Uncovering neuroanatomical correlates of impaired coordinated movement after pallidal deep brain stimulation.

BACKGROUND: The loss of the ability to swim following deep brain stimulation (DBS), although rare, poses a worrisome risk of drowning. It is unclear what anatomic substrate and neural circuitry underlie this phenomenon. We report a case of cervical dystonia with lost ability to swim and dance during active stimulation of globus pallidus internus. We investigated the anatomical underpinning of this phenomenon using unique functional and structural imaging analysis. METHODS: Tesla (3T) functional MRI (fMRI) of the patient was used during active DBS and compared with a cohort of four matched patients without this side effect. Structural connectivity mapping was used to identify brain network engagement by stimulation. RESULTS: fMRI during stimulation revealed significant (Pbonferroni<0.0001) stimulation-evoked responses (DBS ON

Thalamic Local Field Potentials and Closed-Loop Deep Brain Stimulation in Orthostatic Tremor.

BACKGROUND: Orthostatic tremor (OT) is a rare movement disorder characterized by a feeling of unsteadiness and a high-frequency tremor in the legs (13-18 Hz) relieved by sitting or walking. OBJECTIVES: The aims were to study the brain electrophysiology captured chronically in a person with medication-refractory OT while standing and walking and in the semi-recumbent position using bilateral ventral intermedius nucleus deep brain stimulation (DBS) (Medtronic Percept PC) and to describe the clinical use of closed-loop DBS. METHODS: A sensing survey was used to capture baseline local field potentials (LFPs) while standing. Livestreamed LFPs were synchronized with data collected from two accelerometers (legs) and gait analysis during OFF stimulation and continuous and closed-loop DBS. RESULTS: Strong oscillatory coupling between thalamic LFP and leg tremor with significant coherence at 14.65 Hz was found during weight-bearing. Single-threshold adaptive DBS (sensing at this frequency) was superior to continuous stimulation in reducing tremor and stimulation-related gait ataxia. CONCLUSIONS: This study provides new insights into both the pathophysiology and management of OT. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Functional disorders as a common motor manifestation of COVID-19 infection or vaccination.

BACKGROUND AND PURPOSE: There have been over 500 million confirmed cases of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19), across the globe. To date, a broad spectrum of neurological manifestations following acute infections as well as COVID-19 vaccines have been reported. The aim of this study was to describe the spectrum of neurological manifestations seen in the 'COVID-19 clinic' established in a tertiary Movement Disorders clinic. METHODS: In this consecutive case-series study over the period March 2020-January 2022, clinical information regarding demographic data, clinical history and examination findings, investigation results and video recordings of outpatients with motor manifestations associated with COVID-19 infection or vaccination were reviewed. RESULTS: Twenty-one adult patients were reviewed in this ad hoc clinic at Toronto Western Hospital. The majority of the patients were female (76%) and the mean (range) age was 50.7 ± 17.2 (21-80) years. Nine patients (43%) presented with motor manifestations following COVID-19 infection. Twelve patients (57%) developed neurological symptoms following at least one dose of the mRNA or viral vector-based COVID-19 vaccine. The most common manifestation observed was a functional movement disorder (43%). The vaccine group demonstrated a higher number of functional disorders compared to the infection group (58% vs. 22%; p = 0.08). CONCLUSION: Functional motor manifestations can be associated with COVID-19 and are likely to be under-reported. In view of the co-existence of functional symptoms, movement disorders and mental health conditions observed in this study, we would advocate the use of dedicated COVID-19 Neurology clinics with full access to an experienced multidisciplinary team.

Effectiveness of telehealth in preventive care: a study protocol for a randomised controlled trial of tele-exercise programme involving older people with possible sarcopenia or at risk of fall.

BACKGROUND: Continuous loss of muscle mass and strength are the consequences of the ageing process, which increase the risk of falls among older people. Falls can lead to severe consequences such as bone fractures and hampered physical and psychological well-being. Regular exercise is the key to reversing muscle atrophy and relieving sarcopenia. However, the frailty of older people and the recent COVID-19 pandemic may affect their confidence to leave home to attend classes in the community. A feasible and effective alternative should be explored. METHODS: The primary objective is to evaluate the effectiveness of tele-exercise (TE) in relation to physical functioning and exercise adherence among community-dwelling older people at risk of falls in comparison with a community-based group (CB). The secondary objective includes evaluating older people's experience with tele-exercise, emphasizing their psychological welfare, social well-being, and acceptance of the telehealth approach. The design, conduct, and report follow the SPIRIT guidelines (Standard Protocol Items: recommended items to address in a Clinical Trial Protocol and Related Documents). Older people will be recruited from 10 local community centres in Hong Kong and randomly allocated into two groups. All participants will attend the exercise training 3 days per week for 3 months but the mode of delivery will differ, either online as the tele-exercise group (TE) or face-to-face as the community-based group (CB). The outcome measures include muscle strength, physical function, exercise adherence and dropout rate, psychological and social well-being will be assessed at the baseline, and the 3rd, 6th and 12th month. Some participants will be invited to attend focus group interviews to evaluate their overall experience of the tele-exercise training. DISCUSSION: Tele-exercise reduces the barriers to exercise, such as time constraints, inaccessibility to facilities, and the fear of frail older people leaving their homes. Promoting an online home-based exercise programme for older people can encourage them to engage in regular physical activity and increase their exercise adherence even when remaining at home. The use of telehealth can potentially result in savings in cost and time. The final findings will provide insights on delivering exercise via telehealth to older people and propose an exercise delivery and maintenance model for future practice. TRIAL REGISTRATION: Chinese Clinical Trial Registry ( https://www.chictr.org.cn/hvshowprojectEN.html?id=219002&v=1.1 ), registration number: ChiCTR2200063370. Registered on 5 September 2022.

Dystonic crises in dopa-responsive dystonia induced by energy drinks.

We present an interesting case of recurrent dystonic crises in dopa-responsive dystonia (DRD) likely induced by excessive consumption of aspartame-containing products, in particular sugar-free energy drinks. This has a strong practical value as acute presentations to the emergency department can be avoided in these susceptible individuals. Usual medical and dietary advice in the treatment of DRD would include the avoidance of high-dose phenylalanine-containing products, and to this we would advocate the avoidance of high-dose aspartame-containing products.

"Stretched Slinky" Sign: Another Clue to Functional Tremor.

Objective: Functional tremor (FT) is the most common functional movement disorder, although its diagnosis can be challenging. Archimedes spiral drawings can be helpful in eliciting additional signs associated with tremor. Here, we present examples of an unusual looping of Archimedes spirals only seen in FT. Methods: Clinical information regarding demographic data, clinical history, and examination findings (including Archimedes spiral drawings) and investigation results of patients with FT in the movement disorders clinic were reviewed. Results: Three paradigmatic patients with FT demonstrated a unique looping appearance of Archimedes spiral drawings, akin to the appearance of a stretched slinky. The degree of randomness of the spirals varied from patient to patient and often mirrored tremor severity, regardless of the diagnosis. Discussion: The clinical hallmarks of a FT include a variable combination of positive signs, such as inconsistency (variability and distractibility), incongruence with known tremor syndromes, entrainment, and coactivation, although these findings might not always be present. We describe a unique appearance of spiral drawings, which could add as another clinical sign for FT. Consider looping of spirals as another diagnostic clue to FT.

An unusual case of deep brain stimulation-induced insomnia.

Cervical dystonia (CD) is the most common adult-onset focal dystonia. Non-motor symptoms, such as insomnia, can greatly impact the quality of life in CD patients. CD can be treated with deep brain stimulation (DBS) of the globus pallidus pars interna (GPi) although its effect on sleep is not yet fully understood. Here, we report a case of a 66-year-old female patient with cervical dystonia, who developed an unusual form of insomnia following her DBS surgery. Our patient reported recurrent episodes of visual symptoms (flashing lights), which would often wake her up at night. Following surgical revision of the extension wire, these visual symptoms completely resolved. This case provides an example of impedance oscillations caused by pressure on the pillow, which resulted in irregular delivery of current (according to Ohm's law) and recruitment of optic tract fibers secondary to excessive current.

Impact of prefrontal intermittent theta-burst stimulation on working memory and executive function in Parkinson's disease: A double-blind sham-controlled pilot study.

Cognitive impairment is a prevalent non-motor feature of Parkinson's disease (PD) which can present even in early stages of the disease. Impairments in executive processing and working memory (WM) are common and have been attributed, in part, to abnormalities within the dorsolateral prefrontal cortex (DLPFC) and broader fronto-striatal circuitry. Previous studies in cognitively normal adults have suggested intermittent Theta Burst Stimulation (iTBS), an excitatory plasticity-inducing non-invasive brain stimulation technique, can enhance these cognitive functions. Fourteen participants with a diagnosis of idiopathic PD received either Active or Sham iTBS over the left DLPFC across two separate experimental sessions as part of a double-blind sham-controlled crossover experimental design. The Berg's Card Sorting Test (BCST) and N-Back tasks, which measure executive function and WM respectively, were administered prior to iTBS and again five- and 30-minutes following stimulation. Despite being well-tolerated, iTBS failed to modulate performance on any of the cognitive outcome measures. This finding was further supported by Bayes Factor analyses which indicated moderate levels of support for the null hypothesis overall. This initial pilot study therefore does not support single-session iTBS as an efficacious method for modulating either executive processes or WM in PD. We discuss potential reasons for this finding along with directions for future research.

Resting state fMRI entropy probes complexity of brain activity in adults with ADHD.

In patients with attention deficit hyperactivity disorder (ADHD), quantitative neuroimaging techniques have revealed abnormalities in various brain regions, including the frontal cortex, striatum, cerebellum, and occipital cortex. Nonlinear signal processing techniques such as sample entropy have been used to probe the regularity of brain magnetoencephalography signals in patients with ADHD. In the present study, we extend this technique to analyse the complex output patterns of the 4 dimensional resting state functional magnetic resonance imaging signals in adult patients with ADHD. After adjusting for the effect of age, we found whole brain entropy differences (P=0.002) between groups and negative correlation (r=-0.45) between symptom scores and mean whole brain entropy values, indicating lower complexity in patients. In the regional analysis, patients showed reduced entropy in frontal and occipital regions bilaterally and a significant negative correlation between the symptom scores and the entropy maps at a family-wise error corrected cluster level of P<0.05 (P=0.001, initial threshold). Our findings support the hypothesis of abnormal frontal-striatal-cerebellar circuits in ADHD and the suggestion that sample entropy is a useful tool in revealing abnormalities in the brain dynamics of patients with psychiatric disorders.