Chapter 120 - TOS introduction Flashcards
Incidence of the three types of TOS
nTOS: 95%
vTOS: 3%
aTOS: 1%
Etiology of TOS subtypes
nTOS: neck trauma, fall, work related
vTOS: repetitive overhead shoulder movement, coagulopathy
aTOS: cervical rib, anomalous first rib, congenital band
Predisposing factor of TOS subtyes
nTOS: cervical rib, congenital band, scalene triangle muscle variation
vTOS: congenital narrowing of costoclavicular space by costoclavicular ligament or subclavian tendon
aTOS: cervical rib, anomalous first rib
Pathology of TOS subtype
nTOS: comperssion
vTOS: stenosis +/- thrombosis
aTOS: stenosis, thrombosis/aneurysm +/- thrombi
Symptoms of TOS subtypes
nTOS: pain, paresthesia, weakness, neck pain, occipital headache, Raynaud, chest pain (pec minor syndrome)
vTOS: arm swelling, cyanosis, pain
aTOS: pain, parethesia, pallor, coldness, digital ischemia, arm claudication, neck/shoulder symptoms
Physical finding of TOS subtypes
nTOS: positive response to provocative maneuvers, tenderness over scalene, pec minor
vTOS: arm swelling, cyanosis, pain
aTOS: decreased pulses, color change, ischemic tips and emboli
Diagnostic test for TOS subtypes
nTOS: duplex, scalene muscle block, MRI, pec minor block, EMG/NCV/MAC measurement
vTOS: duplex, venogram
aTOS: neck xray, duplex, arteriogram, digital pressure, arteriography
epidemiology of TOS
most 20-50 age
< 5% teen
10% > age 50
vTOS: female 70%
nTOS: 2:1 male more
Spaces of the thoracic outlet
1) Scalene triangle
2) costoclavicular space
3) pectoralis minor space
Brachial plexus origin
Nerve roots C5 to T1
Where does the brachial plexus form 3 trunks
in scalene triangle
Where does the brachial plexus form division and cords
proximal to pec minor space
Phrenic nerve origin
C4 mostly
some C3 and C5
Percentage of phrenic nerves that are single vs double or triple
87% single
Where does the phrenic descend in relation to anterior scalene
Later to medial 84%
remains lateral
Long thoracic nerve origin
C6 mostly
contribution from C5 and C7
Long thoracic nerve course
C5 and C6 go through middle scalene
C7 comes below middle scalene to join the other two branches
Dorsal scapular nerve origin
C5
Course of the dorsal scapular nerve
through the cephalic portion of middle scalene
descend lateral to muscle
Cervical sympathetic chain location
over transverse process of cervical vertebrae
close to origin of anterio and middle scalene
Variations of the scalene muscle
1) splitting anterior scalene around C5, C6 (21% of nTOS)
2) Scalene minimus muscle - from transverse process of lower cervical vertebrae runs in front of C8, T1 then behind subclavian artery –> inserts on first rib/sibson fascia (25-55%)
3) interdigitating muscle fibers - between anterior and middle scalene (75% of nTOS)
4) narrow vs wide scalene triangle (0.3-2.0 cm); nerve root emerg lower in wide triangle; nTOS have narrow triangle
5) congenital bands 63%
6) phrenic nerve: usually posterior to subclavian vein but 5-7% runs anterior (cause vTOS)
7) variation in medial position of subclavian vein close to costoclavicular ligament
Anomous first rib and cervical rib incidence and gender
0.76% and 0.74%
Female : male
7:3
Cervical rib connection with first rib
30% true joint
70% fibrous band
can line within middle scalene muscle
Scalene triangle boarders
Anterior scalene
Middle scalene
First rib
Costoclavicular space boarders
Clavicle
Subclavius muscle
Costoclavicular ligament
First rib
Pec minor space borders
pec minor
ribs of chest wall
(axillary compression syndrome)
rate of pec minor syndrome in recurrent nTOS
75%
First introduction of transaxillary first rib resection
1966 Roos
Pathologic finding in nTOS
1) development anomaly in TO with fibrosis of scalene
2) conversion of muscle from fast twitch to slow twitch
Physical examinations for nTOS
1) Adson test
2) elevated arm stress test (EAST, Roos test)
3) Modified upper limb tension test (Elvey test)
Adson test
1) palpate radial puls
2) extend, abduct and external rotate arm
3) rotate and lateral flex neck to ipsilateral side
4) positive test = decrease radial pulse
EAST/Roos test
1) seated with arms abducted 90 degree in external rotation
2) elbow flex at 90 degree
3) head in neutral position
4) open close hand x 3 min
if able to perform then high NPV for nTOS
Elvey test
1) abduct both arms 90 degree with elbow extended
2) dorsiflex both wrist
3) positive if symptoms on ipsilateral side
4) flex neck on each side
5) test positive if symptoms on contralateral side
Key points about Adson test
only objective test
50% normal individuals test positive anyway
Anterior scalene muscle block
Injection with 1% lidocaine into the anterior scalene muscle
First description of Paget-Schroetter syndrome
Paget 1875
von Schroetter 1884
McCleery syndrome
symptoms characteristic of vTOS without venous thrombosis
Characteristics of VTOS
primary thrombosis of the axillo-subclavian vein secondary to compressive symptoms from thoracic outlet pathology
Percentage of vTOS that have first rib fractures
43%
Rate of pulmonary embolism in nTOS with DVT
12%
vTOS symptoms and frequency
1) arm swelling 93%
2) cyanosis 77%
3) pain with exercise 66%
4) minimal symptoms 8%
Duplex for vTOS sen and spe
Sen 78-100%
spe 82-100%
must do with provocative maneuvers
Anomalies in aTOS and frequency
1) cervical rib 60%
2) anomalous first rib 18%
3) fibrocartilaginous band 15%
4) clavicular fracture 6%
5) enlarged C7 transverse process 1%
False negative rate of conventional angio in diagnosing aTOS
32% in supine position
Rate of coexisting nTOS with aTOS
5%
Medial antebrachial cutaneous (MAC) nerve
lowest branch of inferior trunk of the brachial plexus
most sensitive to compression
