Brain Shift and Pneumocephalus Assessment During Frame-Based Deep Brain Stimulation Implantation With Intraoperative Magnetic Resonance Imaging

Abstract

Brain shift and pneumocephalus are major concerns regarding deep brain stimulation (DBS). To report the extent of brain shift in deep structures and pneumocephalus in intraoperative magnetic resonance imaging (MRI). Twenty patients underwent bilateral DBS implantation in an MRI suite. Volume of pneumocephalus, duration of procedure, and 6 anatomic landmarks (anterior commissure, posterior commissure, right fornix [RF], left fornix [LF], right putaminal point, and left putaminal point) were measured. Pneumocephalus varied from 0 to 32 mL (median = 0.6 mL). Duration of the procedure was on average 195.5 min (118-268 min) and was not correlated with the amount of pneumocephalus. There was a significant posterior displacement of the anterior commissure (mean = -1.1 mm, P < .001), RF (mean = -0.6 mm, P < .001), LF (mean = -0.7 mm, P < .001), right putaminal point (mean = -0.9 mm, P = .001), and left putaminal point (mean = -1.0 mm, P = .001), but not of the posterior commissure (mean = 0.0 mm, P = .85). Both RF (mean = -.7 mm, P < .001) and LF (mean = -0.5 mm, P < .001) were posteriorly displaced after a right-sided burr hole. There was a correlation between anatomic landmarks displacement and pneumocephalus after 2 burr holes (rho = 0.61, P = .007), but not after 1 burr hole (rho = 0.16, P = .60). Better understanding of how pneumocephalus displaces subcortical structures can significantly enhance our intraoperative decision making and overall targeting strategy.