Background: The two middle contacts of directional leads (d-leads) for deep brain stimulation are split into three segments, allowing current steering toward desired axial directions. To facilitate programming, their final orientation needs to be reliably determined. However, it is currently unclear whether d-leads rotate after implantation. Our objective was to assess the degree of d-lead rotation after implantation.
Methods: We retrospectively analyzed d-lead orientation on intraoperative X-rays, postoperative CT scans (latencies to surgery: 108-189 min postoperatively), and rotational fluoroscopies (4-9 days postoperatively) for a consecutive series of 32 implanted d-leads. For five d-leads, a CT scan with a mean follow-up of 57 days (range 28-182) was available. All d-leads were implanted with the marker facing anterior and the intention to hit an "iron sight" (ISi) on the X-ray, indicating anterior orientation (i.e., 0° ± 6°).
Results: In nine d-leads, an ISi was visible on the final X-ray; median orientation was 1.5° (range 0.5-6.0°) at the first follow-up CT, confirming anterior orientation. In d-leads without ISi or where ISi was not evaluable, the median rotation was 15.5° (9.5-35.0°) and 26.5° (5.5-62.0°), respectively. The orientation of the initial CT was comparable with the orientation determined by the postoperative rotational fluoroscopy and second CT in all d-lead groups.
Conclusion: D-lead orientation does not change within the first week after implantation. We provide first indications that d-lead orientation remains stable for several weeks after surgery. Determination of lead orientation using marker-based X-ray alone seems too imprecise; adding the ISi method can increase determination of intraoperative orientation.
Keywords: Deep brain stimulation; Directional leads; Iron sights; Rotational fluoroscopy.