Letter: Guidelines for the Use of Electrophysiological Monitoring for Surgery of the Human Spinal Column and Spinal Cord

To the Editor: We have read with great interest the recent guidelines on the use of intraoperative neurophysiological monitoring (IOM) in spine surgery published by Hadley et al.1 The authors of the guidelines should be first congratulated for their efforts. They reviewed the literature about the use of IOM in each type of spinal surgery from 1966 to 2017, and the papers included were classified as diagnostic, therapeutic, or related to cost-effectiveness and graded in 3 different levels of evidence (level I-III according to a modified North American Spine Society [NASS] criteria). The authors recommended the use of IOM during spinal cord/spinal column surgery only as a diagnostic adjunct to assess spinal cord integrity (level I), while the use of the same monitoring is not recommended as a therapeutic tool during intramedullary tumor resection procedures (level II) or other spinal cord/spinal column surgery (level III). Finally, the authors concluded that IOM can only document a neurological deficit but do not prevent it and, for this reason, the use of IOM during spinal surgery cannot be considered a “standard of care.” We also have seen with the same great interest the critical comments published2-5 and the authors’ replies.6-9 We would like to add some considerations to the previously published letters. Paradoxically, while we are all discussing this systematic review and the subsequent recommendations, a new systematic review and meta-analysis on intraoperative neurophysiological monitoring in spine surgery has been published by Daniel et al10 in August 2018 in Spine, an international leading journal in the field of spine surgery. This new review reaches opposite conclusions about the use of IOM in intramedullary tumors. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines,11 the authors reviewed the comparative studies about the rate of new neurological deficit in spinal surgery with and without IOM. These authors employed a methodological index for nonrandomized studies (MINOR)12 instrument to evaluate the methodological quality of the studies. Six articles were included and analyzed by the authors, and among these, the studies of Sala et al13 and Zielinski et al14 (the last one not included by the authors of the guidelines) were about intramedullary tumors. The studies by Choi et al15 and Harel et al16 (which were fundamental for the guidelines review) are not included because they have not fulfilled the inclusion criteria. Furthermore, the study by Sala et al13 was classified as high-quality comparative study because it reached 16 points at MINOR score (comparative studies with more than 16 points were considered as high quality according to MINORS methodology quality evaluation instrument) differently from the other review. This systematic review and meta-analysis concluded that for intramedullary tumors there was a trend to fewer neurological deficit in patients who underwent surgery with IOM (P = .0550). This fact represents another paradigmatic example of how the application of the evidence-based medicine “alone” without a sense-based approach can lead to contradictory conclusions starting from the same literature. This scenario has recently happened also with the use of corticosteroids in spinal cord injury. In a short time period, 2 important documents were published.17,18 Despite that they revised basically the same papers, they reached opposite conclusions again by scoring differently the published papers. The American guidelines17 did not recommend the use of corticosteroids (class I) and the Cochrane collaboration18 did the opposite. Both studies were published within a month in 2013. In spite of other papers which tried to further clarify the topic,19 this generated a great confusion in the neurosurgical community with a return to an individual-based approach as reported by a study on the use of corticosteroids for spinal cord trauma in Latino America.20 These guidelines have been developed also with the purpose (fully acceptable) of protection from medico legal querelles based on the “mandatory” use of a technique with limited evidence. This hypothesis was confirmed by the authors7 in the letter of reply to Vogel et al3 when they state: “Our interest, like that of many (most) of our colleagues, is in performing due diligence in assessing a technology that has reached the status of ‘requirement’ for some spinal surgery. Indeed, IOM has been used as a legal standard of care so that its lack of use has led to punitive damages, in spite of the absence of case law regarding IOM use…”. We agree that the use of IOM in all cases of cervical spondylosis and in many other spine diseases is difficult to justify, but on the other end we are not aware of any neurosurgeon who will operate an intramedullary spinal cord tumor without IOM in our country and possibly in most European centers. Do the authors really believe that patients with high-risk intramedullary (or even as we have shown high-risk intradural extramedullary21-22) tumors can be operated in any neurosurgical clinic with a good spine surgeon and possibly a microscope? What makes surgery for spinal cord tumors a high-level surgery if not the presence of a qualified multidisciplinary intraoperative team including specialized anesthetists, neurophysiologists, intraoperative navigation, etc??? As we have said already in a comment on the Guidelines for Management of Severe Traumatic Brain Injury, IV edition,23 whenever the best methodology producing guidelines conflict with the best clinical practice, it is the methodology that should be changed not the clinical practice. This letter was very well received and commented24 by the guidelines’ authors who are also part of a Joint American Association of Neurological Surgeons and congress of neurological surgeons (CNS) Commission. Commercial interests to perform IOM are well balanced by the interest of some surgeons (obviously not those ones producing guidelines) to perform complex surgery in nonappropriate settings. In conclusion, we believe that the authors of this important contribution have to realize that they cannot defend an evidence-based approach which is clearly in contradiction with other subsequently published review (also evidence based) and with what we call the actual “best clinical practice.” We have already seen what it will happen: a never-ending discussion and a return to an individually based approach. We cannot believe that this is their target. The solution is, in our opinion, to work together with all the colleagues who wrote the most thoughtful critical comments to integrate an “evidence-based” approach with a strong clinical and neurophysiological approach. There is nothing wrong to move to the future and modify a format for guidelines production which, in ours and many other neurosurgeons’ opinion, after more than 20 yr25 has come to a point where changes are needed. Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.