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Stereotactic functional procedures in the treatment of essential tremor
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
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 Lesional surgery has largely been replaced by deep brain stimulation (DBS).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.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1448
Keyword [en]
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
Neurosurgery
Identifiers
URN: urn:nbn:se:umu:diva-49178ISBN: 978-91-7459-296-2 (print)OAI: oai:DiVA.org:umu-49178DiVA: diva2:453973
Public defence
2011-12-02, Hörsal Betula, Byggnad 6M, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2011-11-11 Created: 2011-11-01 Last updated: 2011-11-11Bibliographically approved
List of papers
1. Thalamotomy for essential tremor: a very long-term follow-up
Open this publication in new window or tab >>Thalamotomy for essential tremor: a very long-term follow-up
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: DBS (deep brain stimulation) is currently the golden standard in the surgical treatment of ET (essential tremor). Despite the benefits of DBS, there remain situations where lesional surgery may provide an alternative.

Objective: To perform a very long-term retrospective evaluation of thalamotomies for ET.

Methods: Nine patients who underwent thalamotomy for ET during 1972–1999 (follow-up period 20.8 ± 5.2 years) were assessed with regard to tremor scores, side effects, and quality of life, as well as lesion size and location.

Results: All patients had tremor recurrence, although hand function remained slightly better on the treated side than on the non-treated side. Side effects that could be attributed to the procedure were frequent and did in some cases result in a disability for the patient. Quality of life was poorer in this group than in an age-adjusted healthy population. No correlation between lesion size, location, and long-term outcome could be established.

Conclusions: In this study population the benefits of thalamotomies were limited, while complications were frequent.

Keyword
Essential tremor, thalamotomy, follow-up, thalamus, Vim
National Category
Neurology
Research subject
Neurosurgery
Identifiers
urn:nbn:se:umu:diva-49175 (URN)
Available from: 2011-11-02 Created: 2011-11-01 Last updated: 2011-11-11Bibliographically approved
2. Thalamic and subthalamic DBS for essential tremor: where is the optimal target?
Open this publication in new window or tab >>Thalamic and subthalamic DBS for essential tremor: where is the optimal target?
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
Keyword
Essential tremor, Deep Brain Stimulation, Posterior Subthalamic Area, Zona incerta, Vim
National Category
Neurology Surgery Neurosciences
Research subject
Neurosurgery
Identifiers
urn:nbn:se:umu:diva-49183 (URN)10.1227/NEU.0b013e318236a809 (DOI)000301934000035 ()
External cooperation:
Available from: 2011-11-02 Created: 2011-11-02 Last updated: 2017-12-08Bibliographically approved
3. Deep brain stimulation in the posterior subthalamic area in the treatment of essential tremor
Open this publication in new window or tab >>Deep brain stimulation in the posterior subthalamic area in the treatment of essential tremor
2010 (English)In: Movement Disorders, ISSN 0885-3185, E-ISSN 1531-8257, Vol. 25, no 10, 1350-1356 p.Article in journal (Refereed) Published
Abstract [en]

To evaluate the posterior subthalamic area (PSA) as a target for deep brain stimulation (DBS) in the treatment of essential tremor (ET). The ventral intermediate nucleus of the thalamus is the traditional target for DBS in the treatment of ET. Recent studies have presented beneficial effects of DBS in the PSA in the treatment of tremor. Twenty-one patients with ET were included in this study. All patients were evaluated before and 1 year after surgery, on and off stimulation, using the essential tremor rating scale (ETRS). A marked microlesional effect was noticed in 83%, in some cases obviating the need for electrical stimulation for many months. The total ETRS was reduced from 46.2 at baseline to 18.7 (60%). Item 5/6 (tremor of the upper extremity) was improved from 6.2 to 0.3 (95%), and items 11 to 14 (hand function) from 9.7 to 1.3 (87%) concerning the contralateral hand. Activities of daily living were improved by 66%. No severe complication occurred. Eight patients presented a postoperative mild dysphasia that regressed within days to weeks. DBS in the PSA resulted in a marked reduction of tremor.

Place, publisher, year, edition, pages
Wiley, 2010
Keyword
DBS, posterior subthalamic area, zona incerta, prelemniscal radiation, essential tremor
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-35530 (URN)10.1002/mds.22758 (DOI)20544817 (PubMedID)
Available from: 2010-08-23 Created: 2010-08-23 Last updated: 2017-12-12Bibliographically approved
4. Influence of age, gender and severity of tremor on outcome after thalamic and subthalamic DBS for essential tremor
Open this publication in new window or tab >>Influence of age, gender and severity of tremor on outcome after thalamic and subthalamic DBS for essential tremor
Show others...
2011 (English)In: Parkinsonism & Related Disorders, ISSN 1353-8020, E-ISSN 1873-5126, Vol. 17, no 8, 617-620 p.Article in journal (Refereed) Published
Abstract [en]

Deep brain stimulation (DBS) is an established treatment for essential tremor (ET). The nucleus ventralis intermedius thalami (Vim) is the target of choice, but promising results have been presented regarding DBS in the posterior subthalamic area (PSA). The aim of this study was to evaluate the possible influence of gender, age and severity of disease on the outcome of these procedures. Sixty eight patients (34 Vim, 34 PSA) with ET were included in this non-randomised study. Evaluation using the Essential Tremor Rating Scale (ETRS) was performed before, and one year after surgery concerning PSA DBS, and at a mean of 28 ± 24 months concerning Vim DBS. Items 5/6 and 11-14 (hand tremor and hand function) were selected for analysis of tremor outcome. The efficacy of DBS on essential tremor was not related to age or gender. Nor was it associated with the severity of tremor when the percentual reduction of tremor on stimulation was taken into account. However, patients with a more severe tremor at baseline had a higher degree of residual tremor on stimulation. Tremor in the treated hand and hand function were improved with 70% in the Vim group and 89% in the PSA group.

Keyword
DBS, Deep Brain Stimulation, Essential Tremor
National Category
Neurology
Research subject
Neurosurgery
Identifiers
urn:nbn:se:umu:diva-46491 (URN)10.1016/j.parkreldis.2011.05.014 (DOI)
Available from: 2011-09-03 Created: 2011-09-03 Last updated: 2017-12-08Bibliographically approved
5. Quality of life following DBS in the caudal zona incerta in patients with essential tremor
Open this publication in new window or tab >>Quality of life following DBS in the caudal zona incerta in patients with essential tremor
2012 (English)In: Acta Neurochirurgica, ISSN 0001-6268, E-ISSN 0942-0940, Vol. 154, no 3, 495-499 p.Article in journal (Refereed) Published
Abstract [en]

Background: Essential tremor (ET) is the most common movement disorder and oftenaffects the quality of life. There are only a few studies evaluating the quality of life after deepbrain stimulation (DBS).

Findings: This is a prospective study of 16 patients undergoing deep brain stimulation in thecaudal Zona incerta (cZi). The quality of life was assessed with Quality of Life in EssentialTremor Questionnaire (QUEST) and SF-36 scores and the tremor was evaluated using theessential tremor rating scale (ETRS).

Results: In the tremor rating hand tremor on the treated side improved by 95%, hand functionby 78% and activities of daily living improved by 74%. The QUEST score showedstatistically significant improvements in the psychosocial and activities of daily livingsubscores. The SF-36 score did not show any significant improvement.

Conclusions: Although very good tremor reduction was achieved, the improvement in thequality of life scores was more modest. This could partly be explained by the quality of lifebeing affected by other factors than the tremor itself.

Place, publisher, year, edition, pages
Wien: Springer, 2012
Keyword
Quality of Life, Essential tremor, Zona incerta, Deep Brain Stimulation
National Category
Neurology
Research subject
Neurosurgery
Identifiers
urn:nbn:se:umu:diva-49176 (URN)10.1007/s00701-011-1230-z (DOI)
Available from: 2011-11-02 Created: 2011-11-01 Last updated: 2017-12-08Bibliographically approved

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