Radiographic lead migration in percutaneous spinal cord stimulator trials

Introduction Lead migration during spinal cord stimulator (SCS) trials is relatively neglected in the literature and presents a different set of challenges compared with fully implanted leads. There is no consensus on what constitutes a clinically significant amount of radiographic lead migration during SCS trials. We wished to evaluate the incidence and extent of radiographic lead migration during percutaneous SCS trials, to investigate the risk factors for lead migration and whether this has impacted on trial success. Methods This prospective observational study of percutaneous SCS trials took place in a tertiary referral center in the UK between April 2021 and January 2022. Radiographs of SCS lead position were taken at baseline and prior to lead removal. Lead migration ≥50% of a vertebral level was deemed significant. Results One hundred trials were included comprising 162 leads. Mean migration distance was 0.55 vertebral levels (SD 0.85) or 12.5 mm (SD 18.2) in a caudal direction. Significant radiographic migration occurred in 50% of all leads (81 of 162 leads), at least one lead in 62% of cases and all leads in 44% of cases. Radiographic lead migration was not found to be associated with reduced trial success. A single lead and mechanical anchors were associated with greater incidence of lead migration. Conclusion Radiographic lead migration of approximately half of a vertebral level in a caudal direction can be expected during percutaneous SCS trials and this can be anticipated by siting leads half of a vertebral level higher to accommodate for this. Additional factors should be considered in the setting of radiographic lead migration to determine whether this can be considered clinically significant.