**About the Editors**

**Aria Nouri** obtained his Master of Science (under the supervision of Michael G. Fehlings) at the University of Toronto, after completing his medical training. In his thesis, he proposed and defined the term "Degenerative Cervical Myelopathy", or DCM. Thereafter, he pursued clinical research fellowships in the department of neurosurgery at Yale University and the University of Cincinnati under the mentorship of Dr. Joseph Cheng. He is currently pursuing neurosurgical residency training at Geneva University Hospitals in Switzerland.

**Enrico Tessitore** is the Vice-Chairman of the Department of Neurosurgery and Director of the Cancer Center at Geneva University Hospitals. Among other projects, he has been leading a prospective clinical study on degenerative cervical myelopathy, which assesses the utility of advanced MRI techniques and electrophysiological testing in diagnosing patients with DCM and predicting surgical outcome.

**Mark Kotter** is an honorary consultant in neurosurgery at the University of Cambridge, focusing on complex spine surgery. He is a co-founder of Myelopathy.org, and is actively engaged in both basic science and clinical research related to spinal problems. With the support of AOSpine, he has been leading RECODE-DCM, an initiative to identify and address research inefficiencies in DCM.

**Joseph Cheng** is the Frank H. Mayfield Chair of Neurosurgery at the University of Cincinnati, focusing on complex spine surgery. Among many noteworthy positions, he has been the chair of the AANS/CNS Spine Section, and is actively engaged in neurosurgical education and health care policy. For his continued service to neurosurgery, he received the AANS Distinguished Service Award in 2020.

### *Editorial* **Degenerative Cervical Myelopathy and the Aging Spine: Introduction to the Special Issue**

### **Aria Nouri 1,2,\*, Renato Gondar 1, Joseph S. Cheng 2, Mark R.N. Kotter <sup>3</sup> and Enrico Tessitore <sup>1</sup>**


Received: 2 August 2020; Accepted: 4 August 2020; Published: 6 August 2020

**Abstract:** Degenerative Cervical Myelopathy (DCM) is the most common cause of spinal cord injury in the world, but despite this, there remains many areas of uncertainty regarding the management of the condition. This special issue was dedicated to presenting current research topics in DCM. Within this issue, 12 publications are presented, including an introductory narrative overview of DCM and 11 articles comprising 9 research papers and 2 systematic reviews focusing on different aspects, ranging from genetic factors to clinical assessments, imaging, sagittal balance, surgical treatment, and outcome prediction. These articles represented contributions from a diverse group of researchers coming from multiple countries, including Switzerland, Germany, Italy, United Kingdom, United States, South Korea, and Canada.

**Keywords:** introduction; focus issue; spinal cord injury; compressive myelopathy; spondylosis

Degenerative Cervical Myelopathy (DCM) is becoming a growing public healthcare burden, attributable principally to an aging population. It represents a group of degenerative changes of the cervical spine that result in static and dynamic compression of the spinal cord, leading to subsequent chronic inflammatory and mechanical damage to neural tissue [1–3]. DCM represents the most common cause of spinal cord impairment in the developed world, leading not only to a decrease in the quality of life of those affected but also is increasingly recognized as a public healthcare and social burden [3,4]. Over the past few years, research on this topic has allowed for a better understanding of its pathological features, natural history, diagnosis, severity, associated conditions, treatment thresholds, and outcomes, collectively helping to provide a better understanding of the condition [1,5]. However, this research effort has also clearly demonstrated the ongoing knowledge gaps that exist and require further investigation [2].

The present Special Issue in the *Journal of Clinical Medicine* was specifically dedicated to presenting current research topics in DCM. Twelve articles were published, comprising 1 narrative review and 11 original articles. The narrative review focused on the past perspectives, present developments, and future directions of DCM and is intended to provide an overview of the current status of DCM [1]. The editors of the issue contributed to this introductory review and decided to limit each of the past, present, and future sections to three themes in an effort to stay focused on the most important topics. The remaining 11 articles included 9 research papers and 2 systematic reviews focusing on different aspects, ranging from genetic factors [6] to clinical assessments [7,8], imaging [9,10], sagittal balance [11], surgical treatment [12], and outcome prediction [13–16] (Table 1). These articles represented contributions from a diverse group of researchers coming from multiple countries, including Switzerland, Germany, Italy, United Kingdom, United States, South Korea, and Canada.

Several interesting findings were observed from this collective body of work. Starting with genetics, Pope et al. [6] evaluated the role of single genes in DCM onset, clinical features, and response to intervention and found genes with an effect on the radiological and clinical onset of spinal cord disease, correlating with the radiological and clinical severity of DCM. Polymorphisms of six genes were also found to have an effect on clinical response to surgery in DCM. The possible implications of this research are large, but further research will certainly be needed before this can be adapted from a clinical point of view.

Imaging-oriented research from D'Avanzo et al. [9] provided evidence that fractionated anisotropy (FA) values from MRI-DTI studies increase after decompression and potentially correlate with hand coordination and dexterity improvement, confirming previous reports that FA has an important role in prognostication. Fontanella et al. [10] reviewed the radiological finding of "snake-eye" appearance in the literature, finding some, albeit little, evidence supporting this appearance as a negative predictor. In their three illustrative cases, patients appeared to have relatively good outcomes, suggesting that further research is necessary to establish the clinical relevance of the "snake-eye" appearance. Kim et al. [11] tested the still complex and not fully understood concept of cervical sagittal balance and discussed the impact of cervical alignment on surgical decision making for laminoplasty. They concluded that the lack of kyphosis reducibility in cervical extension preoperatively should be considered as a contraindication to laminoplasty surgery.

Kalsi-Ryan et al. [7] focused on gait dysfunction in DCM, and demonstrated that DCM severity can be approximated using spatiotemporal gait parameters, providing another element of assessment that can be used to evaluate the degree and presence of functional impairment of patients. This assessment has the potential to also be used as an outcome predictor in future studies.

The majority of research focused on outcome prediction and prognostic factors. Severino et al. [13] supported the findings from D'Avanzo et al. [9], showing that FA can be used to predict surgical outcome and that increasing FA values preoperatively and postoperatively related with neurological function. Nouri at al. [14] investigated the relationship between gastrointestinal comorbidities (GICs) and DCM, as patients with GICs may suffer from anemia, inflammatory changes, and vitamin deficiencies which could be impact neurological healing. It was interesting to note that patients with and without GICs were not considerably different from a neurological function perspective, however, patients with GICs presented with a unique set of diverging characteristics including that they were more commonly female, and nearly a third of patients suffered from psychiatric comorbidities. Gembruch et al. [15] and Wilson et al. [16] focused on surgical outcomes for older patients and collectively showed that older patient clearly benefit from surgery, but may benefit less due to worse baseline neurologic function. Janssen et al. [12] reported a group of DCM patients in the context of rheumatoid arthritis, finding from their limited series that patients experience meaningful improvements in neurological function. They also showed that these patients are principally approached from a posterior approach initially.

Finally, in a topic relevant not only to the cervical spine, Panchagnula et al. [8] assessed the capacity of PROMIS to be used as a surrogate for EQ-5D, demonstrating the possibility of high accuracy mathematical transformations from PROMIS to EQ-5D in large cohorts, but limitations of accuracy of such transformation on an individual basis. This validation permits the use of PROMIS (a free questionnaire available from the NIH for the evaluation of quality of life) data to be used for quality-adjusted life year calculations.

It was the intention of this Special Issue to address a wide range of topics and we believe that the articles contained in the issue have largely achieved this objective. The editorial board also pursued this project with the hope of contributing new research to help tackle this increasingly prevalent and disabling clinical disorder. We would like to thank the various authors and peer-reviewers for helping to amass this excellent body of work.


**1.**SummaryofpublishedpapersinthisSpecial




**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**


© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

### *Review*
