Current Research

Analysis of Spinal Canal Diameter in the Placement of Thoracic Spinal Cord Stimulator Paddle Leads

Brian T. Ragel, MD; Tressa Riedman, BS; Matthew McGehee, MD; Ahmed M. Raslan, MD

Abstract

Background: Neurologic deficit is known as a rare complication of thoracic spinal cord stimulator (SCS) paddle lead implantation, but many believe its incidence after SCS paddle lead placement is under-reported. It is possible that imaging characteristics may be used to help predict safe paddle lead placement.

Objective: This imaging study was undertaken to determine minimum canal diameter required for safe paddle lead placement.

Methods: Patients who underwent thoracic laminectomy for new SCS paddle lead placement from January 2018 to October 2021 were identified retrospectively. Preoperative thoracic canal diameter was measured in the sagittal plane perpendicular to the disc space from T5/6 to T11/12. These thoracic levels were chosen because they span the most common levels targeted for SCS placement. Patients with and without new neurologic deficit were compared using an unpaired Student’s t-test (Prism 9, GraphPad Software).

Results: Of 112 patients initially identified, 107 had thoracic imaging available for review. Two of 112 (2%) patients complained of transient neurologic deficit after thoracic SCS placement. Both patients had SCS paddle lead placement at T8/9 and single-level laminectomy for placement and average canal diameter <12 mm. The average canal diameter of patients with and without neurologic deficit was 10.1 mm (range 6.1–12.3 mm) and 12.3 mm (range 6.9–19.0), respectively (P < 0.0001).

Conclusion: Postoperative neurologic deficit is a rare complication after thoracic laminectomy for SCS paddle lead placement. The authors recommend ensuring a thoracic canal diameter of at least 12 mm to accommodate a SCS paddle lead measuring 2 mm thick. If canal diameter is <12 27 mm, aggressive undercutting of the lamina or a second laminectomy, such as the “Paddle Under-Bridge” technique, should be considered.