Deep brain stimulation: Connectivity profile for bradykinesia alleviation

Abstract

Objective: Subthalamic deep brain stimulation may alleviate bradykinesia in Parkinson patients. Research suggests that this stimulation effect may be mediated by brain networks like the corticocerebellar loop. This study investigated the connectivity between stimulation sites and cortical and subcortical structures to identify connections for effective stimulation. Methods: We retrospectively investigated 21 patients with Parkinson disease with bilateral subthalamic deep brain stimulation. Stimulation effectiveness in reducing bradykinesia, tremor, and rigidity was evaluated for each electrode contact in brain hemispheres contralateral to the affected hemibody. Dysarthric side effects were also examined. Probabilistic tractography based on diffusion-weighted imaging was performed in individual patient-specific brains using electrode contacts as seeds. Connectivity profiles of contacts with effective and noneffective stimulation were compared. Results: Connectivity profiles of effective and noneffective contacts differed. Moreover, the connectivity profile for bradykinesia differed from that for rigidity, tremor, or dysarthria. Regarding bradykinesia, effective contacts were significantly more often connected with the ipsilateral superior cerebellar peduncle and the ipsilateral dentate nucleus, which correspond to the ipsilateral portion of the cerebellothalamocortical pathway. Rigidity was mitigated by stimulation of ascending brainstem and intralaminar thalamic connections. Tremor alleviation was related to connections with the internal capsule (anterior limb) and the pallidum. Dysarthric side effects were associated with connections to the supplementary motor area and the decussating cerebellothalamocortical pathway. Interpretation: Whereas bradykinesia seems to be mitigated by stimulation of the ascending, ipsilateral cerebellothalamocortical pathway, stimulation of the descending corticopontocerebellar pathway may be ineffective. Rigidity, tremor, and dysarthric side effects seem to be influenced by different neural networks.

Pallidal Connectivity Profiling of Stimulation‐Induced Dyskinesia in Parkinson's Disease

“…The clinical effects of DBS, such as improvement in parkinsonism and SID, may ultimately reflect the sum of the effects through different mechanisms. Connectivity profiles associated with postoperative motor improvement in PD patients have been reported, 13,16,31,32 and those associated with stimulation‐induced adverse effects (ie, SID, dysarthria, and psychiatric manifestations) may also be essential for achieving better overall clinical outcomes. Connectivity studies may clarify the mechanism of action of DBS.…”

Recent advances in using diffusion tensor imaging to study white matter alterations in Parkinson’s disease: A mini review

“…DT can define specific axonal trajectories as the basis of pathwayactivation models to provide better anatomical/electrical volume conductor estimations to evaluate the strength and coverage of electric field covering DBS targets (Gunalan et al, 2018). As such, DT helped strategize the best direct or indirect DBS target by delineating and segmenting STN-cortical (Chen et al, 2018;Gunalan et al, 2018), pallido-cortical (Middlebrooks et al, 2018), pedunculopontine (Raghu et al, 2021), and cortico-cerebellar pathways (Strotzer et al, 2019;Coenen et al, 2020) to mitigate PD-related motor symptoms and minimize unwanted side effects, such as depression and impaired cognition (Combs et al, 2015;Irmen et al, 2020).…”

“…Specifically, the authors showed that the postoperative outcome of STN-DBS is strongly associated with active stimulation of contacts connected to the primary cortex and supplementary motor area and that can be individually defined. In addition, both DTI profile and network-based connectivity have served as a preoperative predictor for postoperative outcome (Koirala et al, 2018;Gonzalez-Escamilla et al, 2022) or a targeted indicator to trace the therapeutic effect (Strotzer et al, 2019;Huang et al, 2022).…”

One side effect – two networks? Lateral and postero-medial stimulation spreads induce dysarthria in subthalamic deep brain stimulation for Parkinson’s Disease

“…stimulation spread to corticobulbar fibers, 15,17 or both, involvement of the pyramidal tract and cerebello-thalamic fibers. 16,35 The involvement of these two All rights reserved. No reuse allowed without permission.…”