Objective: We aimed at predicting tremor improvement in essential tremor (ET) patients implanted in the area of the ventral intermediate nucleus (VIM) using brain connectivity pattern. A validated connectivity pattern would serve as a skeleton for inferring the optimal deep brain stimulation (DBS) sweet spot for effective tremor control.

Background: ET is the most prevalent movement disorders and is frequently refractory to medical treatment. DBS offers an alternative potential therapeutic approach that can efficiently control tremor symptoms. Several DBS targets have been discussed for DBS tremor treatment, also with respect to potential side effects such as dysarthria and ataxia [1]. Optimizing DBS therapy for tremor critically includes optimal targeting to modulate the tremor network.

Method: In the current study, we utilized two normative brain connectomes (structural and functional) to depict the pattern of effective DBS electrode connectivity in 33 ET patients. Additionally, we endeavored to segregate the somatotopic brain network based on head and hand tremor scores. Lastly, a connectivity-derived DBS sweet spot was proposed.

Results: Our structural and functional beneficial connectivity models were significantly predictive of post-operative tremor improvement (structural, R = 0.48, p < 10-4; functional, R = 0.41, p = 0.001; leave-one-out validation). Networks predictive of hand and head tremor were successfully separated into the well-known somatotopic motor cortical and cerebellar maps. A connectivity-derived DBS sweet spot was identified in the posterior subthalamic area (PSA), with the spot encroaching on the inferior borders of VIM and sensory thalamus.

Conclusion: Our predictive connectivity models demonstrated large agreement with the previously recognized tremor network in ET. The connectivity-based sweet spot from our cohort complies with clinical observations of effective tremor suppression with DBS targeting PSA [2]. Our results underscore the importance of integrating brain connectivity to optimize DBS target selection.

References: 1. Deuschl G, Raethjen J, Hellriegel H, Elble R (2011) Treatment of patients with essential tremor. Lancet Neurol 10:148–161. 2. Plaha P, Patel NK, Gill SS (2004) Stimulation of the subthalamic region for essential tremor. J Neurosurg 101:48–54.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-optimal-connectivity-profile-of-thalamic-deep-brain-stimulation-electrodes-to-effectively-treat-essential-tremor/