Use of Spinal Cord Diffusion Tensor Imaging to Quantify Neural Ablation and Evaluate Outcome after Percutaneous Cordotomy for Intractable Cancer Pain

Abstract

Background: Up to 20% of patients experience only partial pain relief after percutaneous cordotomy for cancer pain. Objective: To determine whether diffusion tensor imaging (DTI) can quantify neural ablation and help evaluate early postoperative outcomes after cordotomy. Methods: Patients undergoing percutaneous CT-guided cordotomy for intractable cancer pain were prospectively studied. Pre- and postoperative assessment was made using the visual analog scale (VAS) on pain and the pain severity scores of the Brief Pain Inventory Short Form. On postoperative day 1, DTI images of the high cervical spinal cord were obtained. DTI metrics were correlated with the number of ablations as well as early postoperative pain outcomes. Results: Seven patients (4 male, mean age 53.8 ± 4.6 years) were studied. Fractional anisotropy of the hemicord was significantly lower on the side of the lesion as compared to the contralateral side (0.54 ± 0.03 vs. 0.63 ± 0.03, p < 0.001). Mean diffusivity correlated with the improvement in the VAS score at 1 week (r = 0.88, 95% CI = 0.34-1.00, p = 0.008), as well as the change in pain severity scores at 1 week (r = 0.99, 95% CI = 0.82-1.00, p < 0.001). Conclusion: DTI metrics are sensitive to the number of ablations as well as early improvement in pain scores after cordotomy. DTI of the cervical spinal cord is a potential biomarker of neural ablation after percutaneous cordotomy for intractable cancer pain.

Cervical Cordotomy for Intractable Pain: Do Postoperative Imaging Features Correlate with Pain Outcomes and Mirror Pain?

“…Overall, these parameters may indicate the degree of tissue injury, as was previously shown in patients after cordotomy and patients with spinal injuries. 12,[14][15][16] Similar to previous reports, FA was significantly lower in the lesioned side of the cord compared with the nonlesioned side. 12 Our study also demonstrated a significant decrease in tissue FA of the targeted cervical cord area from pre-to postoperative DTI.…”

“…12,[14][15][16] Similar to previous reports, FA was significantly lower in the lesioned side of the cord compared with the nonlesioned side. 12 Our study also demonstrated a significant decrease in tissue FA of the targeted cervical cord area from pre-to postoperative DTI. FA values did not change at 1 month after surgery (P ¼ .225).…”

“…Our results are therefore in line with a previous study that found a correlation between the lesions' MD (but not FA) and the degree of improvement in the 1-week postoperative BPI severity score. 12 A higher MD is believed to be associated with cellular edema, demyelination, and disruption of membranes, which follow RF ablation. 12 Therefore, although MD values on immediate postoperative MR imaging are generally lower in the ablated area compared with nonlesioned tissue, higher MD values may, in fact, indicate better ablation of the neural tissue during cordotomy.…”

“…12 A higher MD is believed to be associated with cellular edema, demyelination, and disruption of membranes, which follow RF ablation. 12 Therefore, although MD values on immediate postoperative MR imaging are generally lower in the ablated area compared with nonlesioned tissue, higher MD values may, in fact, indicate better ablation of the neural tissue during cordotomy.…”

“…[9][10][11] More recent MR imaging-and DWI-based studies found direct correlations between the degree of the lesion's mean diffusivity (MD) as a measurement of local neural damage and improvement on pain assessment scores after surgery. 12 However, data on the mechanisms behind the postoperative contralateral pain phenomenon and its predicting factors are still lacking.…”