Introduction
Cervical fracture dislocation (CFD) has a relatively poor prognosis due to severe instability and spinal cord injury (SCI) [1]. Although several clinical studies on CFD among adults have provided considerable insights into the condition [2–5], there had been a notable lack of research on CFD in adolescents. In this population, the spine is still in the final stage of growth and differs anatomically and biomechanically from the adult spine [6]. This difference should be taken into account when treating adolescents with spinal injuries. Therefore, we conducted this retrospective analysis using national data from the Japanese Diagnosis Procedure Combination (DPC) database to characterize the epidemiology, treatment patterns, and outcomes of adolescent CFD.
Materials and Methods
Study design and data source
This was a retrospective study using data obtained from the DPC database, which uses administrative claims data from >1,000 hospitals, including approximately 50% of all inpatients in acute care [7]. For each patient, the data contained information on hospitalization, diagnoses, medical history, treatments, complications, and outcomes. Diagnoses, comorbidities, and complications were specified using International Classification of Diseases, 10th Revision (ICD-10) codes. The Institutional Review Board at Tokyo Medical and Dental University approved this study (approval no., M2000-788-29). For this study, the need for informed consent was waived due to data anonymity.
Study participants
A total of 4,653 inpatients with a definitive diagnosis of CFD (ICD-10 code, S122) from 2010 to 2021 were identified. In addition to the ICD-10 code, detailed disease names were specified in Japanese. We excluded 14 patients due to scheduled admission. This study enrolled 84 adolescents aged 11–18 years, including 60 boys and 24 girls (Fig. 1).
Data extraction
We extracted the following on patient demographic and clinical characteristics from the DPC database upon admission: age, sex, Barthel index (BI), Japan Coma Scale (JCS) score, presence of mental disorders, and occurrence of cardiopulmonary arrest (CPA). We also collected data on the number of patients who required ventilators, halo vests, steroid pulse therapy, and surgical treatments, such as fusion surgery by anterior, posterior, or combined approaches and any concomitant trauma, including those specified in the comorbid disease names, such as traumatic brain injury (TBI), skull base fracture, maxillofacial fracture, upper or lower extremity fracture, pelvic fracture, pulmonary contusion or hemopneumothorax, ocular injury, other spinal fractures in addition to CFD, SCI, and vertebral artery injury. Any complications that occurred after hospitalization were specified using ICD-10 codes (Supplement 1). These included respiratory infectious diseases, renal and urinary tract infection, meningitis, wound infection, pulmonary embolism or deep vein thrombosis, gastrointestinal bleeding or ulcer, shock, circulatory dysfunction, sepsis, disseminated intravascular coagulation (DIC), multiple organ failure (MOF), acute kidney injury (AKI), respiratory failure, and heart disease or arrhythmia. Finally, we examined clinical outcomes, including in-hospital death, 30-day mortality, complication rates, length of hospital stay, BI at discharge, and proportion of patients discharged home.
Statistical analysis
All statistical analyses were performed using R software ver. 4.1.2 (The R Foundation for Statistical Computing, Vienna, Austria). Continuous data were presented as mean±standard deviation and analyzed using Student t-test or Mann-Whitney U test. Categorical data were analyzed using chi-square or Fisher’s exact test. A two-tailed p-value of <0.05 indicated statistical significance.
Results
CFD in adolescent inpatients was extremely rare, accounting for only 1.8% of all patients with CFD in the DPC database. Table 1 summarizes the clinical and demographic characteristics of the 84 adolescent patients with CFD in this study. The mean age was 16.3±1.5 years. Adolescent CFD was more common in men (71.4%) than in women. The mean BI upon admission was 17.3±31.8 points. More than 90% of the patients were transferred with good consciousness, with JCS of 0–3 points. Three patients (3.6%) were in CPA upon admission, two of whom died. Fusion surgery was performed on 52 patients (61.9%) using anterior approach in 10 (11.9%), posterior approach in 34 (40.5%), and combined approach in eight patients (9.5%). Halo vests were applied in 19 patients (22.6%). Ventilators were required by 24 patients (28.6%). Steroid pulse therapy was administered to 11 patients (13.1%).
The patients were divided into two groups based on the presence or absence of mental disorders. Notably, 17 patients (20.2%) had a history of mental disorders. BI was lacking on admission for most patients with mental disorders; therefore, this variable could not be statistically compared between the two groups. Upon admission, the level of consciousness represented by the JCS score was significantly better in patients without mental disorders than in those with mental disorders (p=0.036) (Table 1).
Table 2 summarizes the presence and types of comorbid trauma and the complications after hospitalization. Polytrauma was observed in 32 patients (38.1%); of these, 14 had mental disorders and 18 did not have mental disorders (p<0.001). The most frequent concomitant trauma was SCI (n=38; 45.2%), followed by TBI or skull base fracture in eight patients (9.5%). There was no difference in the frequency of any of the other trauma types between the two mental disorder groups (p>0.05). Posthospitalization complications were observed in 31 patients (36.9%); of these, seven had mental disorders and 24 did not have mental disorders (p=0.78). Specifically, the complications were infections in 13 patients (15.5%); thrombosis in five patients (6.0%); gastrointestinal hemorrhage or ulcers in seven patients (8.3%); severe systemic complications, including shock, circulatory dysfunction, and sepsis in six patients (7.1%); DIC in five patients (6.0%); MOF in two patients (2.4%); and AKI in three patients (3.6%). None of the patients had heart disease or arrhythmia. Respiratory failure was seen in 13 patients (15.5%) and was the only complication that occurred at a significantly higher rate in patients with mental disorders than in those without mental disorders (six patients [35.3%] vs. seven patients [10.4%], p=0.021).
Table 3 summarizes the clinical outcomes. In-hospital death occurred in eight patients (9.5%), 7 (8.3%) of whom died within 30 days of admission. The average length of hospital stay was 41.9±43.7 days. Upon discharge, the mean BI was 53.7±46.6 points. The overall discharge home rate was relatively high at 44.0% and was the only outcome that was significantly lower in patients with mental disorders than in patients without mental disorders (two patients [11.8%] vs. 35 patients [52.2%], p=0.01).
As shown in Table 4 summarizes the mortality data of eight adolescents in our sample; two had mental disorders, five were comatose upon admission (JCS ≥100), and two experienced CPA during transportation to the hospital. Five had polytrauma, and four of these had TBI. Three patients were in poor overall condition because of AKI, DIC, and MOF. Only two of these patients who died underwent posterior fixation surgery.
Discussion
Spinal injuries in children and adolescent account for only 1%–10% of all spinal injuries [6,8,9], and these occur mainly in adolescence [6]. The frequency of CFD increases with age [8]. Of all spinal injuries, cervical spine injuries (CSI) account for 60%–80% among children and adolescents and only 30%–40% in adults [10]. Allen’s classification is one of the most commonly used systems to classify the type of spinal column damage in CSI and has been closely correlated with neurological outcomes and recovery rates [11]. CSI is classified into six categories: distractive flexion, compressive flexion, compressive extension, vertical compression, distractive extension, and lateral flexion. Lower CFD tends to be caused by distractive flexion injuries [4].
The various mechanisms of CSIs include falls, motor vehicle accidents (MVAs), hanging, diving, sports, and child abuse [6,8–10]; MVAs and falls are the most frequent causes in adults [2,4,5] and children aged >8 years [9,12]. Anatomically, spine ossification begins at approximately the age of 8 years and continues until the age of 12–13 years [13]. CSIs predominantly occur on the upper cervical level among children aged ≤8 years, whereas they mainly affect the lower cervical level in adults and children aged >8 years [10]. Considering spine development in children and adolescents who have greater mobility and hyperflexibility and differ anatomically and biomechanically from adults [6,8], the etiology of CSIs tends to be age-related. A previous study on adult CFD demonstrated lower in-hospital mortality (3.2%) [3], compared with that we observed in adolescent CFD (9.5%). Several studies have documented high mortality rates of 3.2%–16.0% in nonadult patients with spinal injuries [6,8,14]. Therefore, CFD mortality rate appears to be higher in nonadults than in adults.
There is limited literature on the relationship between spinal injuries and mental disorders in nonadult patients. In one case series, 29 of 62 children (46.8%) and adolescents who attempted suicide sustained spinal injuries, 69% of whom had mental health issues, including depression, schizophrenia, and anorexia; this study found little evidence of sex differences (53.2% were female patients) [6]. However, another spinal trauma case series found the presence of mental health problems in 77% of adult suicidal jumpers, majority of who were female patients (67%) [15]. To date, there had been no research that specifically focused on nonadult CFD and mental disorders. In this study, we demonstrated a higher incidence of CFD in male patients, regardless of the presence of mental disorders. However, we were unable to further investigate sex differences due to the small number of cases. Depression and schizophrenia were the most common psychiatric diseases in our cohort. Support from the community and family is essential for patients with CFD, especially when they are adolescents with a history of mental illness [6]. Unfortunately, the DPC database did not include information on the mechanisms of injury. Therefore, we were unable to ascertain any relationships between mental disorders and mechanisms of injury in adolescents with CFD.
In previous studies, spinal trauma was associated with other injuries, including other spinal fractures, in 32%–62% of nonadults [12,16,17]. Similarly, we found that 38.1% of the adolescents with CFD had polytrauma, and half of those who died had accompanying TBI. Head injury is the most frequent polytrauma associated with CSIs [8], with this association having been previously reported in 30%–40% of children and adolescents [14,18]. The lower prevalence of TBI in our cohort (10%) may have resulted from selection bias or underreporting in our database. The outcomes of adolescent patients with CFD may be affected by coincident TBI and other traumatic injuries. Notably, we found that polytrauma was relatively more frequent in those with mental disorders. Although the causes could not be determined from our data, this should be kept in mind when treating adolescent patients with CFD and mental disorders.
This study had several limitations. First, the DPC database lacked clinical and radiographic information on the mechanisms of injury, CFD impairment level, unilateral or bilateral involvement of dislocation, severity of each trauma, and precise cause of in-hospital deaths. Second, the database only contained information recorded during hospitalization, and there were no follow-up data or longitudinal information on functional recovery and neurological prognoses. Moreover, exclusion of outpatients or emergency patients who died before hospitalization may have introduced selection bias. Third, there may have been bias in terms of the treatments given, particularly surgery. Some patients might have received conservative treatment because they were in poor clinical condition to undergo surgery. However, given the relatively small sample size, any adjustment for confounding factors would have potentially invalidated our analyses by limiting the statistical power. Fourth, accuracy of the reported complication and comorbidity data was uncertain due to the possibility of underreporting. Moreover, the database did not indicate whether complications occurred before or after surgery in those who underwent surgical treatment.
Conclusions
This epidemiological study provided novel and meaningful insights into adolescent CFD based on a large and robust nationwide database of 84 patients. Despite its inevitable limitations, our study fills a gap in the existing literature. Further pragmatic research is needed to develop and improve treatments and preventive strategies, as well as to evaluate the long-term functional prognoses of adolescents with CFD.
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