Evaluation of the Rotational Stability of Directional Deep Brain Stimulation Leads: A Case Series and Systematic Review.

Background: The rotational stability of directional deep brain stimulation leads is a major prerequisite for sustained clinical effects. Data on directional lead stability are limited and controversial.

Methods:  We aimed to evaluate the long-term rotational stability of directional leads and define confounding factors in our own population and the current literature. We retrospectively evaluated the orientation of directional leads in patients with available postoperative computed tomography (CT; T1; day of surgery) and an additional postoperative image (T2; CT or rotational fluoroscopy) performed more than 7 days after the initial scan. The potential impact of intracranial air was assessed. We also reviewed the literature to define factors impacting stability.

Results:  Thirty-six leads were evaluated. The mean follow-up between T1 and T2 was 413.3 (7-1,171) days. The difference in rotation between T1 and T2 was 2.444 ± 2.554 degrees (range: 0-9.0 degrees). The volume of intracranial air did not impact the rotation. The literature search identified one factor impacting the stability of directional leads, which is the amount of twist applied at implantation.

Conclusion:  Directional leads for deep brain stimulation show stable long-term orientation after implantation. Based on our literature review, large amounts of twist during implantation can lead to delayed rotation and should thus be avoided.