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Abstract Introduction Functional electrical stimulation (FES) is used to retrain motor function in neurological disorders but typically requires multiple sessions and shows limited benefits in chronic cases. Low‐intensity transcranial focused ultrasound stimulation (TUS) is a noninvasive brain stimulation (NIBS) method offering greater focality and deeper penetration than current NIBS techniques. TUS delivered in a theta burst pattern (tbTUS) for 80 s produces neuroplastic changes with long‐term potentiation‐like effects lasting up to 60 min in healthy adults. Since tbTUS increases cortical excitability, combining it with FES may enhance neuroplasticity. We hypothesized that combining tbTUS with FES would result in increased corticospinal excitability compared to FES alone and lead to greater improvement in fine motor skills as assessed by Nine‐Hole Peg Test (NHPT) scores. Methods Fifteen healthy participants underwent two study visits consisting of real or sham tbTUS of the left motor cortex immediately followed by 30 min of FES of the first dorsal interosseous (FDI) and the opponens pollicis (OP) muscles for fine motor function training of the right hand. Motor‐evoked potentials (MEPs) were recorded from the right FDI, OP, and abductor digiti minimi (ADM) muscles at baseline (BL), immediately after real or sham tbTUS (T0), immediately after 30 min of FES training (T45), and at 15 (T65) and 30 min (T80) post‐FES. NHPT was delivered at BL and at T80. Results Data from 14 participants were analyzed. It showed a significant decrease in MEP amplitudes of FDI and OP at T45 following only real tbTUS+FES with a return to BL at T80. No significant changes were seen in the NHPT scores in either condition. Conclusion Real tbTUS+FES combined with voluntary movement results in immediate corticospinal inhibition with a return to BL at ∼20 min post‐stimulation suggestive of homeostatic metaplasticity. These findings highlight the potential of tbTUS+FES as a neuromodulatory intervention, warranting further exploration in neurological conditions for therapeutic applications.

Background: Transcranial ultrasound stimulation (TUS) is a novel non-invasive brain stimulation technique with high depth penetrance and spatial resolution. Theta-burst TUS (tbTUS) is a plasticity-inducing protocol which increases motor cortical excitability for up to 30 min following 80s of sonication. While this protocol may have therapeutic potential for the treatment of psychiatric and neurological disorders, the mechanisms of action of TUS remain unclear. Objective: We conducted the first pharmacological study to examine the mechanisms of TUS in human primary motor cortex. By administering brain-active drugs with known mechanisms of action, we aimed to elucidate the mechanisms of tbTUS. Methods: Fourteen healthy subjects participated in a within-subjects randomized, double-blind, cross-over study with five visits. At each visit, one of four study drugs (carbamazepine – Na+ channel blocker, nimodipine – L-type Ca2+ channel blocker, lorazepam – positive allosteric modulator of gamma-aminobutyric acid (GABA) type A receptor, dextromethorphan – N-methyl-d-aspartate receptor antagonist) or placebo was administered in random order, followed by tbTUS. Results: The plasticity effects of tbTUS on motor cortex excitability measured by motor-evoked potential amplitudes elicited by transcranial magnetic stimulation were reduced by all study drugs compared to placebo. Conclusion: tbTUS may induce NMDA-dependent synaptic plasticity since the effects are blocked by increased GABAA receptor activities and voltage-gated Na+ and Ca2+ channels blockers. These results are consistent with the hypotheses that tbTUS induced long-term potentiation-like mechanisms and that TUS involves activation of mechanosensitive Na+ and Ca2+ channels. Alternatively, non-specific pharmacologically induced changes in excitatory/inhibitory balance might have interfered with the effects of tbTUS.

Functional movement disorders (FMD) are a subtype of functional neurological disorders which involve abnormal movements and include multiple phenomenologies. There is a growing interest in the mechanism, diagnosis, and treatment of these disorders. Most of the current therapeutic approaches rely on psychotherapy and physiotherapy conducted by a multidisciplinary team. Although this approach has shown good results in some cases, FMD cause a great burden on the health system and other treatment strategies are urgently needed. In this review, we summarize past studies that have applied non-invasive neurostimulation techniques, such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and peripheral nerve stimulation as a treatment for FMD. There is an increasing number of studies related to TMS including randomized controlled trials; however, the protocols amongst studies are not standardized. There is only preliminary evidence for the efficacy of non-invasive neuromodulation in reducing FMD symptoms, and further studies are needed. There is insufficient evidence to allow implementation of these techniques in clinical practice.

Background: The clinical spectrum of anti-glutamic acid decarboxylase (GAD) antibody-associated neurologic syndromes is expanding, with focal, generalized, and atypical forms. Case Report: We describe a 59-year-old female showing continuous right lower limb myoclonus and mild encephalopathy. These symptoms started 2 weeks prior to evaluation. The patient had great improvement with intravenous steroids. An autoantibody panel was positive for anti-GAD. Discussion: Various clinical manifestations, including myoclonus, may relate to anti-GAD antibodies. The treatment options available include symptomatic drugs, intravenous immunoglobulin, steroids, and other immunosuppressant agents.

ABSTRACT Background: Neurophysiological studies are ancillary tools to better understand the features and nature of movement disorders. Electromyography (EMG), together with electroencephalography (EEG) and accelerometer, can be used to evaluate a hypo and hyperkinetic spectrum of movements. Specific techniques can be applied to better characterize the phenomenology, help distinguish functional from organic origin and assess the most probable site of the movement generator in the nervous system. Objective: We intend to provide an update for clinicians on helpful neurophysiological tools to assess movement disorders in clinical practice. Methods: Non-systematic review of the literature published up to June 2019. Results: A diversity of protocols was found and described. These include EMG analyses to define dystonia, myoclonus, myokymia, myorhythmia, and painful legs moving toes pattern; EMG in combination with accelerometer to study tremor; and EEG-EMG to study myoclonus. Also, indirect measures of cortical and brainstem excitability help to describe and diagnose abnormal physiology in Parkinson's disease, atypical parkinsonism, dystonia, and myoclonus. Conclusion: These studies can be helpful for the diagnosis and are usually underutilized in neurological practice.