|Year : 2017 | Volume
| Issue : 1 | Page : 11-15
Mild head injury: Criteria for computed tomography scan
Garba Idris1, Davidson Florence2, Speelman Aladdin2, Tabari Musa Abdulkadir3, Suwaid Muhammad Abba3, Yusuf Lawal3
1 Department of Medical Radiography, Bayero University Kano, Kano, Nigeria
2 Department of Radiography, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Cape Town, South Africa
3 Department of Radiology, Bayero University Kano, Kano, Nigeria
|Date of Web Publication||7-Jun-2017|
Department of Radiology, Bayero University, Kano
Source of Support: None, Conflict of Interest: None
Background: Mild head injury (MHI) is the most common type of head trauma, and represents the vast majority of the injuries seen in the trauma unit. Therefore, this study aimed to use the previously identified clinical risk factors to determine which category of patients with MHI does not need to undergo computed tomography (CT). This may save cost to patients and hospitals and thereby reduce radiation dose to patients, personnel, and members of the public.
Methodology: This was a retrospective study conducted at the trauma unit of an academic hospital situated in Cape Metropolis. CT scans of 50 patients, 14 years and over who had MHI and underwent CT scan were serially retrieved from the archive. Patients' information, clinical presentation, and resultant CT findings were analyzed. Clinical risk factors were correlated with abnormal and normal CT scan findings. Data were analyzed using Chi-square statistics.
Results: Twenty-three (46%) patients had abnormal CT findings, and all presented with one or more of these risk factors, namely, severe headache, skull fracture, scalp injury, loss of consciousness, and intoxication. The results were not statistically significant when compared with the normal CT scans group. Four patients (8%) with no risk factors had normal CT scans. All the patients who presented with the clinical risk factors of nausea and vomiting 6% (n = 50) and seizures 4% (n = 50) had normal CT scan findings.
Conclusion: Certain clinical risk factors can be used to suggest the probability of abnormal CT scan in patients with MHI, whereas patients with no risk factors are more likely to have normal CT findings. Hence, the patients do not need to undergo CT scanning. Further studies with larger sample size may be helpful in validating these findings.
Keywords: Clinical risk factors, computed tomography, mild head injury
|How to cite this article:|
Idris G, Florence D, Aladdin S, Abdulkadir TM, Abba SM, Lawal Y. Mild head injury: Criteria for computed tomography scan. J Med Trop 2017;19:11-5
| Introduction|| |
Mild head injury (MHI) is commonly defined as blunt trauma to the head, after which the patient loses consciousness for <15 min or has a short, posttraumatic amnesia of <1 h, or both, as well as a normal or minimally altered mental status on presentation, namely, a Glasgow coma scale (GCS) score of 13–15., Loss of consciousness (LOC) is defined as a witness viewing the patient in a state of unconsciousness and reporting this fact to the emergency medical personnel, whereas amnesia is defined as a patient being unable to remember or describe the incident that led to the head trauma in the history taken directly by the examining physician.
Recently, there have been debates in medical literature as to which patient requires computed tomography (CT) scan after head trauma. Historically, all patients with the head injury and low GCS score had routine CT scans, whereas those with GCS scores 13 and above were believed to have only MHI, and were often simply observed. A research study, however, has shown that a significant number of patients with the GCS of 13 and above had significant brain injuries, and early CT scan is recommended in this group of patients.,
Other studies have shown that very few patients with MHI and GCS score of >13 require intervention and most of the abnormalities seen on CT scans are minor. These have led to the possibility of a more conservative approach with regard to the patient's management.
This study aimed to use the previously identified clinical risk factors for the South African context, to classify patients with MHI and GCS score of 13 and above who do not need to undergo CT. This may save the medical cost to patients and hospitals, and thereby reduce the radiation dose to patients, personnel, and members of the public.
| Methodology|| |
This retrospective study was conducted at the trauma unit of an academic hospital in Cape Town, South Africa. After obtaining ethics clearance from the Ethics Committee of the Cape Peninsula University of Technology, CT scan results of the patients performed between January 2008 and December 2008 were serially retrieved from the archive. Only patients 14 aged years and above who sustained MHI and underwent CT scans of the brain were included in this study. The reason for excluding patients aged 14 years and younger was because the abnormalities on CT scan are so common and severe in patients below this age limit. All CT scans were performed on a Siemens Somatom Balance (K1508), 64-slice per rotation helical CT scanner, which has an automatic pump injector facility for dynamic phase/vascular studies, its manufactured by Siemens Healthcare GmbHHenkestr. 12791052 ErlangenGermany, in 2007.
Information derived from the patients' records included age, gender, GCS score, clinical request, clinical history, and resultant CT findings. The clinical history recorded on the request forms included severe headache, nausea, vomiting, suspected skull fracture, LOC, seizures, scalp injury, and intoxication, and these were all considered as clinical risk factors. However, clinical history of confusion and disorientation was regarded as nonrisk factors based on the literature reviewed.,,,,, The mechanisms of the head injury were classified as follows: Assault, motor vehicle accident (MVA)/pedestrian vehicle accident (PVA), and others (domestic accident or no cause stated) as recorded on the request forms. Patients' ages were classified based on the WHO age classifications  as follows: Adolescent (14–18) years, young adult (19–39) years, adult (40–59) years, and old adult (60 and above) years.
Clinical risk factors and mechanisms of the head injury were correlated with normal and abnormal CT scan groups, respectively. However, the distribution of GCS scores was correlated with normal and abnormal CT scan findings. Age distribution of patients with the abnormal CT scans and the distribution of the abnormal CT scan findings in patients with clinical risk factors were also analyzed.
An abnormal CT scan was defined as one showing an acute traumatic lesion such as contusion, parenchymal hematoma, epidural hematoma, subdural hematoma, subarachnoid hemorrhage, or a skull fracture, as described in the literature.
Data were analyzed with the Chi-square binary analysis. Relative risk and odds ratio (at 95% confidence interval [CI]) were calculated with their corresponding P values.
| Results|| |
A total of 50 patients were enrolled in the study, consisting of 42 (84%) males and 8 (16%) females. Their ages ranged from 14 to 100 years (mean age 33.52 years). There were 23 (46%) patients who had abnormal scans and 27 (54%) patients had normal CT findings.
No statistically significant difference was noted between the abnormal and normal CT scan groups with respect to the mechanism of the head injury; however, most of the injuries were sustained as a result of assault in 52% (n = 26) and the least was from others in 20% (n = 10) [Table 1].
|Table 1: Mechanism of head injury versus abnormal computed tomography scans|
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[Table 2] compares patients with abnormal and normal CT scans with respect to the clinical risk factors. Severe headache, suspected skull fracture, LOC, scalp injury, and intoxication were more likely predictors of abnormal CT scan, even though no statistically significant difference was noted between the two groups. Forty-six percent of the patients had abnormal CT scans, and all had at least one or more of these risk factors. However, 8% (n = 4) of the patients presented with nonrisk factors, hence had normal CT scans. Patients presenting with the clinical risk factors of nausea and vomiting 6% (n = 3) and seizures 4% (n = 2) had normal CT scan findings.
|Table 2: Comparison of clinical risk factors in normal and abnormal computed tomography scan groups|
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Contusions and skull fractures were the most frequent findings, each occurring in 34.8% (n = 8) and 30.4% (n = 7), respectively, the least being the subarachnoid hemorrhage with a 4.3% (n = 1) incidence [Table 3].
Patients' ages were classified based on the WHO age classifications. Age group of 19–39 years represented the largest sample of patients with MHI and also they had the largest number of abnormal CT scan findings in 78.3% (n = 18), while 60 years and above were the least represented [Table 4].
Patients were divided into three groups based on their GCS scores, 15 (32 patients), 14 (14 patients), and 13 (4 patients) [Table 5].
|Table 5: Distribution of Glasgow coma scale in patients with normal and abnormal computed tomography scans|
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| Discussion|| |
MHI is the most common type of head trauma and represents the vast majority seen in the trauma unit (65–85%). Some authors noted that a 10% reduction in the number of CT scans of these patients would save more than 20 million rand per annum, beside the reduction in radiation dose.
Despite the high incidence and numerous studies performed, there is much controversy about the correct evaluation of these patients. The question of how best to define MHI is of great importance, and it is a source of controversy. Some of these patients will harbor a life-threatening injury, while some may have neurocognitive sequelae for days to months after the head injury. The challenge to the emergency physician is to identify which patients will have acute intracranial brain injury and which patients could be safely sent home.
Saboori et al. stated that some clinical risk factors could be used to predict the probability of abnormal CT scans. The use of these clinical risk factors as a predictor of intracranial lesions in patients with MHI has been evaluated in several studies. In two studies, it has been found that selective use of CT on the basis of clinical findings such as severe headache and vomiting and age over 60 years after MHI with GCS score of >13 identified 96% and 98%, respectively, of patients with abnormalities on CT scans.
Similarly, Miller et al. when studying the clinical significance of risk factors such as severe headache, nausea, vomiting, and depressed skull fracture found that a significant number of patients with CT abnormality had these risk factors. They concluded that if CT in minor head injury was done only on patients with these risk factors, there would be 61% of reduction in the number of CT scans done and still identifying all patients who require neurosurgical intervention. This correlates with the findings of this study, in which severe headache, LOC, suspected skull fracture, intoxication, and scalp injury were likely indicators of abnormal CT scan findings. However, in this study, these risk factors identified 46% (n = 23) of the patients with abnormal CT scans [Table 2]. Similar findings have been reported by the previous studies.,, All the patients who presented with the following clinical risk factors such as nausea and vomiting in 6% (n = 3) and seizures in 4% (n = 2) had normal CT scan findings [Table 2]. Even though all the values were not statistically significant, this could probably due to the small sample size used.
GCS is a numerical expression of the severity of head injury that can be used to correlate the various levels of coma later with a clinical outcome. Jagoda et al. state that the use of GCS score alone is not a good predictor of underlying brain/skull injury in patients with MHI. This may perhaps explain the findings in this study whereby 28% (n = 14) of the patients with a GCS score of 15 had abnormal CT scans [Table 5].
Abdul Latip et al. in their study noted that most of the patients with MHI were young adults. This is in line with the findings in the present study in which patients in this age group represented 64% of the patients with MHI, and 78.3% of the patients with abnormal CT findings [Table 4]. However, most of the mechanisms of the injuries were as a result of assaults in 52% (n = 26) [Table 1]. This might be due to the fact that young adults engaged themselves with activities that could easily cause violence such as alcohol abuse and/or reckless driving. Similar finding had also been reported by Bordignon and Arruda.  However, more males, i.e., 84% (n = 42) presented with MHI than females. This is in keeping with the findings from the previous studies., Contusions in 34.8% (n = 8) and skull fractures in 30.4% (n = 7) were the most common abnormal CT findings found in this study [Table 3], which correlates with the findings of Bordignon and Arruda.
The results show that 46% (n = 23) had abnormal CT scan findings and all had one or more of these clinical risk factors, namely, severe headache, LOC, suspected skull fracture, scalp injury, and intoxication [Table 2]. These included 14 patients with a GCS score of 15, 7 patients with GCS of 14, and 2 patients with GCS of 13 [Table 5]. Likewise, patients with nonrisk factors (confusion and disorientation) 8% (n = 4), had normal CT findings in this study [Table 2]. This correlated with the result reported by Heydel et al., whereby all the patients with positive CT scans had at least one of the risk factors such as headache, vomiting, alcohol intoxication, and seizures, and all the patients without any of the risk factors had normal CT scans.
Overall findings in this study further emphasize the need for brain CT scans to be strongly considered only in the group of patients with highlighted clinical risk factors in our study due to the significant number of patients with abnormal CT scan findings, thereby sparing patients' who fall short of the identified risk factors from radiation dose and cost of investigation.
The limitations of this study include missing or incomplete data in patients' folders. Statistically, due to the small sample size, the results did not attain significance. These findings can be validated in larger sample-sized studies. In addition, findings, thus, may not be generalized to a larger population of MHI seen in trauma patients.
| Conclusion|| |
The goal of this study was to use the previously identified clinical risk factors to categorize patients with MHI who should not undergo a CT scan. The results show that patients who presented with a history of severe headache, LOC, intoxication, scalp injury, or suspected skull fracture are more likely to have abnormal CT findings, and should thus undergo CT scanning of the brain. All the patients with abnormal CT scans had one or more of these risk factors. However, more than half of the patients in the study had normal CT scans, and small percentage of them presented with none of the risk factors used as criteria. No patient with a history of nausea, vomiting, or seizures had abnormal CT findings in this study. All the results were not statistically significant which could probably be ascribed to the small sample size used for this study. Further studies with a larger sample size are recommended to validate these findings.
I would like to thank Mr. A. Speelman for his thorough supervision through the entire research process. My sincere gratitude also goes to Dr. S. Candy (Neuroradiologist) for taking her time to go through my proposal and guide through the data collection process. My humble appreciations, however, go to Dr. Alistair Hunter and Mr. Christopher Trauernicht for their statistical help.
Financial Support and Sponsorship
Conflicts of Interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]