Response to Burke et al.: Efficacy of Ultra-Early (<12 h),Early (12–24 h),and Late (>24–138.5 h) Surgery with Magnetic Resonance Imaging–Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades A,B,and C Cervical Spinal Cord Injury (DOI: 10.1089/neu.2020.7034)

Dear Editor:

The investigators at the University of Maryland would like to thank Drs. Burke, Fehlings, and Dhall for their valuable comments and careful review of our recent publication. ^1,2 Their communication is invaluable for advancing our understanding of the role of timing of decompressive surgery in acute Abbreviated Injury Scale (AIS) grades A–C traumatic cervical spinal cord injury.

First, we note that the terms “surgery” and “decompression” have been used interchangeably in this patient population, to the detriment, we believe, of our collective efforts as a research community. For almost two decades, many surgeons have conveniently accepted that bony realignment and internal fixation, with or without laminectomy, yields “decompression,” without explicitly considering the extent of spinal cord swelling and the surgical technique required to achieve de facto decompression. ^3,4 We know, based on careful evaluation of postoperative magnetic resonance imaging (MRI) studies, that conventional anterior cervical discectomy and fusion alone will decompress the injured spinal cord in only 46.8% of AIS grade A/B cases. ⁴ Similarly, corpectomy without laminectomy also will yield suboptimal (58.6%) decompression in these patients. ⁴

What is listed in Table 7 of our publication ² is a collection of 15 heterogeneous reports with low-level evidence that is insufficient for generalization. To take one example, Burke and colleagues ⁵ reported that “ultra-early” surgery is associated with improved neurological outcome. However, we are skeptical of their conclusion on the basis of their methodology, in which the final evaluation of neurological outcome was determined at the time of acute care discharge (mean length of stay, 37.3, 22.4, and 25.8 days, for 18 ultra-early, 17 early, and 13 late surgery patients, respectively). This timing of outcome is too early to establish AIS grade conversion or American Spinal Injury Association (ASIA) motor score improvement conclusively. There are other issues with the reports listed in our Table 7. Above all is the lack of post-operative confirmation of actual decompression in the cohorts studied, which, in our opinion, constitutes the greatest confounder of all. Without knowing whether the patients enrolled in clinical trials or in retrospective case series have been adequately decompressed, the importance of other variables, including the timing of surgery, will remain obscure. We advocate that the ascertainment of decompression should constitute a minimum requirement for the clinical investigation of traumatic cervical spinal cord injury.

We wish to emphasize that we do not dispute the value of early surgery, which, at the very least, helps with nursing care, ventilatory support, pulmonary care, mobilization, and early rehabilitation. In our article, the median time to surgery was 12 and the mean 18.8 h. Burke and colleagues reported in their letter to the editor that delayed surgery spans from several days to weeks after trauma. As one can gather from our average of 18.8 h, we at the University of Maryland do not support delayed surgery. Nor do we believe that surgery can take place days after the injury without adverse neurological consequences. What we attempted to make clear in our publication is the following: In patients who have undergone confirmed de facto decompressive surgery (the relief of circumferential spinal cord compression at all injured levels), it is the intramedullary lesion length and not the specific timing of surgery that best predicts AIS grade conversion. We reached this conclusion after adjusting for demographics, ASIA motor score, AIS grade, injury mechanism, fracture morphology, surgical technique, and intramedullary lesion length. On the basis of our findings, we suggest that carrying out confirmed de facto decompressive surgery is as important as proper boney realignment and internal fixation when considering optimal neurological outcome.

We trust that the findings in our publication will not be misinterpreted as constituting disagreement with the literature. Our primary aim was to identify potentially confounding variables.

We apologize for the typo in the case of Dr. Lenehan's publication and appreciate Drs. Burke, Fehlings, and Dhall for identifying this error.