Post traumatic unilateral tension pneumocephalus

Clinical History

A 24-year-old male patient presented to our emergency after a road traffic accident with multiple head injuries and poor GCS. The patient was stabilized and a plain CT scan Brain was performed to evaluate the extent and nature of head injuries. The patient was transferred immediately for decompression to the neurosurgery institute.

Imaging Findings

Unenhanced axial CT image showed a large amount of free air in the right subarachnoid space compressing the right frontal lobe and extending along the falx. A large comminuted fracture of the inner table of the right frontal bone and ipsilateral lamina papyracea was seen.

Discussion

DEFINITION:
Tension pneumocephalus is the presence of air or gas in the cranium that is under pressure leading to mass effect on the brain parenchyma (extra-axial mass effect phenomena). It occurs due to disruption of the skull, including trauma to the head or face, after neurosurgical procedures and, occasionally, spontaneously [1]. It can result from trauma, previous surgery, tumours of the paranasal sinuses and infections (abscess rupture).

PATHOPHYSIOLOGY:
It occurs when unidirectional air enters through a dural defect but is unable to escape, akin to a ball-valve mechanism. As the volume of built-up air increases it causes separation and compression of the underlying frontal lobes. When bilateral, it is classically described as ‘Mount Fuji sign’. However, very little data is available on unilateral tension pneumocephalus as described in our case.

CLINICAL PERSPECTIVES:
Patients typically present with severe restlessness, deteriorating consciousness and focal neurological deficits. It can lead to rapid clinical deterioration due to increased intracranial pressure and spontaneous demise.

KEY FINDINGS:
It is essential to differentiate tension pneumocephalus from benign pneumocephalus for management. The specific sign for bilateral tension pneumocephalus is the ‘Mount Fuji sign’ [2] on NECT, with the presence of subdural free air causing resultant compression and separation of the frontal lobes. Other signs for mass effect due to subdural air include accumulation in other intracranial compartments like the intra-ventricular and subarchnoid spaces causing similar pressure effects. There can be multiple small air bubbles scattered through cisterns -"air bubble sign" which can be due to a tear in the arachnoid membrane by increased tension of air in the subdural space. [3]

MANAGEMENT:
Management of tension pneumocephalus involves immediate intracranial pressure reduction through neurosurgical interventions like craniotomy, burr holes, needle aspiration, ventriculostomy placement and closure of the dural defects in cases of large defects. [4, 5]

Differential Diagnosis List

Final Diagnosis

Post-traumatic unilateral tension pneumocephalus

URL:	https://www.eurorad.org/case/13308
DOI:	10.1594/EURORAD/CASE.13308
ISSN:	1563-4086