Introduction: Cervical spondylotic myelopathy (CSM) is a common cause of spinal cord dysfunction. Previous studies have shown diffusion tensor imaging might be a better biomarker compared to T2 signal intensity. There is currently no viable biomarker to identify CSM patients who will improve from surgical decompression. We examined fractional anisotropy (FA) threshold in the cervical spinal cord in a large prospective series of patients as a potential biomarker for clinical improvement following surgical decompression for CSM patients.

Methods: A prospective analysis of 48 patients who had clinical follow up at 12-months after surgery was performed. Preoperative FA was measured at the level of maximum compression (LMC) and cervical 1-2 segment regions. 13 (27%) patients were identified who declined in their modified Japanese Orthopedic Association (mJOA) at 12-month post-operatively compare to pre-operation. Receiver-Operation Characteristic (ROC) Curve was used to determine the threshold for the FA values.

Results: Using ROC curve, we determined that LMC FA (P=0.014) is more accurate compared to FA at C1-2 region (P=0.139) as a biomarker to identify individuals who will benefit from decompression surgery. LMC FA threshold value of 0.528 appeared to separate patients who will decline versus stay stable/improve at 12-months post-operatively. The area under the curve (AUC) was 0.738 with sensitivity of 0.769 and specificity of 0.633 for LMC FA. The AUD was 0.356 with sensitivity of 0.570 and specificity of 0.433 for FA at C1-2 region.

Conclusions: In this larger prospective study of CSM patients, FA value at the LMC is a more sensitive/specific test compared to LMC C1-2 region to predict surgical outcomes at 12-month. FA threshold value of 0.528 at LMC may be used a biomarker in conjunction with existing clinical and radiologic assessments as an integral part of diagnosis and prognostication in patients with CSM and might help in the decision regarding surgical intervention.

Patient Care: FA threshold value of 0.528 at LMC can be used to separate individuals with CSM who will benefit from surgical decompression at 12-months. Therefore, surgical intervention can be tailored more specifically to individuals who will benefit from it.

Learning Objectives: 1. To determine the usefulness of fractional anisotropy (FA) as a biomarker for the severity of CSM 2. To explore using objective biomarkers to predict improvement after decompressive surgery. 3. To compare objective vs. subjective methods of monitoring CSM 4. To understand the importance of DTI as a noninvasive biomarker

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