Symptomatic postoperative spinal epidural hematoma preferentially occurs after anterior cervical discectomy and fusion versus anterior cervical corpectomy and fusion: a retrospective study

Introduction

Cervical spondylotic myelopathy (CSM) is a common cause of neurological morbidity, and can impact quality of life (1,2). Many studies recommend surgical decompression for CSM. Generally, for patients with 2-level CSM, most surgeons prefer anterior surgery (3,4). For example, vertebrectomy may be considered in patients with developmental vertebral stenosis, large posterior osteophytes adjacent to the endplates, retrograde displacement of free disc fragments into the vertebral body, or a need to reduce the number of fusion surfaces (5). Moreover, some surgeons use anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF). Studies have shown that when compression is limited to the disc level, ACDF is superior to ACCF because ACDF has less blood loss, shorter hospital stay, and fewer postoperative complications (6-8). However, when compression is extended to the vertebral level, ACCF is preferable to ACCF because it achieves satisfactory decompression at the vertebral level (6). For ACCF was associated with a higher incidence of complications, including vertebral artery, dura tear, and CSM leakage. ACDF may not be the best choice for incomplete decompression, spinal cord injury, limited visual exposure, and high risk of pseudoarticulation due to an increased number of fused surfaces (9). Meanwhile, among the previous systematic review studies on multilevel cervical spondylosis between ACCF and ACDF, 6 had similar results, and 3 showed that ACCF was superior to ACDF in neurological prognosis (7-9). However, it is difficult to select between ACDF or ACCF for surgery. If 2-level CSM is not included the aforementioned corpectomy criteria, 2-level ACDF or 1-level ACCF for surgery could be an alternative.

Postoperative spinal epidural hematoma (SEH) is a common hematoma that can be identified by computed tomography (CT) scan or magnetic resonance imaging (MRI) in 33–100% of surgical cases (10-15). The majority of these cases have no symptoms (16). However, if cervical spine SEH becomes symptomatic, the consequences can be rapidly progressive quadriplegia, respiratory failure, and even death. Accurate and prompt diagnosis and surgical treatment are imperative to maximize neurological recovery (17-20).

According to our understanding, there was no study has investigated and compared the outcomes and incidence of symptomatic postoperative SEH (SPSEH) after ACDF and ACCF for 2-level CSM. The purpose of the present study was to compare the clinical outcomes and incidence of SPSEH after ACDF and ACCF. The findings of our study will provide a scientific basis for the choice of surgical approach for 2-level CSM. We present the following article in accordance with the STROBE reporting checklist (available at https://apm.amegroups.com/article/view/10.21037/apm-22-488/rc).

Methods

Baseline of clinical data

The clinical records of patients at our hospital who underwent surgical treatment due only to 2-level CSM from January 2009 to February 2015 were reviewed. Patients with cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) were excluded from the study. A total of 551 patients were enrolled in the present study (261 men and 290 women, mean age was 58.1±9.43 years). All patients reported discontinuation of anticoagulant medication for at least 7 days before surgery. Ethical approval was obtained from the medical ethics committee of Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University. Informed consent was obtained from each patient. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Patients were divided into the following 2 groups based on the surgery they received: the ACDF group and the ACCF group. The ACDF group consisted of 302 patients (141 men and 161 women, mean age: 58.80±9.70 years), and the ACCF group consisted of 249 patients (120 men and 129 women, mean age: 57.90±10.10 years).

All surgeries were performed by the same surgical team. The discectomies used cages (Syncage, Synthes, Switzerland) with local autograft bone and semi-constrained plating systems (Atlantis; Medtronic Sofamor Danek, Memphis, TN, USA and Codman; Johnson, Raynham, MA, USA). The corpectomy procedures used titanium mesh cages with local autograft bone and semi-constrained plating systems (Atlantis; Medtronic Sofamor Danek, USA, and Codman; Johnson, USA). All patients wore a semi-rigid cervical collar for immobilization for at least 6 weeks postoperatively.

For the 2 procedures, we reviewed and compared each study participant’s age, sex, body mass index (BMI), bone mineral density (BMD), preoperative coagulation parameters [such as prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet count (PLT)], recent anticoagulant medication, mean arterial pressure (MAP), perioperative parameters (hospital stay, blood loss, and operation time), preoperative and postoperative neurological statuses [Japanese Orthopedic Association (JOA) scores and visual analog scale (VAS) scores of neck and arm pain], complications, fusion rate, and SPSEH incidence. Patients with SPSEH were defined as those who developed some degree of neurological deficit, confirmed by the presence of an SEH after MRI. Once the SPSEH diagnosis was confirmed, emergency surgical resection of the hematoma was carried out as soon as possible. The original site of the surgery was re-explored and the clot removed. Spinal dura mater was washed repeatedly with cold saline to lower the cellular metabolism and reduce bleeding. For subsequent re-exploration, all patients had drains inserted during the immediate postoperative period.

Statistical analysis

Data were recorded and statistical analysis was performed using SPSS 20.0 software (IBM, Armonk, NY, USA). Data were presented as mean ± standard deviation. Intergroup comparisons were made using the t-test, the Mann-Whitney U-test, or χ²-test. P<0.05 indicated statistical significance.

Results

Preoperative parameters

The characteristic of the patients is showed in Table 1. There were no significant differences in terms of age, sex, BMI, BMD, MAP, PT, APTT, PLT, and decompressed segments between the 2 groups (P>0.05).

Perioperative parameters

A summary of the perioperative parameters (hospital stay, blood loss, and operation time) is provided in Table 2. There was a significant difference for blood loss (P<0.05), but there were no significant differences for hospital stay and operation time between the 2 groups (P>0.05).

Complications

A summary of complications is provided in Table 3. None of the patients had infection or tracheal, vascular, or esophageal injuries related to the operation. Surgery related-complications and instrumentation-related and graft-related complications were no difference between the 2 groups (P=0.694).

Clinical outcomes

A summary of the clinical outcomes (JOA score, VAS, and fusion rate) is provided in Table 4. There were no differences in the final follow-up JOA score, VAS score, or fusion rate between the 2 groups (P>0.05).

SPSHE incidence and outcomes

Six of the 551 patients were diagnosed with SPSEH after 2-level ACDF; the overall incidence was 1.9%. A lower SPSEH incidence of 0.4% was observed after 1-level ACCF, as 1 patient in the ACCF group was diagnosed with SPSEH (P<0.05).

The average interval from symptom onset to hematoma removal was 123 minutes. Surgical removal of an SPSEH resulted in neurological improvement in 6 patients. The mean follow up was 15 months (range, 12–18 months). Five patients returned to baseline neurological examination status within 2 h of their surgical decompression. One patient had residual right-hand and right-leg weakness, which mildly improved at the 6-month follow up. Another patient showed no change in neurological function, even after treatment with hyperbaric oxygen and neurotrophic drugs at the 12-month follow up after hematoma removal.

Discussion

CSM is one of the most common disorders following spinal surgery. From 1993 to 2002, the number of spinal fusion procedures performed on MSM patients increased nearly seven-fold (21). Spinal cord compression due to cervical spine degeneration often results in progressive clinical symptoms, and surgical decompression can reduce this process and possibly restore function. It is reported that 92% of patients have improved symptom after anterior or posterior decompression for CSM by Fessler et al. (22). Therefore, surgery is the common choice for CSM treatment.

Although surgical treatment of a CSM is controversial, most surgeons prefer an anterior procedure for patients with 2-level CSM. However, the relative merits of cervical fusion after segmental discectomy or corpectomy in 2-level CSM without OPLL remain debatable. The choice between 2-level ACDF and 1-level ACCF is still difficult.

With the exception of blood loss, our retrospective review of 551 patients who underwent ACDF or ACCF for 2-level CSM found no significant differences between the 2 groups in terms of age, sex, PT, APTT, PLT, decompressed segments, hospital stay, operation time, final follow-up JOA score, VAS score, fusion rate, and complications. Our findings are similar to those of previous studies (7,23). However, in a study of 31 patients with 2-level CSM without OPLL who underwent anterior surgical treatment, it was found that ACDF was superior to ACCF with respect to not only blood loss but also operation time, which is in contrast with our results (5). This difference between Oh et al. (5) and our study could be due to the lack of comparative data available on these 2 surgical treatments for CSM. However, both studies showed that 2-level ACDF could be a better choice than 1-level ACCF for 2-level CSM regardless of SPSEH occurrence.

Although many studies on SPSHE have been published, few have compared 2-level ACDF and 1-level ACCF. In our study, we found that SPSEH was diagnosed in 6 patients for an overall incidence of 1.9% for 2-level ACDF. Only 1 patient was diagnosed with SPSEH; therefore, a low SPSEH incidence of 0.4% was observed for 1-level ACCF.

Postoperative SEH is a well-known complication after spinal surgery. When an SEH of the cervical spine becomes symptomatic, the consequences can be significant, and include rapid progressive quadriplegia, respiratory dysfunction, and even death. In the present study, the rate of symptomatic postoperative SEH was significantly higher in the 2-level ACDF group than in the 1-level ACCF group. Therefore, based on SPSEH incidence, 1-level ACCF could be a better choice for surgical treatment.

The incidence of symptomatic postoperative SEH was significantly higher in the 2-level ACDF group than in the 1-level ACCF group. In the ACCF group, after the titanium mesh cages with a local autograft bone was placed between the 2 vertebral bodies, the intraspinal hematoma could easily flow to the front of the cervical vertebral body through the pores of the titanium interbody cages. Therefore, there was more space for the hematoma to occupy (Figure 1A). For the 2-level ACDF group, the SEH of the cervical spine became symptomatic when the hematoma was large enough; this occurred after the cage was placed between the 2 vertebral bodies, where the cage had a local autograft bone similar to a bottle stopper and created a wall with the other vertebral bodies and disc and stopped the intraspinal hematoma flow to the front of the cervical vertebral body (Figure 1B). In addition, the hematoma could also flow out through the drainage tube. Therefore, the ACCF procedure did not create a hematoma that was large enough to compress the spinal cord, and the SEH of the cervical spine might become symptomatic.

Figure 1 Schematic diagram of surgical hematoma. (A) Cage was similar to a bottle stopper to create a wall with the other vertebral bodies and disc to stop the intraspinal hematoma flow to the front of the cervical vertebral body. (B) Intraspinal hematoma can easily flow to the front of the cervical vertebral body through pores of the titanium interbody cages, as there is more space for the hematoma to occupy.

In clinical practice, choosing to reoperate after spinal surgery because of neurological deterioration, and operating without any complementary radiological investigation, is common. Epidural hematoma should be suspected in patients with new defects after surgery, and prompt surgery is an important factor for complete recovery of neurological function (23-25). However, postoperative cord dysfunction can also be caused by spinal cord injury during surgery, such as incorrect alignment of the spine due to graft complications (26). In the study, one patient presented with symptoms of shortness of breath and neurological dysfunction after surgery. The respiratory symptoms could have been prompted by the administration of piritramide, or the deterioration of spinal cord function at a level higher than that of the surgical site. The neurological signs were consistent with a lesion in the upper region of the cervical spinal cord, rather than the level of the surgical site. Therefore, an MRI examination should be performed before any further surgery (26-29).

The present study has some limitations. The short follow-up period and low number of patients did not allow for a thorough evaluation. As a retrospective study, our study did not use a randomized, controlled trial design. Therefore, long-term follow up and a prospective randomized study that includes a large patient cohort are required in the future. However, we believe that our study provides evidence to help choose between 2-level ACDF and 1-level ACCF for anterior treatment approaches for 2-level CSM.

Conclusions

In the present study, the surgical management of 2-level CSM with either 2-level ACDF or 1-level ACCF did not result in significantly different outcomes, including perioperative parameters (hospital stay and operation time), complications, and clinical outcomes (JOA score, VAS, and fusion rate), although blood loss was an exception. Nonetheless, postoperative epidural hematoma preferentially occurs after ACDF compared with ACCF for 2-level CSM treatment. Our study provides a scientific basis for the choice between 2-level ACDF and 1-level ACCF for the treatment of 2-level CSM.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://apm.amegroups.com/article/view/10.21037/apm-22-488/rc

Data Sharing Statement: Available at https://apm.amegroups.com/article/view/10.21037/apm-22-488/dss

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://apm.amegroups.com/article/view/10.21037/apm-22-488/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was reviewed and approved by the Ethics Committee of Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, and informed consent was taken from all the patients.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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