DBS targeting for essential tremor using intersectional dentato-rubro-thalamic tractography and direct proton density visualization of the VIM: technical note on 2 cases

OBJECTIVEDirect visualization of the ventral intermediate nucleus (VIM) of the thalamus on standard MRI sequences remains elusive. Therefore, deep brain stimulation (DBS) surgery for essential tremor (ET) indirectly targets the VIM using atlas-derived consensus coordinates and requires awake intraoperative testing to confirm clinical benefits. The objective of this study was to evaluate the utility of proton density (PD)–weighted MRI and tractography of the intersecting dentato-rubro-thalamic tract (DRTT) for direct “intersectional” targeting of the VIM in ET.METHODSDBS targets were selected by identifying the VIM on PD-weighted images relative to the DRTT in 2 patients with ET. Tremor reduction was confirmed with intraoperative clinical testing. Intended target coordinates based on the direct intersectional targeting technique were compared with consensus coordinates obtained with indirect targeting. Pre- and postoperative tremor scores were assessed using the Fahn-Tolosa-Marin tremor rating scale (TRS).RESULTSPlanned DBS coordinates based on direct versus indirect targeting of the VIM differed in both the anteroposterior (range 0 to 2.3) and lateral (range −0.7 to 1) directions. For 1 patient, indirect targeting—without PD-weighted visualization of the VIM and DRTT—would have likely resulted in suboptimal electrode placement within the VIM. At the 3-month follow-up, both patients demonstrated significant improvement in tremor symptoms subjectively and according to the TRS (case 1: 68%, case 2: 72%).CONCLUSIONSDirect intersectional targeting of the VIM using PD-weighted imaging and DRTT tractography is a feasible method for DBS placement in patients with ET. These advanced targeting techniques can supplement awake intraoperative testing or be used independently in asleep cases to improve surgical efficiency and confidence.

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Longitudinal follow-up with VIM thalamic deep brain stimulation for dystonic or essential tremor

Neurology ◽

10.1212/wnl.0000000000008875 ◽

2020 ◽

Vol 94 (10) ◽

pp. e1073-e1084 ◽

Cited By ~ 6

Author(s):

Takashi Tsuboi ◽

Zakia Jabarkheel ◽

Pamela R. Zeilman ◽

Matthew J. Barabas ◽

Kelly D. Foote ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Brain Stimulation ◽

Rating Scale ◽

Statistical Significance ◽

Ventral Intermediate Nucleus ◽

Deep Brain

ObjectiveTo assess longitudinal tremor outcomes with ventral intermediate nucleus deep brain stimulation (VIM DBS) in patients with dystonic tremor (DT) and to compare with DBS outcomes in essential tremor (ET).MethodsWe retrospectively investigated VIM DBS outcomes for 163 patients followed at our center diagnosed with either DT or ET. The Fahn-Tolosa-Marin tremor rating scale (TRS) was used to assess change in tremor and activities of daily living (ADL) at 6 months, 1 year, 2–3 years, 4–5 years, and ≥6 years after surgery.ResultsTwenty-six patients with DT and 97 patients with ET were analyzed. Compared to preoperative baseline, there were significant improvements in TRS motor up to 4–5 years (52.2%; p = 0.032) but this did not reach statistical significance at ≥6 years (46.0%, p = 0.063) in DT, which was comparable to the outcomes in ET. While the improvements in the upper extremity tremor, head tremor, and axial tremor were also comparable between DT and ET throughout the follow-up, the ADL improvements in DT were lost at 2–3 years follow-up.ConclusionOverall, tremor control with VIM DBS in DT and ET was comparable and remained sustained at long term likely related to intervention at the final common node in the pathologic tremor network. However, the long-term ADL improvements in DT were not sustained, possibly due to inadequate control of concomitant dystonia symptoms. These findings from a large cohort of DT indicate that VIM targeting is reasonable if the tremor is considerably more disabling than the dystonic features.Classification of evidenceThis study provides Class IV evidence that VIM DBS improves tremor in patients with DT or ET.

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Factors involved in long-term efficacy of deep brain stimulation of the thalamus for essential tremor

Journal of Neurosurgery ◽

10.3171/jns/2008/109/10/0640 ◽

2008 ◽

Vol 109 (4) ◽

pp. 640-646 ◽

Cited By ~ 75

Author(s):

Julie G. Pilitsis ◽

Leo Verhagen Metman ◽

John R. Toleikis ◽

Lindsay E. Hughes ◽

Sepehr B. Sani ◽

...

Keyword(s):

Essential Tremor ◽

Disease Progression ◽

Rating Scale ◽

Long Term Outcomes ◽

Intraoperative Fluoroscopy ◽

Duration Of Disease ◽

Deep Brain ◽

Stimulation Of

Object Although nucleus ventralis intermedius stimulation has been shown to be safe and efficacious in the treatment of essential tremor, there is a subset of patients who eventually lose benefit from their stimulation. Proposed causes for this phenomenon include tolerance, disease progression, and suboptimal location. The goal of this study was to assess the factors that may lead to both stimulation failure, defined as loss of meaningful tremor relief, and less satisfactory outcomes, defined as leads requiring voltages > 3.6 V for effective tremor control. Methods The authors present their clinical outcomes from 31 leads in 27 patients who had effective tremor control for > 1 year following nucleus ventralis intermedius stimulation. All patients postoperatively had a mean decrease in both the writing and drawing subscales of the Fahn-Tolosa-Marin Tremor Rating Scale (p < 0.001). Results After a mean follow-up of 40 months, 22 patients continued to have tremor control with stimulation. Four patients eventually lost efficacy of their stimulation at a mean of 39 months. There was no difference in age, duration of disease, or disease severity between the groups. Examination of perioperative factors revealed that suboptimal anteroposterior positioning as evidenced on intraoperative fluoroscopy occurred significantly more frequently in patients with stimulation failure (p = 0.018). In patients with less satisfactory outcomes, no difference was seen between group demographics. Fluoroscopy again revealed suboptimal positioning more frequently in these patients (p = 0.005). Conclusions This study provides further evidence that suboptimal lead position in combination with disease progression or tolerance may result in less satisfactory long-term outcomes.

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Brain penetration effects of microelectrodes and deep brain stimulation leads in ventral intermediate nucleus stimulation for essential tremor

Journal of Neurosurgery ◽

10.3171/2009.7.jns09150 ◽

2010 ◽

Vol 112 (3) ◽

pp. 491-496 ◽

Cited By ~ 32

Author(s):

Takashi Morishita ◽

Kelly D. Foote ◽

Samuel S. Wu ◽

Charles E. Jacobson ◽

Ramon L. Rodriguez ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Operating Room ◽

Brain Stimulation ◽

Rating Scale ◽

Lead Placement ◽

Ventral Intermediate Nucleus ◽

The Impact ◽

Over Time ◽

Deep Brain

Object Microelectrode recording (MER) and macrostimulation (test stimulation) are used to refine the optimal deep brain stimulation (DBS) lead placement within the operative setting. It is well known that there can be a microlesion effect with microelectrode trajectories and DBS insertion. The aim of this study was to determine the impact of intraoperative MER and lead placement on tremor severity in a cohort of patients with essential tremor. Methods Consecutive patients with essential tremor undergoing unilateral DBS (ventral intermediate nucleus stimulation) for medication-refractory tremor were evaluated. Tremor severity was measured at 5 time points utilizing a modified Tremor Rating Scale: 1) immediately before MER; 2) immediately after MER; 3) immediately after lead implantation; 4) 6 months after DBS implantation in the off-DBS condition; and 5) 6 months after implantation in the on-DBS condition. To investigate the impact of the MER and DBS lead placement, Wilcoxon signed-rank tests were applied to test changes in tremor severity scores over the surgical course. In addition, a generalized linear mixed model including factors that potentially influenced the impact of the microlesion was also used for analysis. Results Nineteen patients were evaluated. Improvement was noted in the total modified Tremor Rating Scale, postural, and action tremor scores (p < 0.05) as a result of MER and DBS lead placement. The improvements observed following lead placement were similar in magnitude to what was observed in the chronically programmed clinic setting parameters at 6 months after lead implantation. Improvement in tremor severity was maintained over time even in the off-DBS condition at 6 months, which was supportive of a prolonged microlesion effect. The number of macrostimulation passes, the number of MER passes, and disease duration were not related to the change in tremor severity score over time. Conclusions Immediate improvement in postural and intention tremors may result from MER and DBS lead placement in patients undergoing DBS for essential tremor. This improvement could be a predictor of successful DBS lead placement at 6 months. Clinicians rating patients in the operating room should be aware of these effects and should consider using rating scales before and after lead placement to take these effects into account when evaluating outcome in and out of the operating room.

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Comparative connectivity correlates of dystonic and essential tremor deep brain stimulation

Brain ◽

10.1093/brain/awab074 ◽

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.

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Direct targeting of the ventral intermediate nucleus of the thalamus in deep brain stimulation for essential tremor: a prospective study with comparison to a historical cohort

Journal of Neurosurgery ◽

10.3171/2021.2.jns203815 ◽

2021 ◽

pp. 1-10

Author(s):

Andre A. Wakim ◽

Natasha A. Sioda ◽

James J. Zhou ◽

Margaret Lambert ◽

Virgilio Gerald H. Evidente ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Brain Stimulation ◽

Anterior Commissure ◽

Proton Density ◽

Historical Cohort ◽

Intermediate Nucleus ◽

Ventral Intermediate Nucleus ◽

Direct Targeting ◽

Deep Brain

OBJECTIVE The ventral intermediate nucleus of the thalamus (VIM) is an effective target for deep brain stimulation (DBS) to control symptoms related to essential tremor. The VIM is typically targeted using indirect methods, although studies have reported visualization of the VIM on proton density–weighted MRI. This study compares the outcomes between patients who underwent VIM DBS with direct and indirect targeting. METHODS Between August 2013 and December 2019, 230 patients underwent VIM DBS at the senior author’s institution. Of these patients, 92 had direct targeting (direct visualization on proton density 3-T MRI). The remaining 138 patients had indirect targeting (relative to the third ventricle and anterior commissure–posterior commissure line). RESULTS Coordinates of electrodes placed with direct targeting were significantly more lateral (p < 0.001) and anterior (p < 0.001) than those placed with indirect targeting. The optimal stimulation amplitude for devices measured in voltage was lower for those who underwent direct targeting than for those who underwent indirect targeting (p < 0.001). Patients undergoing direct targeting had a greater improvement only in their Quality of Life in Essential Tremor Questionnaire hobby score versus those undergoing indirect targeting (p = 0.04). The direct targeting group had substantially more symptomatic hemorrhages than the indirect targeting group (p = 0.04). All patients who experienced a postoperative hemorrhage after DBS recovered without intervention. CONCLUSIONS Patients who underwent direct VIM targeting for DBS treatment of essential tremor had similar clinical outcomes to those who underwent indirect targeting. Direct VIM targeting is safe and effective.

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Thalamic deep brain stimulation for tremor in Parkinson disease, essential tremor, and dystonia

Neurology ◽

10.1212/wnl.0000000000004295 ◽

2017 ◽

Vol 89 (13) ◽

pp. 1416-1423 ◽

Cited By ~ 79

Author(s):

Rubens Gisbert Cury ◽

Valerie Fraix ◽

Anna Castrioto ◽

Maricely Ambar Pérez Fernández ◽

Paul Krack ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Parkinson Disease ◽

Essential Tremor ◽

Brain Stimulation ◽

Rating Scale ◽

Dystonic Tremor ◽

Over Time ◽

Deep Brain

Objective:To report on the long-term outcomes of deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (VIM) in Parkinson disease (PD), essential tremor (ET), and dystonic tremor.Methods:One hundred fifty-nine patients with PD, ET, and dystonia underwent VIM DBS due to refractory tremor at the Grenoble University Hospital. The primary outcome was a change in the tremor scores at 1 year after surgery and at the latest follow-up (21 years). Secondary outcomes included the relationship between tremor score reduction over time and the active contact position. Tremor scores (Unified Parkinson's Disease Rating Scale-III, items 20 and 21; Fahn, Tolosa, Marin Tremor Rating Scale) and the coordinates of the active contacts were recorded.Results:Ninety-eight patients were included. Patients with PD and ET had sustained improvement in tremor with VIM stimulation (mean improvement, 70% and 66% at 1 year; 63% and 48% beyond 10 years, respectively; p < 0.05). There was no significant loss of stimulation benefit over time (p > 0.05). Patients with dystonia exhibited a moderate response at 1-year follow-up (41% tremor improvement, p = 0.027), which was not sustained after 5 years (30% improvement, p = 0.109). The more dorsal active contacts' coordinates in the right lead were related to a better outcome 1 year after surgery (p = 0.029). During the whole follow-up, forty-eight patients (49%) experienced minor side effects, whereas 2 (2.0%) had serious events (brain hemorrhage and infection).Conclusions:VIM DBS is an effective long-term (beyond 10 years) treatment for tremor in PD and ET. Effects on dystonic tremor were modest and transient.Classification of evidence:This provides Class IV evidence. It is an observational study.

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PSA and VIM DBS efficiency in essential tremor depends on distance to the dentatorubrothalamic tract

10.1101/19013656 ◽

2019 ◽

Cited By ~ 3

Author(s):

Till A. Dembek ◽

Jan Niklas Petry-Schmelzer ◽

Paul Reker ◽

Jochen Wirths ◽

Stefanie Hamacher ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Crossover Trial ◽

Rating Scale ◽

Population Based ◽

Stimulation Parameters ◽

Randomized Crossover Trial ◽

Ventral Intermediate Nucleus ◽

Stimulation Amplitude ◽

Deep Brain

AbstractObjectiveTo investigate the relation between deep brain stimulation (DBS) of the posterior-subthalamic-area (PSA) and the ventral-intermediate-nucleus (VIM) and the distance to the dentatorubrothalamic tract (DRTT) in essential tremor (ET).MethodsTremor rating scale (TRS) hemi-scores were analyzed in 13 ET patients, stimulated in both the VIM and the PSA in a randomized, crossover trial. Distances of PSA and VIM contacts to population-based DRTTs were calculated. The relationships between distance to DRTT and stimulation amplitude, as well as DBS efficiency (TRS improvement per amplitude) were investigated.ResultsPSA contacts were closer to the DRTT (p=0.019) and led to a greater improvement in TRS hemi-scores (p=0.005) than VIM contacts. Proximity to the DRTT was related to lower amplitudes (p<0.001) and higher DBS efficiency (p=0.017).ConclusionsDifferences in tremor outcome and stimulation parameters between contacts in the PSA and the VIM can be explained by their different distance to the DRTT.

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Long-term benefits in quality of life after unilateral thalamic deep brain stimulation for essential tremor

Journal of Neurosurgery ◽

10.3171/2012.3.jns112316 ◽

2012 ◽

Vol 117 (1) ◽

pp. 156-161 ◽

Cited By ~ 40

Author(s):

Jules M. Nazzaro ◽

Rajesh Pahwa ◽

Kelly E. Lyons

Keyword(s):

Quality Of Life ◽

Deep Brain Stimulation ◽

Essential Tremor ◽

Brain Stimulation ◽

Rating Scale ◽

Well Being ◽

Deep Brain

Object The goal of this study was to evaluate short- and long-term benefits in quality of life (QOL) after unilateral deep brain stimulation (DBS) for essential tremor (ET). Methods Patients who received unilateral DBS of the ventral intermediate nucleus of the thalamus between 1997 and 2010 and who had at least 1 follow-up evaluation at least 1 year after surgery were included. Their QOL was assessed with the Parkinson Disease Questionnaire-39 (PDQ-39), and ET was measured with the Fahn-Tolosa-Marin tremor rating scale (TRS) prior to surgery and then postoperatively with the stimulation in the on mode. Results Ninety-one patients (78 at 1 year; 42 at 2–7 years [mean 4 years]; and 22 at > 7–12 years [mean 9 years]) were included in the analysis. The TRS total, targeted tremor, and activities of daily living (ADL) scores were significantly improved compared with presurgical scores up to 12 years. The PDQ-39 ADL, emotional well-being, stigma, and total scores were significantly improved up to 7 years after surgery compared with presurgical scores. At the longest follow-up, only the PDQ-39 stigma score was significantly improved, and the PDQ-39 mobility score was significantly worsened. Conclusions Unilateral thalamic stimulation significantly reduces ET and improves ADL scores for up to 12 years after surgery, as measured by the TRS. The PDQ-39 total score and the domains of ADL, emotional well-being, and stigma were significantly improved up to 7 years. Although scores were improved compared with presurgery, other than stigma, these benefits did not remain significant at the longest (up to 12 years) follow-up, probably related in part to changes due to aging and comorbidities.

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Correlation between fractional anisotropy changes in the targeted ventral intermediate nucleus and clinical outcome after transcranial MR-guided focused ultrasound thalamotomy for essential tremor: results of a pilot study

Journal of Neurosurgery ◽

10.3171/2018.10.jns18993 ◽

2020 ◽

Vol 132 (2) ◽

pp. 568-573 ◽

Cited By ~ 2

Author(s):

Hiroki Hori ◽

Toshio Yamaguchi ◽

Yoshiyuki Konishi ◽

Takaomi Taira ◽

Yoshihiro Muragaki

Keyword(s):

Clinical Outcome ◽

Essential Tremor ◽

Fractional Anisotropy ◽

Focused Ultrasound ◽

Rating Scale ◽

Statistical Significance ◽

Intermediate Nucleus ◽

Ventral Intermediate Nucleus ◽

Recurrence Group

OBJECTIVEThis study evaluated changes of fractional anisotropy (FA) in the ventral intermediate nucleus (VIM) of the thalamus after transcranial MR-guided focused ultrasound (TcMRgFUS) thalamotomy and their associations with clinical outcome.METHODSClinical and radiological data of 12 patients with medically refractory essential tremor (mean age 76.5 years) who underwent TcMRgFUS thalamotomy with VIM targeting were analyzed retrospectively. The Clinical Rating Scale for Tremor (CRST) score was calculated before and at 1 year after treatment. Measurements of the relative FA (rFA) values, defined as ratio of the FA value in the targeted VIM to the FA value in the contralateral VIM, were performed before thalamotomy, and 1 day and 1 year thereafter.RESULTSTcMRgFUS thalamotomy was well tolerated and no long-term complications were noted. At 1-year follow-up, 8 patients demonstrated relief of tremor (improvement group), whereas in 4 others persistent tremor was noted (recurrence group). In the entire cohort, mean rFA values in the targeted VIM before treatment, and at 1 day and 1 year after treatment, were 1.12 ± 0.15, 0.44 ± 0.13, and 0.82 ± 0.22, respectively (p < 0.001). rFA values were consistently higher in the recurrence group compared with the improvement group, and the difference reached statistical significance at 1 day (p < 0.05) and 1 year (p < 0.01) after treatment. There was a statistically significant (p < 0.01) positive correlation between rFA values in the targeted VIM at 1 day after thalamotomy and CRST score at 1 year after treatment. Receiver operating characteristic curve analysis revealed that the optimal cutoff value of rFA at 1 day after thalamotomy for prediction of symptomatic improvement at 1-year follow-up is 0.54.CONCLUSIONSTcMRgFUS thalamotomy results in significant decrease of rFA in the targeted VIM, at both 1 day and 1 year after treatment. Relative FA values at 1 day after treatment showed significant correlation with CRST score at 1-year follow-up. Therefore, FA may be considered a possible imaging biomarker for early prediction of clinical outcome after TcMRgFUS thalamotomy for essential tremor.

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Response to Thalamic Ventralis Intermedius Nucleus Deep Brain Stimulation in Essential Tremor vs. Essential Tremor-Plus

Frontiers in Neurology ◽

10.3389/fneur.2021.790027 ◽

2021 ◽

Vol 12 ◽

Author(s):

Gabriela S. Gilmour ◽

Davide Martino ◽

Karen Hunka ◽

Pia Lawrence ◽

Zelma H. T. Kiss ◽

...

Keyword(s):

Deep Brain Stimulation ◽

Essential Tremor ◽

Brain Stimulation ◽

Rating Scale ◽

Patient Characteristics ◽

Response To Treatment ◽

Secondary Outcome ◽

Gait Disturbances ◽

Deep Brain

Introduction: Essential tremor (ET) is a tremor syndrome characterized by bilateral, upper limb action tremor. Essential tremor-plus (ET-plus) describes ET patients with additional neurologic signs. It is unknown whether there is a difference in response to treatment with ventralis intermedius nucleus deep brain stimulation (VIM DBS) in patients with ET and ET-plus. Due to potential variability in underlying etiology in ET-plus, there is a concern that ET-plus patients may have worse outcomes. The aim of this study was to identify whether patients with ET-plus have worse tremor outcomes after VIM DBS than patients with ET.Methods: This is a retrospective chart and video review evaluating VIM DBS outcomes by comparing changes from baseline in the Fahn-Tolosa-Marin Tremor Rating Scale Part B (FTM-B) for the treated limb between patients with ET and ET-plus at follow-up examinations. Patients were re-classified as having ET or ET-plus using pre-operative examination videos by two independent movement disorders neurologists blinded to patient characteristics. As a secondary outcome, we evaluated for correlations and potential predictors of treatment response.Results: Twenty-six patients were included: 13 with ET, 13 with ET-plus. There were no significant differences in the change in FTM-B scores between the ET and ET-plus patients at each follow-up examination. None of the included patients developed new symptoms compatible with dystonia, parkinsonism or gait disturbances.Conclusions: Patients with ET-plus had tremor improvement from VIM DBS, with no differences when compared to those with ET, without emergence of postoperative neurological issues. Patients with ET-plus should still be considered good candidates for VIM DBS for treatment of tremor.

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