Efficacy of Diffusion Tensor Imaging Indices in Assessing Postoperative Neural Recovery in Cervical Spondylotic Myelopathy

Study Design. Prospective observational cohort study. Objective. The aim of this study was to analyze the efficacy of diffusion tensor imaging (DTI) anisotropy indices in predicting the postoperative recovery in cervical spondylotic myelopathy (CSM) patients and to describe postoperative changes in the DTI indices based on neurological recovery after surgery. Summary of Background Data. Surgical results of CSM are unpredictable and cannot be estimated based on preoperative MRI. DTI indices were found to have good sensitivity to detect changes in CSM, but their efficacy in predicting postoperative recovery and postoperative changes in DTI indices has not been studied before. Methods. Thirty-five patients who underwent surgical decompression for cervical spondylotic myelopathy underwent DTI evaluation preoperatively and postoperatively at 12 months. DTI indices-fractional anisotropy, apparent diffusion coefficient (ADC), relative anisotropy, volume ratio, and eigen vectors (E1, E2, and E3)-were obtained and clinical evaluations were made preoperatively and 12 months postoperatively. Results. Twenty-six patients were available for final follow-up at 12 months. Twenty patients showed improvement by at least 1 Nurick grade, five maintained the preoperative Nurick grade status and one patient was noted to have deterioration by 1 grade. The preoperative DTI values could not predict neurological recovery patterns postoperatively. Although conventional MRI showed adequate decompression in all patients irrespective of the clinical outcome, DTI indices showed variable results. There were significant improvements in postoperative DTI indices for ADC (P = 0.002), E1 (P < 0.001), and E2 (P = 0.012) values in patients who showed neurological recovery at 12 months. Postoperative DTI indices for coefficients ADC, E1, and E2 in neurologically static/worsened individuals remained unchanged or insignificant (P = 0.05) Conclusion. The DTI indices were sensitive enough to indicate postoperative neurological recovery observed following surgery. Preoperative DTI evaluation could not predict postoperative recovery for patients with cervical spondylotic myelopathy.