Computed tomographic method to quantify electrode lead deformation and subdural gap after lead implantation for deep brain stimulation

Background: Deep brain stimulation is an effective treatment for movement disorders and psychiatric conditions. Intra-operative and post-operative events can result in brain tissue deformation (i.e. subdural gaps) which may cause lead deformation and its displacement from optimal target. We developed a method to quantify postoperative lead deformation and we present two DBS cases to illustrate the phenomena of lead deformation resulting from the development of subdural gaps. New method: We present a semi-automatic computational algorithm using Computed Tomography scanning with reconstruction to determine lead curvature relative to a theoretical straight lead between the skull entry site and lead tip. Subdural gap was quantified from the CT scan. Results: In 2 patients who had leads implanted, analysis of CT scans was completed within 5 min each. The maximum deviation of the observed lead from the theoretical linear path was 1.1 and 2.6 mm, and the subdural gap was 5.5 and 9.6 mL, respectively. Comparison with Existing Method(s): This is the first method allowing a comprehensive characterization of the lead deformation in situ. Conclusions: The computational algorithms provide a simple, semiautomatic method to characterize in situ lead curvature related to brain tissue deformation after lead placement.