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Thalamic and subthalamic DBS for essential tremor: where is the optimal target?
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
Umeå University, Faculty of Social Sciences, Department of Statistics.ORCID iD: 0000-0003-1524-0851
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
2012 (English)In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 70, no 4, 840-846 p.Article in journal (Refereed) Published
Abstract [en]

Background: The ventrolateral thalamus (Vim, ventral intermediate nucleus) is the traditional target for neurosurgical treatment of essential tremor (ET). The target has, however, varied substantially among different neurosurgeons.

Objective: To evaluate the effect of deep brain stimulation (DBS) in the thalamus and posterior subthalamic area (PSA) in relation to electrode location.

Methods: 36 (17Vim / 19 PSA) patients, with 44 DBS electrodes, were included in this retrospective study. The effect of stimulation was evaluated with standardized settings for each contact using items from the essential tremor rating scale (ETRS).

Results: When each contact was evaluated regarding the treated hand with standardized stimulation, the electrode contact providing the best effect in the individual patient was in 54% located in the zona incerta (Zi) or radiation prelemniscalis (raprl) and in 12 % the Vim. 40 contacts provided a tremor reduction of >90%. Of these, 43% were located in the PSA and 18% in the Vim according to the Schaltenbrandt atlas. 37 of these 40 contacts were found in the PSA group.

Conclusion: More contacts yielding an optimal effect were found in the PSA group than in the Vim. Many patients operated upon in the Vim got the best effect in a contact located in the PSA. This might suggest that the PSA is a more efficient target than the Vim.

Place, publisher, year, edition, pages
Philadelphia: Lippincott, Williams & Wilkins/Congress of Neurological Surgeons , 2012. Vol. 70, no 4, 840-846 p.
Keyword [en]
Essential tremor, Deep Brain Stimulation, Posterior Subthalamic Area, Zona incerta, Vim
National Category
Neurology Surgery Neurosciences
Research subject
URN: urn:nbn:se:umu:diva-49183DOI: 10.1227/NEU.0b013e318236a809ISI: 000301934000035OAI: diva2:453363
Available from: 2011-11-02 Created: 2011-11-02 Last updated: 2016-09-12Bibliographically approved
In thesis
1. Stereotactic functional procedures in the treatment of essential tremor
Open this publication in new window or tab >>Stereotactic functional procedures in the treatment of essential tremor
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Essential tremor (ET) is the most common movement disorder. In cases resistant to pharmacological treatment, functional stereotactic neurosurgery can be an alternative. Lesional surgery has largely been replaced by deep brain stimulation (DBS). The current target of choice is the ventrolateral thalamus (Vim). Vim DBS has generally shown good results, but in some cases it is associated with a suboptimal effect as well as side effects. DBS in the posterior subthalamic area/caudal zona incerta (PSA/cZi) has recently shown promising effects. Recently the role of lesional therapy in selected cases has been discussed.

Aim: The aim is to evaluate stereotactic functional procedures in the treatment of ET, with special emphasis on PSA DBS. Further the effects of DBS in the PSA are evaluated. The optimal target is also assessed by evaluating the effect of Vim and PSA DBS in relation to the position of the electrode. An attempt to identify patient-specific factors of prognostic importance for the outcome after DBS will be made. The quality of life (QoL) of patients treated with PSA DBS for ET will be assessed. Finally, the aim is also to analyze retrospectively the long-term outcome of lesional procedures (thalamotomies).

Method: The thesis consists of five studies. The optimal electrode location is evaluated in a study analyzing the location of the electrode contact yielding the best effect in Vim DBS and PSA DBS groups. The efficacy of PSA DBS in 21 patients is evaluated in a prospective study. The correlation between outcome, age, tremor grade and gender is established in a prospective study consisting of 68 patients. Finally, the degree of improvement in QoL is determined in 16 patients operated on in the PSA. The very long-term effect of lesional surgery has been investigated in a retrospective study of nine patients who have undergone thalamotomy.

Results: In the study of PSA DBS the total score on the Essential Tremor Rating Scale (ETRS) was reduced by 60% compared to the baseline value. Tremor of the arm was improved by 95%. The study evaluating the optimal contact location showed that the best effect was in the PSA in 54% and in the Vim in 12%. The efficacy of DBS was not related to age, gender, or the severity of tremor with regard to the percentage reduction of tremor on stimulation. In patients with a more severe tremor at baseline, a higher degree of residual tremor on stimulation was seen. With regard to QoL, the activities of daily living (ADL) according to the ETRS score were significantly improved, as well as according to the ADL and psychosocial subscores on the Questionnaire for Essential Tremor (QUEST) scale. No significant changes were found on the generic Short Form (SF-36) QoL scale. Thalamotomy had some positive effects, but also a significant amount of side effects that might be attributed to the surgery.

Conclusions: The effect of PSA DBS was very satisfying and compares well with the results from Vim DBS. When both Vim and PSA DBS are considered, the optimal target seems to be located in the PSA. PSA DBS shows good results in improving ADL, but the results have been difficult to demonstrate on QoL scales. The efficacy of DBS could not be shown to be associated with gender or age. Nor was it associated with the severity of tremor regarding the percentage of tremor reduction on stimulation. The preoperative severity of tremor was the most important factor regarding outcome following DBS. With regard to thalamotomies, some possible remaining benefit of the surgery could be seen along with some severe side effects.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2011. 64 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1448
Essential Tremor, Stereotactic Functional Neurosurgery, Deep Brain Stimulation, Posterior Subthalamic Area, Thalamotomy, Zona incerta, caudal Zona incerta, Quality of Life, Vim
National Category
Clinical Medicine
Research subject
urn:nbn:se:umu:diva-49178 (URN)978-91-7459-296-2 (ISBN)
Public defence
2011-12-02, Hörsal Betula, Byggnad 6M, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Available from: 2011-11-11 Created: 2011-11-01 Last updated: 2011-11-11Bibliographically approved

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Sandvik, UlrikaKoskinen, Lars-OweLundquist, AndersBlomstedt, Patric
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