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Effects of deep brain stimulation in the caudal Zona incerta on verbal fluency
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
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2013 (English)In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 91, no 1, 24-29 p.Article in journal (Refereed) Published
Abstract [en]

Background: Deep brain stimulation (DBS) of the caudal zona incerta (cZi) is a relatively unexplored and promising treatment in patients with severe essential tremor (ET). Preliminary data further indicate that the ability to produce language may be slightly affected by the treatment.

Objective: To evaluate the effects on verbal fluency following cZi DBS in patients with ET.

Method: Seventeen consecutive patients who had undergone DBS of the cZi for ET were tested regarding verbal fluency before surgery, 3 days after surgery and after 1 year. Ten patients were also evaluated by comparing performance on versus off stimulation after 1 year.

Results: The total verbal fluency score decreased slightly, but significantly, from 22.7 (SD = 10.9) before surgery to 18.1 (SD = 7.5) 3 days after surgery (p = 0.036). After 1 year the score was nonsignificantly decreased to 20.1 (SD = 9.7, p = 0.2678). There was no detectable difference between stimulation on and off after 1 year.

Conclusion: There was a tendency of an immediate and mostly transient postoperative decline in verbal fluency following cZi DBS for ET. In some of the patients this reduction was, however, more pronounced and also sustained over time.

Place, publisher, year, edition, pages
S. Karger, 2013. Vol. 91, no 1, 24-29 p.
Keyword [en]
Deep brain stimulation, Verbal fluency, Essential tremor, Zona incerta, Posterior subthalamic area
National Category
URN: urn:nbn:se:umu:diva-51870DOI: 10.1159/000342497OAI: diva2:489593

Originally included in thesis in manuscript form

Available from: 2012-02-03 Created: 2012-02-03 Last updated: 2013-03-15Bibliographically approved
In thesis
1. Deep brain stimulation of the posterior subthalamic area in the treatment of movement disorders
Open this publication in new window or tab >>Deep brain stimulation of the posterior subthalamic area in the treatment of movement disorders
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: The posterior subthalamic area (PSA) is essentially composed of the caudal Zona incerta and the prelemniscal radiation. Subthalamotomy in the PSA was renowned for its effectiveness in alleviating movement disorders and particularly tremor. The modern literature on DBS of this area is limited, but promising results have been presented for Parkinson’s disease (PD), essential tremor (ET) and other movement disorders.  

Aim: To evaluate the safety of PSA DBS with emphasis on the panorama of side effects, the distribution of stimulation-induced side effects and the effects of PSA DBS on verbal fluency. To evaluate the therapeutic effect of PSA DBS on less common forms of tremor, tremor-dominant PD, and concerning the long-term results in ET.

Method: 40 patients were evaluated regarding side effects of the procedure. 28 patients with ET were analyzed for stimulation-induced side effects in a standardized manner. The locations of the contacts that caused stimulation-induced side effects were plotted on atlas slides. A 3-D model of the area was created based on these slides. Verbal fluency was analyzed in 17 patients with ET before surgery, after 3 days and finally after 1 year. Five patients with less common forms of tremor and 18 with ET were evaluated according to the ETRS at baseline and one year or 3-5 years after surgery, respectively. 14 patients with mainly unilateral tremor-dominant PD were evaluated a mean of 18 months after surgery according to the motor part of UPDRS.

Results: PSA DBS was associated with few serious side-effects, but a transient and mild postoperative dysphasia was found in 22.5% of the patients. There was a slight transient decline in the performance on verbal fluency tests immediately after surgery. Visualization of the contacts causing stimulation-induced side effects showed that identical responses can be elicited from various points in the PSA and its vicinity. The effect on the less common forms of tremor was excellent except for neuropathic tremor where the effect was moderate. A pronounced and sustained microlesional effect was seen for some of the patients. After a mean of 4 years with unilateral PSA DBS the total ETRS score was improved by 52.4%, tremor by 91.8% and hand function by 78.0% in the patients with ET. There was no increase in the stimulation strength over time. In PD, the scores improved 47.7% for contralateral UPDRS III. Contralateral tremor, rigidity, and bradykinesia improved by 82.2%, 34.3%, and 26.7%, respectively.

Conclusions: PSA DBS generally seem to be a safe procedure, but it may be associated with transient declines of verbal fluency. There was no clear somatotopic pattern with regard to stimulation-induced side effects in the PSA. PSA DBS can alleviate tremor regardless of the etiology. The long-term effects in ET were favorable when compared to our previous results of Vim DBS. The effect on Parkinsonian tremor was satisfying, however, the reductions of rigidity and bradykinesia were less compared to previous studies of PSA DBS for PD.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2012. 64 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1464
Deep brain stimulation, Movement disorders, Posterior subthalamic area, Zona incerta, Prelemniscal radiations, Tremor, Essential tremor, Parkinson's disease
National Category
Research subject
urn:nbn:se:umu:diva-51785 (URN)978-91-7459-328-0 (ISBN)
Public defence
2012-02-24, Sal E04, byggnad 6E, Norrlands Universitetssjukhus, Umeå, Umeå, 13:00 (English)
Available from: 2012-02-03 Created: 2012-02-01 Last updated: 2012-06-04Bibliographically approved

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