Traumatic tension pneumocephalus

Clinical History

A 92-year-old man presented with confusion and a low GCS following a slip on ice.

Imaging Findings

An ambulance was called to evaluate a 92-year-old gentleman who was thought to have slipped on ice and hit his head while falling on the pavement. On the scene his GCS was 15/15. He looked confused but alert and failed to recall the event. On arrival to A&E his GCS dropped to 10. On examination he was considered to be haemodynamically stable. He showed a bruise and a small laceration at his left temple. He also had some bruising around his left orbit. No other sign of injury was identified.

An unenhanced CT evaluation of the brain was performed. This revealed a frontal pneumocephalus which measured 1.8 cm in depth. Some pockets of subdural air were also identified around either temporal lobe. The frontal lobe was obviously displaced, but no accompanying hydrocephalus or signs of herniation were demonstrated. Fluid levels were noted within the sphenoid and the left maxillary sinuses, thought to be likely a representation of a post traumatic bleed. In addition, some soft tissue thickening was seen around the left temporal and left orbital regions which coincided with the patients external injuries. The diagnosis of significant post-traumatic pnemocephalus was made.
No obvious fracture was demonstrated. Unfortunately image acquisition protocols did not allow good quality coronal reconstructions.
The case was promptly discussed with the regional neurosurgical centre, which is located in a different hospital. The patient’s condition however deteriorated so rapidly immediately after the CT scan that urgent transfer was not possible and the patient died.

Discussion

Pneumocephalus is defined as the presence of intracranial air. Tension pneumocephalus is a life threatening scenario when intracranial pressure progressively increases as a result of intracranial air entrapment. Entry of air into the cranial vault can occur following iatrogenic or non-iatrogenic disruption of the skull and dura. The increased pressure of air is thought to be due to a ball-valve mechanism. The trapped air will then result in a space occupying mass effect, which if untreated can lead to death. Any condition or procedures which result in a breach of the dural lining of the nervous system has a potential risk for triggering tension pneumocephalus. Tension pneumocephalus can complicate surgical interventions that include burr-hole evacuation of subdural haematomas, posterior fossa surgery in the sitting position, trans-sphenoidal surgery, skull base surgery, craniofacial surgery, paranasal surgery, ventricular peritoneal shunts, spinal drain placement, spinal anesthesia, penetrating injury, vigorous ambu-bag ventilation and blunt trauma. Invasive neoplasms of the para-nasal sinuses have the capability to breach the skull-dura barrier and hence cause tension pneumocephalus.
CT evaluation of the brain and skull is sufficient in diagnosing intracranial air. In tension pneumocaphalus air can be seen to accumulate in the subdural, epidural, subarachnoid and intraventricular spaces; the subdural space being the most common. Bilateral compression of the frontal lobes by subdural air “peaking sign” has been associated in the literature with tension pneumocephalus. If air is seen to track and separate both frontal lobes anteriorly; this will give rise to the classical “mount Fuji” sign. The “mount Fuji” sign has been closely linked with tension pneumocephalus by Ishiwata et al [3]. They described this radiological sign in 4 out of 5 patients with confirmed post surgical tension pneumocephalus and the sign was not seen in patients with simple non-tension pneumocranium.
Diagnosis should be communicated promptly as urgent intervention is life saving. CT is used to evaluate the location and amount of intracranial air. Effects of trapped air and increased intracranial pressure should be assessed as well. The aetiology and the causative skull-dural defect should be identified if possible; this will aid surgical intervention. Any associated lesions or bleeds should be interrogated and commented on. As soon as diagnosis is made, 100% oxygen should be administered as this is thought to increase resorption of air. The patient should be kept in a supine position. A sitting or standing position will aid continued air flow to the cranial cavity and will exacerbate the problem. Urgent decompression/aspiration of air usually produces immediate improvement [6]. Short term management can include antibiotic cover, medications to reduce brain oedema and a drain may be left in place till the patient is stable and further evaluation has been carried out. Identifying and repairing the cranio-dural defect is the definitive treatment.
In summary, tension pneumocephalus is a serious life threatening complication. It should be suspected in the unwell patient if a significant amount of intracranial air is seen. Rapid recognition and communication is a key factor in this reversible life threatening condition.

Differential Diagnosis List

Final Diagnosis

Traumatic tension pneumocephalus.

URL:	https://www.eurorad.org/case/8235
DOI:	10.1594/EURORAD/CASE.8235
ISSN:	1563-4086