Keywords
cervical vertebrae - diagnosis - magnetic resonance
Palavras-chave
diagnóstico - ressonância magnética - vértebras cervicais
Introduction
Degenerative cervical myelopathy (DCM) is the most common source of spinal cord dysfunction
in patients older than 60 years of age.[1] The development of DCM is associated with age-related degeneration of the cervical
spine and spinal cord compression from the abnormal degenerated tissue.[1]
[2] Patients with symptomatic DCM may present a combination of motor, sensory and autonomic
dysfunctions, and, consequently, reduced quality of life.[1]
[2]
Several questionnaires can be used to assess the severity of the physical disability,
the patient's clinical condition, and the effectiveness of the treatment.[3] Among these instruments, the modified Japanese Orthopaedic Association (mJOA) scale
has become one of the most frequently used outcome measures to assess functional status
in patients with DCM.[4]
[5]
[6]
Although primarily based on clinical assessment, it is well established that magnetic
resonance imaging (MRI) is crucial in the assessment of spinal cord compression and
in the diagnosis of DCM.[7] Previous studies[8]
[9] involving MRI findings have shown that this exam aids in the establishment of the
prognosis of the surgical treatment, but not all parameters have been shown to be
useful. The factors that have been shown to have an impact include the duration of
T2 hyperintensity, congenital stenosis, cervical spondylolisthesis, and T1 hypointensity.[8]
[9]
[10]
[11]
[12]
[13]
[14]
Dynamic magnetic resonance (DMR) imaging, which includes cervical spine evaluation
during flexion and extension, may better reflect the real-time biomechanical impact
of movement on the spinal cord than static MRI alone.[3]
[8]
[9] This is particularly relevant in DCM, in which the symptoms often fluctuate with
neck position, and transient spinal cord compression may not be fully captured on
conventional imaging.[3]
[8]
[9] More recently, other studies[3]
[8]
[9] aimed to investigate the role of DMR imaging in patients with DCM and demonstrated
significant changes in cervical spinal canal measures in a subgroup of patients with
DCM; the authors stated that those findings may explain clinical examination findings
and, consequently, impact the results of the surgical treatment.
Therefore, to establish a correlation between clinical and magnetic resonance findings,
we studied data from a subset of patients enrolled in a prospective research to assess
a correlation between the mJOA score and the DMR findings in patients diagnosed with
DCM.
Materials and Methods
Study Design and Data Collection
Before commencing the study, ethical approval was obtained from the hospital's Ethics
Committee and Internal Review Board, and all participants provided informed consent
before data collection began. The present research was established as a prospective
cohort study aimed at evaluating the reliability of a cervical DMR imaging technique
in patients diagnosed with DCM, based on previously-published preliminary findings.
The participants had a clinical diagnosis of DCM confirmed through MRI scans and were
then submitted to standard surgical procedures for treatment. The inclusion criteria
were patients who filled out the mJOA questionnaire, underwent the DMR exam, and consented
to participate in the study. Those who had undergone prior cervical spine surgery
or had other orthopedic, neurological, or psychiatric conditions that might influence
the clinical outcomes were excluded. Out of 168 potential candidates who filled out
the mJOA questionnaire, 18 (14 male and 4 female) patients met the inclusion criteria
and had DMR imaging available for subsequent analysis.
Imaging Acquisition and Evaluation
All enrolled patients underwent a DMR assessment of the cervical spine using a standardized
1.5-Tesla Achieva device manufactured by Philips. The image analysis was carried out
using the OsiriX MD, version 7.0, 64-bit software (Primeo SARL), with a consistent
zoom level of 300%. Two independent spine surgeons analyzed the images. One of these
observers repeated the assessment after 30 days to evaluate the intraobserver reliability,
following the same protocol and using the same computer and software for consistency.
Anatomical Measurements
The anatomical parameters assessed included the spinal cord diameter (SCD) and the
spinal canal width (SCW). The SCW was calculated by measuring the distance between
the midpoint of the posterior part of the intervertebral disc and the anterior limit
of the yellow ligament ([Fig. 1A]). The SCD was determined as the distance from the anterior to the posterior margins
of the spinal cord at the same point where the SCW was measured ([Fig. 1B]). All measurements were linear and recorded in millimeters (±1.0 mm), captured from
midline images of the T2-weighted sequences in the sagittal plane under neutral position
and in flexion and extension at the disc spaces from C2-C3 to C6-C7.
Fig. 1 T2-weighted sagittal cervical magnetic resonance imaging scan. (A) Spinal cord width. (B) Spinal cord diameter.
Clinical Evaluation
The mJOA scale was chosen to assess the functional status; it is an 18-point DCM scale
that separately scores upper (5 points) and lower (7 points) extremity motor function,
sensation (3 points), and sphincter control (3 points).[5]
Statistical Analysis
The statistical analysis was performed using the STATA13 (StataCorp LLC) software.
The intra- and interobserver reliability of the morphometric parameters of the DMR
were calculated using the intraclass correlation coefficient (ICC), with a 95%CI.
Values of the ICC ranging from 0.00 to 0.20 were considered poor agreement, from 0.21
to 0.40, fair agreement, from 0.41 to 0.60, moderate agreement, from 0.61 to 0.80,
strong agreement, and from 0.81 to 1.00, almost perfect agreement. The statistical
correlation analysis considered the severity of the DCM, represented by the mJOA score,
and the dynamic measures using the Spearman rank correlation test. Values of p < 0.05 were considered statistically significant.
Results
Subjects
A total of 18 eligible patients completed the DMR protocol, fulfilled the inclusion
criteria and were analyzed in the current study. There were 14 men and four women,
with a mean age of 60 (range: 37–76) years.
Interobserver Reliability
Regarding the SCD evaluation, the mean ICC values of all disc levels for interobserver
reliability were of 0.90 in the neutral position, and of 0.92 in flexion and extension
([Table 1]). The SCW interobserver reliability had mean ICC values of 0.80, 0.88, and 0.87
for the neutral, flexion, and extension positions respectively ([Table 1]).
Table 1
Interobserver reliability regarding the spinal canal width and the spinal cord diameter
according to the intraclass correlation coefficient
|
Flexion (95%CI)
|
Neutral position (95%CI)
|
Extension (95%CI)
|
|
Spinal canal width
|
|
C2–C3
|
0.94 (0.86–0.98)
|
0.95 (0.87–0.98)
|
0.97 (0.92–0.98)
|
|
C3–C4
|
0.89 (0.73–0.96)
|
0.98 (0.95–0.99)
|
0.95 (0.88–0.98)
|
|
C4–C5
|
0.87 (0.66–0.95)
|
0.94 (0.86–0.98)
|
0.89 (0.70–0.95)
|
|
C5–C6
|
0.93 (0.83–0.97)
|
0.93 (0.81–0.97)
|
0.92 (0.78–0.98)
|
|
C6–C7
|
0.90 (0.75–0.96)
|
0.83 (0.56–0.93)
|
0.91 (0.78–0.96)
|
|
Spinal cord diameter
|
|
C2–C3
|
0.84 (0.59–0.94)
|
0.96 (0.91–0.98)
|
0.94 (0.86–0.98)
|
|
C3–C4
|
0.92 (0.80–0.97)
|
0.95 (0.88–0.98)
|
0.94 (0.84–0.97)
|
|
C4–C5
|
0.84 (0.57–0.94)
|
0.91 (077.–0.96)
|
0.95 (0.89–0.98)
|
|
C5–C6
|
0.95 (0.87–0.98)
|
0.95 (0.87–0.98)
|
0.90 (0.75–0.96)
|
|
C6–C7
|
0.73 (0.29–0.90)
|
0.82 (0.54–0.93)
|
0.82 (0.52–0.93)
|
Intraobserver Reliability
Regarding the intraobserver reliability of the SCD values, the neutral position had
a mean ICC of 0.97, the flexion position, of 0.96, and the extension position, of
0.97, with all disc levels having an ICC higher than 0.90 in every position. For the
SCW evaluation, the results showed that the neutral position had a mean ICC of 0.94,
with the flexion and extension positions having mean ICC values of 0.87 and 0.94 respectively.
The ICC values for each disc level were higher than 0.8 for every position in all
disc levels. [Table 2] presents the complete description of ICC values for each position and disc level.
Table 2
Intraobserver reliability regarding the spinal canal width and the spinal cord diameter
according to the intraclass correlation coefficient
|
Flexion (95%CI)
|
Neutral position (95%CI)
|
Extension (95%CI)
|
|
Spinal canal width
|
|
C2–C3
|
0.96 (0.91–0.98)
|
0.98 (0.97–0.99)
|
0.99 (0.97–0.99)
|
|
C3–C4
|
0.98 (0.95–0.99)
|
0.99 (0.98–0.99)
|
0.98 (0.97–0.99)
|
|
C4–C5
|
0.94 (0.86–0.98)
|
0.96 (0.91–0.98)
|
0.99 (0.99–0.99)
|
|
C5–C6
|
0.98 (0.96–0.99)
|
0.98 (0.94–0.99)
|
0.93 (0.83–0.97)
|
|
Spinal cord diameter
|
|
C2–C3
|
0.84 (0.59–0.94)
|
0.96 (0.91–0.98)
|
0.94 (0.86–0.98)
|
|
C3–C4
|
0.92 (0.80–0.97)
|
0.95 (0.88–0.98)
|
0.94 (0.84–0.97)
|
|
C4–C5
|
0.84 (0.57–0.94)
|
0.91 (0.77–0.96)
|
0.95 (0.89–0.98)
|
|
C5–C6
|
0.95 (0.87–0.98)
|
0.95 (0.87–0.98)
|
0.90 (0.75–0.96)
|
Correlation between DMR findings and mJOA Score
The mJOA score ranged from 6 to 18 (median: 15) points. The Spearman classification
test, which was used to assess the correlation between the results obtained from the
mJOA score evaluation and the results of the SCD, showed a weak positive correlation
in the flexion position (0.191), with p = 0.448 ([Fig. 2A]), a weak positive monotonic relationship in the neutral position (0.255), with p = 0.307 ([Fig. 2B]), and a weak positive correlation in the extension position (0.265), with p = 0.288 ([Fig. 2C]).
Fig. 2 Correlation between the score on the modified Japanese Orthopaedic Association (mJOA)
scale and spinal cord diameter in flexion (A), neutral position (B), and in extension (C).
When evaluating the correlation between the mJOA score and the SCW results, the Spearman
rank test evidenced a very weak positive correlation (0.089), with p = 0.724 in the flexion position ([Fig. 3A]), a weak positive correlation (0.14), with p = 0.507 in the neutral position ([Fig. 3B]), and a weak negative correlation (−0.032), with p = 0.898 in the extension position ([Fig. 3C]).
Fig. 3 Correlation between the score on the modified Japanese Orthopaedic Association (mJOA)
scale and spinal canal width in flexion (A), neutral position (B), and in extension (C).
Discussion
In the current study, we found no clear association between the DMR imaging findings
and the mJOA questionnaire results in patients with DCM. Degenerative cervical myelopathy
is the most common cause of spinal cord dysfunction, characterized by reduced spinal
canal measurements due to degenerative changes exacerbated by cervical spine movements,
which can be observed through cervical DMR imaging.[15]
[16] Although the literature[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17] presents differing views on the link between MRI findings and clinical features
of DCM, the present study is, to the best of our knowledge, the first to measure morphometric
parameters of the cervical spinal canal using DMR exams and correlate them with mJOA
questionnaire results.
Magnetic resonance imaging is considered an important prognostic tool for DCM patients,
as evidence to support this concept has been published and indicates that reduction
in the cross-sectional area of the cervical spinal canal and signal changes in the
spinal cord of DCM patients are significantly associated with the degree of neurological
severity, the prevalence of specific clinical manifestations, and potential for neurological
recovery.[18]
[19]
[20] In patients with DCM, clinical manifestation results from degenerative anatomical
alterations that cause compression of the spinal canal, and MRI scans of the cervical
spine provide static images of spinal cord compression.[17]
[18]
[19] However, it has been well demonstrated[15] that dynamic compression resulting from hypermobility and instability of the cervical
joint can aggravate an existing spinal canal narrowing. Thus, DMR study data demonstrated
that the different positions (neutral and in flexion and extension) influence the
measurements of the diameter of the cervical spinal canal and the spinal cord.[9]
The present research provided data on the cervical spinal canal and cord morphometric
parameters in patients with DCM based on MRI scans acquired in the neutral, flexion,
and extension positions. We evaluated inter- and intraobserver reliability of the
cervical spinal morphometric parameters acquired based on the DMR protocol adopted
at our institution.[21] The measurements of all dynamic parameters presented at least substantial agreement
for inter and intraobserver reliability. Likewise, Yu et al.[22] showed that DMR has been proven to be a suitable method to identify instability
in the cervical spine. Other authors[15] showed that patients with cervical spine instability had worse mJOA and Nurick scores
and worse electrophysiological findings signals than those without instability. Additionally,
Nigro et al.[16] suggested that, using DMR imaging, surgeons can identify more findings associated
with DCM and worsening compression than with traditional cervical MRI.
The mJOA scale, a helpful tool in assessing DCM, has been evaluated for reliability
and validity.[5]
[6] There is no ideal clinical criterion to evaluate patients with symptoms of spinal
cord compression. The mJOA scale was chosen because it is the most widely used criterion
in clinical studies and is easy to apply. Therefore, as the correlation between findings
on cervical DMR and disease severity remains controversial, the present study tried
to establish a correlation between the cervical DMR exam findings and the score on
the mJOA scale.[5]
[6] However, our results obtained from the correlation of the mJOA scores with the dynamic
morphometric parameters of the cervical spine did not show statistically significant
results. Moreover, although the correlation did not reach a significance level, which
may have occurred due to sample-size issues, none of the cervical positions showed
correlations higher than the others, which might suggest that there is not a clear
straight line between spinal canal diameter and myelopathy, but rather the most significant
factor in predicting changes in clinical conditions could be the changes in the signal
intensity of the spinal cord, as seen in the diffusion tensor imaging (DTI).[23] The absence of a positive correlation between the mJOA score and the SCW in extension
can also be explained by the fact that the group of patients studied presented high
initial and mJOA levels.
Several limitations deserve consideration when interpreting the findings of the current
study. The relatively small sample size and the homogeneity in the severity of clinical
findings, as represented by the limited variation in mJOA scores, could have introduced
a sampling bias and influenced our results. A larger patient cohort, with a wider
range of mJOA scores, may reveal statistically significant correlations between cervical
DMR findings and clinical outcomes. In addition, the present study did not include
an evaluation of spinal cord MRI signal changes, which may serve as indicators of
more severe clinical findings and, consequently, worse mJOA scores. Moreover, the
exclusion of spinal cord signal abnormalities—such as T2 hyperintensity and DTI-based
metrics—represents a significant limitation of our analysis, as these variables may
better capture underlying neural compromise and explain functional deficits more accurately
than morphometric measurements alone. From a clinical standpoint, our findings suggest
that DMR morphometric measurements alone may not be sufficient to estimate functional
impairment in DCM patients, highlighting the need for a more comprehensive imaging
approach that includes spinal cord signal assessment. This insight reinforces the
importance of a multimodal evaluation in the diagnosis and prognostication of DCM.
Despite these limitations, the current study presents an innovative way to correlate
findings on DMR with the mJOA score, representing a model for future studies with
larger and more heterogeneous patient populations, as well as the inclusion of spinal
cord signal intensity metrics, to further elucidate the complex relationship between
dynamic spinal canal morphology and clinical presentation in DCM.
Conclusion
We found results that conflicted with those of previously-published studies, as it
was not possible to identify a correlation between measurements of the cervical spinal
canal in the DMR and the clinical severity of patients with DCM measured using the
mJOA scale. Thus, our results reinforce the need for additional research on DMR, since
the inherent movements of the cervical spine are associated with the pathophysiology
of DCM.
Bibliographical Record
Ricardo André Acácio dos Santos, Raphael de Rezende Pratali, Mariana Demétrio de Sousa
Pontes, Carlos Fernando P. S. Herrero. Dynamic MRI Findings and the mJOA Scale: Establishing
Correlations in the Clinical Assessment. Rev Bras Ortop (Sao Paulo) 2025; 60: s00451811928.
DOI: 10.1055/s-0045-1811928
