Walters, Beverly C. MD, MSc, FRCSC; Hadley, Mark N. MD; Hurlbert, R. John MD, PhD, FRCSC; Aarabi, Bizhan MD, FRCSC; Dhall, Sanjay S. MD; Gelb, Daniel E. MD; Harrigan, Mark R. MD; Rozelle, Curtis J. MD; Ryken, Timothy C. MD, MS; Theodore, Nicholas MD
In 2002, an author group selected and sponsored by the Joint Section on Spine and Peripheral Nerves of the American Association of Neurological Surgeons and Congress of Neurological Surgeons published the first evidence-based guidelines for the management of patients with acute cervical spinal cord injuries (SCIs).1-23 In the spirit of keeping up with changes in information available in the medical literature that might provide more contemporary and more robust medical evidence, another author group was recruited to revise and update the guidelines. The review process has been completed and is published and can be once again found as a supplement to Neurosurgery. The purpose of this article is to provide an overview of the changes in the recommendations as a result of new evidence or broadened scope.
CHANGES IN METHODOLOGY
In accordance with the established practice of guideline development within organized neurosurgery, a thorough review of the medical literature was undertaken for each subject chosen for evaluation. Although literature outside the English language was excluded, a sample of non-English abstracts that could be found in the database of the National Library of Medicine failed to reveal any data significantly different from what we found in the English literature. Each chapter of recommendations contained in the new guidelines uses standard search techniques fully described in each chapter.
After articles appropriate to each review question were identified, a rigorous critical evaluation was undertaken to establish the strength (quality) of the evidence and the level (certainty) of the recommendations. As in previous guidelines, published evidence was divided into Class I (well-designed and -executed randomized controlled trials), Class II (comparative studies, including randomized controlled trials with significant flaws, nonrandomized cohort studies, or case-control studies), and Class III (case series and expert opinion). Different from previous recommendations, the levels that used to be called standards, guidelines, and options are now referred to as Level I, Level II, and Level III, bringing them more in line with other neurosurgical and medical specialty paradigms and allowing the use of the term guidelines to denote the broader scope of the overall recommendations.24 Our author group universally felt that further stratification of guidelines into additional subsets (1a, 1b, 1c, 2a, 2b, 2c, etc)25 would not denote improved certainty or strength but instead would undermine consensus building and promote confusion among the readership.
NOTABLE EXCLUSIONS FROM THE GUIDELINES
Topical areas not included in the current guidelines pertain to the timing of surgery and use of hypothermia. The published evidence for these clinical strategies is so sparse that recommendations cannot be made with any degree of confidence pending further study. A single prospective study on surgical timing has subsequently been published since completion of our SCI guidelines review. Although designed as a prospective, nonrandomized comparative study (Class II), methodological flaws downgrade it to Class III evidence, rendering it unhelpful for establishing quality and certainty in the case of acute surgical intervention in SCI.26 Systemic hypothermia has been studied in animal models of SCI but only anecdotally in humans by way of a single Class II study also published after the current guidelines went to press. Again, in this instance, the evidence is early and cannot support a practice recommendation.27
The use of intraoperative somatosensory evoked potentials in the setting of trauma as a warning of SCI has not been addressed in the current guidelines. Those studies that our author group was able to find were carried out in nonacute (elective) spinal surgical situations. Although we felt that inferences might be made to acute SCI surgery, our supervising Joint Guidelines Committee of the American Association of Neurological Surgeons and Congress of Neurological Surgeons preferred to minimize such extrapolations. Hence, recommendations with respect to intraoperative electrophysiological monitoring will be made under a different (nontraumatic) guidelines initiative.
Functional magnetic resonance imaging may potentially contribute to SCI research, but to date, there are no clinical studies that establish its usefulness in human SCI. Thus, it has been excluded from the current guidelines.28 Similarly, there are no recommendations on the use of drugs,29 biologicals,30 or devices31 aimed at neural regeneration of the spinal cord because of the absence of clinical evidence. It is our hope that such evidence will be forthcoming in time for the next SCI guidelines review.
SCOPE OF THE REVISED GUIDELINES
In this 2013 iteration of the cervical SCIs guidelines, the scope has been broadened, as have the recommendations. In 2002, the guidelines featured 76 recommendations in contrast to 112 recommendations in the present version. Among the new guidelines are 19 Level I recommendations supported by Class I medical evidence. These include assessment of functional outcomes (1); assessment of pain after SCI (1); radiographic assessment (1); pharmacology (2); diagnosis of atlanto-occipital dislocation (1); cervical subaxial injury classification schemes (2); pediatric spinal injuries (1); vertebral artery injuries (1); and venous thromboembolism (1). In addition, there are 11 Level II recommendations, based on Class II evidence, with the remaining 77 recommendations qualifying as Level III recommendations from a variety of Class III medical evidence. The Table highlights these differences between the 2 SCI guidelines processes (used with permission from the published guidelines).32
TABLE-a Comparison o...Image Tools
The most contentious of the present recommendations likely pertains to the use of methylprednisolone in acute SCI and therefore deserves special comment. Methylprednisolone has been used for decades as a standard of care to improve neurological and functional outcome in SCI; however, careful examination, particularly of randomized clinical trials expected to produce Class I data,33-35 reveals many methodological flaws in study design and data analysis that refute the conclusions of the authors.36-38 As these limitations have come to light, there has also been a change in the perception of frontline surgeons treating SCI with respect to the necessity of steroids at all.39-43 In the case of the present guidelines, our author group downgraded them from Class I to Class III because the primary (a priori) outcome measures were all negative. Any positive results reported from either National Acute Spinal Cord Injury Study (NASCIS) II or NASCIS III came from post hoc analysis rather than being preplanned.
In a randomized clinical trial, comparison of data defined by protocol (ie, before data are accrued) is considered Class I evidence, including both primary and secondary outcomes. All other queries within the data set are Class III, whether they are published at the time of initial analysis or 10 years later. Class II is reserved for a priori comparisons within a prospective study in which the study population is nonrandomized but still comparative (eg, cohort studies, case-control studies, or before-and-after studies). This is fundamentally important and explains why retrospective mining of a prospective database still yields Class III evidence (unless in the format of a case-control study). Class of evidence pertains to how the research question was asked (study design). It does not pertain to how the data were accrued.
The underlying tenet is that retrospective examination of prospective data is still a “fishing expedition” or essentially a retrospective exercise unless clearly stated as part of the prospective research question(s). Outside of a priori analyses, any number of post hoc comparisons can be made within a data set (retrospective or prospective) until an interesting result is found. In a perfect world, authors should report how many post hoc comparisons they make and apply a correction to their statistical testing (eg, Bonferroni) before reporting claims of positive results. However, in reality, we know that this rarely happens, including in the case of the NASCIS studies.
The 2013 update on the “Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries” is meant to help the practicing neurosurgeon in his or her efforts to provide up-to-date, evidence-based care to patients with acute SCIs. They are based on a formal critical evaluation of the evidence, with a well-developed relationship between the strength of the evidence and the level of recommendations. This time-consuming and extensive process produces the best estimate of scientific foundation for current SCI care.
For related video content, please access the Supplemental Digital Content: http://www.youtube.com/watch?v=KB1NBEDkw9c
Funding was provided by the Joint Section on Spine and Peripheral Nerves of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons for author travel and accommodation. The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
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