Thoracic Outlet Syndrome (TOS)

Thoracic Outlet Syndrome (TOS)

Thoracic outlet syndrome (TOS) คือกลุ่มอาการที่เกิดจาก compression ของ neurovascular bundle บริเวณ thoracic outlet เหนือ first rib และหลัง clavicle โดยแบ่งตาม structure ที่ถูกกดทับเป็น:

• Neurogenic TOS (nTOS) → brachial plexus compression
• Venous TOS (vTOS) → subclavian vein compression
• Arterial TOS (aTOS) → subclavian artery compression

nTOS พบมากที่สุด >95% ของ cases

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Anatomy ที่สำคัญ

Thoracic outlet มี 3 major compression spaces

1. Scalene triangle (สำคัญที่สุด)

เป็น site ที่พบบ่อยที่สุดของ brachial plexus compression

Contents:

• brachial plexus trunks
• subclavian artery

Borders:

• anterior scalene
• middle scalene
• first rib

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2. Costoclavicular space

ระหว่าง:

• clavicle
• first rib

มัก compress:

• subclavian vein

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3. Pectoralis minor space

แม้ technically ไม่ใช่ thoracic outlet แต่ compression พบได้บ่อย

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Pathogenesis

เกิดจาก combination ของ:

• congenital abnormalities
• repetitive trauma
• muscular hypertrophy
• postural/mechanical stress

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Important Predisposing Factors

Bony abnormalities

Cervical rib

สัมพันธ์กับ TOS มากที่สุด

Important facts

• bilateral ได้
• female predominance
• predispose หลัง whiplash injury

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Fibrous bands

fibrocartilaginous band จาก cervical rib → compress lower trunk

เป็น pathology สำคัญใน “true neurogenic TOS”

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Muscular abnormalities

• scalene hypertrophy
• anomalous scalene insertion
• fused scalene muscles
• pectoralis minor hypertrophy
• subclavius variation

พบบ่อยใน:

• athletes
• weight lifters

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Acquired causes

• whiplash injury
• clavicle fracture
• first rib fracture
• repetitive overhead activity
• pitching/swimming
• repetitive occupational movement

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Clinical Evaluation

ต้องประเมินทั้ง:

• neurologic system
• vascular system

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Important Clinical Pearl

Adson test

specificity ต่ำ
false positive สูง

ไม่ควรใช้ยืนยัน diagnosis

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Neurogenic TOS (nTOS)

พบบ่อยที่สุด

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Symptoms

Typical symptoms

• pain
• dysesthesia
• numbness
• weakness

distribution มักไม่ตรง peripheral nerve เดียว

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Symptoms aggravated by:

• overhead activity
• arm elevation
• typing
• driving
• holding phone
• brushing hair

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Provocative maneuvers

อาจ reproduce symptoms:

• neck rotation
• head tilt
• arm abduction
• external rotation
• upper limb tension test

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Severe/Chronic nTOS

พบ:

• intrinsic hand weakness
• thenar > hypothenar atrophy
• T1 sensory symptoms

reflect lower trunk plexopathy

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Venous TOS (vTOS)

~3% ของ TOS

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Risk group

• repetitive overhead exertion
• athletes

เช่น:

• baseball
• swimming
• weight lifting

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Symptoms

• arm swelling
• cyanosis
• heaviness
• pain
• forearm fatigue
• venous collateral pattern

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Key syndrome

Paget-Schroetter syndrome

= spontaneous effort thrombosis ของ subclavian vein

hallmark ของ vTOS

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Arterial TOS (aTOS)

พบน้อยที่สุด (~1%)

Almost always associated with:

• cervical rib
• anomalous rib

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Symptoms

Distal ischemia

• pain
• pallor
• paresthesia
• coldness

เกิดจาก:

• thromboembolism
• subclavian aneurysm thrombosis

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Important Differential

ใน young female:

• distinguish from Raynaud phenomenon

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Physical Findings

• diminished pulse
• BP asymmetry
• bruit/thrill
• ischemic fingers
• supraclavicular pulsatile mass

Unlike nTOS:

• scalene tenderness absent
• provocative maneuvers usually negative

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Diagnosis

nTOS

Diagnosis difficult เพราะ objective tests sensitivity ต่ำ

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Electrodiagnostic testing

ควรทำใน suspected nTOS

Findings specific but insensitive

ส่วนใหญ่ EMG อาจ negative

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Scalene muscle block test

Inject local anesthetic into anterior scalene

Positive test:

symptoms improve

ช่วย predict surgical success

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Society for Vascular Surgery Criteria

ต้องมี ≥3/4:

1.       symptoms at thoracic outlet

2.       signs of nerve compression

3.       no alternative diagnosis

4.       positive scalene block

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Imaging

Chest X-ray

essential to detect:

• cervical rib
• anomalous rib
• clavicle callus

absence of rib anomaly → makes aTOS unlikely

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Duplex ultrasound

First-line for:

• vTOS
• aTOS

Useful for:

• stenosis
• occlusion
• positional compression

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CT angiography / venography

excellent anatomy detail:

• vascular compression
• relationship to bone/muscle

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MRI / MR neurogram

Useful for:

• brachial plexus compression
• vascular imaging

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Dynamic angiography/venography

Useful in:

• provocative maneuvers
• thrombolysis planning

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Management

Neurogenic TOS

First-line = conservative treatment

อย่างน้อย 4-6 weeks:

• PT
• posture correction
• strengthening
• weight reduction

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Medical therapy

มีการใช้:

• local anesthetic injection
• steroid injection
• botulinum toxin

แต่ evidence จำกัด

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Venous TOS

Preferred treatment

catheter-directed thrombolysis

best outcomes ถ้าทำภายใน 2 weeks

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Important Pearl

หลัง thrombolysis:
persistent compression มักยังอยู่

ดังนั้น:

• definitive decompression surgery มักจำเป็น

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Arterial TOS

ถ้ามี:

• acute ischemia
• embolization
• aneurysm

→ urgent vascular surgery ± thrombolysis

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Thoracic Outlet Decompression Surgery

Indications

Always consider in:

• symptomatic vTOS
• symptomatic aTOS

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nTOS surgery only selected cases

เช่น:

• progressive weakness
• disabling pain
• failed conservative treatment

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Surgical Approaches

Approach	Advantages
Transaxillary	good rib exposure
Supraclavicular	vascular reconstruction/neurolysis
Infraclavicular	excellent venous exposure
Robotic/VATS	minimally invasive

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Outcomes

nTOS

• improvement common
• recurrence possible
• long-term success declines over time

Factors predicting poor outcome:

• depression
• chronic symptoms
• work injury
• diffuse symptoms
• negative scalene block

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vTOS

best surgical outcomes

5-year secondary patency >95%

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aTOS

excellent/good outcomes >90%

แต่ distal embolization worsens prognosis

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Key Clinical Pearls

• nTOS = >95% ของ TOS
• True neurogenic TOS = lower trunk plexopathy from fibrous band/cervical rib
• Overhead activity aggravates nTOS
• Paget-Schroetter syndrome = effort thrombosis from vTOS
• aTOS almost always associated with cervical rib
• Adson test unreliable
• Duplex US = first-line vascular imaging
• EMG often negative in nTOS
• Conservative treatment first-line for nTOS
• vTOS/aTOS มักต้อง surgical decompression

 

Burner / Stinger Syndrome

Burner / Stinger Syndrome

Burner หรือ Stinger syndrome คือ transient upper extremity nerve injury จาก traction/compression ของ upper trunk brachial plexus หรือ C5-C6 nerve roots พบมากใน contact sports โดยเฉพาะ football และ rugby

อาการส่วนใหญ่มัก transient แต่ recurrent injury พบได้บ่อย และบางรายมี prolonged weakness หรือ chronic symptoms ได้

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Pathophysiology

Main lesion

ส่วนใหญ่เป็น:

• upper trunk brachial plexopathy
  หรือ
• C5/C6 radiculopathy

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Mechanisms of Injury

1. Traction injury (พบบ่อย)

เกิดเมื่อ:

• shoulder depressed
• neck bent away from affected side

→ brachial plexus stretch

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2. Direct blow

กระแทก supraclavicular fossa โดยตรง

→ percussive injury to upper trunk

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3. Compression injury

เกิดจาก:

• neck hyperextension
• ipsilateral lateral flexion/rotation

→ foraminal narrowing + root compression

มักสัมพันธ์กับ:

• chronic/recurrent burners
• higher-level athletes

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Peripheral Nerve Injury Classification

Grade I — Neurapraxia

• demyelination only
• axon intact
• recovery usually <3 weeks
• EMG often normal

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Grade II — Axonotmesis

• axonal injury
• Wallerian degeneration
• EMG abnormal after 2-3 weeks

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Grade III — Neurotmesis

• complete transection
• rare in sports

Burners ส่วนใหญ่เป็น Grade I-II

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Epidemiology

พบบ่อยใน:

• American football
• rugby
• wrestling
• hockey
• gymnastics

Recurrence สูงมาก

• recurrent burners ~20-80%

ผู้เล่นหลายคนไม่รายงานอาการ

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Clinical Features

Classic Presentation

หลัง collision/contact:

• sudden burning pain
• radiates down arm
• non-dermatomal pattern

อาจมี:

• numbness
• paresthesia
• transient weakness

ส่วนใหญ่หายภายใน:

• minutes
• occasionally hours

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Important Historical Clues

ถาม:

• exact mechanism
• duration
• recurrence
• weakness persistence
• bilateral symptoms
• neck pain

Recurrent burners

คิดถึง:

• cervical stenosis
• chronic compression

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Physical Examination

Inspection

Acute phase:

• athlete shaking arm
• arm held against body

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Atrophy

Chronic/recurrent cases:

• deltoid atrophy
• supraspinatus atrophy
• shoulder depression

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Red Flags on Exam

NOT typical for simple burner

• focal cervical tenderness
• bilateral symptoms
• lower extremity symptoms
• altered mental status
• persistent neurologic deficit

→ evaluate cervical spine/spinal cord urgently

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Spurling Test

positive → supports cervical root compression

Important point

high specificity but low sensitivity

Negative test does NOT exclude radiculopathy

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Weakness Pattern

ส่วนใหญ่ involve C5-C6 muscles

Common muscles to test

Muscle	Nerve	Root
Deltoid	Axillary	C5-6
Supraspinatus	Suprascapular	C5-6
Infraspinatus	Suprascapular	C5-6
Biceps	Musculocutaneous	C5-6
Pronator teres	Median	C6-7
Triceps	Radial	C7-8
ADM	Ulnar	C8-T1

ADM: abductor digiti minimi

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Important Clinical Pearls

• weakness อาจ delayed several hours-days
• subtle weakness อาจ missed ใน strong athletes
• compare both sides carefully

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Diagnosis

Usually clinical diagnosis

Most cases:

• no imaging needed
• no EMG needed

หาก symptoms transient และ rapidly improving

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Indications for Further Workup

Imaging indicated if:

• severe neck pain
• focal cervical tenderness
• limited ROM
• persistent weakness
• recurrence
• bilateral symptoms
• slow recovery

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Imaging

Plain cervical radiographs

รวม:

• AP
• lateral
• oblique
• flexion/extension views

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MRI cervical spine

best for:

• disc
• nerve root
• spinal cord

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CT

better for:

• spinal stenosis
• bony injury

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Electrodiagnostic Studies

EMG/NCS useful for:

• localization
• severity
• prognosis

Findings:

• fibrillation potentials
• prolonged latency
• conduction delay

Timing

ควรทำเมื่อ symptoms >3 weeks

เพราะ early EMG อาจ normal

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Differential Diagnosis

Serious causes to exclude

• cervical fracture
• cervical dislocation
• spinal cord injury
• shoulder dislocation
• clavicle fracture
• cervical radiculopathy

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Management

Main principles

• symptom resolution
• prevent recurrence
• correct risk factors

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Rehabilitation

Goals

1.       restore pain-free ROM

2.       strengthen neck/shoulder

3.       improve posture

4.       correct sports technique

Important posture

“Chest-out posture”
ช่วย:

• open foramina
• reduce root compression
• reduce scalene pressure

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Protective Equipment

May help reduce recurrence:

• neck roll
• Cowboy collar
• Kerr collar
• custom orthosis
• high-riding shoulder pads

Avoid

helmet-to-shoulder tether straps (unsafe)

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No Role For

• nerve block
• steroid injection

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Return-to-Play Criteria

ต้องมีทั้งหมด:

• complete symptom resolution
• full painless ROM
• full strength
• normal function

Do NOT return if:

• persistent neurologic deficit
• recurrent symptoms during practice

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Important EMG Pearl

EMG abnormalities อาจอยู่ได้นานหลัง symptoms หาย

ดังนั้น:

• ไม่ใช้ EMG normalization เป็น criteria for return-to-play

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Prognosis

Usually good

ส่วนใหญ่ recover completely

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But recurrence common

• recurrence สูงมาก
• chronic symptoms possible

Persistent symptoms → avoid contact sports

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Prevention

Key strategies

• improve neck flexibility
• strengthen shoulder/neck
• optimize tackling technique
• posture correction
• protective equipment

Screening cervical radiographs:

• NOT routine

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Key Pearls สำหรับแพทย์

• Burner = transient upper trunk brachial plexopathy/C5-6 injury
• Burning pain radiating down one arm after contact sport
• Most recover within minutes-hours
• Persistent weakness → evaluate carefully
• Bilateral symptoms or cervical tenderness = spinal cord injury until proven otherwise
• Recurrent burners → consider cervical stenosis
• EMG useful only after ~3 weeks
• Return to play only after full neurologic recovery
• Recurrent injury common

 

Brachial Plexopathy (Brachial Plexus Syndromes)

Brachial Plexopathy (Brachial Plexus Syndromes)

Brachial plexopathy คือความผิดปกติของ brachial plexus ซึ่งอาจเกิดจาก trauma, inflammation, neoplasm, radiation, compression, metabolic disease หรือ iatrogenic injury โดยอาการมักเป็น combination ของ pain + weakness + sensory deficit ใน distribution ที่ไม่ตรงกับ single root หรือ single peripheral nerve ชัดเจน

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Anatomy ที่สำคัญทางคลินิก

Brachial plexus roots

เกิดจาก ventral rami ของ C5-T1

Trunks

• Upper trunk = C5-C6
• Middle trunk = C7
• Lower trunk = C8-T1

Cords

• Lateral cord
• Posterior cord
• Medial cord

Major terminal nerves

• Musculocutaneous
• Axillary
• Radial
• Median
• Ulnar

Important branch nerves

• Long thoracic nerve → serratus anterior
• Suprascapular nerve
• Dorsal scapular nerve

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Pathophysiology

Mechanisms

• Compression
• Traction injury
• Root avulsion
• Ischemia (vasa nervorum)
• Inflammation
• Radiation injury
• Tumor infiltration
• Metabolic injury (เช่น diabetes)

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Clinical Features

Typical symptoms

Acute onset

มักเป็น:

• severe shoulder/upper arm pain
• followed by weakness

มักสัมพันธ์กับ:

• inflammatory
• ischemic
• neuralgic amyotrophy
• trauma

Chronic progressive

คิดถึง:

• neoplasm
• radiation-induced plexopathy
• thoracic outlet syndrome

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Physical Examination

Motor

• weakness
• muscle atrophy
• scapular winging
• reduced reflexes

Sensory

• patchy sensory loss
• non-dermatomal distribution

Important clues

Horner syndrome

คิดถึง:

• lower trunk lesion
• Pancoast tumor

Scapular winging

long thoracic nerve involvement

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Localization Clues

Pattern	Suggest lesion
Shoulder abduction/external rotation weakness	Upper trunk
Hand intrinsic weakness	Lower trunk
Median + ulnar involvement together	Plexus lesion
Normal paraspinal EMG	Plexopathy มากกว่า radiculopathy
Sensory NCS abnormal	Postganglionic lesion (plexus)

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Diagnostic Workup

Electrodiagnostic studies

Nerve conduction studies (NCS)

ช่วย:

• distinguish plexopathy vs radiculopathy
• detect sensory involvement
• localize lesion

Key point

Sensory NCS abnormal → supports plexopathy
(radiculopathy มัก sensory SNAP (nerve action potential) preserved)

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Needle EMG

เป็น test ที่ sensitive ที่สุดต่อ axonal loss

Useful findings

• denervation
• localization
• severity

Timing

fibrillation/positive sharp wave อาจยังไม่เห็นจน >3 weeks หลัง acute injury

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Imaging

MRI brachial plexus

best overall imaging modality

Useful for:

• tumor
• inflammation
• radiation injury
• edema
• thickening
• nerve enhancement

MR neurography

เห็น:

• focal constriction
• nerve edema
• hourglass lesion

CT myelography

useful for:

• root avulsion

Ultrasound

ช่วยดู:

• structural lesion
• traumatic lesion
• hypertrophic neuropathy

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Important Brachial Plexopathy Syndromes

1. Traumatic Plexopathy

พบบ่อยที่สุด

Causes

• motorcycle accident
• traction injury
• sports injury
• falls
• penetrating trauma

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Root avulsion

Mechanism

high-energy traction injury

Clinical clues

• severe weakness
• sensory loss
• severe neuropathic pain
• poor recovery

Common roots

• C8-T1 avulsion มากที่สุด

Diagnosis

• CT myelography
• MRI

Prognosis

poor
เพราะ nerve root torn from spinal cord → regenerate ไม่ได้

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Burner/Stinger syndrome

พบบ่อยใน contact sports

Mechanism

traction/compression of upper trunk

Symptoms

• burning pain
• transient paresthesia
• unilateral arm symptoms

ส่วนใหญ่หายเองภายใน minutes-hours

Red flags

persistent weakness → evaluate further

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Backpack palsy

เกิดจาก prolonged backpack compression

Features

• painless upper plexus weakness
• usually demyelinating lesion
• recovery generally good

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2. Neuralgic Amyotrophy (Parsonage-Turner Syndrome)

important inflammatory plexopathy

Pathophysiology

likely immune-mediated inflammatory neuropathy

Triggers:

• infection
• surgery
• exercise
• vaccination
• pregnancy

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Classic Presentation

Phase 1

sudden severe shoulder pain

Phase 2

days-weeks later:

• weakness
• atrophy

Common nerves involved

• suprascapular
• long thoracic
• anterior interosseous
• axillary
• musculocutaneous

Common sign

scapular winging

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Important Clinical Pearls

Pain characteristics

• severe
• nocturnal
• awakens patient from sleep

Weakness timing

may occur:

• within 24 hr
  OR
• 2 weeks later

Bilateral involvement

พบได้ ~30%

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Extra-brachial involvement

อาจ involve:

• phrenic nerve
• recurrent laryngeal nerve
• lumbosacral plexus

Phrenic neuropathy clues

• orthopnea
• exertional dyspnea
• supine FVC drop

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Diagnosis of Neuralgic Amyotrophy

Clinical diagnosis เป็นหลัก

Supported by:

• EMG
• MRI/MR neurography

Labs เพื่อ exclude mimics

• CBC
• ESR
• glucose/HbA1C
• HIV
• syphilis
• Lyme disease

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Imaging Findings

MRI/MR neurography:

• T2 hyperintensity
• focal thickening
• gadolinium enhancement
• hourglass constriction

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Treatment

Conservative management

• analgesia
• PT/OT

Steroid

มีการใช้ แต่ evidence จำกัด

Prognosis

recovery ช้า:

• months to years

Residual weakness/pain พบได้บ่อย

Recurrence ~25%

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3. Neoplastic Plexopathy

Common cancers

• breast cancer
• lung cancer
• lymphoma

Classic features

• severe pain
• progressive weakness
• lower trunk involvement
• Horner syndrome

Pancoast tumor clues

• shoulder pain
• Horner syndrome
• hand weakness

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Distinguish Neoplastic vs Radiation Plexopathy

Feature	Neoplastic	Radiation
Pain	Early/severe	Mild/late
Lower trunk	Common	Less
Horner syndrome	More common	Rare
Myokymia on EMG	Rare	Common

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4. Radiation-induced Plexopathy

Risk factors

• breast cancer radiation
• supraclavicular radiation
• high dose radiation
• concurrent chemotherapy

Symptoms

• numbness
• paresthesia
• weakness
• less pain than neoplastic plexopathy

EMG clue

myokymic discharges strongly support diagnosis

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5. Thoracic Outlet Syndrome (TOS)

True Neurogenic TOS

rare but important

Pathophysiology

compression/stretch of lower trunk:

• cervical rib
• fibrous band

Symptoms

• hand intrinsic weakness
• ulnar sensory symptoms
• thenar atrophy

motor > sensory

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Electrodiagnostic Pattern

Classic:

• T1 > C8 involvement
• reduced medial antebrachial cutaneous SNAP
• lower trunk denervation

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Treatment

• PT
• posture correction
• surgery in selected cases

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6. Diabetic-related Plexopathy

มักร่วมกับ:

• diabetic amyotrophy
• lumbosacral radiculoplexus neuropathy

Upper limb involvement พบได้

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7. Iatrogenic Plexopathy

Causes

• surgical traction injury
• median sternotomy
• anesthetic block
• hematoma
• compartment syndrome

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Red Flags

Suspect serious pathology if:

• progressive weakness
• severe persistent pain
• Horner syndrome
• cancer history
• bilateral severe involvement
• respiratory symptoms
• scapular winging
• upper + lower trunk involvement together

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Practical Clinical Approach

Step 1 — Localize

• plexus vs root vs mononeuropathy

Step 2 — Pattern

• upper trunk?
• lower trunk?
• diffuse?

Step 3 — Time course

• acute painful → inflammatory/traumatic
• progressive → tumor/radiation

Step 4 — Investigate

• EMG/NCS
• MRI brachial plexus
• cervical spine imaging if needed

Step 5 — Search etiology

• trauma
• cancer
• diabetes
• radiation
• surgery
• infection
• autoimmune

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Key Pearls

• Sensory NCS abnormal → favors plexopathy over radiculopathy
• Severe nocturnal shoulder pain followed by weakness → think neuralgic amyotrophy
• Horner syndrome + shoulder pain → think Pancoast tumor
• Myokymia on EMG → suggests radiation plexopathy
• Scapular winging → long thoracic nerve involvement
• Root avulsion has very poor prognosis
• MRI brachial plexus is imaging of choice
• EMG may be falsely normal in first 2-3 weeks after acute injury