Michael Fehlings MD PhD FACS FRCSC, and Jetan Badhiwala MD Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada DCM is a progressive degenerative spinal condition that results in chronic, nontraumatic compression of the cervical spinal cord and ensuing neurological deficits. The spectrum of disease severity is wide in DCM, and the severity of initial presentation dictates the optimal clinical management of affected patients. Classification of patients into severity groups is by the mJOA scale: mild (mJOA 15–17), moderate (mJOA 12–14), and severe (mJOA <12).1 DCM represents the leading cause of spinal cord dysfunction globally.2 DCM occurs when progressive age‐related osteoarthritic changes (e.g. degenerative disk disease, spondylosis, ossification of the posterior longitudinal ligament) narrow the cervical spinal canal, leading to chronic spinal cord compression.3 There is ischemia and breakdown of the blood–spinal cord barrier, ultimately resulting in neuronal and glial death and a pathological picture consistent with chronic spinal cord injury.4 The natural history of DCM is thought to involve progressive, stepwise decline, with 20–62% of patients deteriorating at 3–6 years of follow‐up, as assessed by the mJOA scale.5,6 Given the limited potential for repair and recovery of the spinal cord, many of the pathological and clinical changes induced by this process are irreversible. With the aging population, DCM will portend a greater burden of disability on our population. Over 70% of individuals over 60–65 years old demonstrate pathological or radiological evidence of cervical degeneration, and approximately one‐quarter of these people become clinically symptomatic from mechanical neural compression.7–9 The proportion of the United States population 65 years or older is expected to nearly double from 13% in 2010 to 22% in 2050.10 Orthopedic and neurosurgeons alike therefore should become comfortable in making decisions related to the management of patients with this clinicopathological entity. Clinical practice guidelines for the management of patients with DCM were published in 2017.11 The evidence for management of DCM is derived primarily from prospective (level II evidence) and retrospective (level III evidence) observational studies. There have been select randomized controlled trials (RCTs); however, these have had several methodological flaws. There have also been several systematic reviews. There is a single RCT comparing the clinical outcomes of operative and nonoperative management for DCM. In 2000, Kadanka et al. published the results of a small RCT of 48 patients with mild or moderate DCM (mJOA ≥12) randomized to conservative or operative treatment.12–16 Surgery consisted of anterior decompression in 22 patients, corpectomy in six patients, and laminoplasty in five patients. Conservative strategies included cervical collar, anti‐inflammatory medications, and intermittent bedrest for patients with pain, discouragement from participation in high‐risk activities, and avoidance of risky environments (e.g. physical overloading, movement on slippery surfaces, manipulation therapies, or prolonged flexion of the head). No significant difference was observed in mean mJOA score within or between the conservative and surgical cohorts over a 36‐month period. At the three‐year mark, 24.1% of the surgical cohort had improved two or more points on the mJOA scale, not significantly different from the corresponding proportion in the conservative cohort (23.3%).13 At the 10‐year mark, mean mJOA score was 15.0 in conservatively and 14.0 in surgically treated patients.15 However, several criticisms have been levied against this trial, most notably that it was underpowered and lacked a sample size calculation.17 A recent sample size estimate for an RCT sponsored by the Patient‐Centered Outcomes Research Institute (PCORI) indicates 159 patients would be needed to demonstrate a difference using the SF‐36 Physical Component Summary (PCS) as the outcome instrument.18 Hence, based on this study and one retrospective cohort study of 91 Chinese DCM patients,19 there is low‐level evidence that nonoperative treatment results in similar outcomes as surgery for patients with milder (mJOA ≥13), single‐level DCM and intramedullary signal change on T2 MRI.20,21 In another prospective comparative study also published in 2000, Sampath et al. enrolled patients with subacute DCM, defined by at least eight weeks of symptoms. Patients were seen by a Cervical Spine Research Society (CSRS) surgeon and prescribed either medical or surgical therapy.22 A total of 23 patients received conservative treatment, including a combination of pharmacotherapy, home exercise, physical therapy, bedrest, cervical traction, and neck bracing. By contrast, 20 patients underwent surgery. At a mean follow‐up of 29.8 months, the surgical group demonstrated significant improvements in overall functional status as well as work and social activities. Conservatively treated patients, too, exhibited functional improvements, but this did not reach statistical significance. Additionally, surgical patients experienced no change in the number of activities that worsened their symptoms from before to after treatment, whereas the number of activities that exacerbated symptoms in the medical cohort increased from baseline to follow‐up (+0.63). Since then, there have been several contemporary prospective studies to support the safety and efficacy of operative treatment in patients with DCM with regard to functional status, disability, pain, and complications. A 2017 systematic review of the literature identified 32 prospective investigations.23 Pooled standard mean differences showed a large effect for improvement in mJOA score from baseline at short‐, medium‐, and long‐term follow‐up: 6–12 months (1.92; 95% confidence interval [CI]: 1.41–2.43); 13–36 months (1.40; 95% CI: 1.12–1.67); and >36 months (1.92; 95% CI: 1.14–2.69) (moderate‐level evidence). There was also low‐level evidence that surgery resulted in significant improvements in Nurick grade, Neck Disability Index (NDI), and Visual Analog Scale (VAS) scores. The cumulative incidence of complications was low (14.1%; 95% CI: 10.1–18.2%). The AOSpine CSM‐NA and CSM‐I trials represent two of the largest multicenter, prospective studies of surgical decompression for DCM.24,25 An extensive battery of outcome metrics were evaluated, including functional status (mJOA, Nurick, 30‐meter walk test [30MWT]), disability (NDI), and quality of life (SF‐36). The CSM‐NA study recruited 278 patients with symptomatic DCM and MRI evidence of spinal cord compression from 12 North American centers over a two‐year period.25 At enrollment, patients were classified into mild (mJOA ≥15), moderate (mJOA 12–14), or severe (mJOA < 2) groups based on disease severity. All patients underwent surgical decompression. There was significant improvement in mJOA score, Nurick grade, NDI, and all SF‐36 dimensions, except general health
111
Cervical Radiculopathy and Myelopathy
Clinical scenario
Top three questions
Question 1: In patients with mild, moderate, or severe degenerative cervical myelopathy (DCM), does surgical decompression provide superior functional outcomes, as graded by the modified Japanese Orthopaedic Association (mJOA) scale, compared to nonoperative management strategies?
Rationale
Clinical comment
Available literature and quality of the evidence
Findings
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
