The vital role of natural history studies in rare disease: insights from X-linked dystonia parkinsonism.

This scientific commentary refers to 'Establishing a natural history of X-linked dystonia parkinsonism', by Acuna et al. (https://doi.org/10.1093/braincomms/fcad106).

Rapid-onset dystonia-parkinsonism is associated with reduced cerebral blood flow without gray matter changes.

Purpose: Previous research showed discrete neuropathological changes associated with rapid-onset dystonia-parkinsonism (RDP) in brains from patients with an ATP1A3 variant, specifically in areas that mediate motor function. The purpose of this study was to determine if magnetic resonance imaging methodologies could identify differences between RDP patients and variant-negative controls in areas of the brain that mediate motor function in order to provide biomarkers for future treatment or prevention trials. Methods: Magnetic resonance imaging voxel-based morphometry and arterial spin labeling were used to measure gray matter volume and cerebral blood flow, respectively, in cortical motor areas, basal ganglia, thalamus, and cerebellum, in RDP patients with ATP1A3 variants (n = 19; mean age = 37 ± 14 years; 47% female) and variant-negative healthy controls (n = 11; mean age = 34 ± 19 years; 36% female). Results: We report age and sex-adjusted between group differences, with decreased cerebral blood flow among patients with ATP1A3 variants compared to variant-negative controls in the thalamus (p = 0.005, Bonferroni alpha level < 0.007 adjusted for regions). There were no statistically significant between-group differences for measures of gray matter volume. Conclusions: There is reduced cerebral blood flow within brain regions in patients with ATP1A3 variants within the thalamus. Additionally, the lack of corresponding gray matter volume differences may suggest an underlying functional etiology rather than structural abnormality.

Temperature instability of a mutation at a multidomain junction in Na,K-ATPase isoform ATP1A3 (p.Arg756His) produces a fever-induced neurological syndrome.

ATP1A3 encodes the α3 isoform of Na,K-ATPase. In the brain, it is expressed only in neurons. Human ATP1A3 mutations produce a wide spectrum of phenotypes, but particular syndromes are associated with unique substitutions. For arginine 756, at the junction of membrane and cytoplasmic domains, mutations produce encephalopathy during febrile infections. Here we tested the pathogenicity of p.Arg756His (R756H) in isogenic mammalian cells. R756H protein had sufficient transport activity to support cells when endogenous ATP1A1 was inhibited. It had half the turnover rate of wildtype, reduced affinity for Na+, and increased affinity for K+. There was modest endoplasmic reticulum retention during biosynthesis at 37 °C but little benefit from the folding drug phenylbutyrate (4-PBA), suggesting a tolerated level of misfolding. When cells were incubated at just 39 °C, however, α3 protein level dropped without loss of ß subunit, paralleled by an increase of endogenous α1. Elevated temperature resulted in internalization of α3 from the surface along with some ß subunit, accompanied by cytoplasmic redistribution of a marker of lysosomes and endosomes, lysosomal-associated membrane protein 1. After return to 37 °C, α3 protein levels recovered with cycloheximide-sensitive new protein synthesis. Heating in vitro showed activity loss at a rate 20- to 30-fold faster than wildtype, indicating a temperature-dependent destabilization of protein structure. Arg756 appears to confer thermal resistance as an anchor, forming hydrogen bonds among four linearly distant parts of the Na,K-ATPase structure. Taken together, our observations are consistent with fever-induced symptoms in patients.

AbobotulinumtoxinA provides flexibility for the treatment of cervical dystonia with 500 U/1 mL and 500 U/2 mL dilutions.

INTRODUCTION: Cervical dystonia (CD) is a neurologic movement disorder with potentially disabling effects and significant impact on quality of life of those affected. AbobotulinumtoxinA (aboBoNT-A) was initially approved for a dilution of 500 U/1 mL and subsequently for a dilution of 500 U/2 mL, providing flexibility for clinicians to treat CD. Here, we explore the safety and efficacy of the 500 U/2 mL dilution versus 500 U/1 mL dilution of aboBoNT-A in a retrospective analysis based on published clinical trial data. METHODS: The safety and efficacy of aboBoNT-A in patients with CD was evaluated in three multicenter, double-blind, randomized, placebo-controlled trials and open-label extensions. Trials 1 (NCT00257660) and 2 (NCT00288509) evaluated the 500 U/1 mL dilution in 80 and 116 patients, respectively; Trial 3 (NCT01753310) evaluated the 500 U/2 mL dilution in 125 patients. RESULTS: Comparison of the adjusted mean difference in TWSTRS total scores at Week 4 from baseline for aboBoNT-A in Trial 1 (-6.0; 95% CI, -10.8, -1.3), Trial 2 (-8.8; 95% CI, -12.9, -4.7), and Trial 3 (-8.7; 95% CI, -13.2, -4.2) showed similar, significant improvements. Dysphagia and muscle weakness patterns were comparable across the three trials, indicating that an increased dilution of aboBoNT-A does not result in an increased risk of diffusion-related adverse events. CONCLUSION: The results of these trials show that aboBoNT-A is similarly efficacious using either dilution, with similar safety and tolerability across trials. Having the 500 U/1 mL and 500 U/2 mL dilution volumes available provides further flexibility in administration, benefiting patient care.

Predictive modeling of spread in adult-onset isolated dystonia: Key properties and effect of tremor inclusion.

BACKGROUND AND PURPOSE: Several clinical and demographic factors relate to anatomic spread of adult-onset isolated dystonia, but a predictive model is still lacking. The aims of this study were: (i) to develop and validate a predictive model of anatomic spread of adult-onset isolated dystonia; and (ii) to evaluate whether presence of tremor associated with dystonia influences model predictions of spread. METHODS: Adult-onset isolated dystonia participants with focal onset from the Dystonia Coalition Natural History Project database were included. We developed two prediction models, one with dystonia as sole disease manifestation ("dystonia-only") and one accepting dystonia OR tremor in any body part as disease manifestations ("dystonia OR tremor"). Demographic and clinical predictors were selected based on previous evidence, clinical plausibility of association with spread, or both. We used logistic regressions and evaluated model discrimination and calibration. Internal validation was carried out based on bootstrapping. RESULTS: Both predictive models showed an area under the curve of 0.65 (95% confidence intervals 0.62-0.70 and 0.62-0.69, respectively) and good calibration after internal validation. In both models, onset of dystonia in body regions other than the neck, older age, depression and history of neck trauma were predictors of spread. CONCLUSIONS: This predictive modeling of spread in adult-onset isolated dystonia based on accessible predictors (demographic and clinical) can be easily implemented to inform individuals' risk of spread. Because tremor did not influence prediction of spread, our results support the argument that tremor is a part of the dystonia syndrome, and not an independent or coincidental disorder.

A Multi-center Genome-wide Association Study of Cervical Dystonia.

BACKGROUND: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. OBJECTIVE: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. METHODS: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. RESULTS: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10-8 ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10-6 ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10-8 , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). CONCLUSION: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia. © 2021 International Parkinson and Movement Disorder Society.

Correction: Sustained functional benefits after a single set of injections with abobotulinumtoxinA using a 2-mL injection volume in adults with cervical dystonia: 12-week results from a randomized, double-blind, placebo-controlled phase 3b study.

[This corrects the article DOI: 10.1371/journal.pone.0245827.].

Longitudinal goal attainment with integrated upper limb spasticity management including repeat injections of botulinum toxin A: Findings from the prospective, observational Upper Limb International Spasticity (ULIS-III) cohort study.

OBJECTIVE: To assess the longitudinal effects of integrated spasticity management incorporating repeated cycles of botulinum toxin A type A (BoNT-A) over 2 years. METHODS: The Upper Limb International Spasticity study was a prospective, observational, cohort study following adult patients over 2 years of integrated upper-limb spasticity management including repeat botulinum toxin (BoNT-A) treatment (any commercially-available product). RESULTS: A total of 1,004 participants from 14 countries were enrolled, of which 953 underwent ≥ 1 BoNT-A injection cycle (median 4 cycles) and had ≥ 1 goal attainment scaling assessment. Most participants (55.9-64.6% across cycles 1-6) saw a therapist after BoNT-A treatment; the most frequent therapy intervention was passive stretch (70.1-79.8% across cycles 1-6). Patients achieved their goals as expected over repeated cycles; mean cumulated goal attainment scaling T-score at 2 years was 49.5 (49.1, 49.9). Mean goal attainment scaling change scores of ≥ 10 were maintained across up to 7 cycles. Higher rates of goal achievement were seen for primary goals related to passive vs active function (86.6% vs 71.4% achievement). Standardized measures of spasticity, pain, involuntary movements, active and passive function improved significantly over the study. CONCLUSION: This large, international study provides evidence for benefit of repeated cycles of BoNT-A, over 2 years captured through person-centred goal attainment and standardized measures.

Sustained functional benefits after a single set of injections with abobotulinumtoxinA using a 2-mL injection volume in adults with cervical dystonia: 12-week results from a randomized, double-blind, placebo-controlled phase 3b study.

Cervical dystonia (CD) is primarily treated with botulinum toxin, at intervals of ≥ 12 weeks. We present efficacy, patient-reported outcomes (PROs), and safety in adults with CD at the last available visit after a single set of abobotulinumtoxinA (aboBoNT-A) injections versus placebo using 500 U in a 2-mL injection volume. In this 12-week, randomized, double-blind trial, patients were ≥ 18 years of age with primary idiopathic CD, had a Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score ≥ 20, and TWSTRS-Severity subscale score > 10 at baseline. Patients (N = 134) were randomized (2:1) to aboBoNT-A (n = 89) or placebo (n = 45), with aboBoNT-A patients treated with 500 units (U) if toxin-naïve, and 250 to 500 U based on previous onabotulinumtoxinA dose if non-naïve. Endpoints included total TWSTRS, Pain Numeric Rating Scale (NRS-Pain; 24-hour), Treatment Satisfaction Questionnaire for Medication, and other PROs for pain, depression, and global health. Results are for the intent-to-treat population, with "Week 12" (Wk12) comprising the last available post-baseline assessment (end-of-study or early withdrawal). Mean TWSTRS total scores improved from 42.5 at baseline to 35.4 at Wk12 with aboBoNT-A and 42.4 to 40.4 with placebo (treatment difference: -4.8; 95% confidence interval [CI]: -8.5, -1.1; p = 0.011). At Wk12, mean (95% CI) change from baseline in NRS-Pain was -1.0 (-1.59, -0.45) for aboBoNT-A and -0.2 (-0.96, 0.65) for placebo. AboBoNT-A demonstrated numeric improvements in other PROs. More aboBoNT-A-treated patients than patients receiving placebo reported being at least "somewhat satisfied" with treatment (60.4% vs 42.2%, respectively), symptom relief (57.0% vs 40.0%), and time for treatment to work (55.8% vs 33.3%). No new adverse events were reported. Results indicate that in patients with CD, treatment with aboBoNT-A using a 2-mL injection provided sustained improvement in the TWSTRS total score and patient-perceived benefits up to 12 weeks. Trial registration: Clinicaltrials.gov Identified: NCT01753310.

Assessing the effectiveness of upper-limb spasticity management using a structured approach to goal-setting and outcome measurement: First cycle results from the ULIS-III Study.

OBJECTIVE: To describe the utility of a structured approach to assessing effectiveness following injection with botulinum toxin-A alongside physical therapies, within the first cycle of the Upper Limb International Spasticity-III (ULIS-III) study. METHODS: ULIS-III (registered at clinicaltrials.gov as NCT02454803) is a large international, observation-al, longitudinal study of adults treated for upper-limb spasticity. It introduces novel methods for the structured evaluation of person-centred goal attainment alongside targeted standardized outcome measures: the Upper limb Spasticity Index, and the Upper Limb Spasticity Therapy Recording Schedule. RESULTS: A total of 953/1,004 enrolled patients (95%) completed cycle 1. Mean overall goal attainment scaling (GAS) T scores were 49.8 (95% confidence interval 49.2-50.3; 67.1% of patients met their primary goal, with highest achievement rates for goals related to involuntary movement, (75.6%) and range of movement (74.4%). Standardized measures of spasticity, pain, involuntary movements, active and passive function, all improved significantly over the treatment cycle. Overall, 59.7% of patients saw a therapist following botulinum toxin-A injection. Interventions varied, as expected, with the set treatment goals. After controlling for concomitant therapies using the upper limb spasticity therapy recording schedule, significant differences in injection intervals (p < 0.001) were seen between the commercially-available botulinum toxin-A agents. CONCLUSION: The results of this study confirm the utility of the Upper Limb Spasticity Index and Upper Limb Spasticity Therapy Recording Schedule as a structured approach to capturing goal-setting, therapy inputs and outcomes assessment.

Misfolding, altered membrane distributions, and the unfolded protein response contribute to pathogenicity differences in Na,K-ATPase ATP1A3 mutations.

Missense mutations in ATP1A3, the α3 isoform of Na,K-ATPase, cause neurological phenotypes that differ greatly in symptoms and severity. A mechanistic basis for differences is lacking, but reduction of activity alone cannot explain them. Isogenic cell lines with endogenous α1 and inducible exogenous α3 were constructed to compare mutation properties. Na,K-ATPase is made in the endoplasmic reticulum (ER), but the glycan-free catalytic α subunit complexes with glycosylated ß subunit in the ER to proceed through Golgi and post-Golgi trafficking. We previously observed classic evidence of protein misfolding in mutations with severe phenotypes: differences in ER retention of endogenous ß1 subunit, impaired trafficking of α3, and cytopathology, suggesting that they misfold during biosynthesis. Here we tested two mutations associated with different phenotypes: D923N, which has a median age of onset of hypotonia or dystonia at 3 years, and L924P, with severe infantile epilepsy and profound impairment. Misfolding during biosynthesis in the ER activates the unfolded protein response, a multiarmed program that enhances protein folding capacity, and if that fails, triggers apoptosis. L924P showed more nascent protein retention in ER than D923N; more ER-associated degradation of α3 (ERAD); larger differences in Na,K-ATPase subunit distributions among subcellular fractions; and greater inactivation of eIF2α, a major defensive step of the unfolded protein response. In L924P there was also altered subcellular distribution of endogenous α1 subunit, analogous to a dominant negative effect. Both mutations showed pro-apoptotic sensitization by reduced phosphorylation of BAD. Encouragingly, however, 4-phenylbutyrate, a pharmacological corrector, reduced L924P ER retention, increased α3 expression, and restored morphology.

Dystonia and Tremor: A Cross-Sectional Study of the Dystonia Coalition Cohort.

OBJECTIVE: To assess the clinical manifestations and predictors of different types of tremors in individuals with different types of isolated dystonia. METHODS: Clinical manifestations of tremor were assessed in a multicenter, international cross-sectional, cohort study of 2,362 individuals with all types of isolated dystonia (focal, segmental, multifocal, and generalized) recruited through the Dystonia Coalition. RESULTS: Methodical and standardized assessments of all participants in this cohort revealed the overall prevalence of any type of tremor was 53.3%. The prevalence of dystonic tremor varied from 36.9% to 48.4%, depending on criteria used to define it. To identify the factors associated with tremors in dystonia, the data were analyzed by generalized linear modeling and cluster analyses. Generalized linear modeling indicated 2 of the strongest factors associated with tremor included body region affected by dystonia and recruitment center. Tremor was also associated with severity of dystonia and duration of dystonia, but not with sex or race. The cluster analysis distinguished 8 subgroups within the whole cohort; defined largely by body region with dystonia, and secondarily by other clinical characteristics. CONCLUSION: The large number of cases evaluated by an international team of movement disorder experts facilitated the dissection of several important factors that influence the apparent prevalence and phenomenology of tremor in dystonia. These results are valuable for understanding the many differences reported in prior studies, and for guiding future studies of the nosology of tremor and dystonia.

The Effect of Repeated abobotulinumtoxinA (Dysport®) Injections on Walking Velocity in Persons with Spastic Hemiparesis Caused by Stroke or Traumatic Brain Injury.

BACKGROUND: Botulinum toxin (BoNT) injections were shown to improve muscle tone of limbs in patients with spasticity. However, limited data are available regarding the effects of repeated BoNT injections on walking ability. OBJECTIVE: To assess changes in walking velocity (WV), step length, and cadence under different test conditions after repeated treatment with abobotulinumtoxinA (aboBoNT-A; Dysport) in spastic lower limb muscles. DESIGN: Secondary analysis of an open-label, multiple-cycle extension (National Clinical Trials number NCT01251367) to a phase III, double-blind, randomized, placebo-controlled, single-treatment cycle study, in adults with chronic hemiparesis (NCT01249404). SETTING: Fifty-two centers across Australia, Belgium, the Czech Republic, France, Hungary, Italy, Poland, Portugal, Russia, Slovakia, and the United States. PATIENTS: 352 Ambulatory adults (18-80 years) with spastic hemiparesis and gait dysfunction caused by stroke or traumatic brain injury, with a comfortable barefoot WV of 0.1 to 0.8 m/s. INTERVENTIONS: Up to four aboBoNT-A treatment cycles, administered to spastic lower limb muscles. MAIN OUTCOME MEASUREMENTS: Changes from baseline in comfortable and maximal barefoot and with shoes WV (m/s), step length (m/step), and cadence (steps/minutes). RESULTS: At Week 12 after four injections, WV improved by 0.08 to 0.10 m/s, step length by 0.03 to 0.04 m/step, and cadence by 3.9 to 6.2 steps/minutes depending on test condition (all P < .0001 to .0003 vs baseline). More patients (7% to 17%) became unlimited community ambulators (WV ≥0.8 m/s) across test conditions compared with baseline, with 39% of 151 patients classified as unlimited community ambulators in at least one test condition and 17% in all four test conditions. CONCLUSIONS: Clinically meaningful and statistically significant improvements in WV, step length, and cadence under all four test conditions were observed in patients with spastic hemiparesis after each aboBoNT-A treatment cycle.

Auditory-perceptual voice and speech evaluation in ATP1A3 positive patients.

INTRODUCTION: Bulbar symptoms are frequent in patients with rapid-onset dystonia-parkinsonism (RDP). RDP is caused by ATP1A3 mutations, with onset typically within 30 days of stressor exposure. Most patients have impairments in speech (dysarthria) and voice (dysphonia). These have not been quantified. We aimed to formally characterize these in RDP subjects as compared to mutation negative family controls. METHODS: We analyzed recordings in 32 RDP subjects (male = 21, female = 11) and 29 mutation negative controls (male = 15, female = 14). Three raters, blinded to mutation status, rated speech and vocal quality. Dysarthria was classified by subtype. Dysphonia was rated via the GRBAS (Grade, Roughness, Breathiness, Asthenia, Strain) scale. We used general neurological exams and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) to assess dysarthria, dystonia, and speech/swallowing dysfunction. RESULTS: The presence of dysarthria was more frequent in RDP subjects compared to controls (72% vs. 17%, p < 0.0001). GRBAS voice ratings were worse in the RDP cohort across nearly all categories. Dysarthria in RDP was associated with concordant cranial nerve 9-11 dysfunction (54%, p = 0.048), speech/swallowing dysfunction (96%, p = 0.0003); and oral dystonia (88%, p = 0.001). CONCLUSIONS: Quantitative voice and speech analyses are important in assessing RDP. Subjects frequently experience dysarthria and dysphonia. Dystonia is not the exclusive voice abnormality present in this population. In our analysis, RDP subjects more frequently experienced bulbar symptoms than controls. GRBAS scores are useful in quantifying voice impairment, potentially allowing for better assessments of progression or treatment effects. Future directions include using task-specific diagnostic and perceptual voice evaluation tools to further assess laryngeal dystonia.

Safety and Stability of Pulmonary Function in Patients with Decreased Respiratory Function Treated for Spasticity with OnabotulinumtoxinA.

Two randomized, placebo-controlled studies evaluated the pulmonary function safety of onabotulinumtoxinA (onabotA) for treatment of upper and/or lower limb spasticity. Patients with stable baseline respiratory status received one or two treatments with placebo, 240 U, or 360 U of onabotA. Pulmonary function tests, adverse events, and efficacy were measured at least every 6 weeks for 18 weeks (Study 1) or 30 weeks (Study 2). Study 1 enrolled 109 patients (n = 36-37/group) and Study 2 enrolled 155 patients (n = 48-54/group). Mean baseline forced vital capacity (FVC) was 76-78% of predicted per group in Study 1 and 71% of predicted per group in Study 2. In Study 1, change from baseline FVC values were significantly (p < 0.05) decreased vs. placebo at weeks 3 (240 U -57 mL vs. placebo +110 mL) and 12 (360 U -6 mL vs. +167 mL placebo). In Study 2, change from baseline FVC values were significantly decreased in the 360 U group vs. placebo at weeks 6 (-78 mL vs. +49 mL placebo), 13 (-60 mL vs. +119 mL placebo), 18 (-128 mL vs. +80 mL placebo), and 24 (-82 mL vs. +149 mL placebo). Individual pulmonary function-related adverse events were not correlated with PFT decreases. The most frequent pulmonary-related adverse events were nasopharyngitis (Study 1) and upper respiratory tract infection (Study 2). Ashworth scores were significantly improved at multiple time points in both studies. Injection of onabotA for spasticity in patients with decreased pulmonary function, at single and repeated doses of up to 360 U, was associated with small but statistically significant decreases in FVC or forced expiratory volume 1 s (FEV1) (>12% and 200 mL) that were subclinical and not correlated with any adverse clinical pulmonary events.

Cardiac phenotype in ATP1A3-related syndromes: A multicenter cohort study.

OBJECTIVE: To define the risks and consequences of cardiac abnormalities in ATP1A3-related syndromes. METHODS: Patients meeting clinical diagnostic criteria for rapid-onset dystonia-parkinsonism (RDP), alternating hemiplegia of childhood (AHC), and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) with ATP1A3 genetic analysis and at least 1 cardiac assessment were included. We evaluated the cardiac phenotype in an Atp1a3 knock-in mouse (Mashl+/-) to determine the sequence of events in seizure-related cardiac death. RESULTS: Ninety-eight patients with AHC, 9 with RDP, and 3 with CAPOS (63 female, mean age 17 years) were included. Resting ECG abnormalities were found in 52 of 87 (60%) with AHC, 2 of 3 (67%) with CAPOS, and 6 of 9 (67%) with RDP. Serial ECGs showed dynamic changes in 10 of 18 patients with AHC. The first Holter ECG was abnormal in 24 of 65 (37%) cases with AHC and RDP with either repolarization or conduction abnormalities. Echocardiography was normal. Cardiac intervention was required in 3 of 98 (≈3%) patients with AHC. In the mouse model, resting ECGs showed intracardiac conduction delay; during induced seizures, heart block or complete sinus arrest led to death. CONCLUSIONS: We found increased prevalence of ECG dynamic abnormalities in all ATP1A3-related syndromes, with a risk of life-threatening cardiac rhythm abnormalities equivalent to that in established cardiac channelopathies (≈3%). Sudden cardiac death due to conduction abnormality emerged as a seizure-related outcome in murine Atp1a3-related disease. ATP1A3-related syndromes are cardiac diseases and neurologic diseases. We provide guidance to identify patients potentially at higher risk of sudden cardiac death who may benefit from insertion of a pacemaker or implantable cardioverter-defibrillator.

Efficacy and Safety of AbobotulinumtoxinA for the Treatment of Hemiparesis in Adults with Lower Limb Spasticity Previously Treated With Other Botulinum Toxins: A Secondary Analysis of a Randomized Controlled Trial.

OBJECTIVE: To examine the safety and efficacy of abobotulinumtoxinA in patients previously treated with botulinum toxin type A (BoNT-A) products other than abobotulinumtoxinA. DESIGN: Secondary analysis from a phase 3, double-blind, single-cycle, randomized, placebo-controlled study. SETTING: Fifty-two centers (11 countries). PATIENTS: Adults with spastic hemiparesis were randomized (1:1:1) to receive abobotulinumtoxinA 1000 U, 1500 U, or placebo in their affected lower limb. MAIN OUTCOME MEASUREMENTS: Muscle tone (6-point Modified Ashworth Scale [MAS], 0-5) for the gastrocnemius-soleus complex (GSC); proportion of MAS responders (≥1-point improvement); angle of catch (XV3 ) and spasticity grade (Y) for the GSC and soleus. Assessments were at weeks 1, 4, and 12 post-injection. Only descriptive statistics are presented. RESULTS: Of 388 patients, 84 received previous BoNT-A treatment (abobotulinumtoxinA 1000 U: N = 30; abobotulinumtoxinA 1500 U: N = 28; placebo: N = 26). At week 4, mean (SD) changes in MAS score in the GSC were - 0.8 (1.1), -0.9 (1.0), and - 0.4 (0.7) for abobotulinumtoxinA 1000 U, 1500 U, and placebo, respectively. Greater MAS responder rates were observed for abobotulinumtoxinA versus placebo at all time points. Mean (SD) changes (week 4) for abobotulinumtoxinA 1000 U, 1500 U, and placebo for XV3 were: GSC, 8° (21), 6° (10) and 1° (7); soleus, 11° (21), 5° (9) and 0° (8), respectively; for Y: GSC, -0.4 (0.7), -0.6 (0.8) and - 0.0 (0.9); soleus, -0.5 (0.7), -0.5 (0.7) and - 0.1 (0.6), respectively. Safety data and adverse events were consistent with the overall known profile of abobotulinumtoxinA. CONCLUSIONS: Patients previously treated with other BoNT-As showed improved muscle tone and spasticity at week 4 following abobotulinumtoxinA injection versus placebo. These findings suggest that abobotulinumtoxinA, at the recommended doses, has a good safety and efficacy profile in adults with lower limb spasticity who were previously treated with other BoNT-A products.

IncobotulinumtoxinA Treatment in Upper-Limb Poststroke Spasticity in the Open-Label Extension Period of PURE: Efficacy in Passive Function, Caregiver Burden, and Quality of Life.

BACKGROUND: Poststroke spasticity affects motor function and the ability to perform activities of daily living, with the potential to affect quality of life (QoL) and increase caregiver burden. OBJECTIVE: To investigate the effect of repeated incobotulinumtoxinA treatment on spasticity-associated functional disability, caregiver burden, and QoL in the 36-week open-label extension of the phase 3 PURE study (NCT01392300). DESIGN: Open-label extension period of a prospective, double-blind, placebo-controlled, randomized, multicenter study. SETTING: Forty-six investigation sites in seven countries (Czech Republic, Germany, Hungary, India, Poland, Russia, United States). PARTICIPANTS: Adults, aged 18-80 years, ≥12 months since last botulinum neurotoxin injection or entirely toxin naïve, with median poststroke upper-limb spasticity of >2 years' duration. METHODS: Participants who completed the 12-week, double-blind main period could enter the open-label extension and receive up to three additional incobotulinumtoxinA treatments (fixed total dose 400 U at 12-week intervals) into the affected muscles of one upper limb. MAIN OUTCOME MEASURES: Functional disability (Disability Assessment Scale; DAS), caregiver burden (Carer Burden Scale), and quality of life (QoL; EuroQol [EQ] 5-dimensions three-level [EQ-5D-3L]). RESULTS: The open-label extension included 296 treated patients. Mean DAS score for the principal target domain improved significantly from the main period baseline to the end-of-study visit (P < .0001). Carer Burden Scale scores also significantly improved from the main period baseline to the end-of-study visit (P < .05 for all caregiving activities except "applying a splint"). At the end-of-study visit, versus the main period baseline, 19.7%-33.3% of patients experienced improvements for each parameter on the EQ-5D-3L, except "mobility," with significant improvement in EQ-5D visual analog scale scores (P < .001). CONCLUSIONS: Repeated incobotulinumtoxinA treatments at 12-week intervals in participants with chronic poststroke upper-limb spasticity resulted in significant improvements in QoL, as well as significant reductions in upper-limb functional disability and caregiver burden.