Is the skull x-ray a useful tool in paediatric blunt head injury and are we familiar with an abnormal finding ?

Skull X-ray (SXR) has been, and sti II is, used in some institutions to detect skull fractures in paediatric head injuries. When no clinical/neurological indication for computed tomography (CT) scanning exists, the presence of a sku II fracture may be used as an indication for this. This case report demonstrates an unusual SXR finding of oval lucencies in a neurologically normal child who had sustai ned a head injury. The subsequent CT scan demonstrated a subacute subdural haemorrhage with ai r pockets, highlighting the need to recognise

in some institutions to detect skull fractures in paediatric head injuries. When no clinical/neurological indication for computed tomography (CT) scanning exists, the presence of a sku II fracture may be used as an indication for this. This case report demonstrates an unusual SXR finding of oval lucencies in a neurologically normal child who had sustai ned a head injury. The subsequent CT scan demonstrated a subacute subdural haemorrhage with ai r pockets, highlighting the need to recognise Introduction Some institutions have previously used and continue to use a skull xray (SXR) in the protocol for investigation of blunt head injury.' Computerised tomography (CT) is recommended as the imaging modality of choice for investigating blunt head trauma and, when normal in a patient with an isolated head injury, allows the clinician to discharge the patient.': 4 It is in mildly injured patients where there are no positive neurological findings or a Glasgow coma scale (GCS) between 13 and 15 that controversy exists on whether a CT scan is routinely indicated. 1 ,2,4,s In an environment where costs and the availability of CT scanning are primary considerations, there is a difficult choice between -1. discharging patients based on negative clinical/neurological findings and running the potential risks of missing an intracranial abnormality; 2. admitting patients for observation without CT scanning, which has been shown by certain authors to be more expensive than the following option 3; 3. subjecting all patients to routine CT scanning.
The place of skull radiography is considered controversial,' but detecting a skull fracture is considered an indication for CT scanning in institutions Is the skull x-ray a useful tool in paediatric blunt head injury and are we farriil iar with an abnornlal finding?
where SXR is still performed. Recognising the skull fracture per se has little clinical benefit, as it has little to do with management or outcome.' It is also well known that in children severe intracranial injury can occur in the absence of skull fractures.' A study from Alder Hey in Liverpool states that SXR is not a reliable predictor of intracranial injury and is indicated only-• in penetrating head injury; • when non-accidental injury (NAI) is suspected, especially in children less than two years of age; • to confirm/ excl ude suspected depressed skull fracture. ' The sensitivity for predicting intracranial injury based on neurological abnormalities was 91 %, while the sensitivity of SXR for predicting intracranial injury was 65%.] Other authors have calculated that in a fully conscious child with a skull fracture, the risk of intracranial haematoma was 80 times higher than in a child without a fracture."These are two typical conflicting views on the value of SXR. Lloyd et al noted that significant injury was not seen in the absence of neurological signs and symptoms, but brain injury is commonly seen in the absence of a skull fracture.' The number of skull fractures detected was also very low at 2,7%. Another feature to note is that intracranial haem atom as sustained from mild head injuries are associated with neither an abnormal skull X-ray nor ab-normal neurological findings in up to 16-20% of cases.' As yet unpublished data from our institution showed that no drainable collection found on CT over a five-year period in patients with mild head injury was present without an associated skull fracture.

Case report
We present a case of a four-yearold boy who presented five days after having sustained a blunt head injury from falling off a bed. There was no history of loss of consciousness, but the patient had complained of headaches for the past week and had vomited twice. The Glasgow coma scale was 15/15 and no neurological abnormalities were detected on clinical examination. A CT scan was not indicated according to the existing protocol, but a skull X-ray was performed and called normal, resulting in the patient being discharged.
When the radiologist reviewed the films the following day, he noted numerous lucencies on the lateral skull film (Figure 1), which were puzzling, The CT scan demonstrated a large right subdural haemorrhage containing air pockets and low densities in keeping with clot evolution (Figures  2 and 3). Review of the skull X-ray showed a fine vertical fracture line traversing the lucencies.