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Pneumomediastinum secondary to an apparently trivial stab wound to the neck: the value of the Hamman’s sign and thorough radiological investigation
  1. L Enguidanos1,
  2. A Pfleiderer1,
  3. W Smith1,
  4. S Ramkumar2
  1. 1Edith Cavell Hospital, Peterborough, Cambridgeshire, UK
  2. 2Luton and Dunstable Hospital, Luton, Bedfordshire, UK
  1. Correspondence to:
 Mr Andrew Pfleiderer
 ENT Department, Edith Cavell Hospital, Bretton, Peterborough PE3 9GZ, UK; agpfleidererdoctors.org.uk

Abstract

Perforation of the pharynx and upper oesophagus after stab wounds to the neck is easily overlooked because of the relative lack of symptoms. A case is reported in which pneumomediastinum occurred after an apparently trivial neck wound.

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Injury to the airway and the major vessels naturally dominates the management in cases of penetrating trauma to the neck. Although the incidence of associated perforation of the pharynx and upper oesophagus is reported to be relatively high,1 it is considered infrequently and can easily be overlooked because of the relative lack of symptoms, as demonstrated in this case.

CASE REPORT

A 25 year old man presented to the A&E department after having been stabbed in the left posterior triangle of the neck with a stiletto knife. Despite this, he was well and observations on admission—including pulse, blood pressure, and respiratory rate—were all normal and remained stable, with no sign of any respiratory distress or injury to major vessels. The presence of mild localised surgical emphysema in the posterior triangle was confirmed but there was no evidence of internal injury to the pharynx or larynx or any air escape from the neck wound on respiration. Although clinical examination of the chest did not show any of the usual signs of pneumothorax, auscultation revealed a positive Hamman’s sign. This is characterised by a peculiar crunching, bubbling, popping, or crackling sound that varies with the phase of the cardiac cycle and is best heard in the left lateral decubitus position. A positive Hamman’s sign usually indicates the presence of a pneumomediastinum but may also be associated with an isolated pneumothorax.2

The presence of this sign prompted a chest x ray (fig 1). This not only showed the expected subcutaneous emphysema in the soft tissues of the neck, but also the presence of air in the mediastinum outlining the whole of the descending aorta and the superior surface of the diaphragm. At the junction of these two structures, the air formed a “V” previously described as Naclerio’s V sign.3 A lateral soft tissue x ray of the neck (fig 2) also showed a large amount of retropharyngeal air, indicating a possible perforation of the pharynx or upper oesophagus, though a subsequent contrast swallow could not demonstrate this. As a result, and because the patient’s condition was stable, he was treated conservatively with prophylactic wide spectrum antibiotics. Sequential chest x rays showed a gradual uncomplicated resolution of the mediastinal air and surgical emphysema, which had completely disappeared after six days, when the patient was discharged home well.

Figure 1

 Chest x ray showing extensive pneumomediastinum and Naclerio’s V sign.

Figure 2

 Lateral soft tissue x ray of the neck showing an extensive pocket of retropharyngeal air.

COMMENT

Unsuspected and undiagnosed perforation of the upper aero-digestive tract may have serious consequences and may even lead to death from advanced mediastinitis. Such events might be avoided by early identification of a perforated viscus and if a significant defect had been identified surgical closure to avoid further complications would have been indicated. Early diagnosis has been reported to reduce the associated mortality from 85.7% to 50%.4 Routine radiological investigations—including a lateral soft tissue x ray of the neck, chest x ray, and barium swallow—are recommended in all cases of penetrating neck injury.

REFERENCES

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