The availability of three therapies for the neuromuscular disease spinal muscular atrophy (SMA) highlights the need to match patients to the optimal treatment. Two of these treatments (nusinersen and risdiplam) target splicing of , but treatment outcomes vary from patient to patient. An incomplete understanding of the complex interactions among SMA genetics, SMN protein and mRNA levels, and gene-targeting treatments, limits our ability to explain this variability and identify optimal treatment strategies for individual patients.
View Article and Find Full Text PDFBackground And Objective: Proximal spinal muscular atrophy (SMA) is caused by deficiency of the ubiquitously expressed survival motor neuron protein. Although primarily a hereditary lower motor neuron disease, it is probably also characterized by abnormalities in other organs. Brain abnormalities and cognitive impairment have been reported in severe SMA.
View Article and Find Full Text PDFThe Hammersmith Functional Motor Scale-Expanded (HFMSE) is a validated outcome measure for monitoring changes in functional strength in patients with spinal muscular atrophy (SMA). The objective of this study was to explore changes in HFMSE item-scores in children with SMA types 2 and 3a treated with nusinersen over a period of six to twenty months. We stratified patients according to motor ability (sitting and walking), and calculated numbers and percentages for each specific improvement (positive score change) or decrease (negative score change) for the total group and each subgroup and calculated frequency distributions of specific score changes.
View Article and Find Full Text PDFBackground: Hereditary proximal spinal muscular atrophy (SMA) is characterized by abnormal alpha motor neuron function in brainstem and spinal cord. Bulbar dysfunction, including limited mouth opening, is present in the majority of patients with SMA but it is unknown if and how these problems change during disease course.
Objective: In this prospective, observational, longitudinal natural history study we aimed to study bulbar dysfunction in patients with SMA types 2 and 3.
Background: Spinal muscular atrophy (SMA) is caused by deficiency of survival motor neuron (SMN) protein. Intrathecal nusinersen treatment increases SMN protein in motor neurons and has been shown to improve motor function in symptomatic children with SMA.
Objective: We used quantitative MRI to gain insight in microstructure and fat content of muscle during treatment and to explore its use as biomarker for treatment effect.
A novel variant of unknown significance c.8A > G (p.Glu3Gly) in was detected in two unrelated families.
View Article and Find Full Text PDFObjective: To investigate the electrophysiological basis of pyridostigmine enhancement of endurance performance documented earlier in patients with spinal muscular atrophy (SMA).
Methods: We recorded surface electromyography (sEMG) in four upper extremity muscles of 31 patients with SMA types 2 and 3 performing endurance shuttle tests (EST) and maximal voluntary contraction (MVC) measurements during a randomized, double blind, cross-over, phase II trial. Linear mixed effect models (LMM) were used to assess the effect of pyridostigmine on (i) time courses of median frequencies and of root mean square (RMS) amplitudes of sEMG signals and (ii) maximal RMS amplitudes during MVC measurements.
Objective: Electrophysiological techniques are emerging as an aid in identifying prognostic or therapeutic biomarkers in patients with spinal muscular atrophy (SMA), but electrophysiological assessments may be burdensome for patients. We, therefore, assessed feasibility and tolerability of multimodal peripheral non-invasive electrophysiological techniques in a cohort of patients with SMA.
Methods: We conducted a single center, longitudinal cohort study investigating the feasibility and tolerability of applying multimodal electrophysiological techniques to the median nerve unilaterally.
Background: Hereditary spinal muscular atrophy (SMA) is a motor neuron disorder with a wide range in severity in children and adults. Two therapies that alter splicing of the Survival Motor Neuron 2 (SMN2) gene, i.e.
View Article and Find Full Text PDFBackground: Progressive lung function decline, resulting in respiratory failure, is an important complication of spinal muscular atrophy (SMA). The ability to predict the need for mechanical ventilation is important. We assessed longitudinal patterns of lung function prior to chronic respiratory failure in a national cohort of treatment-naïve children and adults with SMA, hypothesizing an accelerated decline prior to chronic respiratory failure.
View Article and Find Full Text PDFHereditary proximal spinal muscular atrophy causes weakness and increased fatigability of repetitive motor functions. The neuromuscular junction is anatomically and functionally abnormal in patients with spinal muscular atrophy. Pharmacological improvement of neuromuscular transmission may therefore represent a promising additional treatment strategy.
View Article and Find Full Text PDFNusinersen (Spinraza®) improves survival of infants with hereditary proximal spinal muscular atrophy and motor function in children up to 12 years. Population-based assessments of treatment efficacy are limited and confined to select cohorts of patients. We performed a nationwide, population-based, single-centre cohort study in children with spinal muscular atrophy younger than 9.
View Article and Find Full Text PDFBackground: Respiratory complications are the most important cause of morbidity and mortality in spinal muscular atrophy (SMA). Respiratory muscle weakness results in impaired cough, recurrent respiratory tract infections and eventually can cause respiratory failure. We assessed longitudinal patterns of respiratory muscle strength in a national cohort of treatment-naïve children and adults with SMA, hypothesizing a continued decline throughout life.
View Article and Find Full Text PDFObjective: To assess the association between copy number (CN) variation in the survival motor neuron () locus and multifocal motor neuropathy (MMN), progressive muscular atrophy (PMA), and primary lateral sclerosis (PLS) susceptibility and to determine the association of and CN with MMN, PMA, and PLS disease course.
Methods: In this monocenter study, we used multiplex ligation-dependent probe amplification to determine and CN in Dutch patients with MMN, PMA, and PLS and controls. We stratified clinical parameters for and CN.
Disease course of feeding difficulties in spinal muscular atrophy type 2 is not well documented. Disease-modifying therapies rapidly change the trajectory of motor function and survival in spinal muscular atrophy, but effects on co-morbidities like bulbar function are unknown. We analysed data concerning feeding problems and their standard of care treatment in 146 patients with spinal muscular atrophy type 2.
View Article and Find Full Text PDFObjective: To determine the associations between fatigability and muscle strength, motor function, neuromuscular junction (NMJ) function, and perceived fatigue in spinal muscular atrophy (SMA), we assessed 61 patients with SMA.
Methods: Fatigability was defined as the inability to continue a 20-minute submaximal repetitive task of either walking or proximal or distal arm function and expressed as drop-out on the Endurance Shuttle Test Combined Score (ESTCS). We assessed muscle strength with the Medical Research Council (MRC) sum score, motor function with the Hammersmith Functional Motor Scale Expanded (HFMSE) and Motor Function Measure (MFM), NMJ function with repetitive nerve stimulation of the accessory and ulnar nerve, and perceived fatigue with the PROMIS Fatigue Short Form questionnaire in 61 children and adults with SMA types 2-4.
Clinical severity and treatment response vary significantly between patients with spinal muscular atrophy. The approval of therapies and the emergence of neonatal screening programmes urgently require a more detailed understanding of the genetic variants that underlie this clinical heterogeneity. We systematically investigated genetic variation other than copy number in the locus.
View Article and Find Full Text PDFObjective: To assess longitudinal patterns of muscle strength, motor function, and maximal compound muscle action potential amplitudes (CMAP) in older patients with spinal muscular atrophy (SMA), hypothesizing a continued decline of motor function parameters throughout life.
Methods: We measured muscle strength (Medical Research Council), motor function (Hammersmith Functional Motor Scale Expanded [HFMSE] and Motor Function Measure), and CMAP in treatment-naive patients. We used both longitudinal and cross-sectional data in mixed models to analyze natural history patterns.
The aim of this study was to document upper leg involvement in spinal muscular atrophy (SMA) with quantitative MRI (qMRI) in a cross-sectional cohort of patients of varying type, disease severity and age. Thirty-one patients with SMA types 2 and 3 (aged 29.6 [7.
View Article and Find Full Text PDFObjective: To assess motor unit (MU) changes in patients with spinal muscular atrophy (SMA) using compound muscle action potential (CMAP) scans.
Methods: We performed CMAP scan recordings in median nerves of 24 treatment-naïve patients (median age 39; range 12-75 years) with SMA types 2-4. From each scan, we determined maximum CMAP amplitude (CMAP), a motor unit number estimate (MUNE), and D50 which quantifies the largest discontinuities within CMAP scans.
Background: Respiratory muscle weakness is an important feature of spinal muscular atrophy (SMA). Progressive lung function decline is the most important cause of mortality and morbidity in patients. The natural history of lung function in SMA has, however, not been studied in much detail.
View Article and Find Full Text PDFObjective: To investigate probabilities of survival and its surrogate, that is, mechanical ventilation, in patients with spinal muscular atrophy (SMA).
Methods: We studied survival in a population-based cohort on clinical prevalence of genetically confirmed, treatment-naive patients with SMA, stratified for best acquired motor milestone (i.e.
Objective: To investigate mutations in genes that are potential modifiers of spinal muscular atrophy (SMA) severity.
Methods: We performed a hypothesis-based search into the presence of variants in fused in sarcoma () transactive response DNA-binding protein 43 (), plastin 3 (), and profilin 2 () in a cohort of 153 patients with SMA types 1-4, including 19 families. Variants were detected with targeted next-generation sequencing and confirmed with Sanger sequencing.
Cochrane Database Syst Rev
January 2020
Background: Spinal muscular atrophy (SMA) is caused by a homozygous deletion of the survival motor neuron 1 (SMN1) gene on chromosome 5, or a heterozygous deletion in combination with a (point) mutation in the second SMN1 allele. This results in degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type II do not develop the ability to walk without support and have a shortened life expectancy, whereas children with SMA type III develop the ability to walk and have a normal life expectancy.
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