Microstimulation Is a Promising Approach in Achieving Better Lead Placement in Subthalamic Nucleus Deep Brain Stimulation Surgery

Background: The successful application of subthalamic nucleus (STN) deep brain stimulation (DBS) surgery relies mostly on optimal lead placement, whereas the major challenge is how to precisely localize STN. Microstimulation, which can induce differentiating inhibitory responses between STN and substantia nigra pars reticulata (SNr) near the ventral border of STN, has indicated a great potential of breaking through this barrier.Objective: This study aims to investigate the feasibility of localizing the boundary between STN and SNr (SSB) using microstimulation and promote better lead placement.Methods: We recorded neurophysiological data from 41 patients undergoing STN-DBS surgery with microstimulation in our hospital. Trajectories with typical STN signal were included. Microstimulation was applied near the bottom of STN to determine SSB, which was validated by the imaging reconstruction of DBS leads.Results: In most trajectories with microstimulation (84.4%), neuronal firing in STN could not be inhibited by microstimulation, whereas in SNr long inhibition was observed following microstimulation. The success rate of localizing SSB was significantly higher in trajectories with microstimulation than those without. Moreover, results from imaging reconstruction and intraoperative neurological assessments demonstrated better lead location and higher therapeutic effectiveness in trajectories with microstimulation and accurately identified SSB.Conclusion: Microstimulation on microelectrode recording is an effective approach to localize the SSB. Our data provide clinical evidence that microstimulation can be routinely employed to achieve better lead placement.

Impact of deep brain stimulation surgery on speech and swallowing in patients with essential tremor

Purpose: The ventral intermediate nucleus (VIM) of the thalamus is the typical target of deep brain stimulation (DBS) for controlling tremor in essential tremor (ET). It remains unclear whether the outcomes are significantly different on speech and/or swallowing functions. This study was to compare speech and swallowing outcomes in patients with ET without VIM DBS, and those with unilateral/bilateral VIM DBS.Methods: We conducted a retrospective review of 133 patients with the diagnosis of ET. We analyzed the clinical speech and swallowing evaluations, and compared outcomes across four ‘DBS disposition’ groupings: no DBS, left, right, or bilateral VIM DBS.Results: Speech function was worse in bilateral group versus no DBS and unilateral groups. Orofacial (p=0.000), rate (p=0.001), and prosody (p=0.003) were significantly different between groups. No DBS and unilateral groups demonstrated either no dysarthria or mild hyperkinetic dysarthria versus exhibiting higher rates of dysarthria including an ataxic component in bilateral group. Bilateral group showed more impaired swallowing severity versus no DBS and unilateral groups, however, these differences were not statistically significant.Conclusions: The results demonstrated speech and swallowing changes in the ET patient population after VIM DBS. This data provides support for further study in order to better understand the speech and/or swallowing changes that may occur with VIM DBS.

Lead-OR: A Multimodal Platform for Deep Brain Stimulation Surgery

Deep Brain Stimulation (DBS) electrode implant trajectories are stereotactically defined using preoperative neuroimaging. To validate the correct trajectory, microelectrode recordings (MER) can be used to match the neuroanatomy with expected neurophysiological activity patterns, commonly using up to five trajectories in parallel. However, understanding their location in relationship to basal ganglia anatomy can be challenging. Here we present a tool that integrates resources from stereotactic planning, neuroimaging, MER and high-resolution atlas data to create a real-time visualization of the implant trajectory. We show a general correspondence between features derived from neuroimaging and electrophysiological recordings and present example use cases that demonstrate the functionality of the tool. The software toolbox is made openly available, extendable and holds translational potential in the field of stereotactic neurosurgery.

Deep Brain Stimulation-Induced Transient Effects in the Habenula

The habenula, located in the epithalamus, has been implicated in various psychiatric disorders including mood disorders and schizophrenia. This study explored the transient effects of deep brain stimulation in the habenula. Each of the four patients (two with bipolar disorder and two with schizophrenia) was tested with eight deep brain stimulation contacts. Patients were examined via transient electrical stimulation 1 month after deep brain stimulation surgery. The pulse width was 60 μs and the voltage ranged from 0 V to a maximum of 10 V, increasing in increments of 1 V. Each patient received stimulation at two frequencies, 60 and 135 Hz. A total of 221 out of 385 active trials elicited stimulation-induced effects. The three most common transient effects were numbness, heart rate changes, and pain. The incidence of numbness, heart rate changes, pain, and involuntary movements increased with the increase in stimulation voltage. Through contralateral stimulation, numbness was triggered in all parts of the body except the scalp. The obtained stimulus-response maps suggested a possible somatosensory organization of the habenula.