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CATEGORY:
Research

TITLE:
IMPAIRED INTEGRITY OF COMMISSURAL AND ASSOCIATION FIBERS IN ESSENTIAL TREMOR PATIENTS: EVIDENCE FROM A DIFFUSION TENSOR IMAGING STUDY

DATE:
6 Oct 2020

LINK:
https://pubmed.ncbi.nlm.nih.gov/33021759/?utm_source=Other&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1JUQiFFHYgOoKyzCJtWtxqPbnrPioDoUd2d_45rWsWUURe5w1u&fc=20201004183707&ff=20201006183347&v=2.12.3

DESCRIPTION:
CONCLUSIONS: In our study, major white matter structures changes were found in ET patients. The result suggest that possible neurodegeneration also affects white matter structures in ET patients and duration of tremor and family history are related with impaired integrity of white matter.

CONTENT:
Turk J Med Sci. 2020 Oct 6. doi: 10.3906/sag-2004-305. Online ahead of print.

ABSTRACT

BACKGROUND/AIM: Evolving definition of essential tremor (ET) introduced us a new concept of neurodegenerative disease pointing to diffuse brain network involvement with a wide spectrum of associated motor and non-motor symptoms. Considering the fact that the white matter should also be affected by the nature of the disease, our study aimed to evaluate integrity of white matter and its clinical correlations in ET patients.

MATERIALS AND METHODS: 40 patients diagnosed with ET and 40 age-and gender-matched control subjects (ranged between 18-80 years old) were included in the study. Sociodemographic characteristics and clinical features of the patients were recorded. Tremor was assessed using ?Fahn-Tolosa-Marin Tremor Rating Scale? (FTM-TRS). Diffusion Tensor Imaging (DTI) was performed to evaluate the integrity of white matter. The selected white matter regions used for DTI assessment were corpus callosum (CC) (i.e., largest commissural tract in human brain), superior longitudinal fasciculus (SLF), and inferior longitudinal fasciculus (ILF) (i.e., largest association fiber bundles).

RESULTS: The mean age of ET patients and control subjects were 44.23 ± 18.91 and 37.45 ± 10.95 years (p = 0.542). The fractional anisotropy (FA) values of the CC body (p = 0.003) and ILF (p = 0.016) and the average diffusion coefficient (ADC) values of the CC body (p = 0.001) and genu (p = 0.049), SLF (p < 0.001), and ILF (p < 0.001) were differed between groups. After controlling for age and gender, there was no correlation between tremor severity and DTI parameters, but impaired integrity in genu of CC FA (p = 0.035, r = 0.442) and splenium of CC ADC (p = 0.007, r = 0.543) were related with longer duration of tremor. Finally, positive family history was correlated with splenium of CC FA and ADC (p = 0.008, r = 0.536; p = 0.027, r = -0.461) and ILF ADC (p = 0.011, r = -0.519). CONCLUSIONS: In our study, major white matter structures changes were found in ET patients. The result suggest that possible neurodegeneration also affects white matter structures in ET patients and duration of tremor and family history are related with impaired integrity of white matter. PMID:33021759 | DOI:10.3906/sag-2004-305 SOURCE: Turkish journal of medical sciences IDENTIFIER: pmid:33021759,doi:10.3906/sag-2004-305 PUBMED: pubmed:33021759 DOI: 10.3906/sag-2004-305 DATE - PUBLISHED: 2020 Oct 6 DATE - ADDED: Tue, 06 Oct 2020 06:00:00 -0400 2020-10-06 DATE - FOUND: 10/06/20 06:33PM LINK - PUBMED: https://pubmed.ncbi.nlm.nih.gov/33021759/ LINK - DOI: https://doi.org/10.3906/sag-2004-305 LINK - PUBLISHER: https://online-journals.tubitak.gov.tr/openAcceptedDocument.htm?fileID=1368926&no=296133 COMMENTS: Related to usability. Destination URL is to a PDF that downloads without prompt. This is an undesired usability practice and links to PDFs should at least be labelled accordingly. All caps title is also undesired. This surprise PDF link is being replaced with PubMed link. Title modified manually, alternative title presented.

CATEGORY:
Research

TITLE:
Distribution of tremor among the major degrees of freedom of the upper limb in subjects with Essential Tremor

DATE:
2 Sep 2020

LINK:
https://pubmed.ncbi.nlm.nih.gov/33010725/?utm_source=Other&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1JUQiFFHYgOoKyzCJtWtxqPbnrPioDoUd2d_45rWsWUURe5w1u&fc=20201004183707&ff=20201004183742&v=2.12.3

DESCRIPTION:
CONCLUSIONS: This paper presents a thorough characterization of tremor distribution from the shoulder to the wrist.

CONTENT:
Clin Neurophysiol. 2020 Sep 2;131(11):2700-2712. doi: 10.1016/j.clinph.2020.08.010. Online ahead of print.

ABSTRACT

OBJECTIVE: Although Essential Tremor is one of the most common movement disorders, we do not currently know which muscles are most responsible for tremor. Determining this requires multiple steps, one of which is characterizing the distribution of tremor among the degrees of freedom (DOF) of the upper limb.

METHODS: Upper-limb motion was recorded while 22 subjects with ET performed postural and kinetic tasks involving a variety of limb configurations. We calculated the mean distribution of tremor among the seven DOF from the shoulder to the wrist, as well as the effect of limb configuration, repetition, and subject characteristics (sex, tremor onset, duration, and severity) on the distribution.

RESULTS: On average, kinetic tremor was greatest in forearm pronation-supination and wrist flexion-extension, intermediate in shoulder internal-external rotation and wrist radial-ulnar deviation and then shoulder flexion-extension and elbow flexion-extension, and least in shoulder abduction-adduction. The average distribution of postural tremor was similar except for forearm pronation-supination, which played a smaller role than in kinetic tremor. Limb configuration and subject characteristics did significantly affect tremor, but practically only in forearm pronation-supination and wrist flexion-extension. There were no significant differences between repetitions, indicating that the distribution was consistent over the duration of the experiment.

CONCLUSIONS: This paper presents a thorough characterization of tremor distribution from the shoulder to the wrist.

SIGNIFICANCE: Understanding which DOF exhibit the most tremor may lead to more targeted peripheral tremor suppression.

PMID:33010725 | DOI:10.1016/j.clinph.2020.08.010

SOURCE:
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

IDENTIFIER:
pmid:33010725,doi:10.1016/j.clinph.2020.08.010

PUBMED:
pubmed:33010725

DOI:
10.1016/j.clinph.2020.08.010

DATE – PUBLISHED:
2020 Sep 2

DATE – ADDED:
Sat, 03 Oct 2020 06:00:00 -0400
2020-10-03

DATE – FOUND:
10/04/20 07:21PM

LINK – PUBMED:
https://pubmed.ncbi.nlm.nih.gov/33010725/

LINK – DOI:
https://doi.org/10.1016/j.clinph.2020.08.010

LINK – PUBLISHER:
https://linkinghub.elsevier.com/retrieve/pii/S1388245720304624

CATEGORY:
Research

TITLE:
Closed-loop DBS triggered by real-time movement and tremor decoding based on thalamic LFPs for essential tremor

DATE:

LINK:
https://pubmed.ncbi.nlm.nih.gov/33018782/?utm_source=Other&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1JUQiFFHYgOoKyzCJtWtxqPbnrPioDoUd2d_45rWsWUURe5w1u&fc=20201004183707&ff=20201006072103&v=2.12.3

DESCRIPTION:
High frequency Deep Brain Stimulation (DBS) targeting the motor thalamus is an effective therapy for essential tremor (ET). However, since tremor mainly affects periods of voluntary movements and sustained postures in ET, conventional continuous stimulation may deliver unnecessary current to the brain. Here we tried to decode movement states based on local field potentials (LFPs) recorded from motor thalamus and zona incerta in real-time to trigger the switching on and off of DBS in three…

CONTENT:
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3602-3605. doi: 10.1109/EMBC44109.2020.9175433.

ABSTRACT

High frequency Deep Brain Stimulation (DBS) targeting the motor thalamus is an effective therapy for essential tremor (ET). However, since tremor mainly affects periods of voluntary movements and sustained postures in ET, conventional continuous stimulation may deliver unnecessary current to the brain. Here we tried to decode movement states based on local field potentials (LFPs) recorded from motor thalamus and zona incerta in real-time to trigger the switching on and off of DBS in three patients with ET. Patient-specific models were first identified using thalamic LFPs recorded while the patient performed movements that tended to trigger tremor in everyday life. During the real-time test, LFPs were continuously recorded to decode movements and tremor, and the detection triggered stimulation. Results show that voluntary movements can be detected with a mean sensitivity ranging from 76.8% to 88.6% and a false positive rate ranging from 16.0% to 23.1% Postural tremor was detected with similar accuracy. The closed-loop DBS triggered by tremor detection suppressed intention tremor by 90.5% with a false positive rate of 20.3%.Clinical Relevance- This is the first study on closed-loop DBS triggered by real-time movement and tremor decoding based solely on thalamic LFPs. The results suggest that responsive DBS based on movement and tremor detection can be achieved without any requirement for external sensors or additional electrocorticography strips.

PMID:33018782 | DOI:10.1109/EMBC44109.2020.9175433

SOURCE:
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

IDENTIFIER:
pmid:33018782,doi:10.1109/EMBC44109.2020.9175433

PUBMED:
pubmed:33018782

DOI:
10.1109/EMBC44109.2020.9175433

DATE – PUBLISHED:

DATE – ADDED:
Tue, 06 Oct 2020 06:00:00 -0400
2020-10-06

DATE – FOUND:
10/06/20 07:21AM

LINK – PUBMED:
https://pubmed.ncbi.nlm.nih.gov/33018782/

LINK – DOI:
https://doi.org/10.1109/EMBC44109.2020.9175433

LINK – PUBLISHER:
https://ieeexplore.ieee.org/document/9175433/

CATEGORY:
Research

TITLE:
Effect of Biophysical Model Complexity on Predictions of Volume of Tissue Activated (VTA) during Deep Brain Stimulation

DATE:

LINK:
https://pubmed.ncbi.nlm.nih.gov/33018788/?utm_source=Other&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1JUQiFFHYgOoKyzCJtWtxqPbnrPioDoUd2d_45rWsWUURe5w1u&fc=20201004183707&ff=20201006072103&v=2.12.3

DESCRIPTION:
Deep brain stimulation (DBS) has evolved to an important treatment for several drug-resistant neurological and psychiatric disorders, such as epilepsy, Parkinson’s disease, essential tremor and dystonia. Despite general effectiveness of DBS, however, its mechanisms of action are not completely understood. Simulations are commonly used to predict the volume of tissue activated (VTA) around DBS electrodes, which in turn helps interpreting clinical outcomes and understand therapeutic mechanisms….

CONTENT:
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3629-3633. doi: 10.1109/EMBC44109.2020.9175300.

ABSTRACT

Deep brain stimulation (DBS) has evolved to an important treatment for several drug-resistant neurological and psychiatric disorders, such as epilepsy, Parkinson’s disease, essential tremor and dystonia. Despite general effectiveness of DBS, however, its mechanisms of action are not completely understood. Simulations are commonly used to predict the volume of tissue activated (VTA) around DBS electrodes, which in turn helps interpreting clinical outcomes and understand therapeutic mechanisms. Computational models are commonly used to visualize the extend of volume of activated tissue (VTA) for different stimulation schemes, which in turn helps interpreting and understanding the outcomes. The degree of model complexity, however, can affect the predicted VTA. In this work we investigate the effect of volume conductor model complexity on the predicted VTA, when the VTA is estimated from activation function field metrics. Our results can help clinicians to decide what level of model complexity is suitable for their specific need.

PMID:33018788 | DOI:10.1109/EMBC44109.2020.9175300

SOURCE:
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

IDENTIFIER:
pmid:33018788,doi:10.1109/EMBC44109.2020.9175300

PUBMED:
pubmed:33018788

DOI:
10.1109/EMBC44109.2020.9175300

DATE – PUBLISHED:

DATE – ADDED:
Tue, 06 Oct 2020 06:00:00 -0400
2020-10-06

DATE – FOUND:
10/06/20 07:21AM

LINK – PUBMED:
https://pubmed.ncbi.nlm.nih.gov/33018788/

LINK – DOI:
https://doi.org/10.1109/EMBC44109.2020.9175300

LINK – PUBLISHER:
https://ieeexplore.ieee.org/document/9175300/

CATEGORY:
Research

TITLE:
Rebound effect in deep brain stimulation for essential tremor and symptom severity estimation from neural data

DATE:

LINK:
https://pubmed.ncbi.nlm.nih.gov/33018786/?utm_source=Other&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1JUQiFFHYgOoKyzCJtWtxqPbnrPioDoUd2d_45rWsWUURe5w1u&fc=20201004183707&ff=20201006072103&v=2.12.3

DESCRIPTION:
Deep brain stimulation (DBS) is a safe and established treatment for essential tremor (ET). However, there remains considerable room for improvement due to concerns associated with the initial implant surgery, semi-regular revision surgeries for battery replacements, and side effects including paresthesia, gait ataxia, and emotional disinhibition that have been associated with continuous, or conventional, DBS (cDBS) treatment. Adaptive DBS (aDBS) seeks to ameliorate some of these concerns by…

CONTENT:
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3621-3624. doi: 10.1109/EMBC44109.2020.9175908.

ABSTRACT

Deep brain stimulation (DBS) is a safe and established treatment for essential tremor (ET). However, there remains considerable room for improvement due to concerns associated with the initial implant surgery, semi-regular revision surgeries for battery replacements, and side effects including paresthesia, gait ataxia, and emotional disinhibition that have been associated with continuous, or conventional, DBS (cDBS) treatment. Adaptive DBS (aDBS) seeks to ameliorate some of these concerns by using feedback from either an external wearable or implanted sensor to modulate stimulation parameters as needed. aDBS has been demonstrated to be as or more effective than cDBS, but the purely binary control system most commonly deployed by aDBS systems likely still provides sub-optimal treatment and may introduce new issues. One example of these issues is rebound effect, in which the tremor symptoms of an ET patient receiving DBS therapy temporarily worsen after cessation of stimulation before leveling out to a steady state. Here is presented a quantitative analysis of rebound effect in 3 patients receiving DBS for ET. Rebound was evident in all 3 patients by both clinical assessment and inertial measurement unit data, peaking by the latter at Tp = 6.65 minutes after cessation of stimulation. Using features extracted from neural data, linear regression was applied to predict tremor severity, with $R_{avg{\text{ }}}^2 = 0.82$. These results strongly suggest that rebound effect and the additional information made available by rebound effect should be considered and exploited when designing novel aDBS systems.

PMID:33018786 | DOI:10.1109/EMBC44109.2020.9175908

SOURCE:
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

IDENTIFIER:
pmid:33018786,doi:10.1109/EMBC44109.2020.9175908

PUBMED:
pubmed:33018786

DOI:
10.1109/EMBC44109.2020.9175908

DATE – PUBLISHED:

DATE – ADDED:
Tue, 06 Oct 2020 06:00:00 -0400
2020-10-06

DATE – FOUND:
10/06/20 07:21AM

LINK – PUBMED:
https://pubmed.ncbi.nlm.nih.gov/33018786/

LINK – DOI:
https://doi.org/10.1109/EMBC44109.2020.9175908

LINK – PUBLISHER:
https://ieeexplore.ieee.org/document/9175908/