Mitochondrial dysfunction in Fragile X syndrome and Fragile X-associated tremor/ataxia syndrome: prospect use of antioxidants and mitochondrial nutrients.

Fragile X syndrome (FXS) is a genetic disorder characterized by mutation in the FMR1 gene, leading to the absence or reduced levels of fragile X Messenger Ribonucleoprotein 1 (FMRP). This results in neurodevelopmental deficits, including autistic spectrum conditions. On the other hand, Fragile X-associated tremor/ataxia syndrome (FXTAS) is a distinct disorder caused by the premutation in the FMR1 gene. FXTAS is associated with elevated levels of FMR1 mRNA, leading to neurodegenerative manifestations such as tremors and ataxia.Mounting evidence suggests a link between both syndromes and mitochondrial dysfunction (MDF). In this minireview, we critically examine the intricate relationship between FXS, FXTAS, and MDF, focusing on potential therapeutic avenues to counteract or mitigate their adverse effects. Specifically, we explore the role of mitochondrial cofactors and antioxidants, with a particular emphasis on alpha-lipoic acid (ALA), carnitine (CARN) and Coenzyme Q10 (CoQ10). Findings from this review will contribute to a deeper understanding of these disorders and foster novel therapeutic strategies to enhance patient outcomes.

Prasinezumab slows motor progression in rapidly progressing early-stage Parkinson's disease.

Prasinezumab, a monoclonal antibody that binds aggregated α-synuclein, is being investigated as a potential disease-modifying therapy in early-stage Parkinson's disease. Although in the PASADENA phase 2 study, the primary endpoint (Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) sum of Parts I + II + III) was not met, prasinezumab-treated individuals exhibited slower progression of motor signs than placebo-treated participants (MDS-UPDRS Part III). We report here an exploratory analysis assessing whether prasinezumab showed greater benefits on motor signs progression in prespecified subgroups with faster motor progression. Prasinezumab's potential effects on disease progression were assessed in four prespecified and six exploratory subpopulations of PASADENA: use of monoamine oxidase B inhibitors at baseline (yes versus no); Hoehn and Yahr stage (2 versus 1); rapid eye movement sleep behavior disorder (yes versus no); data-driven subphenotypes (diffuse malignant versus nondiffuse malignant); age at baseline (≥60 years versus <60 years); sex (male versus female); disease duration (>12 months versus <12 months); age at diagnosis (≥60 years versus <60 years); motor subphenotypes (akinetic-rigid versus tremor-dominant); and motor subphenotypes (postural instability gait dysfunction versus tremor-dominant). In these subpopulations, the effect of prasinezumab on slowing motor signs progression (MDS-UPDRS Part III) was greater in the rapidly progressing subpopulations (for example, participants who were diffuse malignant or taking monoamine oxidase B inhibitors at baseline). This exploratory analysis suggests that, in a trial of 1-year duration, prasinezumab might reduce motor progression to a greater extent in individuals with more rapidly progressing Parkinson's disease. However, because this was a post hoc analysis, additional randomized clinical trials are needed to validate these findings.

Resolution of Wing-Beating Tremor and Magnetic Resonance Imaging Lesions in Wilson's Disease Following Penicillamine.

Background: The wing-beating tremor, characteristic of Wilson's disease (WD), is a disabling symptom that can be resistant to anti-copper and anti-tremor medications. Phenomenology Shown: This video illustrates severe bilateral wing-beating tremor, moderate head and lower limb tremors, mild cervical dystonia, and subtle cerebellar ataxia, with nearly resolution after penicillamine treatment. Educational Value: This case highlights a typical aspect of WD, emphasizing the importance of early detection and treatment, and its correlation with MRI findings. Highlights: This case highlights the typical wing-beating tremor in Wilson's disease and its correlation with the involvement of the dentato-rubro-thalamic pathway. The early diagnosis and initiation of treatment with penicillamine resulted in an excellent clinical and radiological response.

Abdominal Tremor in Idiopathic Parkinson's Disease: A Case Report.

Background: Tremor in Parkinson's disease (PD) is commonly seen in the upper extremities and can involve the lower extremities and mouth. We present a case of a patient with idiopathic PD who presented with abdominal tremor. Case Report: A 40-year-old man with a 2-year history of subjective weakness and stiffness in the right arm and leg, followed by emergence of a right hand tremor, subsequently developed abdominal tremor. Patient experienced marked improvement of both abdominal and hand tremor and mobility of the right limbs with levodopa. Discussion: Our case report serves as the second only published report of abdominal tremor in an idiopathic PD patient. Highlights: Tremor in Parkinson's disease (PD) commonly affects the upper and lower extremities and mouth. We describe a 40-year-old man with PD who developed abdominal tremor which was brought under control with levodopa. This case is one of only two published reports of abdominal tremor in PD.

Botulinum toxin treatment in parkinsonism.

Botulinum toxin (BoNT) was approved by the United States Food and Drug Administration (FDA) in 1989 for facial movement disorders and strabismus, but since that time its indications have been expanding beyond neurologic and ophthalmologic disorders. This article is a narrative review of the therapeutic use of BoNT in tremors, dystonia, sialorrhea, bladder and other autonomic symptoms, levodopa-induced dyskinesia and other problems occuring in the setting of parkinsonism. Though FDA approval is lacking for some of these indications, expert experiences have shown that BoNT is often beneficial in this group of patients.

The association between tacrolimus exposure and tremor, headache and insomnia in adult kidney transplant recipients: A systematic review.

PURPOSE: Tremor, headache and insomnia have been linked to the immunosuppressant, tacrolimus. The aim of this systematic review was to determine if there is a correlation between tacrolimus exposure and new-onset tremor, headache and insomnia experienced by adult kidney transplant recipients. METHODS: PubMed, Embase, Cochrane Library and CINAHL databases were searched up to 11 April 2023 for published studies which reported on tacrolimus exposure in adult kidney transplant recipients, alongside information on treatment-emergent neurologic manifestations, including tremor, headache and insomnia. Review articles, case studies, conference abstracts and articles not published in English in peer-reviewed journals were excluded. The Physiotherapy Evidence Database and Newcastle-Ottawa Quality Assessment Scales were used to assess risk of bias. Extracted data was analysed via a narrative synthesis. RESULTS: Eighteen studies involving 4030 patients in total were included in the final analysis. These comprised five randomised control trials and thirteen observational studies. Studies failed to find significant association between tacrolimus trough concentrations in whole blood and the incidence of neurologic side effects such as tremor, headache and insomnia; however, in one study the incidence of toxicity requiring a dose reduction increased with increasing, supratherapeutic targeted levels. Females, especially Black females, and older age were positively associated with the prevalence of neurologic adverse effects. Results were conflicting regarding whether extended-release formulations were associated with fewer neurologic complications than immediate-release formulations. CONCLUSION: The varied study designs and criteria for reporting tremor, headache and insomnia impacted on the quality of the data for exploring the relationship between tacrolimus exposure and the onset of neurologic manifestations experienced after kidney transplantation. Studies that examine defined neurologic complications as the primary outcome, and that consider novel markers of tacrolimus exposure while assessing the potential contribution of multiple covariate factors, are required.

Open-Label Sulforaphane Trial in FMR1 Premutation Carriers with Fragile-X-Associated Tremor and Ataxia Syndrome (FXTAS).

Fragile X (FMR1) premutation is a common mutation that affects about 1 in 200 females and 1 in 450 males and can lead to the development of fragile-X-associated tremor/ataxia syndrome (FXTAS). Although there is no targeted, proven treatment for FXTAS, research suggests that sulforaphane, an antioxidant present in cruciferous vegetables, can enhance mitochondrial function and maintain redox balance in the dermal fibroblasts of individuals with FXTAS, potentially leading to improved cognitive function. In a 24-week open-label trial involving 15 adults aged 60-88 with FXTAS, 11 participants successfully completed the study, demonstrating the safety and tolerability of sulforaphane. Clinical outcomes and biomarkers were measured to elucidate the effects of sulforaphane. While there were nominal improvements in multiple clinical measures, they were not significantly different after correction for multiple comparisons. PBMC energetic measures showed that the level of citrate synthase was higher after sulforaphane treatment, resulting in lower ATP production. The ratio of complex I to complex II showed positive correlations with the MoCA and BDS scores. Several mitochondrial biomarkers showed increased activity and quantity and were correlated with clinical improvements.

Trial of Botulinum Toxin for Isolated or Essential Head Tremor.

BACKGROUND: Local injections of botulinum toxin type A have been used to treat essential head tremor but have not been extensively studied in randomized trials. METHODS: In a multicenter, double-blind, randomized trial, we assigned, in a 1:1 ratio, adult patients with essential or isolated head tremor to receive botulinum toxin type A or placebo. Botulinum toxin or placebo was injected under electromyographic guidance into each splenius capitis muscle on the day of randomization (day 0) and during week 12. The primary outcome was improvement by at least 2 points on the Clinical Global Impression of Change (CGI) scale at week 6 after the second injection (week 18 after randomization). The CGI scale was used to record the patient's assessment of the degree of improvement or worsening of head tremor since baseline; scores range from 3 (very much improved) to -3 (very much worse). Secondary outcomes included changes in tremor characteristics from baseline to weeks 6, 12, and 24. RESULTS: A total of 120 patients were enrolled; 3 patients were excluded during screening, and 117 patients were randomly assigned to receive botulinum toxin (62 patients) or placebo (55 patients) and were included in the intention-to-treat analysis. Twelve patients in the botulinum toxin group and 2 patients in the placebo group did not receive injections during week 12. The primary outcome - improvement by at least 2 points on the CGI scale at week 18 - was met by 31% of the patients in the botulinum toxin group as compared with 9% of those in the placebo group (relative risk, 3.37; 95% confidence interval, 1.35 to 8.42; P = 0.009). Analyses of secondary outcomes at 6 and 12 weeks but not at 24 weeks were generally supportive of the primary-outcome analysis. Adverse events occurred in approximately half the patients in the botulinum toxin group and included head and neck pain, posterior cervical weakness, and dysphagia. CONCLUSIONS: Injection of botulinum toxin into each splenius capitis muscle on day 0 and during week 12 was more effective than placebo in reducing the severity of isolated or essential head tremor at 18 weeks but not at 24 weeks, when the effects of injection might be expected to wane, and was associated with adverse events. (Funded by the French Ministry of Health; Btx-HT ClinicalTrials.gov number, NCT02555982.).

Delayed-Onset Psychosis Secondary to Tacrolimus Neurotoxicity After Lung Transplant: A Case Report and Systematic Review.

BACKGROUND: Tacrolimus is the most common immunosuppressant used after transplant, yet it can result in moderate-to-severe neurotoxicity in up to 32% of patients. Signs of neurotoxicity can vary from mild (tremor or headache) to severe (posterior reversible encephalopathy syndrome or psychosis. Prompt recognition and management is needed to lead to symptom resolution. OBJECTIVE: The objective of this study is to describe the clinical presentation of tacrolimus-induced psychosis, a type of tacrolimus-inducted neurotoxicity, and distinguish it from other central nervous system disturbances, including delirium. METHODS AND RESULTS: We present a case of delayed onset tacrolimus-induced psychosis with focus on unique clinical features and management strategies. We conducted a systematic review of cases of tacrolimus-induced psychosis using the PubMed database and included 15 manuscripts in our review. CONCLUSIONS: Tacrolimus-induced psychosis is a unique presentation of tacrolimus-related neurotoxicity and can present without the cardinal symptoms of delirium. The data on isolated psychotic symptoms are limited with current literature focusing on more common presentations of tacrolimus-induced neurotoxicity, such as delirium and tremor. Development of psychosis can occur later in the treatment course and at normal tacrolimus serum levels. It can improve with antipsychotic therapies, but primary management should include cross-titration to an alternate immunosuppressant regimen.

Amantadine for Refractory Tremor in Parkinson Disease and Other Indications: A Chart Review With Long-Term Follow-up.

OBJECTIVES: The aim of this study was to determine how amantadine was used in a movement disorders clinic and how effective it was. METHODS: A chart review over a 2-month period in 2022 of all patients in a movement disorders clinic who had ever taken amantadine was undertaken. RESULTS: One hundred six charts were included. Amantadine was initiated primarily for tremor and secondly for l -dopa-induced dyskinesias (LIDs). Sixty-two percent of tremor patients improved and tolerated amantadine; 74% of those with LID improved and tolerated the drug. Hallucinations occurred in 23%. Initiating amantadine as a syrup allowed a more conservative titration than other formulations, which is attractive given the high percentage of hallucinations that may occur. Patients who tolerated drug initiation were generally kept on the drug for many years. CONCLUSIONS: Amantadine should be considered as adjunctive therapy in Parkinson disease patients with refractory tremor as well as for LIDs.

Mapping Pharmacologically Evoked Neurovascular Activation and Its Suppression in a Rat Model of Tremor Using Functional Ultrasound: A Feasibility Study.

Functional ultrasound (fUS), an emerging hemodynamic-based functional neuroimaging technique, is especially suited to probe brain activity and primarily used in animal models. Increasing use of pharmacological models for essential tremor extends new research to the utilization of fUS imaging in such models. Harmaline-induced tremor is an easily provoked model for the development of new therapies for essential tremor (ET). Furthermore, harmaline-induced tremor can be suppressed by the same classic medications used for essential tremor, which leads to the utilization of this model for preclinical testing. However, changes in local cerebral activities under the effect of tremorgenic doses of harmaline have not been completely investigated. In this study, we explored the feasibility of fUS imaging for visualization of cerebral activation and deactivation associated with harmaline-induced tremor and tremor-suppressing effects of propranolol. The spatial resolution of fUS using a high frame rate imaging enabled us to visualize time-locked and site-specific changes in cerebral blood flow associated with harmaline-evoked tremor. Intraperitoneal administration of harmaline generated significant neural activity changes in the primary motor cortex and ventrolateral thalamus (VL Thal) regions during tremor and then gradually returned to baseline level as tremor subsided with time. To the best of our knowledge, this is the first functional ultrasound study to show the neurovascular activation of harmaline-induced tremor and the therapeutic suppression in a rat model. Thus, fUS can be considered a noninvasive imaging method for studying neuronal activities involved in the ET model and its treatment.

Tremor Induced by Cyclosporine, Tacrolimus, Sirolimus, or Everolimus: A Review of the Literature.

Calcineurin inhibitors such as cyclosporine and tacrolimus are immunosuppressant drugs that are known to induce tremors. Non-calcineurin inhibitors such as sirolimus and everolimus have also reportedly been accompanied by tremors, albeit less likely. However, the prevalence rates reported in the literature are notably wide, and the risk profiles for these drug-induced tremors are less understood. We searched PubMed to extract data on the risk of tremors with these drugs when prescribed for various transplant and non-transplant indications. We ascertained whether the risk of drug-induced tremor is influenced by the underlying diagnosis, dosing formulations, drug concentrations, and blood monitoring. We extracted data on treatment strategies and outcomes for tremors. Articles were primarily screened based on English language publications, abstracts, and studies with n ≥ 5, which included case series, retrospective studies, case-controlled studies, and prospective studies. We found 81 eligible studies comprising 33 cyclosporine, 43 tacrolimus, 6 sirolimus, and 1 everolimus that discussed tremor as an adverse event. In the pooled analysis of studies with n > 100, the incidence of tremor was 17% with cyclosporine, 21.5% with tacrolimus, and 7.8% with sirolimus and everolimus together. Regarding the underlying diagnosis, tremor was more frequently reported in kidney transplant (cyclosporine 28%, tacrolimus 30.1%) and bone marrow transplant (cyclosporine 40%, tacrolimus 41.9%) patients compared with liver transplant (cyclosporine 9%, tacrolimus 11.5%) and nontransplant indications (cyclosporine 21.5%, tacrolimus 11.3%). Most studies did not report whether the risk of tremors correlated with drug concentrations in the blood. The prevalence of tremors when using the twice-daily formulation of tacrolimus was nearly the same as the once-daily formulation (17% vs 18%). Data on individual-level risk factors for tremors were lacking. Except for three studies that found some benefit to maintaining magnesium levels, there were minimal data on treatments and outcomes. A large body of data supports a substantive and wide prevalence of tremor resulting from tacrolimus use followed by cyclosporine, especially in patients receiving a kidney transplant. However, there is little reporting on the patient-related risk factors for tremor, risk relationship with drug concentrations, treatment strategies, and outcomes.

Effectiveness of Botulinum Toxin on Hand Tremor Intensity and Upper Limb Function in Patients with Parkinson's Disease: Results of a Systematic Review.

Background: Hand tremor is a common symptom of Parkinson's disease (PD). Tremors may be resistant to drug treatments. Therefore, Botulinum toxin (BoNT) could be a good alternative. This study aimed to review and analyze studies on the efficacy and safety of BoNT injection in hand tremor intensity and upper limb function in patients with idiopathic PD. Methods: A comprehensive search was conducted for studies on the effect of local BoNT injections on tremors in PD patients from 1990 to December 2021. Electronic databases such as Cochrane Central Control Records, PubMed, Scopus, Web of Science, EMBASE, Google Scholar, Clinicaltrial.gov, ProQuest, Science Direct, CINAHL, and Psychoinfo were searched systematically. Results: Ten studies, comprising one double-blinded randomized clinical trial and nine pilot open-labeled studies with 131 participants, met eligibility criteria. The reported tremor intensity ranged from 1 to 3, and the average tremor duration of 5.93 ± 2.08 years. The injectable dose was 68-100 units of onabotulinum-toxin-A in each upper limb muscle, mostly wrist flexors. The results showed a decrease in unified Parkinson's disease rating scale (UPDRS)_20 and UPDRS_21 indices by 1.22 ± 1.1 and 1.20 ± 0.9, respectively, without causing severe side effects. The BoNT relative effectiveness in the forearm and arm muscles was reported 6-16 weeks after injection. Discussion: The kinematic, electromyography-guided, and electrical stimulation evaluations allow for accurate muscle localization and minimize the possibility of BoNT diffusion and antibody formation. More extensive randomized clinical trials with uniform measurement criteria are recommended to reduce bias and provide more accurate conclusions. Highlight: Tremor treatment in Parkinson's-disease (PD) is challenging. Drugs effect is temporary, and surgery is critical management. This study reviews the Botulinum-toxin injection efficacy in hand tremor intensity and upper limb function. The results showed a decrease in unified Parkinson's disease rating scale (UPDRS)_20 and UPDRS_21 by 1.22 ± 1.1 and 1.20 ± 0.9, respectively, 6-16 weeks after injection.

Task Specific Tremor in Parkinson's Disease Responds to Apomorphine.

Background: Task specific tremor (TST) is a poorly understood entity without any standard treatments, that may subsequently develop tremor during additional tasks, later develop postural/kinetic tremor (essential tremor criteria), and later develop Parkinson's disease. The pathophysiology is not understood as it has features of tremor, dystonia, and parkinsonism. Objectives: To assess response of TST to apomorphine and thus infer pathophysiology. Methods: We administered sublingual apomorphine to 8 patients diagnosed with Parkinson's disease based on clinical criteria and dopamine imaging, who all initially presented with TST and later presented other parkinsonian signs and dopamine imaging deficits. Results: Apomorphine improved TST, which was refractory to oral levodopa and other tremor therapies, in 6/8 subjects. Discussion: These results offer a treatment option for TST, which is usually refractory to other pharmacologic treatments, in patients with other parkinsonian features, and infers a dopaminergic pathophysiology of TST.

Intravenous Magnesium Sulfate Reduces Tremor Severity: A Case Series.

Introduction: Tremors involve involuntary muscle contractions that can occur at rest or during movement. Parkinson's disease (PD), the most common form of resting tremor, is conventionally treated with dopamine agonists, a therapy with a limited window of efficacy as the disease progresses due to levodopa tachyphylaxis. Complementary and Integrative Health (CIH) interventions represent low-cost options for a disease which is expected to double in prevalence in the next decade. Based on its use in many conditions, magnesium sulfate may have therapeutic potential for patients with tremors. This case series presents findings on the use of intravenous magnesium sulfate for the management of four patients with tremors. Methods: All four patients were seen at the National University of Natural Medicine clinic and screened for contraindications and safety considerations prior to each treatment using the acronym, ATHUMB: allergies, treatment response, health history, urinalysis, medications, and breakfast/meal timing. Magnesium sulfate is given in an initial dose of 2000 mg increasing in increments of 500 mg over the next one-to-two office visits up to a 3500 mg maximum. Results: Reductions in tremor severity were noticed for each patient during and following treatment. All patients reported a 24-48-hour window of relief and improvement in activities of daily living after each IV; 3 of 4 patients reported that window extended to 5-7 days. Conclusion: IV magnesium sulfate was effective in decreasing tremor severity. Future research should explore the impact of IV magnesium sulfate on tremors using objective and self-reported measures to quantify the size and duration of its effect.

Non-lesional treatments for tremor in Parkinson's disease: A systematic review and meta-analysis.

INTRODUCTION: Tremor is often perceived as severely disabling by patients with idiopathic Parkinson's disease (iPD) and yet ranges among the most difficult symptoms to treat. To date, no comprehensive analysis of non-lesional therapies to manage tremor in iPD exists to base recommendations upon. We therefore present a systematic literature review and meta-analysis assessing the efficacy/effectiveness and safety of non-lesional treatments for tremor in iPD. METHODS: Three electronic databases were searched using a combination of title/abstract keywords complemented by hand-searching of reference lists. A random-effects meta-analysis of standardized mean change scores was conducted where appropriate. RESULTS: Some 114 studies met inclusion criteria involving 8045 patients. The meta-analysis revealed an overall reduction of standardized mean change scores by (-0.93 [CI: -1.42; -0.43], p < 0.001) by 14 different dopaminergic and non-dopaminergic classes of agents. No significant differences were identified between direct comparisons. Subgroup analysis comparing dopamine receptor agonists resulted in superior effects of pramipexole and rotigotine compared with ropinirole. There was little cumulative evidence to support the use of individual non-pharmacological interventions for tremor, except for electrical stimulation. CONCLUSIONS: The results of this meta-analysis suggest a large but nonspecific effect of established pharmacological therapies on tremor in iPD. Based on high-quality studies, there is sufficient evidence to support that levodopa, dopamine receptor agonists, and monoamine oxidase inhibitors provide tremor relief in most patients, while evidence supporting other treatments is less well established. Sufficient evidence to draw conclusions on effects of non-lesional treatments in cases with refractory tremor is lacking.

Alcohol and Ganaxolone Suppress Tremor via Extra-Synaptic GABAA Receptors in the Harmaline Model of Essential Tremor.

Background: A long-standing question is why essential tremor often responds to non-intoxicating amounts of alcohol. Blood flow imaging and high-density electroencephalography have indicated that alcohol acts on tremor within the cerebellum. As extra-synaptic δ-subunit-containing GABAA receptors are sensitive to low alcohol levels, we wondered whether these receptors mediate alcohol's anti-tremor effect and, moreover, whether the δ-associated GABAA receptor α6 subunit, found abundantly in the cerebellum, is required. Methods: We tested the hypotheses that low-dose alcohol will suppress harmaline-induced tremor in wild-type mice, but not in littermates lacking GABAA receptor δ subunits, nor in littermates lacking α6 subunits. As the neurosteroid ganaxolone also activates extra-synaptic GABAA receptors, we similarly assessed this compound. The harmaline mouse model of essential tremor was utilized to generate tremor, measured as a percentage of motion power in the tremor bandwidth (9-16 Hz) divided by background motion power at 0.25-32 Hz. Results: Ethanol, 0.500 and 0.575 g/kg, and ganaxolone, 7 and 10 mg/kg, doses that do not impair performance in a sensitive psychomotor task, reduced harmaline tremor compared to vehicle-treated controls in wild-type mice but failed to suppress tremor in littermates lacking the δ or the α6 GABAA receptor subunit. Discussion: As cerebellar granule cells are the predominant brain site intensely expressing GABAA receptors containing both α6 and δ subunits, these findings suggest that this is where alcohol acts to suppress tremor. It is anticipated that medications designed specifically to target α6ßδ-containing GABAA receptors may be effective and well-tolerated for treating essential tremor. Highlights: How does alcohol temporarily ameliorate essential tremor? This study with a mouse model found that two specific kinds of GABA receptor subunits were needed for alcohol to work. As receptors with both these subunits are found mainly in cerebellum, this work suggests this is where alcohol acts to suppress tremor.