Air leak – Beware of the invisible injury

Clinical History

A 10-year-old boy presented with anterior blunt neck injury due to a fall in the bathroom. He complained of pain, bleeding and air leak at the site of injury. His vitals were stable. Respiratory rate was 18/min. Clinically crepitus was palpable in anterior aspect of the neck and bilateral supraclavicular regions.

Imaging Findings

X-ray, soft tissues of neck showed air in the subcutaneous planes of the neck with pneumomediastinum. Air was seen tracking along the spine. Well-defined, normal soft tissue shadow of thyroid was noted at C5, C6 level. Cervical spine appeared normal.

Chest X-ray delineated pneumomediastinum, pneumopericardium and subcutaneous emphysema in the neck on both sides. "Spinnaker sail sign" was noted (air between thymus and heart). Hemithoraces appeared normal. There was no evidence of pneumothorax. Bones appeared normal.

MSCT of the neck revealed air in fascial planes of the neck (carotid triangle, prevertebral & visceral space) with pneumomediastinum. Air noted in "danger space" extending from the neck into the mediastinum along the spine.

Trachea showed a focal defect in the anterior membranous wall at C6 level. Cervical spine, vessels and musculature appeared unremarkable. Oesophagus, pharynx and larynx revealed normal boundaries and wall thickness.

Oral floor muscles, parotid, submandibular and thyroid glands appeared normal.

Follow-up imaging after 5 days depicted successful recovery.

Discussion

A. Background [1]: Tracheal trauma is an uncommon occurrence in children because of their short neck, increased elasticity of tissues and compressibility of the upper sternal area which absorbs blunt forces without the risk of injury. Occasionally, a fall or blow to the neck disrupts this anatomical protection. A classical mechanism is a fall on a bicycle handlebar with the neck extended. Child abuse should be ruled out.

Tracheal disruption is seen in 14% of penetrating neck trauma and 0.34% to 1.5% of blunt neck trauma cases. Posterior tracheal tears are more common than anterior, because the deformed cartilaginous rings create stress on the membranous portion of the posterior trachea.

B. Clinically tracheal injury presents with subcutaneous air and crepitus, air leak, presence of a sucking wound and respiratory distress. Neck tenderness, haematoma, tracheal deviation and obliteration of normal tracheal landmarks. Concomitant laryngeal injury may present with stridor, hoarseness, aphonia, cough, haemoptysis or cyanosis. [2]

C. Chest radiography is the initial imaging modality. It may show cervical emphysema, pneumomediastinum, pneumothorax or abnormal tracheal contour with displacement and associated cervical spine fractures. Unossified laryngeal cartilages of children are not visualised well. [3]

Indications for CT of the injured paediatric neck:
Stable airway with significant airway oedema/haematoma on endoscopy or if the child is uncooperative for flexible endoscopy - To assess occult injuries.
Unstable airway with tracheal rupture or laryngeal crush injury - For operative planning [3]

CT may show deep cervical air, pneumomediastinum, pneumothorax, overdistension of endotracheal tube cuff or displacement. Direct tracheal injury is rarely seen as a wall defect because posterior tears are commoner. It is sensitive in 87% of cases. Oesophagus can also be assessed (with oral contrast). CT may be limited in locating degloving injuries.

D. Children with stable airway can be managed conservatively. Our patient was managed with an air-sealed bandage and antibiotics. Voice rest was advised with parenteral nutrition and he was kept nil by mouth for expeditious recovery. Imaging after 5 days revealed successful recovery. [4]
Unstable airway requires attempt to establish orotracheal airway by intubation. If it fails, rigid operative laryngotracheoscopy is done, and if major laryngotracheal injury is present, tracheostomy is performed. [5]

E. Teaching points: Clinical suspicion is a key aspect for prompt diagnosis and subsequent management. Conventional radiography should be the first method of imaging followed by endoscopy. CT can assess soft tissue symmetry, airway patency and occult laryngotracheal injuries. Sagittal and coronal reconstructions are a must. CT can help select patients with pneumomediastinum for endoscopy.

Differential Diagnosis List

Final Diagnosis

Cervical tracheal perforation and pneumomediastinum in a child with blunt neck injury.

URL:	https://www.eurorad.org/case/11967
DOI:	10.1594/EURORAD/CASE.11967
ISSN:	1563-4086