Quantitative MRI Shows High Sensitivity in Detecting Progression in Degenerative Cervical Myelopathy

Peer Reviewed

Quantitative magnetic resonance imaging (MRI) has a high sensitivity in detecting neurological progression in patients with degenerative cervical myelopathy (DCM) and can aid in surgical decision making when applied to a treatment algorithm, according to a prospective longitudinal study of 26 patients published April 17 in PLOS ONE.

“Treatment of DCM has evolved considerably over the last generation,” said senior author Michael G. Fehlings, MD, PhD, FRCSC, FACS. Two decades ago, surgery was considered primarily as a last resort for patients with severe DCM. However, more recently, findings suggest that a majority of patients with DCM who have moderate to severe impairment benefit from surgery.

“What is also clear is that the patients who seem to benefit the most from surgery are those with milder degrees of impairment, because early intervention can help patients maintain a high level of functioning,” said Dr. Fehlings, who is Professor of Neurosurgery and Co-Director of the Spine Program at the University of Toronto in Ontario, and Chair of the AOSpine International Spinal Cord Injury Knowledge Forum. “The challenge is that not all patients with mild myelopathy require surgery; some patients remain stable for long periods of time with only minor impairment that doesn’t affect quality of life. This is where decision-making becomes critical.”

cervical spine, C4-C5 spinal cord compressionCervical spinal cord compression, cervical myelopathy.

Surgical Decision-Making Is Challenging in Degenerative Cervical Myelopathy
“Presently, cervical myelopathy is a clinical diagnosis that is defined by the physical examination and is supplemented with the use of radiography,” commented James S. Harrop, MD, FACS, who is a SpineUniverse editorial board member and not affiliated with this study. “The issue is that cervical myelopathy is a heterogeneous disease, and patients’ examination findings can vary. Clearly, severe forms of the disease benefit from surgery; however, how do we know which patients are going to get worse?,” said Dr. Harrop, who is Professor in the Departments of Neurological and Orthopedic Surgery and Director of the Division of Spine and Peripheral Nerve Surgery at Thomas Jefferson University in Philadelphia, PA.

Currently, there is no gold standard measure for determining neurological progression in DCM, resulting in varied clinical practice and reliance on patients’ subjective impression of neurological deterioration, which is prone to recall bias and other factors such as personality and anxiety, the researchers noted.

To better determine which patients are at risk for deterioration at an earlier level, the researchers developed a multiparametric quantitative MRI (qMRI) protocol that measures tissue changes in the spinal cord and detects axonal injury, demyelination, and atrophy. The approach can be applied to any 3 or 1.5 tesla MRI scanner in a clinical facility, and takes approximately 20 minutes to conduct, Dr. Fehlings said.

The study included 26 patients (mean age, 57.6 years; 15 men and 11 women) with DCM at a single center who were initially managed non-operatively and were re-evaluated approximately 1 year later. A total of 22 subjects had complete follow-up data available, including modified Japanese Orthopedic Association (mJOA) score, anatomical MRI, a battery of clinical assessments, and qMRI. Subjective neurological worsening at follow-up was used as the clinical case definition of myelopathic progression.

qMRI Provides the Greatest Sensitivity in Detecting Neurological Worsening in Degenerative Cervical Myelopathy
Eleven patients (42.3%) reported subjective neurological worsening, and the remaining 15 patients reported feeling the same or better. In comparison, myelopathic progression was detected in 11.5% of patients using mJOA score, 20% using anatomical MRI, 54.6% using comprehensive examination, and 68.2% using qMRI. As shown in Figure 1, qMRI showed greater sensitivity than mJOA and anatomical MRI in detecting myelopathic progression, but was less specific than these other measures.

chart, comparison of methods to monitor for myelopathic progression in degenerative cervical myelopathyFigure 1. Comparison of methods to monitor for myelopathic progression in degenerative cervical myelopathy. Source: Martin et al. PLOS ONE. 2018;13(4):e0195733.

Figure 1. Comparison of methods to monitor for myelopathic progression in degenerative cervical myelopathy. Diagnostic accuracy of each measure was measured relative to patients’ subjective impression, which was selected as the clinical case definition.
mJOA, modified Japanese Orthopedic Association.
Source: Martin et al. PLOS ONE. 2018;13(4):e0195733.

Algorithm Aids in Clinical Decision-Making in Degenerative Cervical Myelopathy
A decision-making algorithm that incorporates progression identified on qMRI with patient’s subjective impression of worsening and objective measures of progression recommended surgery for 11 subjects (42.3%; Figure 2).

chart, Decision-making algorithm for degenerative cervical myelopathy in patients initially managed non-operativelyFigure 2. Decision-making algorithm for degenerative cervical myelopathy in patients initially managed non-operatively. Source: Martin et al. PLOS ONE. 2018;13(4):e0195733.

Figure 2. Decision-making algorithm for degenerative cervical myelopathy in patients initially managed non-operatively. The decision-making algorithm requires clinical and quantitative MRI data collection at 2 time-points, and takes into account the patient’s subjective impression of worsening and objective measures of progression, including mJOA, a battery of clinical assessments, anatomical MRI, or quantitative MRI.
Source: Martin AR, et al. PLOS ONE. 2018;13(4):e0195733.

Future Research on qMRI Planned
Dr. Harrop concluded that while qMRI has the potential to markedly improve surgical decision-making in DCM, more research is necessary. “I think we are at the infancy of this technology,” he told SpineUniverse.

Dr. Fehlings and colleagues plan to launch a multicenter study of qMRI in patients with mild DCM to collect data on a larger number of patients, and to investigate use of qMRI in combination with more sensitive measures of progression in DCM, including measures of hand and walking function. In addition, the researchers plan to combine qMRI with potential blood biomarkers of myelopathic progression, which are currently under investigation.

He concluded that findings from the current study “are very promising and hold a significant degree of potential as a breakthrough in the management of patients with mild DCM.”

Disclosures
Dr. Fehlings has no relevant disclosures.
Dr. Harrop is a consultant for DePuy Spine and has received honorarium from Stryker and Globus Medical.

 

Updated on: 05/07/18
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Michael G. Fehlings, MD, PhD, FRCSC, FACS
Professor of Neurosurgery
Department of Surgery
University of Toronto
James S. Harrop, MD, FACS
Professor
Departments of Neurological
and Orthopedic Surgery
Thomas Jefferson University
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