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SYMPOSIUM
Year : 2020  |  Volume : 68  |  Issue : 8  |  Page : 187-195

Deep Brain Stimulation for Tremor and Dystonia


Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication5-Dec-2020

Correspondence Address:
Prof. Manmohan Singh
Room No 715, C N Centre, All India Institute of Medical Sciences, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.302472

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 » Abstract 


Deep brain stimulation (DBS) is the most commonly used surgical treatment for drug-refractory movement disorders such as tremor and dystonia. Appropriate patient selection along with target selection is important to ensure optimal outcome without complications. This review summarizes the recent literature regarding the mechanism of action, indications, outcome, and complications of DBS in tremor and dystonia. A comparison with other modalities of surgical interventions is discussed along with a note of the recent advances in technology. Future research needs to be directed to understand the underlying etiopathogenesis of the disease and the way in which DBS modulates the intracranial abnormal networks.


Keywords: Deep brain stimulation, dystonia, neuromodulation, review, stimulation, tremor
Key Message: DBS is currently the surgical procedure of choice for selected cases of drug refractory tremor and dystonia. Technological advances in hardware and improved target localization techniques have further cemented the role of DBS as compared to other surgical techniques.


How to cite this article:
Singh M, Agrawal M. Deep Brain Stimulation for Tremor and Dystonia. Neurol India 2020;68, Suppl S2:187-95

How to cite this URL:
Singh M, Agrawal M. Deep Brain Stimulation for Tremor and Dystonia. Neurol India [serial online] 2020 [cited 2021 Sep 28];68, Suppl S2:187-95. Available from: https://www.neurologyindia.com/text.asp?2020/68/8/187/302472




Surgical treatment of movement disorders initially started with the ablation of stereotactically localized intracranial targets.[1],[2] But several surgical complications were observed due to the uncontrolled irreversible lesioning of a critical brain structure.[1],[2] Technological advances led to the development of deep brain stimulation (DBS) as an alternative.[1],[2] DBS involves the delivery of current or stimulation to distinct intracranial targets via the stereotactic implantation of electrodes. It is a reversible procedure whose effects can be titrated by changing the stimulation settings. After initial positive reports in the 1990s,[3],[4] DBS has now become the surgical procedure of choice for movement disorders. FDA approval for DBS was first granted in 1997 for essential tremor and Parkinson related tremor, followed by more generalized cases of Parkinson disease (PD) in 2002 and on humanitarian grounds for dystonia in 2003.[2],[5] PD has become the most well-known indication for DBS, However, over the last two decades DBS has proven to be very effective for ET and dystonia as well.

ET is the commonest form of adult movement disorder.[6],[7],[8] It is a progressive disease which predominantly affects the distal extremities and can significantly worsen the quality of life of a patient.[6],[7],[8],[9] Pharmacotherapy in the form of propranolol and primidone have been used for treatment, but more than half of these patients derive no benefit or eventually become drug refractory.[10] Surgery offers an effective treatment alternative for such patients. Tremor related to other causes such as PD, multiple sclerosis, and dystonia has also been successfully treated.[11],[12],[13]

Dystonia causes abnormal repetitive movements and posturing of muscle groups which may be sustained.[14] A recent consensus statement classified dystonia syndromes as per clinical features (age of onset, body distribution, temporal evolution, other co-existing movement disorders, and neurological deficits) and etiology (genetic, idiopathic, or acquired/secondary).[15] The definite etiopathogenesis of dystonia is unproven. Thus there is no verified treatment of choice for dystonia.[16] Botulinum injections and medications such as trihexyphenidyl and clonazepam provide symptomatic relief only.[16] Surgical interventions like DBS target the underlying abnormal disease network and has been shown to be effective in appropriately chosen patients.[16]


 » Mechanisms of Action of DBS Top


The exact mechanism of action of DBS in movement disorders remains unknown. Several hypotheses have been proposed based on various techniques such as animal models, microdialysis, functional imaging, and computational modeling. Animal models were initially used to provide evidence for its use. PD was iatrogenically induced by injecting a toxin (MPTP - 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) which selectively damaged dopaminergic neurons in the subtahalamic nucleus. Symptoms in such animals were seen to improve by the use of high-frequency stimulation,[17] which was thought to inhibit abnormal motor activity in the basal ganglia. The applied electrical field results in the opening or closing of ionic channels, causing action potentials and the release of specific neurotransmitters.[1],[18] Constant application of the external current blocks the intrinsic activity of the target area, resulting in a phenomenon known as ‘information blockade’.[18],[19] High-frequency stimulation has also been seen to inhibit the synaptic transmission of the abnormal low-frequency oscillations seen in movement disorders.[18],[19] Recently, it has been identified that astrocytes might play an effect on neurotransmitter release and long-term synaptic plasticity to modify the effects of DBS.[18],[19],[20],[21] Movement disorders are caused due to an abnormality in the corticobasal ganglia thalamocortical loop. It is increasingly been understood that recognition and modulation of the network, which is unique to each patient, might hold the key to effective intervention.[22] DBS modulates this network in a positive fashion, the exact mechanism of which remains to be definitely proven.


 » Indications Top


Optimal patient selection is a complex process and is essential in order to ensure favorable postoperative outcomes.[23] The symptoms should be disabling as assessed by validated scoring scales (Clinical Rating Scale for Tremor – CRST[24] and Burke-Fahn-Marsden Dystonia Rating Scale – BFMDRS[25]). The patients should be drug refractory and medically fit to be able to tolerate an invasive procedure. Premorbid psychiatric conditions or cognitive dysfunction should be ruled out.[26] Fixed skeletal deformities, spasticity and myelopathy should be documented. MRI should be screened for any structural abnormality.[27]

1. Tremor:

ET predominantly affecting the distal part of the upper limbs responds best to DBS. Proximal tremor may be difficult to treat.[28] Complex tremors such as associated with multiple sclerosis and dystonia can show variable response,[10],[11],[12],[13] and thus, should be differentiated preoperatively to prognosticate patients adequately.

2. Dystonia:

Isolated and generalized idiopathic dystonia, predominantly affecting the neck, trunk, and limbs has been seen to respond best to DBS.[23],[29] It has also been effective in alleviating dystonia associated with PD, and focal dystonia such as writer's cramp, musician's dystonia, and cervical dystonia.[27],[30],[31] Outcome has been seen to be poorer with secondary dystonia.[23],[32] Specific preoperative evaluation includes the exclusion of conditions that would respond more favorably to pharmacological treatments, such as levodopa trial to rule out dopamine responsive dystonia and tests for Wilson's disease.[23],[32],[33] Genetic predictors of response to stimulation like the presence of DYT-1 gene in primary dystonia, DYT-11 in early-onset dystonia and DYT-11 gene in dystonia associated with myoclonus, should be assessed to prognosticate patients accordingly.[23],[32]

Intracranial targets

1. Tremor:

The target described for use in patients with a tremor has been the ventral intermediate nucleus (VIM) of the thalamus. The  Atlas More Details-based co-ordinates for localizing the VIM have traditionally been identified as 13–15 mm lateral and 5 mm posterior to the mid-commissural point (MCP) at the level of the line joining the anterior and posterior commissures (AC/PC line).[33] [Figure 1]
Figure 1: Schalterbrand atlas (in blue) superimposed on the patient's axial (a) and parasagittal (b) inversion recovery image. Target is marked in red. (MCP – midcommissural point, VIM – ventral intermediate nucleus)

Click here to view


Direct targeting, which is based upon the visualization of the target on each patient's individual MRI, is more commonly utilized. Studies have been undertaken to identify the exact region within the thalamus which can result in ideal outcome with no complications. Cerebello thalamic tract (CTT) in the posterior subthalamic area (PSA) were shown to have a high density of clinically relevant fibers for targeting.[34] Researchers found that leads positioned in the ventral part of VIM, i.e., the distal contacts were better as compared to the proximal contacts.[35],[36] These contacts were stimulating the CTT in the PSA. Studies comparing PSA and VIM DBS have shown the requirement of a lower stimulation amplitude for PSA DBS, a greater distal as well as proximal tremor improvement, with a comparable complication rate.[37] In a randomized double-blind trial with one year of follow-up, greater tremor and quality of life (QoL) improvement was seen with PSA as compared to VIM stimulation.[38] However, few researchers have found no clear benefit of PSA stimulation over VIM. In a retrospective study evaluating 19 patients with 38 implanted electrodes (12-VIM, 12-PSA, and 14-intermediate), authors found 63% tremor reduction in the VIM group, 47% in the PSA group and 67% in the intermediate group. No significant difference was observed in between groups.[39]

2. Dystonia:

Postero ventral lateral portion of the globus pallidus interna (GPi) is the most commonly used target site for DBS. Atlas-based co-ordinates for GPi are 19-22 mm lateral and 2 mm anterior from MCP and 4 mm ventral to AC/PC line[33] [Figure 2]. Other targets such as STN, thalamus and cerebellum have been used with varying success.[40],[41],[42] These may have a role depending upon the type of dystonia being treated. A retrospective cohort study evaluating 14 patients with GPi-DBS and 16 with STN-DBS found the former better for alleviating axial symptoms (93% vs 83% improvement in the axis sub score of BFMDRS). On the other hand, STN-DBS warranted lesser delivery of electrical energy ((124 ± 52 vs 192 ± 65 μJ) which led to lesser battery consumption.[40]
Figure 2: Schalterbrand atlas (in orange) superimposed on the patient's axial (a) and coronal (b) T2W image, depicting the GPi target on the right (blue trajectory) and left (yellow trajectory)

Click here to view


Vim-DBS has been described for patients with dystonic tremor.[41] Recently, deep anterior cerebellar lobe DBS has been used with some success in patients with cerebral palsy associated spastic dystonia.[42]

Outcome

1. Tremor:

The first reports of high-frequency stimulation in six patients with essential tremor were published in a landmark study by Benabid et al.[43] Since then several studies on DBS for ET have shown favorable results.[44] A recent meta-analysis involving 1714 patients from 46 studies showed a pooled improvement in tremor scores of 61.3% at a mean follow-up of 20.0 ± 17.3 months.[45] Others have analyzed the predictors of clinical benefit and found that best outcomes are seen in older patients with greater baseline severity of disease who were unresponsive to benzodiazepine treatment.[46]

The studies reporting long-term efficacy more than two years have been compiled.[47],[48],[49],[50],[51],[52],[53],[54],[55],[56],[57],[58] [Table 1] Although favorable outcome is maintained, some loss of efficacy has been seen over time with a significant gradual increase in stimulation parameters.[55] This phenomenon has been associated with various factors, chief amongst which are the natural progression of the disease process and habituation to stimulation.[19],[59]
Table 1: Long term (>2 years) outcome after DBS for essential tremor

Click here to view


A recent study assessed the long-term outcomes with VIM-DBS in 26 patients with dystonic tremor (DT) and 97 patients with ET. They found significant improvement in rating scale scores up to 52.2% at 4-5 years of follow-up in both the cohorts. The improvements seen in activities of daily living were not sustained in the DT group, probably because of the co-existent dystonia.[11]

Tremor associated with multiple sclerosis has seen moderate improvements with DBS.[60] Dual lead DBS targeting the VIM and ventralis oralis (VO) was performed in 12 patients. A 29.6% reduction in tremor scores was noted at six months follow-up.[12]

Improvements in head and voice tremor were observed in 9/10 and 6/7 patients respectively at a mean follow-up of 10 months following bilateral DBS of the thalamus.[61] Similar significant improvement was observed in another prospective study.[62]

Limited evidence in the form of case reports and case series is also becoming available showing the efficacy of DBS in tremor due to uncommon causes like Holmes tremor, orthostatic tremor and tremor due to genetic etiology.[63] Further clarification is needed to define the selection criteria and appropriate targets.

2. Dystonia:

Class I evidence in the form of an RCT published in 2006 had 20 patients in the treatment group and an equal number in the sham group.[64] After three months of the procedure, significantly greater degree of improvement was observed in the GPi stimulation group (-15.8 points) as compared to the sham group (-1.4 points). Overall 75% in the treatment group had a favourable outcome and patients who switched over to active treatment also showed similar benefits. Dysarthria (n = 5) and infection (n = 4) at stimulator site were the most common adverse effects. Upon long-term follow-up of five years of the same cohort of patients, a sustained good outcome was seen in 30 (83%) of 36 patients at 6 months, 29 (94%) of 31 at 3 years, and 26 (81%) of 32 patients.[65]

A recent meta-analysis of 523 patients showed 65.2% improvement in BFMDRS score at a mean follow-up of 32.5 months. A 58.6% improvement in the disability score was observed as well. Higher pre-operative motor scores and younger age at surgery were found to be significant predictors of improved outcomes.[66] Similarly improvement was also reported in a meta-analysis of pediatric patients (n = 321) in which the authors co-related older age at onset of dystonia, idiopathic dystonia, inherited dystonia without neurological pathology and truncal involvement to better postoperative outcome.[67]

A retrospective analysis of outcome in three patients with DYT-6 mutation vs 23 patients with DYT-1 mutation showed better outcomes in the latter group.[68] Another comparative multicentre study in GPi-DBS showed best improvement of 60% in BFMDRS score in patients with DYT-1 mutation (9 patients), followed by 52% in the non-DYT group (38 patients). The least improvement was seen in the DYT-6 group (32% - 8 patients).[32] However at long-term follow-up (22–92 months) no significant difference in the rate of improvement between the three groups could be observed.[32] Earlier intervention, absence of fixed skeletal deformities and younger age at surgery have all been correlated to a favorable outcome, especially in DYT-1 cases.[32],[66],[69],[70],[71]

An RCT was conducted for DBS in cervical dystonia including 60 patients.[72] At 3 months, a significant reduction in dystonia severity was seen with stimulation (–5·1 points [SD 5·1], 95% CI –7·0 to –3·5) as compared to sham group (–1·3 [2·4], –2·2 to –0·4, P = 0·0024). Dysarthria was the most commonly observed side effect.

Craniocervical dystonia is also effectively treated using DBS.[73],[74] An analysis of 75 patients revealed 66.9% improvement in BFMDRS motor score and 56% improvement in disability score. No correlation was seen with the age at onset and disease duration.[73] This improvement has been sustained at long-term follow-up as seen in six patients with 53% improvement in various sub scores maintained at five years after surgery.[74] Other forms of dystonia such as blepharospasm have shown quick resolution after DBS.[75] Thalamic (ventralis oralis/ventralis intermedius) DBS has been found to be more effective than GPi DBS in treating writer's cramp.[76]

A review was published on myoclonic dystonia of the upper extremities, which combined the results of DBS in 40 patients from various case reports.[77] 93.5% of patients showed at least a 50% improvement in UMRS (myoclonus scores), while 72.7% showed at least a 50% improvement in BFMDRS. Improvements in myoclonus scores were similar for both GPi (75.7%) and VIM (70.4%), while the recovery in dystonia scores was more with GPi (60.2%), as compared to VIM (33.3%).[77]

An RCT has shown the efficacy of pallidal DBS for tardive dystonia/dyskinesia.[78] A review of the literature identified 117 patients with tardive dyskinesia.[79] At a mean follow-up of 25.6 months, 62 ± 15% improvement was seen in 51 patients reporting the Abnormal Involuntary Movement Scale, while 76 ± 21% improvement was observed in 67 cases reporting the BFMDRS.[79]

DBS used in other secondary causes of dystonia like trauma, stroke, neurodegenerative diseases has shown heterogenous results.[80],[81],[82]

Recently DBS has even been used to status dystonicus. A series of five patients with DYT-1 positive status dystonicus treated with DBS showed significant improvement in four patients. Extubation time was shorter as compared to other case reports of pharmacological treatment alone.[83],[84] In another series, surgery was performed on five patients, who all improved within 1–7 days after surgery, with no recurrence.[84]

Cognitive benefits have been observed in patients undergoing GPi DBS. In a study including 12 patients (8 – focal, 4 – generalized dystonia), with a mean follow-up of 13.1 months, statistically significant improvement was noted in working memory, executive functioning, anxiety, and depression.[85] Other studies have found that GPi-DBS has no effect on neuropsychiatric symptoms or cognition.[86] A recent systematic review of 610 patients with various types of dystonia found an improvement in physical quality of life but not so much when considering the mental QoL.[40]


 » Complications Top


Surgical complications include the risk of intracranial hemorrhage and stroke which has been seen to range from 0-4% for all DBS patients.[69],[87] In a large series of 728 patients, the incidence of asymptomatic intracerebral hemorrhage was 0.5% (4 patients), symptomatic intracranial hemorrhage was 1.1% (8 patients), intraventricular hemorrhage was 3.4% (25 patients) and infarction was 0.4% (3 patients). Seizures were seen in 2 patients (0.3%).[87] Mortality rate of 0.4% in the first 30 days following surgery has been reported, due to pneumonia, pulmonary embolism, hepatic failure and severe multiple sclerosis.[88]

Hardware-related complications such as lead breakage and implant extrusion have also been reported in up to 25% of cases.[87],[89],[90] This usually requires additional surgery to correct. These complications have been more frequently seen in dystonia as compared to PD, because of the increased risk with abnormal movements of the head and neck.[69],[90] The incidence of device infection is variable, and maybe seen in up to 10% of cases.[69],[88],[91],[92] Management usually includes explantation, although it has also been reported to have been managed with antibiotics alone.[93]

Stimulation related side effects are related to the electrodeposition and the surrounding areas which get activated by the delivered current, and are thus distinct for different targets.

GPi shares proximity to the internal capsule, which can cause motor adverse effects such as dysarthria and abnormal gait. Indeed, these are the two most common complications seen with GPi-DBS.[64],[65] The optic tract lies below the target and surgeon has to be careful not to injure it inadvertently.[33]

The VIM nucleus is an extremely small structure and cannot be clearly visualized on structural MRI.[94] It is surrounded by critical structures like the corticospinal tract (CST) and medial lemniscus (ML).[34],[95] VIM-DBS has been associated with complications related to these structures which includes dysarthria (3-18%), paraesthesia (6–36%), ataxia (3-8%) and limb weakness (4–8%).[45],[49]


 » Comparison with Other Surgical Modalities Top


For any other surgical technique to replace DBS as the procedure of choice for refractory ET, it has to prove itself as at par, if not better than DBS. Comparative studies between radiofrequency ablation (RFA) and DBS for tremor have reported better improvement in function and fewer adverse effects with DBS.[96] Long-term follow-up of patients undergoing DBS and RFA respectively has shown some decrease in efficacy with time, albeit lesser in the DBS group.[97] Ablative procedures have traditionally been shown to have significant corticobulbar adverse effects such as dysphagia, dysarthria and effects on cognition, especially with bilateral procedures.[98],[99] However, a recently published cases series comparing GPi DBS to pallidotomy showed comparable efficacy with both. Long-term hardware related complications were seen in 37.5% cases after DBS, while no surgical complications were noted with pallidotomy.[100] Drug refractory secondary dystonia has also been successfully treated with pallidotomy.[101] It has been found to be extremely cost-effective when compared to DBS.[102] Ablative procedures are the procedure of choice in resource constrained countries, on in patients with fixed contractures or thin body habitus who are otherwise unfit to undergo device implantation.[16]

Gamma knife thalamotomy (GKT) was first described in the 1990s. It's a non-invasive procedure and its efficacy has been proven in a few prospective studies.[103],[104] Some case reports on the use of GKT for dystonia have been published.[105] But the inability to monitor real time clinical response, variation in the size of the lesion produced, unpredictable radiation effects and a delay in clinical response have resulted in GKT being reserved for patients who are otherwise unfit for DBS.[106]

Another recently adopted surgical modality is MR-guided focused ultrasound (MRgFUS).[107],[108] Some of the advantages of this technique over the other available procedures include non-invasiveness, with real time control over the target and temperature at which the lesion is created, the ability to monitor patient response while creating the lesion, no hardware related complications and no need for repeat patient visits for programming.[109] In a retrospective analysis of RFA, DBS and MRgFUS for ET, outcomes and complication rates of the procedures between the three groups were not statistically different.[110] A recent study,[111] compared a trial on the use of VIM DBS for ET,[112] with the RCT done by Elias et al.[108] They found a greater percentage improvement with DBS, although the patients in DBS group had worse baseline tremor scores. The MRgFUS group had increased incidence of neurological complications as compared to the DBS group, although trajectory related complications were more in the latter.

ET and dystonia are usually progressive disorders, with most patients having bilateral symptoms with time.[14],[113] DBS has proven efficacy with bilateral implantation, while the lesioning procedures have primarily been utilized for unilateral pathology only.


 » Recent Advances and Future Direction Top


DBS hardware

Technological advances in order to increase the longevity of the implant and to improve current delivery to the target site are rapidly being made.[1],[114] The battery sizes have considerably decreased in the past decade, with contouring to facilitate easy implantation. Innovative miniature generators which may even be implanted in the skull are being designed.[1],[114] Rechargeable batteries with longer lifespan are being increasingly used. Thus physicians donot have to worry about early battery drainage while treating more severe forms of disease.[1]

Adaptive closed-loop DBS which can provide on demand stimulation after recognizing abnormal oscillations within the cortico-basal ganglia network has been developed recently.[115] The concept of segmented and directional leads has been developed in order to be able to modify the stimulation fields at the implanted site guided by individualized patient outcome and complications.[116]

Targeting techniques

Advances in hardware can only be effective as long as the target is accurate. Technological advances in MRI techniques have led to a better visualization of the targets.[117] Preliminary studies using DTI have led to delineation of the target along with the surrounding critical tracts, and have demonstrated improved outcome and reduced side effect profile as compared to traditional atlas based targeting.[95] Some limitations which need to be overcome are the standardization of DTI tracking method and software, seamless integration of the planning system with DTI, a need for specialized personnel trained in technical aspects and troubleshooting of DTI.

Computational models have been developed to aid in the positioning and programming of electrodes and predict outcomes.[118] The concept of volume of tissue activated has been developed to provide optimal coordinates for lead implantation.[119]


 » Conclusion Top


DBS is currently the surgical procedure of choice for selected cases of drug-refractory tremor and dystonia. Technological advances in hardware and improved target localization techniques have further cemented the role of DBS as compared to other surgical techniques. Further research needs to be directed to understand the underlying etiopathogenesis of the disease and the way in which DBS modulates the abnormal involved network.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Lozano AM, Lipsman N, Bergman H, Brown P, Chabardes S, Chang JW, et al. Deep brain stimulation: Current challenges and future directions. Nat Rev Neurol 2019;15:148-60.  Back to cited text no. 1
    
2.
Gardner J. A history of deep brain stimulation: Technological innovation and the role of clinical assessment tools. Soc Stud Sci 2013;43:707-28.  Back to cited text no. 2
    
3.
Benabid AL, Pollak P, Gervason C, Hoffmann D, Gao DM, Hommel M, et al. Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus. Lancet 1991;337:403-6.  Back to cited text no. 3
    
4.
Benabid AL, Pollak P, Gao D, Hoffmann D, Limousin P, Gay E, et al. Chronic electrical stimulation of the ventralis intermedius nucleus of the thalamus as a treatment of movement disorders. J Neurosurg 1996;84:203-14.  Back to cited text no. 4
    
5.
Doshi PK. Expanding indications for deep brain stimulation. Neurol India 2018;66(Suppl S1):102-12.  Back to cited text no. 5
    
6.
Deuschl G, Bain P, Brin M. Consensus statement of the movement disorder society on tremor. Ad Hoc scientific committee. Mov Disord 1998;13(Suppl 3):2-23.  Back to cited text no. 6
    
7.
Bhatia KP, Bain P, Bajaj N, Elble RJ, Hallett M, Louis ED, et al. Consensus statement on the classification of tremors. From the task force on tremor of the International Parkinson and Movement disorder society. Mov Disord 2018;33:75-87.  Back to cited text no. 7
    
8.
Louis ED, Ferreira JJ. How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor. Mov Disord 2010;25:534-41.  Back to cited text no. 8
    
9.
Kamble N, Pal PK. Tremor syndromes: A review. Neurol India 2018;66(Suppl S1):36-47.  Back to cited text no. 9
    
10.
Deuschl G, Raethjen J, Hellriegel H, Elble R. Treatment of patients with essential tremor. Lancet Neurol 2011;10:148-61.  Back to cited text no. 10
    
11.
Tsuboi T, Jabarkheel Z, Zeilman PR, et al. Longitudinal follow-up with VIM thalamic deep brain stimulation for dystonic or essential tremor. Neurology 2020;94:e1073-84.  Back to cited text no. 11
    
12.
Oliveria SF, Rodriguez RL, Bowers D, Kantor D, Hilliard JD, Monari EH, et al. Safety and efficacy of dual-lead thalamic deep brain stimulation for patients with treatment-refractory multiple sclerosis tremor: A single-centre, randomised, single-blind, pilot trial. Lancet Neurol 2017;16:691-700.  Back to cited text no. 12
    
13.
Ramirez-Zamora A, Okun MS. Deep brain stimulation for the treatment of uncommon tremor syndromes. Expert Rev Neurother 2016;16:983-997.  Back to cited text no. 13
    
14.
Batla A. Dystonia: A review. Neurol India 2018;66(Suppl S1):48-58.  Back to cited text no. 14
    
15.
Albanese A, Bhatia K, Bressman SB, Delong MR, Fahn S, Fung VSC, et al. Phenomenology and classification of dystonia: A consensus update. Mov Disord 2013;28:863-73.  Back to cited text no. 15
    
16.
Jinnah HA, Factor SA. Diagnosis and treatment of dystonia. Neurol Clin 2015;33:77-100.  Back to cited text no. 16
    
17.
Benazzouz A, Gross C, Féger J, Boraud T, Bioulac B. Reversal of rigidity and improvement in motor performance by subthalamic high-frequency stimulation in MPTP-treated monkeys. Eur J Neurosci 1993;5:382-9.  Back to cited text no. 17
    
18.
McIntyre CC, Anderson RW. Deep brain stimulation mechanisms: The control of network activity via neurochemistry modulation. J Neurochem 2016;139 Suppl 1(Suppl 1):338-45.  Back to cited text no. 18
    
19.
Wong JK, Hess CW, Almeida L, Middlebrooks EH, Christou EA, Patrick EE, et al. Deep brain stimulation in essential tremor: Targets, technology, and a comprehensive review of clinical outcomes. Expert Rev Neurother 2020;20:319-31.  Back to cited text no. 19
    
20.
Quartarone A, Pisani A. Abnormal plasticity in dystonia: Disruption of synaptic homeostasis. Neurobiol Dis 2011;42:162-70.  Back to cited text no. 20
    
21.
Miocinovic S, Somayajula S, Chitnis S, Vitek JL. History, applications, and mechanisms of deep brain stimulation. JAMA Neurol 2013;70:163-71.  Back to cited text no. 21
    
22.
McIntyre CC, Hahn PJ. Network perspectives on the mechanisms of deep brain stimulation. Neurobiol Dis 2010;38:329-37.  Back to cited text no. 22
    
23.
Albanese A, Asmus F, Bhatia KP, Elia AE, Elibol B, Filippini G, et al. EFNS guidelines on diagnosis and treatment of primary dystonias. Eur J Neurol 2011;18:5-18.  Back to cited text no. 23
    
24.
Fahn S, Tolosa E, Marin C. Clinical rating scale for tremor. In: Jankovic J, Tolosa E, editors. Parkinson's Disease and Movement Disorders. Baltimore: Williams & Wilkins; 1993. p. 271-80.  Back to cited text no. 24
    
25.
Albanese A, Sorbo FD, Comella C, Jinnah HA, Mink JW, Post B, et al. Dystonia rating scales: Critique and recommendations. Mov Disord 2013;28:874-83.  Back to cited text no. 25
    
26.
Hogg E, Wertheimer J, Graner S, Tagliati M. Deep brain stimulation and nonmotor symptoms. Int Rev Neurobiol 2017;134:1045-89.  Back to cited text no. 26
    
27.
Fox MD, Alterman RL. Brain stimulation for torsion dystonia. JAMA Neurol 2015;72:713-9.  Back to cited text no. 27
    
28.
Nguyen JP, Degos JD. Thalamic stimulation and proximal tremor. A specific target in the nucleus ventrointermedius thalami. Arch Neurol 1993;50:498-500.  Back to cited text no. 28
    
29.
Singh M, Garg K. Pallidal deep brain stimulation in dystonia. Neurol India 2017;65:1232-3.  Back to cited text no. 29
[PUBMED]  [Full text]  
30.
Singh M, Garg K. Musician's dystonia-What a neurosurgeon can offer! Neurol India 2020;68:152-3.  Back to cited text no. 30
    
31.
Manjunath M, Yadav R, Dwarakanath S, Jhunjhunwala K, Jafar A, Surathi P, et al. Experience of pallidal deep brain stimulation in dystonia at a tertiary care centre in India: An initial experience. Neurol India 2017;65:1322-9.  Back to cited text no. 31
[PUBMED]  [Full text]  
32.
Brüggemann N, Kühn A, Schneider SA, Kamm C, Wolters A, Krause P, et al. Short- and long-term outcome of chronic pallidal neurostimulation in monogenic isolated dystonia. Neurology 2015;84:895-903.  Back to cited text no. 32
    
33.
Singh M, Shabari Girishan KV, Bajaj J, Garg K. Deep brain stimulation for movement disorders: Surgical nuances. Neurol India 2018;66(Suppl S1):122-30.  Back to cited text no. 33
    
34.
Gallay MN, Jeanmonod D, Liu J, Morel A. Human pallidothalamic and cerebellothalamic tracts: Anatomical basis for functional stereotactic neurosurgery. Brain Struct Funct 2008;212:443-63.  Back to cited text no. 34
    
35.
Gross RE, Jones EG, Dostrovsky JO, Bergeron C, Lang AE, Lozano AM. Histological analysis of the location of effective thalamic stimulation for tremor. Case report. J. Neurosurg 2004;100:547-52.  Back to cited text no. 35
    
36.
Hamel W, Herzog J, Kopper F, Pinsker M, Weinert D, Müller D, et al. Deep brain stimulation in the subthalamic area is more effective than nucleus ventralis intermedius stimulation for bilateral intention tremor. Acta Neurochir (Wien) 2007;149:749-58; discussion 758.  Back to cited text no. 36
    
37.
Herzog J, Hamel W, Wenzelburger R, Pötter M, Pinsker MO, Bartussek J, et al. Kinematic analysis of thalamic versus subthalamic neurostimulation in postural and intention tremor. Brain 2007;130:1608-25.  Back to cited text no. 37
    
38.
Barbe MT, Reker P, Hamacher S, Franklin J, Kraus D, Dembek TA, et al. DBS of the PSA and the VIM in essential tremor: A randomized, double-blind, crossover trial. Neurology 2018;91:e543-50.  Back to cited text no. 38
    
39.
Degeneffe A, Kuijf M, Ackermans L, Temel Y, Kubben PL. Comparing deep brain stimulation in the ventral intermediate nucleus versus the posterior subthalamic area in essential tremor patients. Surg Neurol Int 2018;9:244.  Back to cited text no. 39
  [Full text]  
40.
Lin S, Wu Y, Li H, Zhang C, Wang T, Pan Y, et al. Deep brain stimulation of the globus pallidus internus versus the subthalamic nucleus in isolated dystonia. J Neurosurg 2019;1-12. doi: 10.3171/2018.12.JNS181927. Online ahead of print.  Back to cited text no. 40
    
41.
Cury RG, Fraix V, Castrioto A, Pérez Fernández MA, Krack P, Chabardes S, et al. Thalamic deep brain stimulation for tremor in Parkinson disease, essential tremor, and dystonia. Neurology 2017;89:1416-23.  Back to cited text no. 41
    
42.
Sokal P, Rudaś M, Harat M, Szylberg Ł, Zieliński P. Deep anterior cerebellar stimulation reduces symptoms of secondary dystonia in patients with cerebral palsy treated due to spasticity. Clin Neurol Neurosurg 2015;135:62-8.  Back to cited text no. 42
    
43.
Benabid AL, Pollak P, Gervason C, Hoffmann D, Gao DM, Hommel M, et al. Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus. Lancet 1991;337:403-6.  Back to cited text no. 43
    
44.
Flora ED, Perera CL, Cameron AL, Maddern GJ. Deep brain stimulation for essential tremor: A systematic review. Mov Disord 2010;25:1550-9.  Back to cited text no. 44
    
45.
Lu G, Luo L, Liu M, Zheng Z, Zhang B, Chen X, et al. Outcomes and adverse effects of deep brain stimulation on the ventral intermediate nucleus in patients with essential tremor. Neural Plast 2020;2020:Article ID 2486065, 13 pages. https://doi.org/10.1155/2020/2486065.  Back to cited text no. 45
    
46.
Sandoe C, Krishna V, Basha D, Sammartino F, Tatsch J, Picillo M, et al. Predictors of deep brain stimulation outcome in tremor patients. Brain Stimul 2018;11:592-9.  Back to cited text no. 46
    
47.
Koller WC, Lyons KE, Wilkinson SB, Troster AI, Pahwa R. Long-term safety and efficacy of unilateral deep brain stimulation of the thalamus in essential tremor. Mov Disord 2001;16:464-8.  Back to cited text no. 47
    
48.
Sydow O, Thobois S, Alesch F, Speelman JD. Multicentre european study of thalamic stimulation in essential tremor: A six year follow-up. J Neurol Neurosurg Psychiatry 2003;74:1387-91.  Back to cited text no. 48
    
49.
Putzke JD, Wharen RE Jr, Obwegeser AA, Wszolek ZK, Lucas JA, Turk MF, et al. Thalamic deep brain stimulation for essential tremor: Recommendations for long-term outcome analysis. Can J Neurol Sci 2004;31:333-42.  Back to cited text no. 49
    
50.
Lee JYK, Kondziolka D. Thalamic deep brain stimulation for management of essential tremor. J Neurosurg 2005;103:400-3.  Back to cited text no. 50
    
51.
Pahwa R, Lyons KE, Wilkinson SB, Simpson Jr RK, Ondo WG, Tarsy D, et al. Long-term evaluation of deep brain stimulation of the thalamus. J Neurosurg 2006;104:506-12.  Back to cited text no. 51
    
52.
Earhart GM, Hong M, Tabbal SD, Perlmutter JS. Effects of thalamic stimulation frequency on intention and postural tremor. Exp Neurol 2007;208:257-63.  Back to cited text no. 52
    
53.
Papavassiliou E, Rau G, Heath S, Abosch A, Barbaro NM, Larson PS, et al. Thalamic deep brain stimulation for essential tremor: Relation of lead location to outcome. Neurosurgery 2004;54:1120-30.  Back to cited text no. 53
    
54.
Earhart GM, Clark BR, Tabbal SD, Perlmutter JS. Gait and balance in essential tremor: Variable effects of bilateral thalamic stimulation. Mov Disord 2009;24:386-91.  Back to cited text no. 54
    
55.
Zhang K, Bhatia S, Oh MY, Cohen D, Angle C, Whiting D. Long-term results of thalamic deep brain stimulation for essential tremor. J Neurosurg 2010;112:1271-6.  Back to cited text no. 55
    
56.
Fasano A, Herzog J, Raethjen J, Rose FEM, Volkmann J, Falk D, et al. Lower limb joints kinematics in essential tremor and the effect of thalamic stimulation. Gait Posture 2012;36:187-93.  Back to cited text no. 56
    
57.
Rodríguez Cruz PM, Vargas A, Fernández-Carballal C, Garbizu J, De La Casa-Fages B, Grandas F. Long-term thalamic deep brain stimulation for essential tremor: Clinical outcome and stimulation parameters. Mov Disord Clin Pract 2016;3:567-72.  Back to cited text no. 57
    
58.
Paschen S, Forstenpointner J, Becktepe J, Heinzel S, Hellriegel H, Witt K, et al. Long-term efficacy of deep brain stimulation for essential tremor: An observer-blinded study. Neurology 2019;92:e1378-86.  Back to cited text no. 58
    
59.
Barbe MT, Liebhart L, Runge M, Pauls KA, Wojtecki L, Schnitzler A, et al. Deep brain stimulation in the nucleus ventralis intermedius in patients with essential tremor: Habituation of tremor suppression. J Neurol 2011;258:434-9.  Back to cited text no. 59
    
60.
Brandmeir NJ, Murray A, Cheyuo C, Ferari C, Rezai AR. Deep brain stimulation for multiple sclerosis tremor: A meta-analysis. Neuromodulation 2020;23:463-8.  Back to cited text no. 60
    
61.
Taha JM, Janszen MA, Favre J. Thalamic deep brain stimulation for the treatment of head, voice, and bilateral limb tremor. J Neurosurg 1999;91:68-72.  Back to cited text no. 61
    
62.
Obwegeser AA, Uitti RJ, Turk MF, Strongosky AJ, Wharen RE. Thalamic stimulation for the treatment of midline tremors in essential tremor patients. Neurology 2000;54:2342-4.  Back to cited text no. 62
    
63.
Artusi CA, Farooqi A, Romagnolo A, Marsili L, Balestrino R, Sokol LL, et al. Deep brain stimulation in uncommon tremor disorders: Indications, targets, and programming. J Neurol 2018;265:2473-93.  Back to cited text no. 63
    
64.
Kupsch A, Benecke R, Müller J, Trottenberg T, Schneider GH, Poewe W, et al. Pallidal deep-brain stimulation in primary generalized or segmental dystonia. N Engl J Med 2006;355:1978-90.  Back to cited text no. 64
    
65.
Volkmann J, Wolters A, Kupsch A, Müller J, Kühn AA, Schneider GH, et al. Pallidal deep brain stimulation in patients with primary generalised or segmental dystonia: 5-year follow-up of a randomised trial. Lancet Neurol 2012;11:1029-38.  Back to cited text no. 65
    
66.
Moro E, LeReun C, Krauss JK, Albanese A, Lin J-P, Autiero SW, et al. Efficacy of pallidal stimulation in isolated dystonia: A systematic review and meta-analysis. Eur J Neurol 2017;24:552-60.  Back to cited text no. 66
    
67.
Elkaim LM, Alotaibi NM, Sigal A, Alotaibi HM, Lipsman N; North American Pediatric DBS Collaboration. Deep brain stimulation for pediatric dystonia: A meta-analysis with individual participant data. Dev Med Child Neurol 2019;61:49-56.  Back to cited text no. 67
    
68.
Panov F, Tagliati M, Ozelius LJ, Fuchs T, Gologorsky Y, Cheung T, et al. Pallidal deep brain stimulation for DYT6 dystonia. J Neurol Neurosurg Psychiatry 2012;83:182-7.  Back to cited text no. 68
    
69.
Panov F, Gologorsky Y, Connors G, Tagliati M, Miravite J, Alterman RL. Deep brain stimulation in DYT1 dystonia: A 10-year experience. Neurosurgery 2013;73:86-93.  Back to cited text no. 69
    
70.
Andrews C, Aviles-Olmos I, Hariz M, Foltynie T. Which patients with dystonia benefit from deep brain stimulation? A metaregression of individual patient outcomes. J Neurol Neurosurg Psychiatry 2010;81:1383-9.  Back to cited text no. 70
    
71.
Isaias IU, Volkmann J, Kupsch A, Burgunder JM, Ostrem JL, Alterman RL, et al. Factors predicting protracted improvement after pallidal DBS for primary dystonia: The role of age and disease duration. J Neurol 2011;258:1469-76.  Back to cited text no. 71
    
72.
Volkmann J, Mueller J, Deuschl G, Kühn AA, Krauss JK, Poewe W, et al. Pallidal neurostimulation in patients with medication-refractory cervical dystonia: A randomised, sham-controlled trial. Lancet Neurol 2014;13:875-84.  Back to cited text no. 72
    
73.
Wang X, Zhang C, Wang Y, Liu C, Zhao B, Zhang JG, et al. Deep brain stimulation for craniocervical dystonia (Meige syndrome): A report of four patients and a literature-based analysis of its treatment effects. Neuromodulation 2016;19:818-23.  Back to cited text no. 73
    
74.
Sobstyl M, Brzuszkiewicz-Kuźmicka G, Zaczyński A, Pasterski T, Aleksandrowicz M, Ząbek M. Long-term clinical outcome of bilateral pallidal stimulation for intractable craniocervical dystonia (Meige syndrome). Report of 6 patients. J Neurol Sci 2017;383:153-7.  Back to cited text no. 74
    
75.
Luthra NS, Mitchell KT, Volz MM, Tamir I, Starr PA, Ostrem JL. Intractable Blepharospasm Treated with Bilateral Pallidal Deep Brain Stimulation. Tremor Other Hyperkinet Mov (N Y) 2017;7:472.  Back to cited text no. 75
    
76.
Fukaya C, Katayama Y, Kano T, Nagaoka T, Kobayashi K, Oshima H, et al. Thalamic deep brain stimulation for writer's cramp. J Neurosurg 2007;107:977-82.  Back to cited text no. 76
    
77.
Rughani AI, Lozano AM. Surgical treatment of myoclonus dystonia syndrome. Mov Disord 2013;28:282-7.  Back to cited text no. 77
    
78.
Gruber D, Südmeyer M, Deuschl G, Falk D, Krauss JK, Mueller J, et al. Neurostimulation in tardive dystonia/dyskinesia: A delayed start, sham stimulation-controlled randomized trial. Brain Stimul 2018;11:1368-77.  Back to cited text no. 78
    
79.
Macerollo A, Deuschl G. Deep brain stimulation for tardive syndromes: Systematic review and meta-analysis. J Neurol Sci 2018;389:55-60.  Back to cited text no. 79
    
80.
Elia AE, Bagella CF, Ferré F, Zorzi G, Calandrella D, Romito LM. Deep brain stimulation for dystonia due to cerebral palsy: A review. Eur J Paediatr Neurol 2018;22:308-15.  Back to cited text no. 80
    
81.
Elias GJB, Namasivayam AA, Lozano AM. Deep brain stimulation for stroke: Current uses and future directions. Brain Stimul 2018;11:3-28.  Back to cited text no. 81
    
82.
Timmermann L, Pauls KAM, Wieland K, Jech R, Kurlemann G, Sharma N, et al. Dystonia in neurodegeneration with brain iron accumulation: Outcome of bilateral pallidal stimulation. Brain 2010;133:701-12.  Back to cited text no. 82
    
83.
Ben-Haim S, Flatow V, Cheung T, Cho C, Tagliati M, Alterman RL. Deep brain stimulation for status dystonicus: A case series and review of the literature. Stereotact Funct Neurosurg 2016;94:207-15.  Back to cited text no. 83
    
84.
Lobato-Polo J, Ospina-Delgado D, Orrego-González E, Gómez-Castro JF, Orozco JL, Enriquez-Marulanda A. Deep brain stimulation surgery for status dystonicus: A single-center experience and literature review. World Neurosurg 2018;114:e992-1001.  Back to cited text no. 84
    
85.
de Gusmao CM, Pollak LE, Sharma N. Neuropsychological and psychiatric outcome of GPi-deep brain stimulation in dystonia. Brain Stimul 2017;10:994-6.  Back to cited text no. 85
    
86.
Eggink H, Szlufik S, Coenen MA, van Egmond ME, Moro E, Tijssen MAJ. Non-motor effects of deep brain stimulation in dystonia: A systematic review. Parkinsonism Relat Disord 2018;55:26-44.  Back to cited text no. 86
    
87.
Fenoy AJ, Simpson RK Jr. Risks of common complications in deep brain stimulation surgery: Management and avoidance. J Neurosurg 2014;120:132-9.  Back to cited text no. 87
    
88.
Voges J, Hilker R, Bötzel K, Kiening KL, Kloss M, Kupsch A, et al. Thirty days complication rate following surgery performed for deep-brain-stimulation. Mov Disord 2007;22:1486-9.  Back to cited text no. 88
    
89.
Blomstedt P, Hariz MI. Hardware-related complications of deep brain stimulation: A ten year experience. Acta Neurochir (Wien) 2005;147:1061-4.  Back to cited text no. 89
    
90.
Baizabal Carvallo JF, Simpson R, Jankovic J. Diagnosis and treatment of complications related to deep brain stimulation hardware. Mov Disord 2011;26:1398-406.  Back to cited text no. 90
    
91.
Kumar R, Lozano AM, Sime E, Lang AE. Long-term follow-up of thalamic deep brain stimulation for essential and parkinsonian tremor. Neurology 2003;61:1601-4.  Back to cited text no. 91
    
92.
Ortiz RM, Scheperjans F, Pekkonen E. Deep brain stimulation for dystonia in Finland during 2007-2016. BMC Neurol 2019;19:137.  Back to cited text no. 92
    
93.
Sillay KA, Larson PS, Starr PA. Deep brain stimulator hardware-related infections: Incidence and management in a large series. Neurosurgery 2008;62:360-7.  Back to cited text no. 93
    
94.
Lemaire JJ, Sakka L, Ouchchane L, Caire F, Gabrillargues J, Bonny JM. Anatomy of the human thalamus based on spontaneous contrast and microscopic voxels in high-field magnetic resonance imaging. Neurosurgery 2010;66 (3 Suppl Operative):161-72.  Back to cited text no. 94
    
95.
Ranjan M, Elias GJB, Boutet A, Zhong J, Chu P, Germann J, et al. Tractography-based targeting of the ventral intermediate nucleus: Accuracy and clinical utility in MRgFUS thalamotomy. J Neurosurg 2019;1-8. doi: 10.3171/2019.6.JNS19612. Online ahead of print.  Back to cited text no. 95
    
96.
Schuurman PR, Bosch DA, Bossuyt PM, Bonsel GJ, van Someren EJ, de Bie RM, et al. A comparison of continuous thalamic stimulation and thalamotomy for suppression of severe tremor. N Engl J Med 2000;342:461-8.  Back to cited text no. 96
    
97.
Schuurman PR, Bosch DA, Merkus MP, Speelman JD. Long-term follow-up of thalamic stimulation versus thalamotomy for tremor suppression. Mov Disord 2008;23:1146-53.  Back to cited text no. 97
    
98.
Nagaseki Y, Shibazaki T, Hirai T, Kawashima Y, Hirato M, Wada H, et al. Long-term follow-up results of selective VIM-thalamotomy. J Neurosurg 1986;65:296-302.  Back to cited text no. 98
    
99.
Jankovic J, Cardoso F, Grossman RG, Hamilton WJ. Outcome after stereotactic thalamotomy for parkinsonian, essential, and other types of tremor. Neurosurgery 1995;37:680-7.  Back to cited text no. 99
    
100.
Levi V, Zorzi G, Messina G, Romito L, Tramacere I, Dones I, et al. Deep brain stimulation versus pallidotomy for status dystonicus: A single-center case series. J Neurosurg 2019;1-11. doi: 10.3171/2019.10.JNS191691. Online ahead of print.  Back to cited text no. 100
    
101.
Marras CE, Rizzi M, Cantonetti L, Rebessi E, Benedictis AD, Portaluri F, et al. Pallidotomy for medically refractory status dystonicus in childhood. Dev Med Child Neurol 2014;56:649-56.  Back to cited text no. 101
    
102.
Blomstedt P, Hariz GM, Hariz MI. Pallidotomy versus pallidal stimulation. Parkinsonism Relat Disord 2006;12:296-301.  Back to cited text no. 102
    
103.
Ohye C, Higuchi Y, Shibazaki T, Hashimoto T, Koyama T, Hirai T, et al. Gamma knife thalamotomy for Parkinson disease and essential tremor: A prospective multicenter study. Neurosurgery 2012;70:526-36.  Back to cited text no. 103
    
104.
Witjas T, Carron R, Krack P, Eusebio A, Vaugoyeau M, Hariz M, et al. A prospective single-blind study of Gamma Knife thalamotomy for tremor. Neurology 2015;85:1562-8.  Back to cited text no. 104
    
105.
Tripathi M, Sharan S, Mehta S, Deora H, Yagnick NS, Kumar N, et al. Gamma knife radiosurgical pallidotomy for dystonia: Not a fallen angel. Neurol India 2019;67:1515-8.  Back to cited text no. 105
[PUBMED]  [Full text]  
106.
Higuchi Y, Matsuda S, Serizawa T. Gamma knife radiosurgery in movement disorders: Indications and limitations. Mov Disord 2017;32:28-35.  Back to cited text no. 106
    
107.
Harary M, Segar DJ, Huang KT, Tafel IJ, Valdes PA, Cosgrove GR. Focused ultrasound in neurosurgery: A historical perspective. Neurosurg Focus 2018;44:E2.  Back to cited text no. 107
    
108.
Elias WJ, Lipsman N, Ondo WG, Ghanouni P, Kim YG, Lee W, et al. A randomized trial of focused ultrasound thalamotomy for essential tremor. N Engl J Med 2016;375:730-9.  Back to cited text no. 108
    
109.
Schreglmann SR, Krauss JK, Chang JW, Bhatia KP, Kägi G. Functional lesional neurosurgery for tremor: A systematic review and meta-analysis. J Neurol Neurosurg Psychiatry 2018;89:717-26.  Back to cited text no. 109
    
110.
Kim M, Jung NY, Park CK, Chang WS, Jung HH, Chang JW. Comparative evaluation of magnetic resonance-guided focused ultrasound surgery for essential tremor. Stereotact Funct Neurosurg 2017;95:279-86.  Back to cited text no. 110
    
111.
Harary M, Segar DJ, Hayes MT, Cosgrove GR. Unilateral thalamic deep brain stimulation versus focused ultrasound thalamotomy for essential tremor. World Neurosurg 2019;126:e144-52.  Back to cited text no. 111
    
112.
Wharen RE Jr, Okun MS, Guthrie BL, Uitti RJ, Larson P, Foote K, et al. Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial. Parkinsonism Relat Disord 2017;40:18-26.  Back to cited text no. 112
    
113.
Louis ED, Agnew A, Gillman A, Gerbin M, Viner AS. Estimating annual rate of decline: Prospective, longitudinal data on arm tremor severity in two groups of essential tremor cases. J Neurol Neurosurg Psychiatry 2011;82:761-5.  Back to cited text no. 113
    
114.
Lee DJ, Lozano CS, Dallapiazza RF, Lozano AM. Current and future directions of deep brain stimulation for neurological and psychiatric disorders. J Neurosurg 2019;131:333-42.  Back to cited text no. 114
    
115.
Piña-Fuentes D, Beudel M, Little S, van Zijl J, Elting JW, Oterdoom DLM, et al. Toward adaptive deep brain stimulation for dystonia. Neurosurg Focus 2018;45:E3.  Back to cited text no. 115
    
116.
Steigerwald F, Matthies C, Volkmann J. Directional deep brain stimulation. Neurotherapeutics 2019;16:100-4.  Back to cited text no. 116
    
117.
Middlebrooks EH, Domingo RA, Vivas-Buitrago T, Okromelidze L, Tsuboi T, Wong JK, et al. Neuroimaging advances in deep brain stimulation: Review of indications, anatomy, and brain connectomics. AJNR Am J Neuroradiol 2020;41:1558-68.  Back to cited text no. 117
    
118.
Krack P, Volkmann J, Tinkhauser G, Deuschl G. Deep brain stimulation in movement disorders: From experimental surgery to evidence-based therapy. Mov Disord 2019;34:1795-810.  Back to cited text no. 118
    
119.
Reich MM, Horn A, Lange F, Roothans J, Paschen S, Runge J, et al. Probabilistic mapping of the antidystonic effect of pallidal neurostimulation: A multicentre imaging study. Brain 2019;142:1386-98.  Back to cited text no. 119
    


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