Deterioration After Surgery for DCM: An Observational Study

The RECODE-DCM initiative calls upon the global community of healthcare professionals working with DCM, and individuals living with DCM, to come together to solve the Top 10 Research Priorities — 10 critical questions that are relevant to the whole community. In this blog, focusing on Research Priority 6: Perioperative Rehabilitation, we will hear from Nathan Evaniew, Clinical Assistant Professor at The University of Calgary.

We welcome comments from our community on our RECODE-DCM blog posts. Please share your perspectives by emailing — we’re listening!


Amongst those with DCM, treatment options are extremely limited; for most experiencing moderate-to-severe symptoms of the condition, the primary option available is surgical intervention. Whilst surgery can frequently be successful, with many seeing marked improvements in their symptoms following, a significant proportion will have no change in their condition, with a few actually facing deterioration.

In a recent study, led by Dr. Nathan Evaniew at the University of Calgary, researchers investigated the incidence, etiology, and outcomes of patients who experience such postoperative neurological deterioration.

This study was performed by the Canadian Spine Outcomes and Research Network (CSORN). CSORN is a group of Canadian spine surgeons and rehabilitation specialists who have interest in multicenter research that evaluates the effects of both surgical and nonsurgical treatments for a wide range of spinal disorders. This group was founded in 2015, and has been running a prospective observational cohort substudy of patients with Degenerative Cervical Myelopathy (DCM) since that time. As of 2023, over one thousand patients have been enrolled, and it is important to highlight that it is their participation that fundamentally makes this type of research possible. This allows our team to ask important questions and answer them reliably, in order to optimize care and outcomes not only in Canada but around the world. 

map of canadian spine society locations on a map of canada

In this study, we aimed to understand the issue of neurological deterioration after surgery for DCM. It is well-established that most patients experience substantial improvement of their neurological impairments following surgery for DCM, but – unfortunately – some patients actually worsen. The frequency of this worsening, as well as the reasons for it happening and the short and long-term outcomes of patients who experience it, have been poorly understood.  Given that this is one of the most undesirable complications that can occur after surgery for DCM, further research was needed to help improve our understanding of this problem in order to confidently inform patients, surgeons, researchers, and other evidence users.

We analyzed data from 428 participants who were enrolled and underwent surgery between 2015 and 2021, from across 8 sites in Canada. Of these 428 patients, we found that 50 patients – or approximately 1 in 10 – experienced a deterioration according to a drop by at least one point on their Modified Japanese Orthopaedic Association (mJOA) scores from between before surgery and approximately three months after surgery. The mJOA is a clinician-reported instrument to assess and score losses of balance and dexterity, numbness in the arms or the legs, and bowel or bladder dysfunction. 

One of the most important findings of our study was that many of these deteriorations were actually very small, and therefore perhaps unimportant or unreliable, and some were unrelated to actual spinal cord impairment. Among many patients with drops in their mJOA scores, other outcomes such as patient-reported pain, disability, and health-related quality of life were often unaffected.

Risk factors for deterioration included older age, female sex, and milder disease. Among those who deteriorated, 13 experienced contributing intraoperative or postoperative adverse events such as post-operative bleeding, spinal fluid leak leading to wound healing problems, or C5 nerve root palsies. Six actually had completely unrelated alternative diagnoses leading to their apparent loss of function such as disabling hip arthritis, severe lumbar spinal stenosis, worsening shoulder arthritis, or a stroke. There were no patients that experienced catastrophic intraoperative spinal cord injuries. 

pictogram of affected patients

This study is important because the results can inform the process of shared decision-making that occurs between patients and their care providers in the clinic, by allowing a better understanding of an undesirable outcome that can and does happen. This study is also important, because the results highlight how interpretation of mJOA scores without detailed clinical context can be misleading, because scores may seem to worsen despite the absence of new postoperative spinal cord pathology. 

About the Author

Dr. Nathan Evaniew is currently a Clinical Assistant Professor at the McCaig Institute for Bone and Joint Health, University of Calgary.

Evaniew’s research focuses on improving the lives of patients with spinal disorders through the paradigm of evidence-based medicine, primarily via clinical trials and collaborative multicenter studies.