scholarly journals Intermittent cortical involvement in the preservation of tremor in essential tremor

2017 ◽  
Vol 118 (5) ◽  
pp. 2628-2635 ◽  
Author(s):  
Sarvi Sharifi ◽  
Frauke Luft ◽  
Rens Verhagen ◽  
Tjitske Heida ◽  
Johannes D. Speelman ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Motor Cortex ◽  
Essential Tremor ◽  
Cortical Neurons ◽  
Cognitive Task ◽  
Electrophysiological Study ◽  
Hand Tremor ◽  
Corticomuscular Coherence ◽  
Cognitive States ◽  
Cortical Involvement

Cortical involvement in essential tremor, an involuntary action tremor supposedly of subcortical origin, is uncertain. Conflicting results of corticomuscular coherence studies in essential tremor suggest an intermittent corticomuscular coupling. On the basis of the literature, we hypothesized that corticomuscular coupling is influenced by bilateral motor synchronization and “cognitive states” such as awareness of tremor. In the present study, we investigated 1) the existence of intermittent corticomuscular coherence (CMC) in essential tremor and 2) factors that influence CMC strength. In 18 essential tremor patients and 18 healthy controls, who mimicked tremor, we simultaneously recorded 64-channel EEG and 6-channel bipolar surface EMG from right and left wrist extensors and flexors. Right-sided (mimicked) hand tremor was recorded with and without a cognitive arithmetic task and with left-sided (mimicked) hand tremor. CMC values per task were compared within and between groups. Changes in CMC strength during tasks were calculated. Our main findings are 1) significant CMC around the (mimicked) tremor frequency across all tasks in both groups; 2) significant differences in CMC between unilateral tasks, with the highest values during the cognitive task only in the essential tremor group; and 3) significant fluctuations of CMC strength over time, independent of the tremor intensity, only in the essential tremor group. Our results suggest a limited role, and certainly not a continuous steering role, of sensorimotor cortical neurons in the generation of tremor. In clinical practice, these findings might help to standardize tremor registration and the interpretation of the analysis. NEW & NOTEWORTHY The part of the motor cortex involved in essential tremor is uncertain. The current electrophysiological study is the first to assess corticomuscular coherence systematically. The study shows a dynamic nature of corticomuscular coherence and a possible influence of cognitive states. The results elucidate the involvement of the motor cortex in tremor and help interpret the varying results in the literature. In clinical practice, the findings may guide in standardizing tremor registration and its interpretation.

scholarly journals Connectivity profile of thalamic deep brain stimulation to effectively treat essential tremor

2019 ◽  
Author(s):  
Bassam Al-Fatly ◽  
Siobhan Ewert ◽  
Dorothee Kübler ◽  
Daniel Kroneberg ◽  
Andreas Horn ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Motor Cortex ◽  
Essential Tremor ◽  
Brain Stimulation ◽  
Brain Connectivity ◽  
Clinical Care ◽  
Hand Tremor ◽  
Intermediate Nucleus ◽  
Ventral Intermediate Nucleus ◽  
Deep Brain

AbstractEssential tremor is the most prevalent movement disorder and is often refractory to medical treatment. Deep brain stimulation offers a therapeutic approach that can efficiently control tremor symptoms. Several deep brain stimulation targets (ventral intermediate nucleus, zona incerta, posterior subthalamic area) have been discussed for tremor treatment. Effective deep brain stimulation therapy for tremor critically involves optimal targeting to modulate the tremor network. This could potentially become more robust and precise by using state-of-the-art brain connectivity measurements. In the current study, we utilized two normative brain connectomes (structural and functional) to show the pattern of effective deep brain stimulation electrode connectivity in 36 essential tremor patients. Our structural and functional connectivity models were significantly predictive of post-operative tremor improvement in out-of-sample data (p< 0.001 for both structural and functional leave-one-out cross-validation). Additionally, we segregated the somatotopic brain network based on head and hand tremor scores. These resulted in segregations that mapped onto the well-known somatotopic maps of both motor cortex and cerebellum. Crucially, this shows that slightly distinct networks need to be modulated to ameliorate head vs. hand tremor and that those networks could be identified based on somatotopic zones in motor cortex and cerebellum.Finally, we propose a multi-modal connectomic deep brain stimulation sweet spot that may serve as a reference to enhance clinical care, in the future. This spot resided in the posterior subthalamic area, encroaching on the inferior borders of ventral intermediate nucleus and sensory thalamus. Our results underscore the importance of integrating brain connectivity in optimizing deep brain stimulation targeting for essential tremor.

Excitation of rat prefrontal cortical neurons by dopamine: An in vitro electrophysiological study

1987 ◽  
Vol 425 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Jacqueline Penit-Soria ◽  
Etienne Audinat ◽  
Francis Crepel
Keyword(s):  
Cortical Neurons ◽  
Electrophysiological Study ◽  
Prefrontal Cortical

Motor Cortex Inhibition is Increased During a Secondary Cognitive Task

2014 ◽  
Vol 46 ◽  
pp. 672 ◽  
Author(s):  
Katherine G. Holste ◽  
Alia L. Yasen ◽  
Anita D. Christie
Keyword(s):  
Motor Cortex ◽  
Cognitive Task

Cortical Involvement in the Generation of Essential Tremor

2007 ◽  
Vol 97 (5) ◽  
pp. 3219-3228 ◽  
Author(s):  
Jan Raethjen ◽  
R. B. Govindan ◽  
Florian Kopper ◽  
M. Muthuraman ◽  
Günther Deuschl
Keyword(s):  
Essential Tremor ◽  
Hot Spot ◽  
Power Spectra ◽  
Emg Activity ◽  
Cortical Circuits ◽  
Coherent Signals ◽  
Cortical Motor ◽  
Tremor Frequency ◽  
Cortical Involvement

Conflicting results on the existence of tremor-related cortical activity in essential tremor (ET) have raised questions on the role of the cortex in tremor generation. Here we attempt to address these issues. We recorded 64 channel surface EEGs and EMGs from forearm muscles in 15 patients with definite ET. EEG and EMG power spectra, relative power of the rhythmic EMG activity, relative EEG power at the tremor frequency, and EEG–EMG and EEG–EEG coherence were calculated and their dynamics over time explored. Corticomuscular delay was studied using a new method for narrow-band coherent signals. Corticomuscular coherence in the contralateral central region at the tremor frequency was present in all patients in recordings with a relative tremor EMG power exceeding a certain level. However, the coherence was lost intermittently even with tremors far above this level. Physiological 15- to 30-Hz coherence was found consistently in 11 patients with significantly weaker EMG activity in this frequency range. A more frontal (mesial) hot spot was also intermittently coupled with the tremor and the central hot spot in five patients. Corticomuscular delays were compatible with transmission in fast corticospinal pathways and feedback of the tremor signal. Thus the tremor rhythm is intermittently relayed only in different cortical motor areas. We hypothesize that tremor oscillations build up in different subcortical and subcortico-cortical circuits only temporarily entraining each other.

Three-year follow-up of prospective trial of focused ultrasound thalamotomy for essential tremor

Neurology ◽  
2019 ◽  
Vol 93 (24) ◽  
pp. e2284-e2293 ◽  
Author(s):  
Casey H. Halpern ◽  
Veronica Santini ◽  
Nir Lipsman ◽  
Andres M. Lozano ◽  
Michael L. Schwartz ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Adverse Events ◽  
Essential Tremor ◽  
Focused Ultrasound ◽  
Rating Scale ◽  
Prospective Trial ◽  
Postural Tremor ◽  
Hand Tremor

ObjectiveTo test the hypothesis that transcranial magnetic resonance–guided focused ultrasound (tcMRgFUS) thalamotomy is effective, durable, and safe for patients with medication-refractory essential tremor (ET), we assessed clinical outcomes at 3-year follow-up of a controlled multicenter prospective trial.MethodsOutcomes were based on the Clinical Rating Scale for Tremor, including hand combined tremor–motor (scale of 0–32), functional disability (scale of 0–32), and postural tremor (scale of 0–4) scores, and total scores from the Quality of Life in Essential Tremor Questionnaire (scale of 0–100). Scores at 36 months were compared with baseline and at 6 months after treatment to assess for efficacy and durability. Adverse events were also reported.ResultsMeasured scores remained improved from baseline to 36 months (all p < 0.0001). Range of improvement from baseline was 38%–50% in hand tremor, 43%–56% in disability, 50%–75% in postural tremor, and 27%–42% in quality of life. When compared to scores at 6 months, median scores increased for hand tremor (95% confidence interval [CI] 0–2, p = 0.0098) and disability (95% CI 1–4, p = 0.0001). During the third follow-up year, all previously noted adverse events remained mild or moderate, none worsened, 2 resolved, and no new adverse events occurred.ConclusionsResults at 3 years after unilateral tcMRgFUS thalamotomy for ET show continued benefit, and no progressive or delayed complications. Patients may experience mild degradation in some treatment metrics by 3 years, though improvement from baseline remains significant.Clinicaltrials.gov identifierNCT01827904.Classification of evidenceThis study provides Class IV evidence that for patients with severe ET, unilateral tcMRgFUS thalamotomy provides durable benefit after 3 years.

Temporal Integration by Stochastic Recurrent Network Dynamics With Bimodal Neurons

2007 ◽  
Vol 97 (6) ◽  
pp. 3859-3867 ◽  
Author(s):  
Hiroshi Okamoto ◽  
Yoshikazu Isomura ◽  
Masahiko Takada ◽  
Tomoki Fukai
Keyword(s):  
Cortical Neurons ◽  
Cognitive Task ◽  
Temporal Integration ◽  
Activity Patterns ◽  
Recurrent Network ◽  
External Input ◽  
Delay Period ◽  
Anterior Cingulate ◽  
Population Activity ◽  
The Individual

Temporal integration of externally or internally driven information is required for a variety of cognitive processes. This computation is generally linked with graded rate changes in cortical neurons, which typically appear during a delay period of cognitive task in the prefrontal and other cortical areas. Here, we present a neural network model to produce graded (climbing or descending) neuronal activity. Model neurons are interconnected randomly by AMPA-receptor–mediated fast excitatory synapses and are subject to noisy background excitatory and inhibitory synaptic inputs. In each neuron, a prolonged afterdepolarizing potential follows every spike generation. Then, driven by an external input, the individual neurons display bimodal rate changes between a baseline state and an elevated firing state, with the latter being sustained by regenerated afterdepolarizing potentials. When the variance of background input and the uniform weight of recurrent synapses are adequately tuned, we show that stochastic noise and reverberating synaptic input organize these bimodal changes into a sequence that exhibits graded population activity with a nearly constant slope. To test the validity of the proposed mechanism, we analyzed the graded activity of anterior cingulate cortex neurons in monkeys performing delayed conditional Go/No-go discrimination tasks. The delay-period activities of cingulate neurons exhibited bimodal activity patterns and trial-to-trial variability that are similar to those predicted by the proposed model.

Coherence between low-frequency activation of the motor cortex and tremor in patients with essential tremor

The Lancet ◽  
2000 ◽  
Vol 355 (9210) ◽  
pp. 1149-1153 ◽  
Author(s):  
DM Halliday ◽  
BA Conway ◽  
SF Farmer ◽  
U Shahani ◽  
AJC Russell ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Essential Tremor ◽  
Low Frequency

Evaluation of a Child with Spells: A “Prefixed” Approach

2019 ◽  
Vol 18 (01) ◽  
pp. 007-012
Author(s):  
Jatinder S. Goraya
Keyword(s):  
Clinical Practice ◽  
Electrical Activity ◽  
Cortical Neurons ◽  
Diagnostic Errors ◽  
Clinical History ◽  
Clinical Problem ◽  
Detailed Account ◽  
History Taking ◽  
Clinical Events ◽  
Common Clinical Problem

AbstractSpells are a common clinical problem in children and can be broadly classified into epileptic and nonepileptic spells. Epileptic spells are clinical events that result from abnormal, excessive, and synchronous electrical activity of the cortical neurons. All other spells are included under the category of nonepileptic events. Precise differentiation between epileptic and nonepileptic spells, and their final characterization depend chiefly on obtaining a detailed account of the episode from the patient and/or witness. Physical and neurological examinations are generally non-revealing. In clinical practice, however, misdiagnosis of nonepileptic spells as epilepsy is fairly common and often is a result of incomplete history-taking. Explicit guidelines to elicit a thorough history in children who present with spells are lacking. The purpose of this article is to describe an instinctive and easy-to-remember approach to clinical history-taking in children with spells so as to minimize diagnostic errors.

scholarly journals Tolerability and Efficacy of Customized IncobotulinumtoxinA Injections for Essential Tremor: A Randomized, Double-Blind, Placebo-Controlled Study

Toxins ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 807
Author(s):  
Mandar Jog ◽  
Jack Lee ◽  
Astrid Scheschonka ◽  
Robert Chen ◽  
Farooq Ismail ◽  
...  
Keyword(s):  
Essential Tremor ◽  
Upper Limb ◽  
Motor Performance ◽  
Controlled Study ◽  
Tolerability Profile ◽  
Double Blind ◽  
Hand Tremor ◽  
Global Impression Of Change ◽  
Amplitude Versus ◽  
Favorable Tolerability Profile

In this first, double-blind, randomized, placebo-controlled exploratory trial, we evaluate the efficacy and safety of incobotulinumtoxinA and feasibility of using kinematic tremor assessment to aid in the planning of muscle selection in a multicenter setting. Reproducibility of the planning technology to other clinical sites was explored. In this trial (NCT02207946), patients with upper-limb essential tremor (ET) were randomized 2:1 to a single treatment cycle of incobotulinumtoxinA or placebo. A tremor kinematic analytics investigational device was used to define a customized muscle set for injection, related to the pattern of the wrist, forearm, elbow, and shoulder tremor for each patient, and the incobotulinumtoxinA dose per muscle (total ≤ 200 U). Fahn–Tolosa–Marin (FTM) Part B motor performance score, Global Impression of Change Scale (GICS), and kinematic analysis-based efficacy evaluations were assessed. Thirty patients were randomized (incobotulinumtoxinA, n = 19; placebo, n = 11). FTM motor performance scores showed greater improvement with incobotulinumtoxinA versus placebo at Week 4 (p= 0.003) and Week 8 (p= 0.031). The physician-rated GICS score indicated improvement with incobotulinumtoxinA versus placebo at Week 4 (p < 0.05). IncobotulinumtoxinA also decreased accelerometric hand-tremor amplitude versus placebo from baseline to Week 4 (p= 0.004) and Week 8 (p < 0.001), with persistent tremor reduction up to 24 weeks post-injection. IncobotulinumtoxinA produced a slight and transient reduction of maximal grip strength versus placebo; two patients reported localized finger muscle weakness. Customized incobotulinumtoxinA injections decreased tremor severity and improved hand motor function in patients with upper-limb ET after a single injection cycle, with a favorable tolerability profile. The study showed that tremor kinematic analytics technology could be successfully scaled for use in other clinical sites.

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