly into the subclavian
Full addcution then in 90degree of abduction with external rotation (hand on head)
Collaterization can mean that it is chronic situation
What are tx strategies for vTOS?
classic rest/elevation and antocoag. 40% persia symptoms with morbidity
thrombi therapy. 82-100% success. need within 14 d
surgical decompression
how do you do thrombi therapy in vTOS?
tpa, trellis peripheral infusion system, anjiojet
Angiojet high-pressure injection with simultaneous aspiration eddy creation aids in clot maceration
Trellis multilumen catherter with two compliant balloons and distal end and infusion holes b/w balloons. Oscillating wire macerates the clot then it is aspirated through the catherter lumen
if thrombolysis unsuccessful, then what?
warfarin for 3-6 months if no compression
if compression then surgery or 3-6 months anticoagulation
what are role of stents in vTOS?
no role radial force inadequate to overcome compression
what surgical approaches for vTOS?
paraclavicular
infraclavicular
transaxillary
What are the border of the scalene triangle?
anterior scalene (ant) middle scalene (post) first rib (inf)
What are the borders of the costoclavicular border and why is this space important?
subclavius muscle and clavicle (ant)
first rib (post)
scapula (post)
site of compression of subclavian vein
What is the third space near the TO? What are the borders?
What passes in this location?
What can narrow this space?
the subcoracoid space
coracoid process and pec minor
the neruovascular bundle b/w them
tight band of clavipec fascia or costocoracoid ligament or hypertrophy of the pec min can narrow this space
What are four anatomical disadvantages to axillary approach?
T1 prone to injury
subclavian vein prone to injury
congenital fibromuscular bands are medial to first rib and hidden by neurovasc trunk
can correct arterial pathology
What are important nerves that relate to TOS?
brachial plexus (C5-T1 become 3 trunks in scalene triangle)
Phrenic nerve (C3-5)
Long thoracic nerve (C5-7, muscel belly of middle scalene)
Dorsal scapular nerve (C5, cephalic portion of middle scalene)
Cervical sympathetic chain (usually not inoperative field, near origin of ant/mid scalene, cautery can injure)
Name 7 abnormalities of the scalene triangle.
splitting of the anterior scalene (C5-C6)
scalene minimus muscle
interdigitating muscel fibers (b/w AS and MS)
narrow triangle
congenital bands
phrenic nerve runs anterior to vein
vein lies more medial and compressed by costoclav ligament
Where is the compression in pec minor syndrome?
subcoracoid space
What is the aetiology of pec minor syndrome?
activities they hyperabduct the shoulder and stretch PM muscle
PM attached to coracoid process
tight PM comporesees the branches of BP and axillary vessels
What are symptoms of pec minor?
pain neck, trap, shoulder
ant portion of chest
tenderness of PM insertion
What is PM syndrome diagnosis?
PM muscle block
may co-exist with nTOS
if PM block insufficient, then Scalene block.
What is PMS treatment?
physio, avoid hyperabd exercises
surgical treatment
divide PM at coracoid process and excise 2-3 cm of muscle
