Subcutaneous Emphysema: Symptoms, Types, Causes and Treatment

Subcutaneous emphysema (SE) is a fascinating yet potentially alarming medical condition that occurs when gas or air becomes trapped in the subcutaneous layer under the skin. While often benign and self-limiting, SE can sometimes signal severe underlying problems or lead to life-threatening complications. Understanding its symptoms, various types, underlying causes, and management options is crucial for patients and healthcare professionals alike. This article offers a comprehensive, evidence-based overview of SE, synthesizing insights from a wide range of clinical cases and systematic reviews.

Symptoms of Subcutaneous Emphysema

Recognizing the symptoms of subcutaneous emphysema is essential for timely diagnosis and appropriate management. SE can present subtly or manifest dramatically, depending on the amount and rapidity of air accumulation, as well as the underlying cause.

Symptom	Nature	Severity/Impact	Source(s)
Swelling	Soft, diffuse	Localized or widespread	2 5 7 8 15
Crepitus	Crackling feel/sound	Pathognomonic	2 6 7 12
Pain	Neck/chest/limb	Mild to severe	2 5 4 7
Dyspnea	Shortness of breath	Can be severe	2 3 5 8
Disfigurement	Visible swelling	May cause distress	1 13 8
Fever	Occasional	Rare, with infection	5 7
Odynophagia	Painful swallowing	Cervical involvement	5

Table 1: Key Symptoms of Subcutaneous Emphysema

Understanding the Symptoms

SE is most commonly recognized by the sudden onset of swelling, often accompanied by a characteristic "crepitus"—a crackling or popping sensation felt on palpation of the skin. This is caused by the presence of air bubbles beneath the skin surface 2 6 7 12.

Swelling and Crepitus

• Swelling can be mild and localized, especially after minor trauma or dental procedures, or more extensive, spreading rapidly over the neck, chest, face, or limbs 2 7 8.
• Crepitus is considered pathognomonic—its presence almost certainly indicates subcutaneous air 6 7.

Pain and Discomfort

• Patients may experience pain, particularly in the neck, chest, or site of air entry 2 4 5 7.
• The swelling and pressure can lead to discomfort, a feeling of tightness, and distress due to rapid changes in appearance 1 13.

Respiratory Symptoms

• Dyspnea (shortness of breath) may occur if SE spreads to the chest or mediastinum, potentially compromising airway or lung function 2 3 5 8.
• In rare cases, massive SE can cause airway compromise, respiratory failure, or even death 8 15.

Other Symptoms

• Fever is rare and usually suggests secondary infection or underlying pathology 5 7.
• Odynophagia (painful swallowing) may occur if SE extends into the cervical tissues 5.

Severity

Symptoms can range from barely noticeable to rapidly progressive and severe, depending on the amount of air, its spread, and the underlying cause 1 8 15.

Types of Subcutaneous Emphysema

Subcutaneous emphysema can manifest in different anatomical patterns, severities, and etiological contexts. Classifying SE helps guide management and anticipate possible complications.

Type	Description	Distribution	Source(s)
Localized	Confined to small area	Face, neck, limb	7 9
Regional	Involvement of broader region	Chest wall, neck	1 4 5 8
Extensive (Massive)	Widespread, multi-region	Chest, neck, upper limbs, abdomen, scrotum	1 8 13
Benign	Non-infectious, self-limiting	Usually localized	7 8 11
Infectious	Gas-producing infection	Rapidly progressive	7
Iatrogenic	Procedure-induced	Varies	6 9 10

Table 2: Types of Subcutaneous Emphysema

Explaining the Types

SE is classified by distribution, etiology, and clinical impact.

By Anatomical Distribution

• Localized SE: Limited to a small area, such as after minor trauma or dental work. Symptoms are often mild, and complications are rare 7 9.
• Regional SE: Involves a larger area, such as the entire neck or one side of the chest wall 1 8.
• Extensive/Massive SE: Air tracks through tissue planes and may involve the neck, chest, upper limbs, abdomen, even scrotum and face. This can be alarming and potentially dangerous, particularly if it compromises airways 1 8 13.

By Etiology

• Benign SE: Most cases are benign, arising from minor trauma, dental, or surgical procedures. These typically resolve without intervention 7 8 11.
• Infectious SE: Caused by gas-forming organisms (e.g., gas gangrene, necrotizing fasciitis). These require urgent intervention and antibiotics, as they progress rapidly and can be fatal 7.
• Iatrogenic SE: Results from medical or dental procedures, such as chest tube placement, endotracheal intubation, dental extractions, or surgeries involving mucosal penetration 6 9 10.

By Severity

A grading system from base of the neck (mild) to involvement of neck, chest, orbit, scalp, and other regions (severe) is sometimes used to assess the clinical impact and guide intervention 1.

Causes of Subcutaneous Emphysema

Understanding what leads to air entering the subcutaneous tissues is critical for prevention and tailored management. SE can be caused by trauma, medical procedures, infections, or spontaneous events.

Cause	Mechanism	High-Risk Settings	Source(s)
Trauma	Direct air entry via wound/fracture	Blunt/penetrating injury, rib fracture, liposuction	1 7 12
Medical/Surgical	Air forced into tissue by instruments	Dental, thoracic, ENT, biopsy procedures	6 9 10 4 5
Iatrogenic	Complication of treatment/intervention	Chest tube, ventilation, root canal, intubation	6 8 9 14
Infection	Gas-forming bacteria produce air	Gas gangrene, necrotizing fasciitis	7
Spontaneous	Alveolar rupture, pressure changes	Pneumothorax, COPD, COVID-19	1 3 8 15
Barotrauma	Pressure-induced rupture	Mechanical ventilation, scuba diving	3 12
Others	Self-induced, unusual behaviors	Nose blowing, Valsalva	9 11

Table 3: Causes of Subcutaneous Emphysema

Delving Into the Causes

Traumatic Causes

• Blunt or penetrating trauma to the chest, face, or limbs can create a direct pathway for air into the subcutaneous tissues 1 7 12.
• Rib fractures, especially with associated pneumothorax, are classical causes 1.

Iatrogenic and Procedural Causes

Medical and Dental Procedures:

• Chest tube insertions, transthoracic lung biopsies, and thoracentesis may introduce air, especially if there is a large air leak or poor technique 8 10 15.
• Dental extractions, especially of mandibular molars, root canal treatments, and use of air-driven dental instruments are common sources of iatrogenic SE in the head and neck region 6 9 11 14.
• ENT surgeries like tonsillectomy and adenoidectomy, though rare, have occasionally resulted in SE 4 5.

Mechanical Ventilation and Intubation:

• Barotrauma from high ventilatory pressures or endotracheal tube placement can cause alveolar rupture with subsequent air leakage 3 6 12.

Infectious Causes

• Gas-forming bacterial infections, such as gas gangrene or necrotizing fasciitis, can rapidly generate subcutaneous air and are associated with severe systemic illness 7.

Spontaneous Causes

• Spontaneous alveolar rupture, often seen in patients with underlying lung disease (COPD, severe asthma, COVID-19), can result in air dissecting into the subcutaneous tissue 1 3 8 15.
• Rarely, spontaneous perforations of the gastrointestinal tract (e.g., diverticulitis) can track air retroperitoneally to the subcutaneous tissues 2.

Unusual Behaviors and Miscellaneous

• Activities like forceful nose blowing, Valsalva maneuvers, or even self-inflicted injuries have been implicated 9 11.

Treatment of Subcutaneous Emphysema

Management of SE is dictated by its cause, severity, and associated complications. Most cases are benign and resolve with minimal intervention, while severe or life-threatening cases require advanced therapies.

Treatment Method	Indication	Comments/Outcomes	Source(s)
Treat Underlying Cause	Always necessary	E.g., repair pneumothorax	8 15
Observation	Mild, uncomplicated SE	Most cases resolve naturally	7 8 9 14
Oxygen Therapy	Moderate/severe cases	May hasten air resorption	11 14
Antibiotics	Infection risk or dental source	Prevents secondary infection	7 9 14
Analgesics/NSAIDs	Symptom relief	Common adjunct	11 14
Cold/Hot Compresses	Minor SE, comfort	Supportive	11 14
Surgical Decompression	Severe, massive, or airway compromise	Blow holes, drains, incisions	1 13 15 16
Negative Pressure Therapy	Massive refractory SE	Newer, promising option	17
Hospitalization	Extensive, complicated, or uncertain cases	Monitor for complications	8 9 14

Table 4: Key Treatment Approaches for Subcutaneous Emphysema

Approaches to Treatment

General Principles

• Always address the underlying cause—whether it's a pneumothorax, ongoing air leak, or infection 8 15.
• In most mild to moderate cases, observation and reassurance suffice, as subcutaneous air is gradually reabsorbed 7 8 9 14.

Supportive Care

• Oxygen therapy may accelerate the resorption of subcutaneous air due to increased nitrogen washout 11 14.
• Analgesics and NSAIDs help control pain and discomfort 11 14.
• Antibiotics are recommended when SE is associated with infection risk (e.g., dental source, gas-producing organisms, or immunocompromised patients) 7 9 14.
• Cold or hot compresses may provide symptomatic relief 11 14.

Interventional and Surgical Management

Indications for Intervention:

• Severe, extensive SE especially with airway compromise, respiratory distress, or progression despite conservative measures 1 13 15 16.

Techniques:

• Blow-hole incisions: Small, deliberate incisions in the skin (often infraclavicular) to release trapped air 1 13 15.
• Subcutaneous drains/catheters: Fenestrated catheters or angio-catheters placed subcutaneously allow continuous evacuation of air 13 16.
• Negative pressure wound therapy: Recent case series suggest that applying negative pressure devices over incisions can rapidly resolve massive SE with good outcomes 17.

Surgical Management:

• Reserved for refractory cases, or when conservative and minimally invasive approaches fail 16.
• Surgical interventions are generally safe, with low complication rates when performed appropriately 1 16 17.

Hospitalization and Monitoring

• Hospitalization is warranted for extensive cases, those with risk of airway compromise, or when the underlying cause is significant or unclear 8 9 14.
• Close monitoring for progression, complications, or new symptoms is essential.

Conclusion

Subcutaneous emphysema is a distinctive medical condition, often benign but occasionally a harbinger of serious pathology. Prompt recognition, identification of the underlying cause, and appropriate management are essential for optimal outcomes.

Key Takeaways:

• Symptoms: Swelling, crepitus, pain, dyspnea, and sometimes visible disfigurement are hallmark features; severity varies widely 2 3 5 7 8.
• Types: SE ranges from localized, benign forms to extensive, life-threatening variants; classification helps guide management 1 7 8 9.
• Causes: Trauma, medical/dental procedures, infections, and spontaneous events are primary drivers; identifying the cause is vital 1 6 7 8 9 10 11 12 14 15.
• Treatment: Most cases resolve with observation and supportive care; severe or complicated cases may require surgical decompression or negative pressure therapy 1 8 13 15 16 17.

A clear understanding of subcutaneous emphysema empowers clinicians to provide timely, effective care while reassuring and educating patients.