scholarly journals Ventral Intermediate Nucleus structural connectivity-derived segmentation: anatomical reliability and variability

2021 ◽  
Author(s):  
Salvatore Bertino ◽  
Gianpaolo Antonio Basile ◽  
Alessia Bramanti ◽  
Rossella Ciurleo ◽  
Adriana Tisano ◽  
...  
Keyword(s):  
Data Quality ◽  
Essential Tremor ◽  
Dentate Nucleus ◽  
Structural Connectivity ◽  
Classification Criteria ◽  
Signal Modeling ◽  
Intermediate Nucleus ◽  
Subject Variability ◽  
Ventral Intermediate Nucleus ◽  
Voxel Classification

The Ventral intermediate nucleus (Vim) of thalamus is the most targeted structure for the treatment of drug-refractory tremors. Since methodological differences across existing studies are remarkable and no gold-standard pipeline is available, in this study, we tested different parcellation pipelines for tractography-derived putative Vim identification. Thalamic parcellation was performed on a high quality, multi-shell dataset and a downsampled, clinical-like dataset using two different diffusion signal modeling techniques and two different voxel classification criteria, thus implementing a total of four parcellation pipelines. The most reliable pipeline in terms of inter-subject variability has been picked and parcels putatively corresponding to motor thalamic nuclei have been selected by calculating similarity with a histology-based mask of Vim. Then, spatial relations with optimal stimulation points for the treatment of essential tremor have been quantified. Finally, effect of data quality and parcellation pipelines on a volumetric index of connectivity clusters has been assessed. We found that the pipeline characterized by higher-order signal modeling and threshold-based voxel classification criteria was the most reliable in terms of inter-subject reliability regardless data quality. The maps putatively corresponding to Vim were those derived by precentral- and dentate nucleus-thalamic connectivity. However, tractography-derived functional targets showed remarkable differences in shape and sizes when compared to a ground truth model based on histochemical staining on seriate sections of human brain. Thalamic voxels connected to contralateral dentate nucleus resulted to be the closest to literature-derived stimulation points for essential tremor but at the same time showing the most remarkable inter-subject variability. Finally, the volume of connectivity parcels resulted to be significantly influenced by data quality and parcellation pipelines. Hence, caution is warranted when performing thalamic connectivity-based segmentation for stereotacting targeting.

Comparative connectivity correlates of dystonic and essential tremor deep brain stimulation

Brain ◽  
2021 ◽  
Author(s):  
Takashi Tsuboi ◽  
Joshua K Wong ◽  
Robert S Eisinger ◽  
Lela Okromelidze ◽  
Mathew R Burns ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Essential Tremor ◽  
Brain Stimulation ◽  
Rating Scale ◽  
Structural Connectivity ◽  
Cortical Network ◽  
Dystonic Tremor ◽  
Intermediate Nucleus ◽  
Ventral Intermediate Nucleus ◽  
Deep Brain

Abstract The pathophysiology of dystonic tremor and essential tremor remains partially understood. In patients with medication-refractory dystonic tremor or essential tremor, deep brain stimulation (DBS) targeting the thalamus or posterior subthalamic area has evolved into a promising treatment option. However, the optimal DBS targets for these disorders remains unknown. This retrospective study explored the optimal targets for DBS in essential tremor and dystonic tremor using a combination of volumes of tissue activated estimation and functional and structural connectivity analyses. We included 20 patients with dystonic tremor who underwent unilateral thalamic DBS, along with a matched cohort of 20 patients with essential tremor DBS. Tremor severity was assessed preoperatively and approximately 6 months after DBS implantation using the Fahn-Tolosa-Marin Tremor Rating Scale. The tremor-suppressing effects of DBS were estimated using the percentage improvement in the unilateral tremor-rating scale score contralateral to the side of implantation. The optimal stimulation region, based on the cluster centre of gravity for peak contralateral motor score improvement, for essential tremor was located in the ventral intermediate nucleus region and for dystonic tremor in the ventralis oralis posterior nucleus region along the ventral intermediate nucleus/ventralis oralis posterior nucleus border (4 mm anterior and 3 mm superior to that for essential tremor). Both disorders showed similar functional connectivity patterns: a positive correlation between tremor improvement and involvement of the primary sensorimotor, secondary motor and associative prefrontal regions. Tremor improvement, however, was tightly correlated with the primary sensorimotor regions in essential tremor, whereas in dystonic tremor, the correlation was tighter with the premotor and prefrontal regions. The dentato-rubro-thalamic tract, comprising the decussating and non-decussating fibres, significantly correlated with tremor improvement in both dystonic and essential tremor. In contrast, the pallidothalamic tracts, which primarily project to the ventralis oralis posterior nucleus region, significantly correlated with tremor improvement only in dystonic tremor. Our findings support the hypothesis that the pathophysiology underpinning dystonic tremor involves both the cerebello-thalamo-cortical network and the basal ganglia-thalamo-cortical network. Further our data suggest that the pathophysiology of essential tremor is primarily attributable to the abnormalities within the cerebello-thalamo-cortical network. We conclude that the ventral intermediate nucleus/ventralis oralis posterior nucleus border and ventral intermediate nucleus region may be a reasonable DBS target for patients with medication-refractory dystonic tremor and essential tremor, respectively. Uncovering the pathophysiology of these disorders may in the future aid in further improving DBS outcomes.

Feasibility of Staged Bilateral Radiofrequency Ventral Intermediate Nucleus Thalamotomy for Bilateral Essential Tremor

2019 ◽  
Vol 125 ◽  
pp. e992-e997 ◽  
Author(s):  
Ghate Prajakta ◽  
Shiro Horisawa ◽  
Takakazu Kawamata ◽  
Takaomi Taira
Keyword(s):  
Essential Tremor ◽  
Intermediate Nucleus ◽  
Ventral Intermediate Nucleus

scholarly journals Effects of ventral intermediate nucleus deep brain stimulation across multiple effectors in essential tremor

2020 ◽  
Vol 131 (1) ◽  
pp. 167-176 ◽  
Author(s):  
B.J. Wilkes ◽  
A. Wagle Shukla ◽  
A. Casamento-Moran ◽  
C.W. Hess ◽  
E.A. Christou ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Essential Tremor ◽  
Brain Stimulation ◽  
Intermediate Nucleus ◽  
Ventral Intermediate Nucleus ◽  
Deep Brain

scholarly journals Microelectrode recording findings within the tractography-defined ventral intermediate nucleus

2017 ◽  
Vol 126 (5) ◽  
pp. 1669-1675 ◽  
Author(s):  
Nicolas Kon Kam King ◽  
Vibhor Krishna ◽  
Diellor Basha ◽  
Gavin Elias ◽  
Francesco Sammartino ◽  
...  
Keyword(s):  
Firing Rate ◽  
Local Field ◽  
Local Field Potential ◽  
Structural Connectivity ◽  
Field Potential ◽  
Area Under The Curve ◽  
Microelectrode Recording ◽  
Intermediate Nucleus ◽  
Beta Power ◽  
Ventral Intermediate Nucleus

OBJECTIVEThe ventral intermediate nucleus (VIM) of the thalamus is not visible on structural MRI. Therefore, direct VIM targeting methods for stereotactic tremor surgery are desirable. The authors previously described a direct targeting method for visualizing the VIM and its structural connectivity using deterministic tractography. In this combined electrophysiology and imaging study, the authors investigated the electrophysiology within this tractography-defined VIM (T-VIM).METHODSThalamic neurons were classified based on their relative location to the T-VIM: dorsal, within, and ventral to the T-VIM. The authors identified the movement-responsive cells (kinesthetic and tremor cells), performed spike analysis (firing rate and burst index), and local field potential analysis (area under the curve for 13–30 Hz). Tremor efficacy in response to microstimulation along the electrode trajectory was also assessed in relation to the T-VIM.RESULTSSeventy-three cells from a total of 9 microelectrode tracks were included for this analysis. Movement-responsive cells (20 kinesthetic cells and 26 tremor cells) were identified throughout the electrode trajectories. The mean firing rate and burst index of cells (n = 27) within the T-VIM are 18.8 ± 9.8 Hz and 4.5 ± 5.4, respectively. Significant local field potential beta power was identified within the T-VIM (area under the curve for 13–30 Hz = 6.6 ± 7.7) with a trend toward higher beta power in the dorsal T-VIM. The most significant reduction in tremor was also observed in the dorsal T-VIM.CONCLUSIONSThe electrophysiological findings within the VIM thalamus defined by tractography, or T-VIM, correspond with the known microelectrode recording characteristics of the VIM in patients with tremor.

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