[A long-term follow up study of cervical spondylotic myelopathy using diffusion tensor imaging]

Objective: To analyze the correlation between the parameters of diffusion tensor imaging (DTI) and the clinical function scores before and 5 years after anterior cervical discectomy and fusion (ACDF) by measuring the DTI signal of the maximum compression level (MCL) of the cervical spinal cord in patients with cervical spondylotic myelopathy (CSM). Methods: A prospective study was conducted and clinical data of 37 patients with CSM treated by ACDF in Beijing Chaoyang Hospital from February 2014 to February 2020 were analyzed. The MCL was studied with diffusion tensor imaging (DTI) of MRI. The changes of diffusion indexes (fractional anisotropy (FA)), and clinical function score including Modified Japanese Orthopedic Association (mJOA), neck disability index (NDI) and visual analog scale (VAS) of pain were compared among each follow-up point. The FA value and clinical function score were collected and the data was analyzed to determine whether the high signal intensity could be observed in T₂-weighted imaging (T₂WI) at each follow-up point. The changes of preoperative and postoperative data were compared, and the correlation between FA value and other two clinical function score were analyzed at each follow-up point. Results: There were 14 males and 23 females with a mean age of (55±10) years in this study. All patients received the surgery and the medullary symptoms improved significantly postoperatively. After 3 months, the mJOA and FA value were improved by 2.62±1.41 and 0.14±0.11 on average, respectively (both P<0.05); and there were significant differences in these two indexes between each follow-up point in two years after the operation (all P<0.05). At the MCL, there were strong correlations between the FA value and mJOA score pre-and postoperatively (r_s=0.770, 0.729, both P<0.01). There was no significant correlation between mJOA, NDI and VAS (both P>0.05). Conclusions: The DTI sensitively reflects the improvement of spinal cord function and can be used as an important tool to predict and evaluate the state of spinal cord dysfunction in patients with CSM.