Diagnosis, heritability, and outcome assessment in cervical myelopathy: a consensus statement

Duration of symptoms in the quantification of upper limb disability and impairment for individuals with mild degenerative cervical myelopathy (DCM)

Objectives

Degenerative cervical myelopathy (DCM) involves spinal cord compression, which causes neurological decline. Neurological impairment in DCM is variable and can involve complex upper limb dysfunction including loss of manual dexterity, hyper-reflexia, focal weakness, and sensory impairment. DCM can cause progressive loss of manual dexterity, reduced upper limb (UL) function and disability. The purpose of this study was to define relationships between impairment and disability of the UL and determine the impact of duration of symptoms on disease severity.

Design

An observational cross-sectional study quantifying disease severity, UL impairment and disability at time of diagnosis was conducted. A second observational longitudinal cohort was studied at the time of diagnosis and 1 year later.

Setting

Toronto Western Hospital, Spine Program.

Subjects

The cross sectional study included 140 study subjects diagnosed with mild, moderate or severe DCM. For the longitudinal study, 61 study subjects with mild DCM were enrolled and split into two groups, one group with less than 12 months of symptom duration and more than 12 months.

Main measures

Modified Japanese Orthopaedic Assessment (mJOA); Graded Redefined Assessment of Sensation, Strength and Prehension (GRASSP); Quick Disability of the Arm, Shoulder and Hand (QuickDASH).

Results

Pearson correlation coefficients between GRASSP and QuickDASH revealed significant relationships between strength, sensation and dexterity for all patients to varying degrees. The covariate (mJOA) was significantly related to QuickDASH, indicating duration of symptoms has an important effect on UL disability in the mild severity group.

Conclusions

Strength, sensation and dexterity play a defining role in disability of the UL across all severities of DCM and are discriminant measures. Duration of symptoms has a significant impact on self-perceived disability, where a longer duration in mild patients results in diminished disability, suggesting adaptation. Duration of symptoms is an important factor to consider in the treatment plan for patients with mild disease.

Genetic factors of cervical spondylotic myelopathy-a systemic review

BACKGROUND

Cervical spondylotic myelopathy (CSM) is a degenerative disorder of the neck. Recent studies have reported the roles of single nucleotide polymorphisms and abnormal gene expression in the etiology and development of CSM. However, a systemic review of these findings is currently unavailable.

METHODS

A systemic review of genetic factors of CSM was conducted through searching PubMed and EMbase databases. A total of 9 studies were included in this study, which included 8 genes: brain derived neurotrophic factor (BDNF), osteopontin (OPN), bone morphogenic protein (BMP) 4, collagen IX, vitamin D receptor (VDR), apolipoprotein E (ApoE), hypoxia-inducible factor α (HIF-1α), and cyclooxygenase 2 (COX-2).

RESULTS

The polymorphisms of 6 genes (OPN, BMP-4, collagen IX, VDR, HIF-1α) showed significant association with the susceptibility to or risk of CSM. The polymorphisms of 3 genes (BMP-4, ApoE4, HIF-1α) were significantly associated with the postoperative outcome. The polymorphism of BDNF, VDR, and expression of COX-2 were associated with the severity of disease.

CONCLUSION

This review demonstrates that 8 genes were associated with CSM although there is no repeated study. This review also suggests that large scale and high quality studies are needed to provide more reliable evidence for future evaluation.

A systematic review of clinical and surgical predictors of complications following surgery for degenerative cervical myelopathy

OBJECTIVE

Although generally safe and effective, surgery for the treatment of cervical spondylotic myelopathy (CSM) is associated with complications in 11%-38% of patients. Several predictors of postoperative complications have been proposed but few are used to detect high-risk patients. A standard approach to identifying "at-risk" patients would improve surgeons' ability to prevent and manage these complications. The authors aimed to compare the complication rates between various surgical procedures used to treat CSM and to identify patient-specific, clinical, imaging, and surgical predictors of complications.

METHODS

The authors conducted a systematic review of the literature and searched MEDLINE, MEDLINE in Process, EMBASE, and Cochrane Central Register of Controlled Trials from 1948 to September 2013. Cohort studies designed to evaluate predictors of complications and intervention studies conducted to compare different surgical approaches were included. Each article was critically appraised independently by 2 reviewers, and the evidence was synthesized according to the principles outlined by the Grading of Recommendation Assessment, Development and Evaluation (GRADE) Working Group.

RESULTS

A total of 5472 citations were retrieved. Of those, 60 studies met the inclusion criteria and were included in the review. These studies included 36 prognostic cohort studies and 28 comparative intervention studies. High evidence suggests that older patients are at a greater risk of perioperative complications. Based on low evidence, other clinical factors such as body mass index, smoking status, duration of symptoms, and baseline severity score, are not predictive of complications. With respect to surgical factors, low to moderate evidence suggests that estimated blood loss, surgical approach, and number of levels do not affect rates of complications. A longer operative duration (moderate evidence), however, is predictive of perioperative complications and a 2-stage surgery is related to an increased risk of major complications (high evidence). In terms of surgical techniques, higher rates of neck pain were found in patients undergoing laminoplasty compared with anterior spinal fusion (moderate evidence). In addition, with respect to laminoplasty techniques, there was a lower incidence of C-5 palsy in laminoplasty with concurrent foraminotomy compared with nonforaminotomy (low evidence).

CONCLUSIONS

The current review suggests that older patients are at a higher risk of perioperative complications. A longer operative duration and a 2-stage surgery both reflect increased case complexity and can indirectly predict perioperative complications.

Responsiveness of the Chinese versions of the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire and Neck Disability Index in postoperative patients with cervical spondylotic myelopathy

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To evaluate the postoperative responsiveness of the Chinese versions of the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and the Neck Disability Index (NDI) in a cohort of patients with cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

We have recently completed the translation and cross-cultural adaptation of a Chinese version of JOACMEQ. However, the postoperative responsiveness of the Chinese JOACMEQ and how it compares with the more commonly used NDI remain undetermined.

METHODS

Forty-five patients with cervical spondylotic myelopathy undergoing surgical decompression were recruited. All patients completed the Chinese JOACMEQ and the NDI preoperatively and again at 3-month follow-up together with an 11-point Global Rating of Change scale. Patients were dichotomized either as "Improved" or "Stable" on the basis of Global Rating of Change. Paired t test, standardized effect sizes, and Guyatt responsiveness index were used to determine internal responsiveness. External responsiveness was evaluated by the area under the receiver operating characteristic curve and the minimal clinically important change was determined as the optimal cutoff point for patient discrimination anchor-based on Global Rating of Change classification.

RESULTS

Bladder function and quality of life (QOL) domains (P < 0.03) of the JOACMEQ and the NDI (P = 0.004) reached statistically significant difference with the paired t test. After the dichotomization, the standardized effect size was strong for the QOL domain in the improved group (0.85) and the Cervical spine function (0.97) in the stable group, respectively. Based on the Guyatt responsiveness index, strong responsiveness was found for the Bladder function (0.88) and QOL (0.76) domains of the JOACMEQ and moderate responsiveness (0.55) for the NDI. The Bladder function (area = 0.82; minimal clinically important change = 6) and QOL (0.83; minimal clinically important change = 8.5) also produced largest area under the receiver operating characteristic curve.

CONCLUSION

Bladder function and QOL domains of the JOACMEQ seem to demonstrate the strongest postoperative responsiveness and thus may be more appropriate than NDI when attempting to determine treatment efficacy in cervical spondylotic myelopathy.

LEVEL OF EVIDENCE

3.

Translation, cross-cultural adaptation, and validation of a Chinese version of the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire

STUDY DESIGN

Translation and psychometric testing of a questionnaire.

OBJECTIVE

To adapt the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) cross-culturally to Chinese language and to investigate the psychometric properties of the translated Chinese JOACMEQ.

SUMMARY OF BACKGROUND DATA

The recently developed JOACMEQ is a self-reported questionnaire used to assess the severity of the cervical spondylotic myelopathy. Despite its acceptance in the literature, the JOACMEQ has not been translated and validated for Chinese-speaking patients.

METHODS

Translation and cross-cultural adaptation of the original JOACMEQ was performed according to published guidelines. A total of 105 patients with a predominant complain of neck pain that included but not limited to patients with a clinically confirmed cervical spondylotic myelopathy were included. Psychometric testing of the responses included construct validity (factor analysis), internal consistency (Cronbach α), test-retest reproducibility (intraclass correlation coefficient), and concurrent validity (Spearman ρ). The discriminatory power of differentiating those with myelopathy from those without was assessed by the area under the receiver operating characteristic curve and with the optimal cutoff points determined.

RESULTS

Construct validity testing revealed a comparable factorial structure of the Chinese JOACMEQ with the original JOACMEQ. The Cronbach α of the Chinese JOACMEQ was 0.88, indicating good internal consistency. Good to excellent test-retest reliability was demonstrated for all 5 domain scores (intraclass correlation coefficient range = 0.79-0.90). A significant strong association between the Chinese Neck Disability Index and the quality of life domain of the Chinese JOACMEQ (Spearman ρ= -0.76, P < 0.01) was identified. The upper and lower extremity function domain scores were found to be significant, with the area under the receiver operating characteristic curve found to be 0.75 (P = 0.04) and 0.82 (P = 0.02), respectively.

CONCLUSION

The results indicated that the Chinese JOACMEQ successfully retained the psychometric properties of the original JOACMEQ and support the usefulness of the Chinese JOACMEQ as an appropriate supplementary diagnostic and outcome measure for Chinese patients suspected of cervical spondylotic myelopathy.