Thoracic Outlet Syndrome
Aetiology
- Vascular (subclavian artery) or neurologic compression
- Neurogenic less common
- Females > males
- <30 years old
- BP lower trunk most often
Sites of Compression (c, s, c, s, c, s, p)
- Cervical rib
- Scalene muscle
- Clavicle malunion
- SCM
- Congenital fibrous bands
- Scapula ptosis
- Pancoast’s tumour
Clinical Features
- Paresthesias from shoulder to fingers
- Affects C8/T1 distribution normally
- Intrinsic wasting or weakness
- Vascular symptoms
- Symptoms positional or activity-related
- Overhead tasks
- Night symptoms
Diagnosis
Clinical
- NCS & EMG – useful to rule out peripheral lesions
- Adson’s Test
- Extend neck, turn head towards affected side & take deep breaths
- Wright’s Test
- Abduction, ER & extension of arm with head turned away
CXR/CT/MRI
- Cervical rib
- Tumour
- Anomalous muscle
- MR directly visualizes plexus
- CT/MR arterial and venous studies
Management
Physio
- Relaxation techniques, posture control
Operative
- If neurologic deficit
- Identifiable cause
- Transaxillary 1st rib resection
- 90% improvement but high complication rate
Suprascapular Nerve Compression
Causes
- Spinoglenoid notch cyst
- Ganglion
- Entrapment under suprascapular notch ligament
- Fracture callus
- Late cocking phase – SS & IS tendon compresses nerve
Clinical Features
- Depend on where nerve is trapped
- Prior to spinoglenoid notch → SS & IS weakness & atrophy
- At spinoglenoid notch or after → only IS problem
- Dull, non-specific ache over dorsum shoulder common to both
Investigations
- NCS & EMG – confirm where lesion is and which muscle affected
- MRI – screen for associated SLAP tear, ganglion, or cyst
Management
- Repair SLAP and decompress cyst
- Decompress nerve as necessary depending on offending structure
Long Thoracic Nerve Palsy
- Results in weakness of serratus anterior
- Causes medial scapular winging – trapezius still active
Causes
- Compression (e.g., backpackers)
- Traction (e.g., weightlifters)
Management
- Observe as most improve spontaneously
- May take as long as 18 months
- Pectoralis major transfer for those that don’t
Quadrilateral Space Syndrome
- Caused by compression of axillary nerve in quadrilateral space
- Pain and paresthesia around shoulder – vague
- Typical in throwing athletes
- ER, ABD, EXT causes compression of axillary nerve
- Late cocking phase
Diagnosis
- EMG, NCS – may be negative as symptoms are dynamic
- Arteriogram
- Compression of posterior humeral circumflex in quadrilateral space
Management
- Decompression if no improvement with activity modification
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