A teenager with head injury

Case History

A teenage cyclist attended the emergency department after colliding with another bike during competition and fell on his right side. The patient sustained a right-side head injury with helmet. The patient complained of amnesia but claimed there was no loss of consciousness or vomiting. On examination, the patient was alert and conscious with Glasgow Coma Scale 15/15. Vital signs were stable. Pupils were 3 mm equal bilaterally and reactive to light. There was a 10-cm deep laceration wound from his right forehead just above the lateral end of eyebrow down to zygomatic region and a 2-cm laceration wound over his philtrum. Examination of the patient’s right ear revealed hemotympanum. Computed tomography (CT) of brain was done.

Questions

1. Describe the CT findings (Figure 1).

2. What is the diagnosis?

3. What is the prognosis of the patient?

Figure 1.

Computed tomography (CT) of brain.

Answers

1. The CT brain revealed multiple air bubbles in the subarachnoid spaces (white arrows) and a thin rim of left frontal acute subdural hematoma (white arrow heads). Bone window of CT scan showed fracture at right greater wing of sphenoid (black arrow) (Figure 2).

2. Skull base fracture with extensive pneumocephalus.

3. Injuries associated with multiple air bubbles have poor prognosis.

Figure 2.

CT Brain showed air bubbles in the subarachnoid spaces (white arrows) and left frontal acute subdural hematoma (white arrow heads). Fracture at right greater wing of sphenoid was seen in bone window of the CT (black arrow).

Discussion

Pneumocephalus refers to the presence of gas within any intracranial compartments of the cranial vault. ¹ Air may be situated in the extradural, subdural, subarachnoid spaces or intracranially. Trauma is the most common cause of pneumocephalus from a review of 295 patients, accounting for 73.9% of the cases. ² It is present in 0.5%–1.0% of patients with traumatic brain injury. ³ Other causes include neurosurgical interventions (e.g. trans-sphenoidal or endoscopic sinus surgery), otorhinolaryngology procedures (e.g. paranasal sinuses surgery), barotraumas, tumors or infections of the frontal and paranasal sinuses and infections of the central nervous system caused by gas-forming micro-organisms which produce the gas in situ. ⁴

Two mechanisms for the development of pneumocephalus have been proposed.^1,4 The first one is Dandy’s theory of “ball valve.” There is a unidirectional entry of air whenever the extracranial pressure exceeds the intracranial pressure. Air is then trapped due to tamponade of the entry site by pressured intracranial tissues. The second mechanism is Horowitz’s “inverted soda bottle” effect. A continuous loss of cerebrospinal fluid results in a negative intracranial pressure, drawing air into the skull cavity.

Symptoms of pneumocephalus include headache, nausea, vomiting, irritability and altered consciousness.^5,6 Tension pneumocephalus occurs when there is excessive air entering intracranial compartment. ⁵ It results in intracranial hypertension and rapid neurological deterioration from venous air embolism and brainstem herniation. ³

CT scan is highly sensitive to detect pneumocephalus. ⁵ In a retrospective review of patients with acute traumatic intracranial pneumocephalus, injuries associated with a pneumatocele or a single intracranial air bubble had good prognosis, while injuries with multiple air bubbles were associated with high energy of trauma and poor prognosis. ⁷

Most cases of post-traumatic pneumocephalus resolve spontaneously and can be managed with conservative treatment. ⁸ Non-operative treatments^4,5,6 include high-concentration oxygen therapy, bed rest with head of the bed elevated, avoidance of Valsalva maneuver, analgesics, prophylactic antibiotics and frequent review. Surgical intervention should be considered in patients with recurrent pneumocephalus, signs of increasing intracranial pressure suggestive of tension pneumocephalus, or persistent cerebrospinal fluid leak. ⁴

The patient subsequently underwent emergency operation for wound exploration and duroplasty. Inferior right temporal squama fracture with dura defect was found intra-operatively and the dura defect was repaired.