Timing of Recovery After Surgery for Patients With Degenerative Cervical Myelopathy: An Observational Study From the Canadian Spine Outcomes and Research Network : Neurosurgery

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Research—Human—Clinical Studies: Spine

Timing of Recovery After Surgery for Patients With Degenerative Cervical Myelopathy: An Observational Study From the Canadian Spine Outcomes and Research Network

Evaniew, Nathan MD, PhD*; Coyle, Matthew MD, MSc*; Rampersaud, Y. Raja MD; Bailey, Christopher S. MD, MSc§; Jacobs, W. Bradley MD*; Cadotte, David W. MD, PhD*; Thomas, Kenneth C. MD, MHSc*; Attabib, Najmedden MBBCH; Paquet, Jérôme MD; Nataraj, Andrew MD, MSc#; Christie, Sean D. MD**; Weber, Michael H. MD, PhD††; Phan, Philippe MD, PhD‡‡; Charest-Morin, Raphaële MD§§; Fisher, Charles G. MD, MHSc§§; Hall, Hamilton MD; McIntosh, Greg MSc‖‖; Dea, Nicolas MD, MSc§§

Author Information
Neurosurgery 92(2):p 271-282, February 2023. | DOI: 10.1227/neu.0000000000002213
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Abstract

ABBREVIATIONS:

DCM
degenerative cervical myelopathy
EQ5D
EuroQol 5D
MCID
minimal clinical important difference
mJOA
modified Japanese Orthopedic Association
NDI
Neck Disability Index
NPRS
Numerical Pain Rating Scale
SF-12 MCS
Short Form 12 Mental Component Summary
SF-12 PCS
Short Form 12 Physical Component Summary.

Degenerative cervical myelopathy (DCM) arises when degenerative changes in the cervical spine lead to spinal cord compression and cause neurological impairment.1 Surgical decompression is the only effective treatment for patients with progressive clinical symptoms, and recent research has focused on understanding the extent to which patients experience desirable and undesirable outcomes.2,3 Patients undergoing surgery for DCM were historically counseled that the goal of surgery was simply to halt disease progression, but recent studies have shown that many patients achieve meaningful improvement.4,5

The time course over which neurological recovery occurs after surgery for DCM is poorly understood but is of great interest to patients, clinicians, researchers, and other evidence users.6,7 Indeed, perioperative rehabilitation and monitoring of changes in disease state before or after surgery were recently identified as top research priorities by the AO Spine RECODE-DCM investigators.2,8,9 Discussions about postoperative expectations are an important part of shared decision making, and knowledge of anticipated postoperative trajectories can guide the implementation of resources by surgeons, rehabilitation specialists, allied health professionals, and health care administrators.

The purpose of this study was to investigate the timing of recovery after surgery among patients with DCM who had been enrolled in the ongoing Canadian Spine Outcomes and Research Network prospective cohort study. Our primary objective was to determine the time point at which patients experience significant neurological improvement. Our secondary objective was to determine the time points at which patients experience significant improvements of pain, disability, and health-related quality of life.

METHODS

We analyzed data from patients with DCM who are part of an ongoing multicenter prospective observational cohort study that we have previously reported on.3,4,10 Consecutive patients diagnosed with DCM were enrolled by participating academic orthopedic or neurosurgery spine surgeons from centers across Canada between 2015 and 2018. Local research ethics board approvals were obtained at each site, and informed consent was provided by all patients before their participation.

Patient Sample

Patients were diagnosed with DCM when they presented with clinical signs and symptoms of cervical myelopathy such as sensory changes, loss of dexterity, loss of balance, and sphincter dysfunction and had concordant MRI findings of cervical spinal cord compression secondary to degenerative pathology such as spondylosis, ossification of the posterior longitudinal ligament, or hypertrophy of the ligamentum flavum.11 Surgical procedures were performed according to the recommendations and preferences of the local surgeons at each site, each of whom were fellowship-trained subspecialist spine surgeons. For this study, we included all eligible patients who had achieved 2 years of follow-up after surgery.

Data Sources

We collected outcome measures using validated instruments at baseline before surgery and at 3 months, 1 year, and 2 years after surgery. Our primary outcome was neurological function, measured using the modified Japanese Orthopedic Association scale (mJOA). The mJOA is a validated clinician-reported instrument,12 and it was completed by the attending surgeons or their delegates at each patient visit. Our secondary outcomes were pain, disability, and health-related quality of life according to patient-reported outcome measures (PROMs) that were completed by patients and collected in-person, through post, or with an online portal. These secondary measures were Numerical Pain Rating Scales (NPRSs) for neck and arm pain, the Neck Disability Index (NDI), Short Form 12 Physical and Mental Component Summaries (SF-12; PCS and MCS), and EuroQol 5D (EQ5D). EQ-5D dimension scores were converted to summary index scores using North American value sets for health states.

We also collected overall patient-reported satisfaction, global rating of change, and preferences about repeating surgery. These items were scored with a 5-point Likert scale that ranged from very positive to very negative with neutral in the middle. At each visit, patients were asked to rate their current experience in comparison with their state before surgery. Ratings were dichotomized as favorable vs no change or unfavorable by grouping the 2 positive categories against neutral or the 2 negative categories.

Statistical Analysis

We report discrete variables as counts or proportions, normally distributed continuous variables as means with SDs, and skewed continuous variables as medians with IQRs. We compared unpaired and paired means with independent samples and paired samples t tests, respectively, and proportions with χ2tests or Fisher exact test. We used 1-way analysis of variance with Tukey Honest Significant Difference post hoc test to compare changes across follow-up time points.13 We implemented minimal clinical important differences (MCIDs) to guide interpretation of mJOA scores with respect to categories of baseline disease severity. As described by Tetreault et al,12,14 the MCID for patients with mild DCM (mJOA scores of 15 or greater) is 1 point, for patients with moderate DCM (12-14) is 2 points, and for patients with severe DCM (11 or less) is 3 points.

We performed an adjusted analysis to evaluate factors potentially associated with achievement of the MCID for the mJOA at 3 months vs later than 3 months. We tested the effects of age, sex, number of levels treated, number of comorbidities, duration of symptoms, use of physiotherapy before surgical management, and baseline disease severity (mJOA). We did not have reliable data to test the use of physiotherapy or other rehabilitation modalities after surgery.

All tests of significance were 2-tailed, and P values <.05 were considered significant. Patients with missing data were excluded from each analysis where appropriate, and imputations were not performed. We used IBM SPSS version 26.0.0.1, 2019 (SPSS Inc) and Microsoft Excel 2011 (Microsoft Corp). Our primary statistical analysis plan was formulated to address the study objectives before reviewing data for this study.

RESULTS

We identified 330 patients who were diagnosed with DCM, underwent surgery, and had follow-up at 2 years (Figure 1). An additional 141 were potentially eligible but were lost to follow-up and therefore excluded; we presented their baseline characteristics separately in Supplemental Digital Content, Appendix 1, https://links.lww.com/NEU/D442, and note that they did not differ significantly from those included for baseline PROMs.

F1
FIGURE 1.:
Identification of the study cohort: 330 patients who underwent surgery for DCM. DCM, degenerative cervical myelopathy; EQ5D, EuroQol 5D; mJOA, modified Japanese Orthopedic Association scale; NDI, Neck Disability Index; NPRS, Numerical Pain Rating Scale; SF-12 MCS, Short Form 12 Mental Component Summary; SF-12 PCS, Short Form 12 Physical Component Summary.

The 2-year completion rate of the clinician-reported mJOA was 73%, while completion rates for all the PROMs were 98% or greater. We present baseline characteristics in Table 1. The mean age was 60.8 (SD 11.5) years, 62% were male, and the mean preoperative mJOA was 12.9 (SD 2.6). DCM disease severity was mild in 28% (mean mJOA 16.0, SD 0.9), moderate in 40% (mean mJOA 13.0, SD 0.8), severe in 28% (mean mJOA 9.7, SD 1.2), and missing in 4%. We observed statistically significant improvements across all outcome measures from baseline to 2 years of follow-up (Table 2).

TABLE 1. - Baseline Characteristics of 330 Patients Who Underwent Surgery for DCM
Variable Value
Age: mean (SD) 60.8 (11.5)
Male sex (%) 206 (62%)
Body mass index: mean (SD) 28.7 (5.3)
Duration of symptoms (mo): mean (SD) 18.6 (7.8)
Lives alone (%) 57 (17%)
Education greater than high school (%) 177 (54%)
Current smoker (%) 56 (17%)
Current disability claims (%) 45 (14%)
Comorbidities: mean (SD) 3.1 (2.0)
Daily opiate use (%) 51 (15%)
No. of vertebral levels operated on: mean (SD) 3.8 (1.7)
Preoperative symptoms, health-related quality of life, and function: mean (SD)
mJOA 12.9 (2.6)
 Mild 94 (28%)
 Moderate 130 (40%)
 Severe 94 (28%)
 Missing 12 (4%)
NPRS—neck 5.5 (3.0)
NPRS—arm 5.7 (2.9)
NDI 40.0 (19.8)
SF-12—physical component summary 34.7 (9.7)
SF-12—mental component summary 47.4 (9.7)
EQ5D 0.7 (0.1)
DCM, degenerative cervical myelopathy; EQ5D, EuroQol 5D; mJOA, modified Japanese Orthopedic Association scale; NDI, Neck Disability Index; NPRS, Numerical Pain Rating Scale; SF-12 MCS, Short Form 12 Mental Component Summary; SF-12 PCS, Short Form 12 Physical Component Summary.

TABLE 2. - Neurological Symptoms, Pain, Function, and Health-Related Quality of Life Among 330 Patients Who Underwent Surgery for DCM.
Instrument Preoperative Follow-up
3 mo 1 y 2 y
mJOA All: 12.8 (2.7) n = 318
Mild: 16.0 (0.9) n = 94
Mod: 13.0 (0.8) n = 130
Severe: 9.6 (1.2) n = 94
14.6 (2.4) n = 292
Mild: 16.1 (1.8) n = 85
Mod: 14.5 (2.3) n = 125
Severe: 13.1 (2.2) n = 85
14.7 (2.4) n = 271
Mild: 16.1 (1.9) n = 75
Mod: 14.8 (2.2) n = 125
Severe: 13.1 (2.2) n = 71
14.8 (2.5) n = 242
P < .01
Mild: 16.2 (1.9) n = 71
P = .37
Mod: 14.9 (2.1) n = 109
P < .01
Severe: 12.9 (2.6) n = 62
P < .01
NPRS neck 5.5 (3.0) n = 316 3.6 (2.4) n = 303 2.2 (2.6) n = 294 3.5 (2.7) n = 326
P < .01
NPRS arm 5.7 (2.9) n = 320 3.3 (2.8) n = 303 3.2 (2.9) n = 294 3.5 (3.0) n = 325
P < .01
NDI 40.0 (19.8) n = 322 33.6 (17.9) n = 301 27.8 (18.9) n = 293 28.7 (19.5) n = 326
P < .01
SF-12-PCS 34.7 (9.7) n = 323 39.4 (9.2) n = 296 41.4 (9.3) n = 293 40.3 (10.1) n = 322
P < .01
SF-12-MCS 47.4 (9.7) n = 323 50.4 (7.8) n = 296 50.9 (7.8) n = 293 50.5 (7.9) n = 322
P < .01
EQ5D 0.7 (0.1) n = 330 0.8 (0.1) n = 330 0.8 (0.1)
330
0.8 (0.1)
330 P < .01
DCM, degenerative cervical myelopathy; EQ5D, EuroQol 5D; mJOA, modified Japanese Orthopedic Association scale; NDI, Neck Disability Index; NPRS, Numerical Pain Rating Scale; SF-12 MCS, Short Form 12 Mental Component Summary; SF-12 PCS, Short Form 12 Physical Component Summary.
P values indicate significance of changes in scores from preoperative to 2 years of follow-up.
Bolded P values indicate statistical significance.

The mean mJOA improved to 14.6 (SD 2.4) at 3 months, 14.7 (SD 2.4) at 1 year, and 14.8 (SD 2.5) at 2 years. The difference in means was statistically significant (t test P < .01) at the interval for baseline to 3 months postoperatively, but not from 3 months to 1 year or 1 to 2 years. This result indicates that most mJOA improvement occurs by 3 months after surgery (Figure 2). This finding was consistent among the subgroups of patients with moderate and severe disease, but patients with mild DCM did not experience statistically significant improvement at any interval (Figure 3).

F2
FIGURE 2.:
Timing of neurological recovery among 330 patients who underwent surgery for degenerative cervical myelopathy. Asterisk indicates time point after which improvement was no longer statistically significant. mJOA, modified Japanese Orthopedic Association score.
F3
FIGURE 3.:
Timing of neurological recovery among subgroups of patients with mild (mJOA 15 or greater), moderate (12-14), or severe (11 or less) degenerative cervical myelopathy. Asterisk indicates time point after which improvement was no longer statistically significant. mJOA, modified Japanese Orthopedic Association score.

Two hundred eight patients achieved the MCID on the mJOA by 2 years of follow-up (63% of the study cohort). There were 161 (49% of 330) who achieved it by 3 months, followed by 32 more (10%) at 1 year and 15 more (5%) at 2 years (Figure 4). Among the subgroup of patients with mild disease, we found that 39 (41% of 94) achieved the MCID (1 point change) by 3 months, followed by 8 more (9%) at 1 year and 6 more (6%) at 2 years (cumulative total: 53/94 [56%]). Among those with moderate disease, 71 (55% of 130) achieved the MCID (2 point change) by 3 months, followed by 16 more (12%) at 1 year and 8 more (6%) at 2 years (cumulative total: 95/130 [73%]). Among those with severe disease, 51 (54% of 94) achieved the MCID (3 point change) by 3 months, followed by 8 more (9%) at 1 year and 1 more (1%) at 2 years (cumulative total: 60/94 [64%]).

F4
FIGURE 4.:
Proportions of patients who achieved the MCID for the mJOA at intervals from preoperative to 3 months of follow-up, 3 months to 1 year, and 1 to 2 years after surgery for degenerative cervical myelopathy according to baseline disease severity. MCID, minimal clinical important difference; mJOA, modified Japanese Orthopedic Association score.

The results of an adjusted analysis are presented in Supplemental Digital Content, Appendix 2, https://links.lww.com/NEU/D442. The only variable significantly associated with achievement of the MCID by 3 months vs later than 3 months was baseline disease severity, whereby those with milder disease were less likely to achieve the MCID at 3 months (odds ratio 0.84, 95% CI 0.73-0.97, P = .02).

Changes in pain, function, and health-related quality of life according to the NPRS, NDI, SF-12 PCS and MCS, and EQ5D scales are presented in in Table 2 and Figure 5. Neck pain, arm pain, SF12 PCS, and SF12 MCS all improved significantly by 3 months, while NDI and EQ5D continued to have significant improvement at 1 year. No measures significantly changed from 1 to 2 years. Although EQ5D scores deteriorated slightly between 1 and 2 years, this change was not statistically significant.

Time to plateau of recovery for pain, function, and health-related quality of life among 330 patients who underwent surgery for DCM. Asterisks indicate time point after which improvement was no longer statistically significant. A, NPRS for neck and B, arm pain; C, NDI; D, SF-12 PCS; E, SF-12 MCS; and F, EQ5D. DCM, degenerative cervical myelopathy; EQ5D, EuroQol 5D; mJOA, modified Japanese Orthopedic Association scale; NDI, Neck Disability Index; NPRS, Numerical Pain Rating Scale; SF-12 MCS, Short Form 12 Mental Component Summary; SF-12 PCS, Short Form 12 Physical Component Summary.

F5a
F5b
F5c

Overall patient-reported satisfaction, global rating of change, and preferences about repeating surgery are presented in Table 3. At 3 months, 85% reported being extremely or somewhat satisfied, 71% reported feeling much better or better, and 86% reported that they would definitely or probably repeat having surgery. There were no statistically significant differences in proportions for any of these items between 3 months and 1 year or between 1 and 2 years.

TABLE 3. - Patient-Reported Satisfaction, Global Rating of Change, and Preferences About Repeating Surgery Among 330 Patients Who Underwent Surgery for DCM
Item Follow-up
3 mo 1 y 2 y
Overall satisfaction (vs preoperative):
Extremely or somewhat satisfied
249 (85%) n = 293 233 (80%) n = 292
P = .10
254 (79%) n = 323
P = .72
Global rating of change (vs preoperative):
Much better or better
214 (71%) n = 301 203 (70%) n = 291
P = .72
217 (67%) n = 326
P = .39
Would repeat having surgery (vs preoperative):
Definitely or probably yes
255 (86%) n = 298 244 (84%) n = 292
P = .50
260 (80%) n = 324
P = .29
DCM, degenerative cervical myelopathy.
P values indicate χ2 test results for differences in proportions in comparison with the prior time point.

DISCUSSION

We investigated the timing of recovery after surgery among 330 patients with DCM. We found that most significant neurological improvement occurred within 3 months after surgery, while most significant improvements in pain, disability, and health-related quality of life occurred either within 3 months or within 1 year after surgery. Among 208 patients who achieved the MCID for the mJOA, 77% did so by 3 months and 93% did so by 1 year, with only 15 patients requiring the 2-year follow-up. No significant improvements were seen for any outcome measure across the cohort after 1 year.

Relationship to Previous Literature

Recovery after surgery for DCM has garnered substantial recent research interest, and our results contribute to an understanding that patients' neurological recovery happens sooner than was historically assumed. In our analysis of subgroups according to baseline category of mJOA disease severity, we found that patients with mild DCM were less likely to experience significant improvement. This finding has been described previously and is believed to reflect a ceiling effect of the mJOA in combination with poor sensitivity to subtle changes in patients with minimal impairment.4,15,16 Further studies are currently in progress investigating the accuracy, reliability, cost-effectiveness, and practical implementation of alternative outcome measures for patients with mild DCM.9,17-19 Lack of benefit with surgery among patients with mild disease supports the option of nonoperative treatment with close clinical follow-up.

Fehlings et al20 reported on 479 patients from the prospective multicenter AO Spine CSM international observational cohort study and found that the mean mJOA scores improved from 12.5 (95% CI, 12.2-12.8) to 14.9 (95% CI, 14.6-15.2) at 24 months postoperatively but that study did not report on early outcomes, and it was undertaken before current thinking about MCIDs. Khan et al6 reported on a sample of 2156 patients and found that most patients who obtained a 2-point improvement on their mJOA (405/2156) achieved maximal recovery by the 3-month time point. They also found that patients with lower mJOA scores had the greatest potential for mJOA recovery, which our results support. However, they did not implement MCIDs according to disease severity and did not report on any secondary outcomes such as pain scales, NDI, SF12, or EQ5D.

It is possible that meaningful recovery occurs even earlier than 3 months after surgery. Neurological recovery is a continuous phenomenon necessarily measured at discrete points in time. One of the main limitations of our study is that we did not measure outcomes earlier than 3 months after surgery, which means that we were unable to further explore this issue. In a prospective study of 67 patients, Moussellard et al7 evaluated unmodified JOA scores at 1, 6, 12, 18, and 24 months after surgery and found that scores significantly improved only from preoperative to 1 month.

Implications

Our results have implications for issues such as trial design and standardized reporting, clinical care pathways, and patient counseling. For example, routine follow-up beyond 12 months might not be warranted for the outcomes of mJOA, NPRS, NDI, SF12, and EQ5D among patients undergoing surgery for DCM, and funding, effort, time, and patient commitment purely for the purpose of longer-term PROMs might best be directed elsewhere. Our results for pain and quality of life scores and for mJOA scores among patient with severe DCM could be interpreted to suggest possible trends toward deterioration, which raises interesting implications. However, we identified no statistically significant changes between 1 and 2 years postoperatively for any of these outcomes. Further studies are warranted to explore the incidence of and reasons for deterioration after surgery for DCM. Investigators should still consider whether specific long-term follow-up is desirable to collect data about mechanical failure, adjacent segment degeneration, and other late adverse events.

Our data suggest that patients and clinicians can expect approximately two-thirds of those who undergo surgery for DCM to experience meaningful neurological improvement by 2 years postoperatively, but most improvement will occur within the first 3 months after surgery. Furthermore, most improvements in neck or arm pain, disability, and health-related quality of life will occur within 3 months or 1 year. These findings greatly facilitate valid discussions about postoperative expectations during shared clinical decision making between patients and their surgeons. Our data also allow stratification of discussions according to baseline disease severity.

Strengths and Limitations

The main strength of this study is the use of high-quality data from an ongoing prospective multicenter observational study. This yielded high completion rates for most outcome measures, and data that reflect “real-world” practice with results generalizable to a variety of settings worldwide. Our study is also strengthened by our use of MCIDs to inform about patient important changes and by implementation of multiple validated PROMs for secondary outcomes.

We were unable to examine the potential role of postoperative physiotherapy or rehabilitation for optimizing functional recovery. Specialized physiotherapy has been associated with superior outcomes among patients with acute traumatic spinal cord injuries, but its importance in the management of patients with DCM is unknown.21,22

We excluded 141 patients because they did not complete their 2-year follow-ups despite being eligible. We have previously noted similar attrition in Canadian Spine Outcomes and Research Network among patients with DCM and patients with other pathologies, which is suboptimal.4,10,23-25 However, these losses still left us with 70% of eligible participants and a relatively large sample size of 330. Interestingly, our finding of 98% or greater completion of PROMs vs 73% completion of clinician-reported mJOA scores at 2 years suggests that getting surgeons to complete follow-up outcome measures may in fact be more challenging than getting patients to complete them.

CONCLUSION

Among patients who underwent surgery for DCM, most significant neurological improvement occurred by 3 months after surgery, while most significant improvements pain, disability, and health-related quality of life occurred either within 3 months or within 1 year after surgery. These findings greatly facilitate valid discussions about postoperative expectations during shared clinical decision making between patients and their surgeons, and they may also allow evidence-based decisions about optimal length of follow-up for future research.

Acknowledgments

The authors thank all the patients who participated in this study and the support and research coordinator staff and investigators from the CSORN contributing sites.

Funding

The Canadian Spine Outcomes and Research Network (CSORN) is funded by the Canadian Spine Research & Education Foundation (CSREF). CSREF had no involvement in the development of this study, analysis or interpretation of data, writing of the manuscript, or decision to submit for publication.

Disclosures

Dr Rampersaud has a financial relationship with Medtronic. Dr Jacobs has financial relationships with Stryker, Medtronic, and DePuy Synthes and has a consulting agreement with Cerapedics. Dr Christie has a financial relationship with Medtronic Canada. Dr Phan has received consulting fee of $CAD13000 for salesman training and new products testing and has a grant for research on cervical MRI with DTI of 192 000 over 3 years. Dr Fisher has financial relationships with Medtronic and Nuvasive and has fellowship support from Medtronic and AO Spine (paid to institution). Dr Dea has financial relationships with Stryker, Baxter, and Medtronic.

REFERENCES

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2. Mowforth OD, Davies BM, Goh S, O’Neill CP, Kotter MRN. Research inefficiency in degenerative cervical myelopathy: findings of a systematic review on research activity over the past 20 years. Glob Spine J. 2020;10(4):476-485.
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4. Evaniew N, Cadotte DW, Dea N, et al. Clinical predictors of achieving the minimal clinically important difference after surgery for cervical spondylotic myelopathy: an external validation study from the Canadian Spine Outcomes and Research Network. J Neurosurg Spine. 2020;33(2):129-137.
5. Tetreault L, Wilson JR, Kotter MRN, et al. Predicting the minimum clinically important difference in patients undergoing surgery for the treatment of degenerative cervical myelopathy. Neurosurg Focus. 2016;40(6):E14.
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7. Moussellard HP, Meyer A, Biot D, Khiami F, Sariali E. Early neurological recovery course after surgical treatment of cervical spondylotic myelopathy: a prospective study with 2-year follow-up using three different functional assessment tests. Eur Spine J. 2014;23(7):1508-1514.
8. Mowforth OD, Khan DZ, Wong MY, et al. Gathering global perspectives to establish the research priorities and minimum data sets for degenerative cervical myelopathy: sampling strategy of the first round consensus surveys of AO spine RECODE-DCM. Glob Spine J. 2022;12(1_suppl):8S-18S.
9. Tetreault L, Garwood P, Gharooni AA, et al. Improving assessment of disease severity and strategies for monitoring progression in degenerative cervical myelopathy [AO spine RECODE DCM research priority number 4]. Glob Spine J. 2021;12(1_suppl):64S-77S.
10. Evaniew N, Charest-Morin R, Jacobs WB, et al. Cervical sagittal alignment in patients with cervical spondylotic myelopathy: an observational study from the Canadian Spine Outcomes and Research Network. Spine. 2022;47(5):E177-E186.
11. Nouri A, Tetreault L, Singh A, Karadimas SK, Fehlings MG. Degenerative cervical myelopathy: epidemiology, genetics, and pathogenesis. Spine (Phila Pa 1976). 2015;40(12):E675-E693.
12. Tetreault L, Kopjar B, Nouri A, et al. The modified Japanese Orthopaedic Association scale: establishing criteria for mild, moderate and severe impairment in patients with degenerative cervical myelopathy. Eur Spine J. 2017;26(1):78-84.
13. Ayling OGS, Ailon T, McIntosh G, et al. Clinical outcomes research in spine surgery: what are appropriate follow-up times? J Neurosurg Spine. 2018;30(3):397-404.
14. Tetreault L, Nouri A, Kopjar B, Côté P, Fehlings MG. The minimum clinically important difference of the modified Japanese orthopaedic association scale in patients with degenerative cervical myelopathy. Spine. 2015;40(21):1653-1659.
15. Badhiwala JH, Witiw CD, Nassiri F, et al. Efficacy and safety of surgery for mild degenerative cervical myelopathy: results of the AOSpine North America and international prospective multicenter studies. Neurosurgery. 2019;84(4):890-897.
16. Bond M, McIntosh G, Fisher C, et al. Treatment of mild cervical myelopathy: factors associated with decision for surgical intervention. Spine. 2019;44(22):1606-1612.
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19. Martin AR, De Leener B, Cohen-Adad J, et al. Can microstructural MRI detect subclinical tissue injury in subjects with asymptomatic cervical spinal cord compression? A prospective cohort study. BMJ Open. 2018;8(4):e019809.
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Supplemental Digital Content

Supplemental Digital Content. Appendix 1. Baseline characteristics and scores of 141 patients who underwent surgery for degenerative cervical myelopathy (DCM) but did not complete 2-year follow-up in comparison with the included study sample of 330 patients. Supplemental Digital Content. Appendix 2. Adjusted associations between baseline patient characteristics and achievement of the MCID for the mJOA by 3 months vs later than 3 months among 330 patients who underwent surgery for degenerative cervical myelopathy (DCM).

COMMENTS

“What can I expect—When will I recover?” Frequent questions in those undergoing surgery for degenerative cervical myelopathy (DCM).1a,2a

Landmark studies have shown we can move away from the axiom “surgery is only to prevent further deterioration” and council patients to anticipate improvement not only in function3a but also pain.4a This new study through the Canadian Spine Outcomes and Research Network (CSORN) extends this. It includes an adjusted analysis for known determinants of outcome, coverage across patient critical outcomes,5a and patient perspective using an impression of change score, showing most meaningful recovery occurs by 3 months.

In DCM where the timing and type of surgery can remain open to interpretation, this information is important to facilitate shared decision making. This can be time intensive—the event has been referred to as “clinic crashing6a—but nevertheless time well spent, given its association with improved experience and less discourse.7a

The choice of 3 months while earlier than previous studies is somewhat arbitrary. The study too does not explore the significance of type of surgery. From the perspective of shared decision making, this is becoming more relevant, given broad equivalence on outcomes where surgical options exist, but differing short-term surgical morbidity (eg, pain, time to discharge, or adverse events).8a Understanding how we individualize our surgery is a global research priority and is as much about establishing the disease determinants for each operation as effective shared decision making.9a

While the results too suggest short-term follow-up may be sufficient, offering significant cost and time benefits to clinical trials, the long-term outcomes remain relevant. Surgery for most patients is a one-off event, but the experience of DCM is life-long. Although nonsignificant, the downward trend in quality of life and pain, but not neurological function, shown in this study from 1 to 2 years therefore warrants further investigation.

Ultimately, disability and socioeconomic cost remain high10a in DCM, while research investment and activity relatively low.11a New and practice relevant insights have emerged from a multicentre collaboration. DCM needs more of this.12a

Benjamin Davies

Cambridge, United Kingdom

Iwan Sadler

Cardiff, United Kingdom

References

1a. Davies BM, Khan DZ, Barzangi K, et al. We choose to call it ‘degenerative cervical myelopathy’: findings of AO Spine RECODE-DCM, an international and multi-stakeholder partnership to agree a standard unifying term and definition for a disease. Glob Spine J. 2022;29:21925682221111780.
2a. Umeria R, Mowforth O, Grodzinski B, et al. A scoping review of information provided within degenerative cervical myelopathy education resources: towards enhancing shared decision making. PLoS One. 2022;17(5):e0268220.
3a. Fehlings MG, Ibrahim A, Tetreault L, et al. A global perspective on the outcomes of surgical decompression in patients with cervical spondylotic myelopathy: results from the prospective multicenter AOSpine international study on 479 patients. Spine. 2015;40(17):1322-1328.
4a. Cook CE, George SZ, Asher AL, et al. High-impact chronic pain transition in surgical recipients with cervical spondylotic myelopathy. J Neurosurg Spine. 2022;37(1):31-40.
5a. Davies B, Mowforth O, Sadler I, et al. Recovery priorities in degenerative cervical myelopathy: a cross-sectional survey of an international, online community of patients. BMJ Open. 2019;9(10):e031486.
6a. Matters M. Education & myelopathy - knowledge is power? Accessed September 15, 2022. https://soundcloud.com/myelopathymatters/s2e5-education-myelopathy.
7a. Mondloch MV, Cole DC, Frank JW. Does how you do depend on how you think you’ll do? A systematic review of the evidence for a relation between patients’ recovery expectations and health outcomes. CMAJ. 2001;165(2):174-179.
8a. Ghogawala Z, Terrin N, Dunbar MR, et al. Effect of ventral vs dorsal spinal surgery on patient-reported physical functioning in patients with cervical spondylotic myelopathy. JAMA. 2021;325(10):942-951.
9a. Rodrigues-Pinto R, Montenegro TS, Davies BM, et al. Optimizing the application of surgery for degenerative cervical myelopathy [AO Spine RECODE-DCM Research Priority Number 10]. Glob Spine J. 2022;12(1_suppl):147S-158S.
10a. Davies BM, Phillips R, Clarke D, et al. Establishing the socio-economic impact of degenerative cervical myelopathy is fundamental to improving outcomes [AO Spine RECODE-DCM Research Priority Number 8]. Glob Spine J. 2022;12(1_suppl):122S-129S.
11a. Davies BM, Mowforth O, Wood H, et al. Improving awareness could transform outcomes in degenerative cervical myelopathy [AO Spine RECODE-DCM Research Priority Number 1]. Glob Spine J. 2022;12(1_suppl):28S-38S.
12a. Grodzinski N, Grodzinski B, Davies BM. Can co-authorship networks be used to predict author research impact? A machine-learning based analysis within the field of degenerative cervical myelopathy research. PLoS One. 2021;16(9):e0256997.
Keywords:

Degenerative cervical myelopathy; Surgery; Outcomes; Recovery; Cervical myelopathy; Spine; Spinal cord

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