Optimization of Deep Brain Stimulation site and algorithm patterns for Essential Tremor - a randomized two arm pilot study

Recruitment & Eligibility

Status: Recruiting

Sex: All

Target Recruitment: 24

Inclusion Criteria

1.Male or female aged 21 years minimum and 85 years maximum on the day of experimental procedures
2.Diagnosed with Essential Tremor (ET) affecting their hand(s)
3.Patients with essential tremor who are eligible for Vim/DRT DBS Surgery according to the guidelines of the DGN (www.dgn.org) or patients with Essential Tremor and VIM/DRT-DBS implantation and undergoing replacement of their battery-depleted IPG
4.Implanted with DBS lead(s) in the thalamic ViM/DRT region to treat ET and whose leads are temporarily externalized via extension cables. Lead(s) may be implanted initially (first time) or chronically (patient undergoing replacement of their battery-depleted IPG)
5.For acute stimulation setting: Presence of tremor in the hand of grade 2 or more on a clinical rating scale with OFF medication/OFF stimulation state on the day of experiment. The tremor needs to be markedly reduced (++ improvement according to Coenen et al. 2020) by means of conventional tonic DBS, as determined by the Investigator
6.Patients who have provided written informed consent

Exclusion Criteria

1.For acute stimulation setting: Presence of factors that may make assessment of the tremor ambiguous on the day of the experiment (e.g. lead implantation stun effect, alcohol consumption), as determined by the Investigator

For acute and chronic study:
2.Imaging of the leads in relation to neural structures not available
3.Dementia symptoms
4.Pregnant or breastfeeding women
5.Implanted with another active device (cardiac pacemaker etc.)

Study & Design

Study Type: interventional

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Chronic Part: Time to treatment failure defined as reduction in FTMTRS improvement (rate ) to less than 50% in 3 consecutive FTMTRS readings. <br><br>Acute Part: Explore acute effects of tonic DBS and intermittent DBS programmed per study algorithm. Clinical assessment using Fahn-Tolosa-Marin-Tremor Rating Scale (FTMTRS) (for optimized stimuli). Tremor spectral power density (calculated from the wearable motion sensors). The maximum percentage stimulus pause which still results in a measurable tremor reduction as compared to no stimulation (calculated from the drawing task). Dose response relations between tremor (spectral power) and stimulus parameters (% stimulus pause time, amplitude and frequency). Parameters of the hand trajectories made during the drawing tasks (e.g. time to complete the task, deviation from the average trajectory). Energy of the tonic and intermittent stimulus as optimized per study algorithm

Secondary Outcome Measures

Name	Time	Method
Chronic Study Part only:<br><br>1. SARA score (with and without tremor item 6) at 3, 6, 9, 12, 15, 18 months to<br>explore effects of differential dominant DRTx or DRTu stimulation and their effects on short-term and long-term evolution of ataxia.<br><br>2. Fahn-Tolosa-Marin-Tremor Rating Scale (FTMTRS) at 3, 6, 9,12, 15, 18 months. Quantitative Tremor Analysis (accelerometry and non-invasive electromyography, nystagmography) measuring frequency and total power at 6, 12, 18 months. In order to xplore effects of differential dominant DRTx or DRTu stimulation and their effects on short-term and long-term efficacy.<br><br>3. Quality of Life in Essential Tremor (QUEST) at 6, 12, 18 months. To explore quality of life of various temporal patterns to control tremor symptoms in the hand by DBS for ET.