Sequential Brain Shift Patterns During Staged Bilateral Deep Brain Stimulation Surgery for Parkinson's Disease

Brain shift is a major contributor to targeting errors in stereotactic procedures. This study investigates sequential brain shift patterns during deep brain stimulation (DBS) surgery and discusses the clinical implications of using a staged bilateral targeting strategy in Parkinson's disease.

Quantitative image analysis was conducted for 210 DBS procedures in 105 patients with Parkinson's disease undergoing staged bilateral operations. Brain shift was quantified by coordinate displacements of subcortical structures, including the globus pallidus internus (GPi) and subthalamic nucleus (STN), across 4 MRI sessions during the 2 staged DBS procedures. Brain shift was evaluated in 3 configurations: pre-first vs post-first DBS MRIs (ⅰ), pre-first vs post-second DBS MRIs (ⅱ), and pre-second vs post-second DBS MRIs (ⅲ).

Brain shift was predominant in posterior, inferior, and medial directions, with greater magnitude in the GPi than in the STN. After the first DBS procedure (ⅰ), clinically relevant brain shift (displacement >3 mm) was observed in 6.8% of the GPi, while none was noted in the STN. After the second DBS procedure (ⅱ), brain shift was observed in up to 20.3% of the GPi and 4.1% of the STN on the second targeted side. However, when evaluated relative to the rescanned MRI (ⅲ), brain shifts within the second DBS procedure were reduced to 4.1% for the GPi and none for the STN, supporting the importance of precise target adjustment via a staged bilateral strategy. The extent of pneumocephalus showed the strongest correlation with the posterior displacement of the GPi, and low intraoperative mean arterial pressure appeared to be significantly associated with an increased risk of brain shift in this cohort.

These findings suggest that brain shift should be an important consideration in bilateral DBS surgery, and staged operations may provide particular advantages when targeting the GPi.