Neuropsychological assessment protocol in an ongoing randomized controlled trial on posterior subthalamic area vs. ventral intermediate nucleus deep brain stimulation for essential tremor.

Objective: Patients with essential tremor (ET) may experience cognitive-affective impairment. Deep brain stimulation (DBS) of different targets, such as the ventral intermediate nucleus (VIM) of the thalamus or the posterior subthalamic area (PSA), has been shown to be beneficial for refractory ET. However, there is little evidence regarding the possible neuropsychological effects of PSA-DBS on patients with ET, and there are few studies comparing it with VIM-DBS in this population.In this study, we aim to present the evaluation protocol and neuropsychological battery as used in an ongoing trial of DBS for ET comparing the already mentioned targets. Methods: As part of a randomized, double-blind, crossover clinical trial comparing the effectiveness and safety of PSA-DBS vs. VIM-DBS, 11 patients with refractory ET will undergo a multi-domain neuropsychological battery assessment. This will include a pre-/post-implantation assessment (3 months after the stimulation of each target and 6 months after an open stage of DBS on the most optimal target). Conclusion: Evidence on the neuropsychological effects of DBS in patients with refractory ET is very scarce, particularly in lesser-explored targets such as PSA. This study could contribute significantly in this field, particularly on pre-procedure safety analysis for tailored patient/technique selection, and to complete the safety analysis of the procedure. Moreover, if proven useful, this proposed neuropsychological assessment protocol could be extensible to other surgical therapies for ET.

An initial experience with intraoperative O-Arm for deep brain stimulation surgery: can it replace post-operative MRI?

Deep brain stimulation (DBS) is used to treat movement disorders, severe psychiatric disorders, and neuropathic pain, among other diseases. Advanced neuroimaging techniques allow direct or indirect localization of the target site, which is verified in many centers by the intraoperative recording of unitary neuronal activity. Intraoperative image acquisition technology (e.g., O-Arm) is increasingly used for accurate electrode positioning throughout the surgery. The aim of our study is to analyze the initial experience of our team in the utilization of O-Arm for planning DBS and monitoring its precision and accuracy throughout the procedure. The study included 13 patients with movement disorders. All underwent DBS with the intraoperative O-arm image acquisition system (iCT) and Medtronic StealthStation S7 cranial planning system, placing a total of 25 electrodes. For each patient, we calculated the difference between real and theoretic x, y, z coordinates, using the paired Student's t test to evaluate absolute and directional differences and the one-sample Student's t test to analyze differences in Euclidean distances. No statistically significant differences were found in absolute, directional, or Euclidean distances between intended and actual x, y, and z coordinates, based on iCT scan. Our experience confirms that utilization of the O-Arm system in DBS provides accurate and precise verification of electrode placements throughout the procedure. Recent studies found no significant differences between iCT and postoperative MRI, the current gold standard. Further prospective studies are warranted to test the elimination of postoperative MRI when this system is used.