Genotype-phenotype relations for episodic ataxia genes: MDSGene systematic review.

BACKGROUND: Most episodic ataxias (EA) are autosomal dominantly inherited and characterized by recurrent attacks of ataxia and other paroxysmal and non-paroxysmal features. EA is often caused by pathogenic variants in the CACNA1A, KCNA1, PDHA1, and SLC1A3 genes, listed as paroxysmal movement disorders (PxMD) by the MDS Task Force on the Nomenclature of Genetic Movement Disorders. Little is known about the genotype-phenotype correlation of the different genetic EA forms. METHODS: We performed a systematic review of the literature to identify individuals affected by an episodic movement disorder harboring pathogenic variants in one of the four genes. We applied the standardized MDSGene literature search and data extraction protocol to summarize the clinical and genetic features. All data are available via the MDSGene protocol and platform on the MDSGene website (https://www.mdsgene.org/). RESULTS: Information on 717 patients (CACNA1A: 491, KCNA1: 125, PDHA1: 90, and SLC1A3: 11) carrying 287 different pathogenic variants from 229 papers was identified and summarized. We show the profound phenotypic variability and overlap leading to the absence of frank genotype-phenotype correlation aside from a few key 'red flags'. CONCLUSION: Given this overlap, a broad approach to genetic testing using a panel or whole exome or genome approach is most practical in most circumstances.

Dopamine transporter imaging in essential tremor with and without parkinsonian features.

Mild parkinsonian features can be observed in patients with essential tremor (ET). Although dopamine transporter (DAT) imaging is usually normal in ET, some studies found mild dopaminergic deficit in ET patients compared to healthy controls (HC). We analyzed clinical and DAT imaging data in ET patients with and without parkinsonian features. Thirty-nine ET patients with and without parkinsonian features and 13 HC underwent detailed examination by a movement disorders neurologist and 123-I ioflupane SPECT. Two independent radiologists "blinded" to the clinical diagnosis analyzed images visually and by semi-quantitative calculation of striatal binding ratios in different volumes of interests. ET patients were divided into pure ET group (no parkinsonian features, n = 22), ET-P [one parkinsonian feature not sufficient for the clinical diagnosis of Parkinson's disease (PD), n = 9], and ET + PD (two or more parkinsonian features meeting diagnostic criteria for PD, n = 8). As expected, ET + PD patients had the lowest striatal binding ratios. We also found a trend toward slightly lower striatal binding ratios in ET patients ET compared to HC, especially in caudate nucleus. There was no significant correlation between striatal binding ratios, ET severity or duration. Patients with ET and parkinsonian features represent a heterogeneous group that includes ET + PD and ET-P. The latter group shares some clinical features with PD but has no dopaminergic deficit on DAT imaging as determined by visual image interpretation. On the other hand, minimal dopaminergic deficit (as compared to controls) is detected in some ET patients with semi-quantitative image analysis, although the pattern may be different from that of PD.

Rechargeable deep brain stimulation implantable pulse generators in movement disorders: patient satisfaction and conversion parameters.

OBJECTIVES: Rechargeable (RC) implantable pulse generators (IPGs) for deep brain stimulation (DBS) in movement disorders have recently become available. No guidelines exist for parameter adjustment after conversion of non-RC to RC IPGs, or reports of patient satisfaction with RC IPGs when used as initial DBS device or after conversion from non-RC IPGs. MATERIALS AND METHODS: Patients who underwent placement of Activa RC IPG (Medtronic, Inc.) were surveyed by phone about device satisfaction. Their charts were retrospectively reviewed and DBS settings were analyzed. The stimulation settings before and after conversion to RC were compared. RESULTS: Thirty-one patients (age 15-90; 18 male) with movement disorders (nine Parkinson's disease, nine dystonia, eight essential tremor, five others) were identified. Twelve subjects had initial RC IPG implantation; 19 were converted from non-RC IPGs (Soletra; Medtronic, Inc.) 2-14 years after initial DBS implant (mean 6.3 ± 3.44 years). Twenty-six patients (17 conversions) were surveyed an average of 12.1 months since RC IPG implantation. Overall satisfaction with RC was high. Patients converted to RC were more likely to choose it again than those with initial RC. Patients denied differences in symptom control after conversion. Mean amplitude, pulse width, and frequency were slightly lower after conversion regardless of diagnosis and remained lower after three postconversion reprogramming with slow drift of amplitude back to preconversion settings, more in the GPi group. CONCLUSIONS: RC IPGs in DBS for movement disorders are well received by patients as initial therapy and after conversion. Mild reduction in stimulation parameters might be allowed after conversion to RC IPG.

Real-World Evidence of Transcutaneous Afferent Patterned Stimulation for Essential Tremor.

Background: Transcutaneous afferent patterned stimulation (TAPS) is a prescription, wrist-worn device-delivered, non-invasive neuromodulation therapy for treatment of hand tremor in patients with essential tremor (ET). This retrospective post-market surveillance study evaluated real-world effectiveness of TAPS from patients using therapy on-demand for at least 90 days between August 2019 through June 2021. Methods: Demographics were summarized from TAPS prescriptions received from the patient's healthcare provider. Therapy usage and effectiveness were analyzed from device logs, which included tremor measurements from onboard motion sensors. Tremor history and patient-reported outcomes were assessed from a voluntary survey. Results: A total of 321 patients (average age 71 years, 32% female) met the criteria for this analysis, 216 of whom had tremor measurements available for analysis and 69 of whom completed the survey. Total usage period ranged from 90 to 663 days, with 28% of patients using the device for over one year. Patients used therapy 5.4 ± 4.5 (mean ± 1 standard deviation) times per week. TAPS reduced tremor power by 71% (geometric mean) across all sessions, with 59% of patients experiencing >50% tremor reduction after their sessions. Eighty-four percent (84%) of patients who returned the voluntary survey reported improvement in at least one of eating, drinking, or writing, and 65% of patients reported improvement in quality of life. Self-reported device-related safety complaints were consistent with adverse events in prior clinical trials. Discussion: Real-world evidence is consistent with prior clinical trials and confirms TAPS provides safe and effective tremor control for many patients with ET. Future work assessing multi-year safety and effectiveness would be valuable to extend these data.

Prospective Home-use Study on Non-invasive Neuromodulation Therapy for Essential Tremor.

Highlights: This prospective study is one of the largest clinical trials in essential tremor to date. Study findings suggest that individualized non-invasive neuromodulation therapy used repeatedly at home over three months results in safe and effective hand tremor reduction and improves quality of life for many essential tremor patients. Background: Two previous randomized, controlled, single-session trials demonstrated efficacy of non-invasive neuromodulation therapy targeting the median and radial nerves for reducing hand tremor. This current study evaluated efficacy and safety of the therapy over three months of repeated home use. Methods: This was a prospective, open-label, post-clearance, single-arm study with 263 patients enrolled across 26 sites. Patients were instructed to use the therapy twice daily for three months. Pre-specified co-primary endpoints were improvements on clinician-rated Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS) and patient-rated Bain & Findley Activities of Daily Living (BF-ADL) dominant hand scores. Other endpoints included improvement in the tremor power detected by an accelerometer on the therapeutic device, Clinical and Patient Global Impression scores (CGI-I, PGI-I), and Quality of Life in Essential Tremor (QUEST) survey. Results: 205 patients completed the study. The co-primary endpoints were met (p≪0.0001), with 62% (TETRAS) and 68% (BF-ADL) of 'severe' or 'moderate' patients improving to 'mild' or 'slight'. Clinicians (CGI-I) reported improvement in 68% of patients, 60% (PGI-I) of patients reported improvement, and QUEST improved (p = 0.0019). Wrist-worn accelerometer recordings before and after 21,806 therapy sessions showed that 92% of patients improved, and 54% of patients experienced ≥50% improvement in tremor power. Device-related adverse events (e.g., wrist discomfort, skin irritation, pain) occurred in 18% of patients. No device-related serious adverse events were reported. Discussion: This study suggests that non-invasive neuromodulation therapy used repeatedly at home over three months results in safe and effective hand tremor reduction in many essential tremor patients.

Effect of using a wearable device on clinical decision-making and motor symptoms in patients with Parkinson's disease starting transdermal rotigotine patch: A pilot study.

BACKGROUND: Feedback from wearable biosensors may help assess motor function in Parkinson's disease (PD) patients and titrate medication. Kinesia 360 continuously monitors motor symptoms via wrist and ankle sensors. METHODS: PD0049 was a 12-week pilot study to investigate whether using Kinesia 360 at home could improve motor symptom management in PD patients starting transdermal dopamine agonist rotigotine. Adults with PD and insufficiently controlled motor symptoms (prescribed rotigotine) were randomized 1:1 to Control Group (CG) or Experimental Group (EG) before starting rotigotine. Motor symptoms were assessed in all patients at baseline and Week 12 (W12) using Unified PD Rating Scale (UPDRS) III and Kinesia ONE, which measures standardized motor tasks via a sensor on the index finger. Between baseline and W12, EG used Kinesia 360 at home; clinicians used the data to supplement standard care in adjusting rotigotine dosage. RESULTS: At W12, least squares mean improvements in UPDRS II (-2.1 vs 0.5, p = 0.004) and UPDRS III (-5.3 vs -1.0, p = 0.134) were clinically meaningfully greater, and mean rotigotine dosage higher (4.8 vs 3.9 mg/24 h) in EG (n = 19) vs CG (n = 20). Mean rotigotine dosage increase (+2.8 vs + 1.9 mg/24 h) and mean number of dosage changes (2.8 vs 1.8) during the study were higher in EG vs CG. Tolerability and retention rates were similar. CONCLUSION: Continuous, objective, motor symptom monitoring using a wearable biosensor as an adjunct to standard care may enhance clinical decision-making, and may improve outcomes in PD patients starting rotigotine.

Paroxysmal movement disorders.

Paroxysmal dyskinesias represent a group of episodic abnormal involuntary movements manifested by recurrent attacks of dystonia, chorea, athetosis, or a combination of these disorders. Paroxysmal kinesigenic dyskinesia, paroxysmal nonkinesigenic dyskinesia, paroxysmal exertion-induced dyskinesia, and paroxysmal hypnogenic dyskinesia are distinguished clinically by precipitating factors, duration and frequency of attacks, and response to medication. Primary paroxysmal dyskinesias are usually autosomal dominant genetic conditions. Secondary paroxysmal dyskinesias can be the symptoms of different neurologic and medical disorders. This review summarizes the updates on etiology, pathophysiology, genetics, clinical presentation, differential diagnosis, and treatment of paroxysmal dyskinesias and other episodic movement disorders.

Asterixis related to gabapentin intake: a case report and review.

Asterixis has been reported as a side effect of toxic and metabolic abnormalities. The current literature contains very little evidence of gabapentin-related neurotoxicity. Our observations reveal that neurotoxic side effects of gabapentin use may be seen even when dose adjustments are made for patients with mild-to-moderate renal dysfunction. Clinical vigilance for possible neurotoxic effects of gabapentin therapy in patients with renal dysfunction is warranted.

An update on tardive dyskinesia: from phenomenology to treatment.

Tardive dyskinesia (TD), characterized by oro-buccal-lingual stereotypy, can manifest in the form of akathisia, dystonia, tics, tremor, chorea, or as a combination of different types of abnormal movements. In addition to movement disorders (including involuntary vocalizations), patients with TD may have a variety of sensory symptoms, such as urge to move (as in akathisia), paresthesias, and pain. TD is a form of tardive syndrome-a group of iatrogenic hyperkinetic and hypokinetic movement disorders caused by dopamine receptor-blocking agents. The pathophysiology of TD remains poorly understood, and treatment of this condition is often challenging. In this update, we provide the most current information on the history, nomenclature, etiology, pathophysiology, epidemiology, phenomenology, differential diagnosis, and treatment of TD.

Blepharospasm plus Cervical Dystonia with Predominant Anterocollis: A Distinctive Subphenotype of Segmental Craniocervical Dystonia?

BACKGROUND: Dystonia of the eyelids often spreads to affect other muscles in the craniocervical region. Certain blepharospasm-plus subphenotypes may be clinically unique. METHODS: Seven subjects with the subphenotype of late-onset blepharospasm with apraxia of eyelid opening and cervical dystonia with predominant anterocollis were identified from a database of over 1800 patients with primary dystonia. RESULTS: Blepharospasm was the first affected site in 6/7 subjects, followed by spread of the disease to the cervical muscles. Although four patients also had other forms of dystonia (laryngeal, lower face), none showed spread outside the craniocervical region. A family history of dystonia was present in 4/7. No mutations were identified in THAP1 or TOR1A. Overall, blepharospasm was difficult to treat, typically requiring both myectomy and substantial doses of botulinum toxin into the pretarsal orbicularis oculi muscles. In one subject, anterocollis markedly improved after deep brain stimulation. DISCUSSION: Delineation and characterization of craniocervical dystonia subphenotypes may serve to guide genetic and therapeutic studies, in addition to clinical interventions. The blepharospasm with apraxia of eyelid opening and anterocollis subphenotype can be therapeutically challenging.