Is early surgical intervention effective for traumatic severe cervical spinal cord injury? A retrospective study secondary publication

2.1 Patients and data collection

The study was approved by the Ethics Committee of Nara Medical University Hospital, and the requirement of informed consent was waived for all the patients enrolled in this study (approval number: 1027). This study has been reported according to the STROBE guidelines.

This study was performed at our Department of Emergency and Critical Care Medicine. We included patients with traumatic severe CSCI with AIS grade A to B as consecutive patients with traumatic spinal cord injury who underwent surgery between December 2007 and May 2018. Patients with severe head injury with an Abbreviated Injury Scale Score $\ge$4 and those who died within 24 h following hospital admission before the surgery were excluded. Participants were classified into an “early” surgery group comprising those who underwent surgery within 24 h and a “late” surgery group comprising those who underwent surgery after 24 h, which were retrospectively compared.

The collected patient information included age, sex, body mass index (BMI), ISS score, Glasgow Coma Scale (GCS) score, neurogenic shock status at admission, details of steroid administration, and presence of fracture and/or dislocation of the cervical spine. The primary outcomes were the AIS grade and the neurological level of injury (NLI) at 1 month following surgical treatment, whereas the secondary outcomes were the ICU-LOS and occurrence of respiratory complications and cardiac arrest during hospitalisation.

2.2 Statistical analysis

Continuous variables were compared using the Mann–Whitney U test, and categorical variables were compared using the Fisher’s exact test. To evaluate the efficacy of early surgical intervention, logistic regression analysis with inverse probability of treatment weighting (IPTW) was performed using a propensity score [10] (PS) adjusted for age, sex, ISS score, GCS score, and neurogenic shock at admission. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated in these models. All data were analysed using the SPSS 22.0 software (The International Business Machines Corporation, Armonk, New York). All p values of $<$0.05 were considered statistically significant.

3.1 Participants

The inclusion and exclusion criteria were applied to a total of 254 patients who underwent spinal surgery for traumatic SCI at our centre, and 42 patients were included in the final analysis (Fig. 1). Their average age was 66 years (19–85 y), and 34 participants (81%) were males. The early and late surgery groups comprised 32 (76%) and 10 (24%) patients with an average time to surgery from injury of 10.25 h (4–23 h) and 161.5 h (31–336 h), respectively. Thirty-five (83%) patients were classified to have AIS grade A. The NLI was C4, C5, C6, and C7 in 15 (36%), 14 (33%), 8 (19%), and 5 (12%) cases, respectively. Overall, 71% (30 cases) of the injuries were caused by falls (Table 1).

Fig. 1.Flowchart depicting the process of patient inclusion/exclusion in the present study. AIS, American Spinal Injury Association (ASIA) Impairment Scale; SCI, spinal cord injury.

3.2 Outcomes

There was no significant difference between the early and late surgery groups based on the patient information at admission; however, the ISS score (25 vs. 29, p = 0.08) was lower and the GCS score (14 vs. 12, p = 0.07) was higher in the early surgery group than in the late surgery group. Steroids were not administered to any patient in either group (Table 1). All 10 cases of delayed surgery were due to transfer of patients from other hospitals, the absence of the doctor in charge of the surgery, or unavailability of an operating room. None of the patients were unable to undergo surgery within 24 hours due to their life-threatening general condition.

In the univariate analysis, there was no significant difference between the groups in the rate of neurological improvement at 1 month following surgery, assessed as an improvement by one, two, and one or more AIS grades (p = 1, 0.17, and 0.13, respectively) and by one, two, three, and one or more NLI levels (p = 0.47, 0.31, 1, and 0.15, respectively) (Table 2). However, the ICU-LOS was significantly shorter in the early surgery group than in the late surgery group (7.4 vs. 21.4 days, p = 0.0001), and there were significant differences in the occurrence of postoperative respiratory complications (37.5% in early surgery vs. 90% in late surgery, p = 0.009) and cardiac arrest (9.4% in early surgery vs. 40% in late surgery, p = 0.04) during hospitalisation between the study groups (Table 2).

The PSs of all the patients were generated using age, sex, ISS scores, GCS scores, and neurogenic shock at admission, and an IPTW analysis using the inverse number of PSs was performed. There were significant differences between the groups in neurological improvement, as indicated by improvements of one or more AIS grades 1 month following surgery (OR: 17.1, 95% CI: 1.9–156.7, p = 0.012), the ICU-LOS $>$7 days (OR: 0.14, 95% CI: 0.02–0.90, p = 0.04), the occurrence of respiratory complications (OR: 0.08, 95% CI: 0.01–0.73, p = 0.03), and the occurrence of cardiac arrest (OR: 0.13, 95% CI: 0.02–0.85, p = 0.03) during hospitalisation (Table 3).

4.1 Improved neurological outcomes

In a large multicentre prospective cohort study, Fehlings et al. [8] reported significant neurological improvement with surgical intervention within 24 h in 313 patients with AIS grade A–D traumatic CSCI. Similarly, Dvorak et al. [11] reported that surgical intervention within 24 h significantly improved the neurological prognosis and shortened the hospital stay in 888 patients with AIS grade A–D traumatic CSCI. Following the results of these large studies, there has recently been a consensus that early surgical intervention within 24 h may improve the neurological prognosis of patients with traumatic CSCI; however, patients in these studies had AIS grades A–D, and only a few results reported were limited to severe CSCI cases. In a meta-analysis, Wengel et al. [12] reported that early surgery within 24 h was associated with a better neurological outcome than late surgery in patients with complete traumatic CSCI. Consistent with the results of a previous study, the results of our study, which focused on severe cases such as AIS grade A and B, also showed an improved neurological prognosis at 1 month. Univariate analysis revealed a tendency for early surgery to improve the neurological outcomes by one or more AIS grades (p = 0.13); however, no significant difference was observed. In contrast, IPTW using a PS revealed a significant difference, and this discrepancy may be due to the small sample size of the late surgery group. This suggests that early surgical intervention is effective even in severe cases of CSCI. There have been several recent reports of surgery for CSCI performed earlier than 24 h following injury [13, 14, 15]. Jug et al. [13] reported that the prognosis associated with surgery within 8 h following injury was good; however, the severity of the injuries varied. Even in severe cases, such as AIS grades A and B as in our study, surgery earlier than 24 hours after injury may be beneficial. However, these factors should be considered in further studies.

4.2 Improved respiratory and cardiac outcomes and ICU-LOS

Considering the complications, McKinley et al. [16] demonstrated that compared to early surgical intervention, surgical intervention following 72 h increased the prevalence of respiratory complications, such as pneumonia and atelectasis, in patients with AIS grades A–D traumatic SCI in a multicentre retrospective case series. In a single-centre retrospective cohort study, Bourassa et al. [1] compared patients with AIS grades A–D traumatic SCI who underwent surgery within 24 h and 24–72 h, and after 72 h after injury, and found that the shorter the time from injury to surgery, the lower the rate of pneumonia. Although these studies did not elucidate the reason for the reduced rate of complications in early surgeries, it has been suggested that the duration for which the patients are in the supine position could be related to the occurrence of complications. We permitted sitting immediately following the operation since early mobilisation of patients with severe CSCI could reduce the risk of respiratory complications, as indicated in previous reports [1]. Guest et al. [17] found that in patients with central SCI, early surgery within 24 h following injury resulted in shorter ICU and hospital stays than surgery after 24 h. Additionally, Mac-Thiong et al. [18] revealed that patients with AIS grades A–D traumatic SCI in the early surgery group (within 24 h) had a significantly shorter hospital stay than patients in the late surgery group (after 24 h). In a recent meta-analysis, Qiu et al. [19] reported that surgery within 24 hours of injury for acute spinal cord injury was associated with fewer complications and shorter hospital stays than surgery after that time.

The results of these studies suggest that early surgery for traumatic CSCI is effective in terms of complications and length of hospital and ICU stays; however, these studies do not consider the severity of cases, in the same manner as neurological prognosis. The severity is especially important in terms of complications and hospitalisation management, and greater severity of CSCI has been reportedly associated with a higher incidence of cardiac and respiratory complications [1, 20]. Therefore, pneumonia should be prevented by frequent sputum suctioning, repositioning, and positioning the patient sitting. In addition, patients with hypotension and bradycardia require vasopressors to stabilise their hemodynamic status and need greater nursing care than patients with mild or moderate cases of CSCI. Consequently, the more severe the CSCI, the longer the ICU-LOS. Therefore, performing early surgery for neurogenic shock recovery and repositioning and ensuring a sitting position could prevent complications and reduce ICU-LOS. Based on our results, patients who underwent early surgery (within 24 h) had a reduced risk of respiratory complications, cardiac arrest, and ICU-LOS compared to patients who underwent late surgery (after 24 h), which is consistent with the results of previous studies that included AIS grade A–D [1, 7, 8]. Prevention of complications and reduction of ICU-LOS are especially important in severe cases, such as patients with AIS grades A and B. Early surgery within 24 h after injury should be considered from these perspectives and that of neurological prognosis. In terms of complications, there are few reports of surgery earlier than 24 h. In terms of complications, there are few reports of surgery earlier than 24 h. In a single-centre prospective, randomised controlled study, Cengiz et al. [21] compared patients with thoracolumbar SCI who underwent surgery within 8 h (early group) and at 3–15 days (late group) following injury and found that the early surgery group had a significantly shorter overall hospital and ICU stay and fewer systemic complications, such as pneumonia, than the late surgery group. In cervical spinal cord injury, surgery earlier than 24 h may be beneficial in preventing complications, and these factors should be considered in further studies.

4.3 Limitations

There are several limitations to this study. This retrospective study was non-randomised and included a small number of patients. Moreover, although the patient background data were adjusted by the IPTW method using PSs, the influence of unknown confounding factors was not considered. In addition, the possibility of conservative natural recovery from paralysis was not evaluated. Neurological evaluation was only performed for 1 month following the surgery since our centre is tertiary, and the patients were referred to another hospital for rehabilitation after 1 month following the operation. Another limitation is that the study period was approximately 10 years. In this study, no major changes were made to the drug treatment or surgical techniques; however, postoperative management has progressed over the past 10 years, and this may have affected the results. To address these limitations, future validation studies with more patients and longer observation periods are warranted.

Although there have been various reports on the effectiveness of early surgeries for traumatic CSCI, the severity of the injury varies, and only a few studies have focused on severe cases of AIS grades A and B [12]. The results of this study are highly beneficial to patients with severe CSCI since surgical interventions within 24 h following injury improved the neurological outcomes and reduced the rate of complications. Surgery within 24 h following injury may be difficult to achieve in some facilities for various reasons; however, in others, the surgeon and the other operating staff could consider surgery within 24 h, allowing sufficient time to prepare, including ordering and sterilising implants. Similarly, it allows sufficient time to inform the family of the required course of action and acquire the necessary consent to proceed with treatment. Considering these expediencies, we believe that the present findings could contribute to prompt clinical practice.