Stimulation maps: visualization of results of quantitative intraoperative testing for deep brain stimulation surgery

Abstract

Deep brain stimulation (DBS) is an established therapy for movement disorders such as essential tremor (ET). Positioning of the DBS lead in the patient's brain is crucial for effective treatment. Extensive evaluations of improvement and adverse effects of stimulation at different positions for various current amplitudes are performed intraoperatively. However, to choose the optimal position of the lead, the information has to be "mentally" visualized and analyzed. This paper introduces a new technique called "stimulation maps," which summarizes and visualizes the high amount of relevant data with the aim to assist in identifying the optimal DBS lead position. It combines three methods: outlines of the relevant anatomical structures, quantitative symptom evaluation, and patient-specific electric field simulations. Through this combination, each voxel in the stimulation region is assigned one value of symptom improvement, resulting in the division of stimulation region into areas with different improvement levels. This technique was applied retrospectively to five ET patients in the University Hospital in Clermont-Ferrand, France. Apart from identifying the optimal implant position, the resultant nine maps show that the highest improvement region is frequently in the posterior subthalamic area. The results demonstrate the utility of the stimulation maps in identifying the optimal implant position.

Should the Globus Pallidus Targeting Be Refined in Dystonia?

“…A preliminary estimation of VTA position and size can be performed during the surgical planning. 9 65 The registration of the patient images to a normalized coordinate space, such as MNI, allows the surgeon to evaluate whether the expected electrical field generated by the electrode will contemplate portions of GPi that are somatotopic related to the regions of the body where symptoms are more severe and to place the lead as close as possible. Tractography images may be used to assess the direction of the fibers that are included within the VTA.…”

Computational Models in Deep Brain Stimulation : Patient‐Specific Simulations, Tractography, and Group Analysis

“…The clinical settings are most frequently used, but some studies include data from screening sessions. Another, more rare alternative, is to use intra-operative stimulations [149]. Screening and clinical data have different characteristics.…”

Deep Brain Stimulation: Emerging Tools for Simulation, Data Analysis, and Visualization

“…Electrophysiological methods, such as LFP and microelectrode recording (MER), are often combined with intraoperative stimulation tests. Wrist accelerometer recording of stimulation response during surgery for search of optimal target position in relation to intraoperative VIM implantations for tremor and rigidity has been described ( Shah et al, 2017 ; Shah et al, 2020 ) ( Figure 5A ). Impedance measurements ( Zrinzo and Hariz, 2008 ) is another intraoperative guidance methods, but with rather low resolution ( Johansson et al, 2009 ) when compared to optical techniques such as diffuse reflectance spectroscopy (DRS) ( Giller et al, 2003 ; Antonsson et al, 2008 ) and laser Doppler flowmetry (LDF) ( Wårdell et al, 2013b ).…”

“…In contrast, a more precise estimation can be done by using in silico simulations of single patient distribution of the EF ( Åström et al, 2010 , 2018 ; Hemm et al, 2016 ; Akbarian-Tefaghi et al, 2017 ; Naesstrom et al, 2021 ). Implementation of this method can also be expanded to visualize induced improvements and adverse effects in patient-specific stimulation maps ( Shah et al, 2020 ). Stimulation maps from several patients can then be projected into the anatomical template space to set-up disease specific stimulation atlases as we have generated for patients with ET with implants in the VIM ( Vogel et al, 2021 ) and in the cZi ( Nordin et al, 2021b ; Stenmark Persson et al, 2021 ).…”

“…Different ways of summarizing have been proposed. Examples are unweighted frequency “n-map” ( Elias et al, 2021 ), minimum, maximum ( Shah et al, 2020 ), and weighted “mean-maps” ( Nordin et al, 2021b ) or “p-maps” denoting the degree of confidence for the stimulation at a voxel associated to a clinical change ( Elias et al, 2021 ). Once the stimulation atlas is set-up including the anatomical template, some researchers project information such as coordinates of activated electrode contacts ( Dergachyova et al, 2018 ) or connectivity profiles ( Horn et al, 2017b ) to new patients to test the predictability of target location.…”