Nerve Disorders

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)

1. Cervical rib
2. Scalene muscle
3. Clavicle malunion
4. SCM
5. Congenital fibrous bands
6. Scapula ptosis
7. 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

1. Spinoglenoid notch cyst
2. Ganglion
3. Entrapment under suprascapular notch ligament
4. Fracture callus
5. 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