What are the causes and management of subcutaneous emphysema of the neck?

Subcutaneous Emphysema of the Neck: Causes and Management

Subcutaneous emphysema of the neck is primarily caused by air leakage from the respiratory or digestive tract into soft tissues, requiring prompt identification of the source and appropriate management based on severity and underlying etiology.

Causes of Subcutaneous Emphysema in the Neck

Traumatic Causes

• Penetrating neck injuries: Can damage the trachea, bronchi, or esophagus 1
• Maxillofacial trauma: Even minor trauma can lead to air dissection into soft tissues 2
• Tracheal and bronchial injuries: Both penetrating and blunt trauma can cause rupture leading to air leakage 1

Iatrogenic Causes

• Surgical procedures: Complications from head and neck surgery, tonsillectomy 1
• Airway interventions: Tracheal intubation, tracheostomy, or cricothyroidotomy complications 1
• Dental procedures: Particularly those using high-pressure air drills 3
• Oxygen delivery devices: Nasopharyngeal cannulas can cause mucosal damage 4

Pathological Causes

• Pneumothorax: Air from a pneumothorax can track into neck tissues 1
• Esophageal perforation: From foreign bodies, instrumentation, or spontaneous rupture
• Infections: Necrotizing fasciitis or gas-forming infections 5

Diagnosis

Clinical Presentation

• Painless swelling of tissues in the neck
• Characteristic crepitus (crackling sensation) upon palpation 6
• May be associated with dyspnea, dysphonia, or dysphagia in severe cases

Diagnostic Approach

1. Physical examination:

   • Palpation for characteristic crepitus
   • Auscultation with stethoscope over affected area to hear bubbles bursting 6
   • Assessment for signs of airway compromise

2. Imaging studies:

   • CT angiography (CTA): First-line imaging modality with high sensitivity (90-100%) and specificity (98.6-100%) for vascular injuries and simultaneous identification of soft-tissue injuries 7
   • Chest X-ray: To evaluate for pneumomediastinum or pneumothorax
   • MRI: For suspected spinal involvement 7

Management

Initial Assessment and Stabilization

1. Airway assessment: Evaluate for signs of airway compromise

   • If severe subcutaneous emphysema causes airway obstruction, secure the airway immediately 1
   • In life-threatening situations, tracheostomy or cricothyroidotomy may be necessary 1

2. Hemodynamic assessment:

   • Evaluate for signs of shock or mediastinal involvement
   • Patients with "hard signs" (active hemorrhage, expanding hematoma, hemodynamic instability) require immediate surgical intervention 7

Treatment Based on Etiology and Severity

Mild to Moderate Cases

• Conservative management:
  • Close observation
  • Supplemental oxygen
  • Avoidance of positive pressure ventilation when possible
  • Analgesics as needed
  • Manual lymphatic drainage has been reported as an option for aesthetic improvement 4

Severe Cases or Those with Identified Source

• Source control:

  • Repair of tracheal or bronchial injuries 1
  • Management of pneumothorax with chest tube drainage 1
  • Repair of esophageal perforations

• Surgical intervention:

  • For patients with airway compromise, mediastinitis, or necrotizing fasciitis 5
  • Surgical exploration for penetrating neck injuries with "hard signs" 1
  • Small (10-14F) chest tubes for pneumothorax management 1

• Antibiotic therapy:

  • Indicated when infection is suspected or for contaminated injuries
  • High-dose antibiotics for cases with potential mediastinitis or deep neck infection 3

Monitoring and Follow-up

• Close monitoring for progression of emphysema
• Serial imaging to assess resolution
• Observation for complications such as mediastinitis, pneumomediastinum, or airway compromise

Special Considerations

• Subcutaneous emphysema may be a symptom of life-threatening conditions like mediastinitis or necrotizing fasciitis requiring immediate surgical intervention 5
• The absence of a visible mucosal tear does not exclude the diagnosis 4
• Clamping chest tubes in patients with pneumothorax and subcutaneous emphysema may convert simple pneumothoraces into tension pneumothoraces 1

Prevention

• Careful technique during airway procedures
• Appropriate management of pneumothorax
• Early recognition and management of tracheal or esophageal injuries

Most cases of subcutaneous emphysema resolve spontaneously with conservative management, but thorough evaluation for underlying causes is essential to prevent serious complications.