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Quantitative methods for evaluating the efficacy of thalamic deep brain stimulation in patients with essential tremor.

Wastensson G, Holmberg B, Johnels B, Barregard L - Tremor Other Hyperkinet Mov (N Y) (2013)

Bottom Line: Our aim was to examine the possible use of certain quantitative methods for evaluating the efficacy of thalamic DBS in ET patients in clinical practice, and to compare these methods with traditional clinical tests.The agreement between kinetic tremor as assessed by the ETRS and the main outcome variable from the EKM test was low (rs = 0.34).The lack of agreement indicates that the EKM test is not comparable with the clinical test.

View Article: PubMed Central - PubMed

Affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden.

ABSTRACT

Background: Deep brain stimulation (DBS) of the thalamus is a safe and efficient method for treatment of disabling tremor in patient with essential tremor (ET). However, successful tremor suppression after surgery requires careful selection of stimulus parameters. Our aim was to examine the possible use of certain quantitative methods for evaluating the efficacy of thalamic DBS in ET patients in clinical practice, and to compare these methods with traditional clinical tests.

Methods: We examined 22 patients using the Essential Tremor Rating Scale (ETRS) and quantitative assessment of tremor with the stimulator both activated and deactivated. We used an accelerometer (CATSYS tremor Pen) for quantitative measurement of postural tremor, and a eurythmokinesimeter (EKM) to evaluate kinetic tremor in a rapid pointing task.

Results: The efficacy of DBS on tremor suppression was prominent irrespective of the method used. The agreement between clinical rating of postural tremor and tremor intensity as measured by the CATSYS tremor pen was relatively high (rs = 0.74). The agreement between kinetic tremor as assessed by the ETRS and the main outcome variable from the EKM test was low (rs = 0.34). The lack of agreement indicates that the EKM test is not comparable with the clinical test.

Discussion: Quantitative methods, such as the CATSYS tremor pen, could be a useful complement to clinical tremor assessment in evaluating the efficacy of DBS in clinical practice. Future studies should evaluate the precision of these methods and long-term impact on tremor suppression, activities of daily living (ADL) function and quality of life.

No MeSH data available.


Related in: MedlinePlus

A. The CATSYS tremor pen B. The eurythmokinesimeter.Tremor intensity measured by the CATSYS tremor pen, and Fitts' Law constant measured by a eurythmokinesimeter in the dominant hand, in 22 patents with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.
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f03: A. The CATSYS tremor pen B. The eurythmokinesimeter.Tremor intensity measured by the CATSYS tremor pen, and Fitts' Law constant measured by a eurythmokinesimeter in the dominant hand, in 22 patents with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.

Mentions: Tremor intensity was significantly lower when the stimulator was activated (Table 3). The tremor registrations from one of the ET patients are shown in Figure 2. The median ratio of tremor intensity in the “on” vs. “off” condition (n = 22) was 0.11 (Wilcoxon signed ranked test, p<0.0001). Nearly all (20/22) patients showed improvement (lower intensity) when the stimulator was activated; the remaining two patients showed higher tremor intensity (Figure 3A). The frequency dispersion was significantly higher and the harmonic index was significantly lower in the “on” condition. However, no significant change was seen in center frequency between conditions (Table 3).


Quantitative methods for evaluating the efficacy of thalamic deep brain stimulation in patients with essential tremor.

Wastensson G, Holmberg B, Johnels B, Barregard L - Tremor Other Hyperkinet Mov (N Y) (2013)

A. The CATSYS tremor pen B. The eurythmokinesimeter.Tremor intensity measured by the CATSYS tremor pen, and Fitts' Law constant measured by a eurythmokinesimeter in the dominant hand, in 22 patents with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822146&req=5

f03: A. The CATSYS tremor pen B. The eurythmokinesimeter.Tremor intensity measured by the CATSYS tremor pen, and Fitts' Law constant measured by a eurythmokinesimeter in the dominant hand, in 22 patents with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.
Mentions: Tremor intensity was significantly lower when the stimulator was activated (Table 3). The tremor registrations from one of the ET patients are shown in Figure 2. The median ratio of tremor intensity in the “on” vs. “off” condition (n = 22) was 0.11 (Wilcoxon signed ranked test, p<0.0001). Nearly all (20/22) patients showed improvement (lower intensity) when the stimulator was activated; the remaining two patients showed higher tremor intensity (Figure 3A). The frequency dispersion was significantly higher and the harmonic index was significantly lower in the “on” condition. However, no significant change was seen in center frequency between conditions (Table 3).

Bottom Line: Our aim was to examine the possible use of certain quantitative methods for evaluating the efficacy of thalamic DBS in ET patients in clinical practice, and to compare these methods with traditional clinical tests.The agreement between kinetic tremor as assessed by the ETRS and the main outcome variable from the EKM test was low (rs = 0.34).The lack of agreement indicates that the EKM test is not comparable with the clinical test.

View Article: PubMed Central - PubMed

Affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden.

ABSTRACT

Background: Deep brain stimulation (DBS) of the thalamus is a safe and efficient method for treatment of disabling tremor in patient with essential tremor (ET). However, successful tremor suppression after surgery requires careful selection of stimulus parameters. Our aim was to examine the possible use of certain quantitative methods for evaluating the efficacy of thalamic DBS in ET patients in clinical practice, and to compare these methods with traditional clinical tests.

Methods: We examined 22 patients using the Essential Tremor Rating Scale (ETRS) and quantitative assessment of tremor with the stimulator both activated and deactivated. We used an accelerometer (CATSYS tremor Pen) for quantitative measurement of postural tremor, and a eurythmokinesimeter (EKM) to evaluate kinetic tremor in a rapid pointing task.

Results: The efficacy of DBS on tremor suppression was prominent irrespective of the method used. The agreement between clinical rating of postural tremor and tremor intensity as measured by the CATSYS tremor pen was relatively high (rs = 0.74). The agreement between kinetic tremor as assessed by the ETRS and the main outcome variable from the EKM test was low (rs = 0.34). The lack of agreement indicates that the EKM test is not comparable with the clinical test.

Discussion: Quantitative methods, such as the CATSYS tremor pen, could be a useful complement to clinical tremor assessment in evaluating the efficacy of DBS in clinical practice. Future studies should evaluate the precision of these methods and long-term impact on tremor suppression, activities of daily living (ADL) function and quality of life.

No MeSH data available.


Related in: MedlinePlus