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Abstract
Introduction NICE guidelines provide clear indications for the investigation of head injuries with CT. A patient on anticoagulation is required to have lost consciousness to warrant a CT scan unless obvious stronger indications exist. We recently observed three patients who had been assessed following head injuries that did not fulfil the NICE criteria for a CT scan, but who subsequently were found to have significant brain injury, all of whom were on warfarin. This experience prompted us to categorise whether the CT scans for head injuries performed were done so with indications consistent with the NICE guidelines, and then examine the outcomes to determine the effectiveness of the NICE guidelines for picking up positive pathology.
Methods All patients presenting to the emergency department with isolated head injuries investigated with CT scan were included for the 3-month period April to June 2008. Notes were examined retrospectively to look at age, sex, mechanism of injury, coexisting coagulopathy, indication for CT scan and the corresponding CT scan result.
Results 39 patients were included. 28/39 CT scans were unremarkable. 11 identified acute pathology. 23 scans were performed according to NICE guidelines, which revealed pathology in 10 patients. Ten scans were not performed according to NICE guidelines and none of these revealed pathology. Six scans were performed for unclear reasons and one revealed pathology. 6/39 patients were taking warfarin. Three of these six scans revealed intracranial pathology. The mean age of these six patients was 84 y.
Conclusion While NICE guidelines provide a valuable tool for the investigation of head injuries, we feel that elderly patients on anticoagulation may be at risk of having significant head injuries missed and a lower threshold for scanning should be adopted.
- Imaging
- CT/MRI
- trauma
- trauma
- head
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Introduction
The National Institute for Health and Clinical Excellence (NICE) guidelines 20071 provide clear indications for the investigation and management of head injuries. However, over the last year we have observed three patients who had been assessed following head injuries that did not fulfil the NICE criteria for a CT scan but who subsequently were found to have significant brain injury, all of whom were on warfarin.
Case 1 patient presented following a fall, suffering a scalp contusion but no loss of consciousness or amnesia. As per NICE guidelines a scan was not ordered. At re-attendance several days later it was apparent that there was a large subdural bleed.
Case 2 patient presented with a minor head injury. Again there was no loss of consciousness or amnesia. Following a period of observation, slurred speech and drowsiness developed. CT head scan revealed a large subdural haematoma.
Case 3 patient presented following a minor blow to the head several days earlier. There had been no loss of consciousness but progressive unsteadiness. CT head scan revealed a subdural haematoma.
Current evidence, from which the NICE guidelines are established, identifies several risk factors for brain injury in patients with closed head injury. The positive predicators for the risk of brain injury are shown in table 1.
What we already know about risk of brain injury
However, without evidence of decreased consciousness, focal neurology, post-injury seizure, suspected base of skull fracture, >1 episode of vomiting or significant amnesia, the NICE guidelines require a patient on anticoagulation to have lost consciousness to warrant a CT scan.
This experience prompted us to categorise whether the CT scans for head injuries performed were done so with indications consistent with the NICE guidelines and then examine the outcomes to determine the effectiveness of the NICE guidelines for picking up positive pathology.
Methods
All patients presenting to our emergency department with a diagnosis of ‘head injury’ were identified for the 3-month period 1 April 2008 to 30 June 2008. The medical notes of those who were subsequently investigated with head CT scans were examined to look at age, sex, mechanism of injury, coexisting coagulopathy, indication for CT scan and the corresponding CT scan result.
Depending on the clinical indication for the CT scan, patients were divided into two groups: those scanned according to NICE and those scanned outside the NICE guidance.
Results
Head CT scans were performed on 39 patients out of the 726 patients we identified as having an isolated head injury over this 3-month period. Ages ranged from 4 –97 y (median 42, SD 29.1), 8/39 were ≤16 y old, 24/39 (62%) were men and 15/39 (38%) were women.
The attributed mechanisms of injury were mechanical falls (n=10), assault (n=9), sport related (n=6), collapse (n=4), following road traffic collision (n=2) and uncertain (n=6).
In total, 28/39 CT scans were unremarkable while 11 identified acute pathology. These 11 are summarised as:
two cranial fracture without intracranial haemorrhage
three extradural haematoma
three subdural haematoma
two subarachnoid haemorrhage
one intraparencymal haematoma.
In 23 patients, the indication for CT scan correlated with NICE guidelines, and 8/23 scans revealed intracranial pathology (a further 2/23 revealed skull fracture without intracranial disruption). In 10 patients, the indication for CT scan did not correlate to NICE guidelines and 0/10 scans revealed pathology. In six patients the clinical indication was uncertain due to misfiling of notes and one scan was abnormal.
Figure 1 demonstrates the outcomes diagrammatically.
CT scans by indication category. Individual indications for the scans performed not according to the NICE guidelines included headache, amnesia and loss of consciousness in patients >65 y.
Overall, six patients were identified as having a coagulopathy (all were taking warfarin). Of these six patients who underwent CT scan, three had intracranial pathology. The mean age of these patients was 84 y.
Discussion
Although this short report provides only a small insight into the large numbers of head injuries seen in our emergency departments, we believe some valuable lessons can be learnt. In our experience, the NICE guidelines provide an excellent tool to decide whether or not to perform an early CT scan following a head injury; however, we feel that in elderly patients on anticoagulation a greater level of concern needs to be raised. In such cases, subdural haematomata may become apparent some time after presentation.
The Canadian CT head rules were established to derive an accurate, reliable and clinically sensible decision rule for the use of CT in patients with minor head injury. The NICE guidelines are largely based on this evidence; however, it should be noted that the Canadian CT head rules excluded patients with ‘a bleeding disorder or using oral anticoagulants’.5
Without evidence of decreased Glasgow Coma Score, focal neurology, post-injury seizure, suspected base of skull fracture, >1 episode of vomiting or significant amnesia, the NICE guidelines require a patient on anticoagulation to have lost consciousness to warrant a CT scan. Of the six patients on warfarin who underwent a CT scan in our study, three had intracranial pathology and two had CT scans only when they deteriorated. With evidence suggesting that those over 65 y of age are at over four times greater risk,5 and those on warfarin being over 10 times more likely to have a bleed than the general population,3 4 we believe special consideration must be made in this patient group and a lower threshold for CT scanning is indicated, which should be incorporated into the NICE guidelines. It should also be noted that due to age, the patient risk from ionising radiation in this group is minimal.
As our report only looked at patients who had a CT scan following head injury, we are unable to comment on those patients who did not receive a CT scan and may have had significant intracranial pathology missed. A prospective study is required to establish formal guidelines for patients on anti-coagulation particularly in the elderly population.
Conclusion
While NICE guidelines provide a valuable tool for the early investigation of head injuries, we feel that elderly patients on anticoagulation may be at risk of having significant head injuries missed and a lower threshold for scanning may need to be formally incorporated into national guidance.
Footnotes
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
Detail has been removed from these case descriptions to ensure anonymity.