Although infectious and congenital diseases have decreased significantly as major causes of pediatric death owing to developments in modern medicine, traumas such as traffic accidents and falls have emerged as the major causes of death in children²⁰⁾. Among these, a traumatic head injury (THI) is a leading cause that can induce a long-term cognitive, behavioral, and personality disorders as well as death.

Unlike adults, children do not have fully developed central nervous system, and traumas and their prognoses in children differ in nature owing the differences in the head injury mechanisms and the structures of their skull^2-6,11,17). In attempts to focus on this, there have been efforts to analyze pediatric THI; however, such efforts have been confined to patients admitted to single hospital, and there has been few nationwide epidemiologic survey. To this end, we conducted this study with the participation of multiple hospitals to analyze the clinical features of THI in hospitalized pediatric patients, determine effective treatments, and estimate prognoses.

We conducted this study as a retrospective study using THI information collected by the Korean Neurotrauma Data Bank System (KNTDBS), which was established with participations of 23 university hospitals nationwide from 2010 to 2014. From a total of 2617 patients who hospitalized with THI, we analyzed data on 256 pediatric patients (under age 19) on gender, age, level of consciousness at admission with Glasgow coma scale (GCS), cause and type of trauma, whether or not surgery was performed, and the death rates.

We divided the child patients by age: infants (under age 1), preschoolers (age 1 to 5), schoolchildren (age 6 to 12), and adolescents (age 13 to 18). We classified the severity of each head injury based on GCS score as mild (13 to 15), moderate (9 to 12), and severe (3 to 8) groups. We only analyzed treatment outcomes in 184 cases for were conducted only in 184 cases for which the Glasgow outcome scale (GOS) scores were available, and we classified the outcomes as death (GOS I), poor outcome (GOS II-III), or good (GOS IV-V).

We classified specific injuries by type as skull fracture, epidural hemorrhage (EDH), subdural hemorrhage (SDH), subarachnoid hemorrhage (SAH) and intraventricular hemorrhage (IVH), pneumocephalus, diffuse axonal injury (DAI), brain contusion and parenchymal hemorrhage.

For statistical verification, we conducted the Chi-square test and Fisher exact test, using the statistical program SPSS version 20.0 (SPSS Inc., Chicago, IL, USA) for the analyses. We defined statistical significances as a p-value less than 0.05.

Owing to modern medical advances, the infectious diseases that had previously been the major causes of death in children decreased significantly in number, and trauma is now a leading cause of death in children in Korea²⁰⁾. In the United States, from 2002 to 2006, there were an average of 697347 pediatric patients with THI annually, and of these, 60032 patients were hospitalized and 6169 died¹⁹⁾. The nationwide statistics are not yet available, but in a study conducted with pediatric patients admitted to the university hospital emergency rooms in five regions, pediatric THI patients accounted for 32.7% of all pediatric trauma patients¹²⁾.

It has been reported in the United States that the most prevalent age group for pediatric head injury is 0 to 4 years, but the highest rate of head injury among inpatient is in the age 10 to 14 range¹⁹⁾. One study in Korea conducted patients who were admitted to the emergency room also found that the most prevalent age group for head injury in children was 0 to 4 years^12), but a study among inpatients found the highest prevalence among 6 to 10 years¹⁸⁾. In this study, we found the highest prevalence of head injury among the adolescents age 13 to 18. The two studies above showed different age of prevalence. It appeared that the differences arose because infants with head injuries cannot express their symptoms, so their guardians brought them to hospital to have the injuries examined because of concerns about the potential sequelae, but many of the falls that had resulted in head injury in the infants and toddlers were low energy falls^2), and most had resulted in minor damage that did not require hospitalization^10,16).

As reported in previous studies and our study, there were more male pediatric patients than the female^2,9,12,21), and in particular, THI incidences was most prominent among schoolchildren; the implication is that boys have more physical activities than girls.

Falls and traffic accidents account for the majority of injuries in pediatric head trauma^{2,7-9,12-14,19-21)}. We found similar results in this study. As age increased, the incidence of falls decreased but that of traffic accidents increased greatly. Seventy-three patients among the adolescents group were injured in traffic accidents, twice as many as in the younger groups. As age increases, the opportunity to travel independently increases, leading to increased chances of traffic accidents and increased incidence of damage from higher energy impacts. These are considered the reason that the severity of brain damage tends to increase with age. Thus, safety education is necessary regarding both falls and traffic accidents. Most of this education takes place among school-age children; it should remind them that preventing these accidents is the most important matter, and it should take place regularly both at school and at home.

In this study, we found that skull fracture was the most common injury at 51.2%, which was consistent with the results from a previous domestic study among hospitalized patients that reported injury rates of 45.6-57.3%^8,13,14). The authors of that study reported that most cases of intracranial hematomas were EDH^8,14), whereas in this study, we found the incidence of intracranial hematomas to be 31.3% EDH and 17.6% SDH.

In this study, severe brain damage had occurred at high level in patients with DAI, SAH or IVH, and SDH, and the patients with severe brain damage showed poor outcomes. These results were similar to the results of other studies that reported that low GCS score accompanied by DAI was important for the prognoses. Luerssen et al.¹⁵⁾ reported that the ages of the children themselves acted as a prognostic factor, but Berger et al.¹⁾ found that age and prognosis were not related. In this study, there were no differences in prognosis according to age. Mortality rates in pediatric THI patients have ranged from 0.06-7.3% in different reports^{8,12,14,19,21),} and we found a similar rate, 1.171%.

Most pediatric patients with THI show no specific sequelae and good prognoses, but the cases accompanied by DAI, SAH, and SDH show poor prognoses, and thus, it is necessary to observe these patients more carefully.

This study has a number of limitations. First, because of wide variation in hospitals and individual variation of registration, there was a potential selection bias. Second, we could not perform regional analysis because there were differences in the degrees of participation among the hospitals, even after considering their sizes and numbers of beds. Third, there was difference of numbers of hospitals among regions and a few large hospitals did not participate in the KNTDBS. Fourth, there were no details on the trauma mechanisms such as the height of the fall or whether the child was a pedestrian or was in the car during traffic accidents. Fifth, because of the retrospective nature of the study, we did not have complete control over the variables; data were missing or incorrect data in many fields, so we excluded data on 72 patients from the statistical analysis of outcomes. We also did not analyze other factors such as prehospital care, neuro-monitoring, or use of the anticonvulsant mannitol.

To overcome these limitations, the next KNTDBS project should be planned to provide specific registration guides and validated data and it is required that more hospitals, especially regional trauma centers, should participate in KNTDBS.

This study is the first study using KNTDBS, Korea’s version of a neurotrauma data bank system, on pediatric patients who were hospitalized with THI. We expect that this study can help to prevent THI in children and to better determine their prognoses when injuries do occur, make registration guides, and attract new participants. Additional studies are needed to enable early detection of patients who in particular may require more aggressive treatment through the use of more clinical information.