Impact of Spinal Canal Anatomy on Pain Outcomes in Spinal Cord Stimulation Therapy for Chronic Pain

Objective: To investigate whether thoracic spinal canal and cord anatomy, as visualized on preoperative magnetic resonance imaging (MRI), predicts pain outcomes following spinal cord stimulation (SCS) for chronic pain. Methods: A retrospective review identified 70 patients who underwent thoracic percutaneous SCS implantation between 2016 and 2024 with ≥ 12 months of follow-up. Preoperative T1-weighted and T2-weighted MRI scans were used to measure anatomical parameters at T8 and T9 levels, including dorsal canal distance, dorsal cerebrospinal fluid layer thickness, and percentage of free canal area. Patients were categorized as “successful” or “unsuccessful” based on ≥ 50% pain reduction documented in follow-up visits. Associations between anatomical measurements, SCS outcomes, lead migration, and surgical duration were analyzed. Results: Of 70 patients, 61.4% achieved successful pain relief. No significant differences were found in spinal canal dimensions between success and failure groups. Stratification into “small” and “large” anatomical subgroups similarly showed no significant association with outcomes. However, a smaller free canal area and dorsal canal triangle area at T8 were modestly associated with increased lead migration (r = −0.345 and −0.306, P < 0.05). No significant relationship was observed between lumbar access parameters and surgical duration. Conclusions: Preoperative thoracic spinal anatomy, as measured on supine MRI, was not predictive of SCS therapy success. While smaller canal dimensions may increase lead migration risk, they do not appear to affect long-term pain outcomes. These findings support a shift toward dynamic, patient-specific, and computational models for improving SCS efficacy and patient selection.