TMS excitability study in essential tremor: Absence of gabaergic changes assessed by silent period recordings

Khedr, Eman M.; Fawal, Bastawy; Abdel-Warith, Abdel-Wahab A.; Nasreldein, Ahmed; Rothwell, John C.; Saber, Mostafa

doi:10.1016/j.neucli.2019.05.065

Cited by 6 publications

(3 citation statements)

References 28 publications

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“…The EMG signals were monitored and recorded for 20 ms before stimulation. The r MT is defined as the minimum TMS intensity sufficient to produce a predefined motor-evoked potential (MEP) in the contralateral APB in at least 50% of 10 trials, with the muscle at rest 40 .…”

Section: Methodsmentioning

confidence: 99%

A double-blind randomized clinical trial of high frequency rTMS over the DLPFC on nicotine dependence, anxiety and depression

Abdel‐Rahman

Noaman

Fawzy

et al. 2021

Sci Rep

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High frequency repetitive transcranial magnetic stimulation (HF-rTMS) over the left dorsolateral prefrontal cortex (L-DLPFC) is a widely applied treatment protocol for chronic smoking and major depressive disorder. However, no previous study has measured the effects of rTMS on both nicotine consumption and anxiety/depression in the same volunteers despite the relationship between them. The aim of this work was to evaluate the efficacy of 10 daily sessions of HF-rTMS over the L-DLPFC in chronic cigarette smokers’ addiction and investigate the possible beneficial effects of this treatment procedure on symptoms of depression and anxiety in the same subjects. The study included 40 treatment-seeking nicotine-dependent cigarette smokers. Onset/duration of smoking, number of cigarettes/day, Fagerstrom Test of Nicotine Dependence (FTND), Tobacco Craving Questionnaire-Short Form (TCQ-SF), Hamilton depression and anxiety scales (HAM-D and HAM-A) were recorded. Participants were randomly assigned to the active or the sham treatment group. Those in the active group received 10 trains of 20 Hz stimulation, at 80% of the resting motor threshold (rMT) for 10 consecutive working days over L-DLPFC. Participants were reassessed immediately after treatment, and then 3 months later using all rating scales. There were no differences between active and sham groups at baseline. The cigarette consumption/day, and scores on FTND, and TCQ decreased significantly in both groups (p = 0.0001 for each) immediately after treatment. However, improvement persisted to 3 months in the active group but not in the sham group. Moreover, there was a significant reduction in HAM-D and HAM-A scores immediately after treatment in the active but not the sham group. Subjects with a longer history of smoking had a lower percent improvement in FTND (p = 0.005). Our findings revealed that HF-rTMS over L-DLPCF for 10 days reduced cigarette consumption, craving, dependence, and improved associated symptoms of anxiety and depression.ClinicalTrials.gov Identifier: NCT03264755 registered at 29/08/2017.

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Section: Methodsmentioning

confidence: 99%

A double-blind randomized clinical trial of high frequency rTMS over the DLPFC on nicotine dependence, anxiety and depression

Abdel‐Rahman

Noaman

Fawzy

et al. 2021

Sci Rep

Self Cite

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“…Essential tremor seems to be a disorder of a cerebellothalamocortical circuit, but what makes this circuit oscillate is still unclear. 21–23 Although abnormal GABAergic inhibitory transmission has been proposed as a candidate mechanism, some findings do not support this. 21 Despite the uncertainty regarding the exact mechanism, it is clear that hand movement in ET is attributable to various constellations of connections among the cerebellum, brainstem, thalamus, and cortex.…”

Section: Discussionmentioning

confidence: 98%

“…21–23 Although abnormal GABAergic inhibitory transmission has been proposed as a candidate mechanism, some findings do not support this. 21 Despite the uncertainty regarding the exact mechanism, it is clear that hand movement in ET is attributable to various constellations of connections among the cerebellum, brainstem, thalamus, and cortex. Even direct connections between deep cerebellar nuclei and the cervical spinal cord have been considered as the origin of tremor in ET.…”

Section: Discussionmentioning

confidence: 98%

Does Essential Tremor Alter the Axonal Excitability Properties of Lower Motor Neurons?

Kim

Lee

et al. 2020

Journal of Clinical Neurophysiology

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Purpose: Automated nerve excitability testing has identified that the altered excitability of lower motor neuron (LMN) axons in central diseases is because of trans-synaptic plasticity. Essential tremor (ET) is considered a central disorder caused by an altered cerebellar circuit. This study aimed to identify alterations in the excitability of distal motor axons in subjects with ET, with the intention of clarifying whether a trans-synaptic mechanism or LMN adaptation for tremor affects the LMNs of subjects with ET.Methods: Twenty-one consecutive patients diagnosed with ET underwent a clinical and electrophysiological evaluation. For the enrolled cases and 45 age-and gender-matched healthy controls, automated nerve excitability testing with threshold tracking techniques (QTRACS software with TRONDF multiple-excitability protocol) was used to evaluate multiple nerve excitability indices in distal median nerve motor axons. Results:The automated protocol calculated the strength-duration time constant, parameters of threshold electrotonus and current-threshold relationship, and the recovery cycle of excitability. Comparisons of the automated nerve excitability testing parameters revealed no significant differences between the ET and control groups in any of strength-duration time constant, threshold electrotonus, current-threshold relationship, and recovery cycle, whereas the rheobase was higher in the ET group (3.4 6 1.1 vs. 2.3 6 1.1, mean 6 standard error mean; P , 0.01).Conclusions: With the exception of an increased rheobase in ET subjects, no significant differences were observed in LMN excitability between the ET subjects and their controls. The extent of plasticity or adaptation in LMNs may be limited to a major change in central processes that exert marked effects on the pool of LMNs.

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Effect of chronic nicotine consumption on motor cortical excitability: A transcranial magnetic stimulation study

Khedr

Tony

Abdel-Warith

et al. 2020

Neurophysiologie Clinique

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TMS excitability study in essential tremor: Absence of gabaergic changes assessed by silent period recordings

Cited by 6 publications

References 28 publications

A double-blind randomized clinical trial of high frequency rTMS over the DLPFC on nicotine dependence, anxiety and depression

A double-blind randomized clinical trial of high frequency rTMS over the DLPFC on nicotine dependence, anxiety and depression

Does Essential Tremor Alter the Axonal Excitability Properties of Lower Motor Neurons?

Effect of chronic nicotine consumption on motor cortical excitability: A transcranial magnetic stimulation study

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