Deep brain stimulation in essential tremor: targets, technology, and a comprehensive review of clinical outcomes

Background: Deep brain stimulation is an efficacious treatment for refractory essential tremor, though targeting the intra-thalamic nuclei remains challenging.Objectives: We sought to develop an inverse approach to retrieve the position of the leads in a cohort of patients operated on with optimal clinical outcomes from anatomical landmarks identifiable by 1.5 Tesla magnetic resonance imaging.Methods: The learning database included clinical outcomes and post-operative imaging from which the coordinates of the active contacts and those of anatomical landmarks were extracted. We used machine learning regression methods to build three different prediction models. External validation was performed according to a leave-one-out cross-validation.Results: Fifteen patients (29 leads) were included, with a median tremor improvement of 72% on the Fahn–Tolosa–Marin scale. Kernel ridge regression, deep neural networks, and support vector regression (SVR) were used. SVR gave the best results with a mean error of 1.33 ± 1.64 mm between the predicted target and the active contact position.Conclusion: We report an original method for the targeting in deep brain stimulation for essential tremor based on patients' radio-anatomical features. This approach will be tested in a prospective clinical trial.

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Thalamic organization in essential tremor patients with neuropathy: implication for functional neurosurgery

10.1101/2021.02.21.21251847 ◽

2021 ◽

Author(s):

Francesco Sammartino ◽

Vinayak Narayan ◽

Barbara Changizi ◽

Aristide Merola ◽

Vibhor Krishna

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Clinical Outcomes ◽

Brain Stimulation ◽

Element Model ◽

Target Coverage ◽

Thalamic Nuclei ◽

Intermediate Nucleus ◽

Ventral Intermediate Nucleus ◽

Deep Brain

AbstractBackgroundMechanisms underlying the suboptimal effect of ventral intermediate nucleus deep brain stimulation in patients with essential tremor and co-morbid peripheral neuropathy remain unclear.ObjectivesWe compared disease-related (location and extension of the ventral intermediate nucleus) and surgery-related (targeting, intraoperative testing) factors in essential tremor patients with and without peripheral polyneuropathy treated with deep brain stimulation of the ventral intermediate nucleus, testing whether the overlap between volume of tissue activated and ventral intermediate nucleus (target coverage) was associated with clinical outcomes.MethodsPreoperative diffusion magnetic resonance imaging was used for thalamic segmentation, based on preferential cortical connectivity. The target coverage was estimated using a finite element model. Tremor severity was scored at rest, posture, action, and handwriting at baseline, 6, and 12 months. Tremor improvement <50% at 12 months was deemed suboptimal. Vertex-wise shape analysis and edge analysis were performed to compare the ventral intermediate nucleus location and extension.Results9.7% (18/185) of essential tremor patients treated with deep brain stimulation had co-morbid polyneuropathy. These patients showed a more medial (p=0.03) and anterior (p=0.04) location of the ventral intermediate nucleus, lower target coverage (p=0.049), and worse clinical outcomes (p=0.006) compared to those without polyneuropathy. No differences were observed in the volume of tissue activated between the two groups. Optimal clinical outcomes were associated with greater target coverage (optimal coverage >48%).ConclusionsIn essential tremor, co-morbid polyneuropathy may result in suboptimal deep brain stimulation outcomes and lower target coverage, likely related to a reorganization of the ventral thalamic nuclei.

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