Metabolic syndrome is common in adults with 5q-spinal muscular atrophy and impacts quality of life and fatigue.

INTRODUCTION/AIMS: Spinal muscular atrophy (SMA) is a multisystem disorder. We assessed metabolic syndrome (MetS) prevalence in adults with SMA and its association with motor function, quality of life (QoL), fatigue, and depression. METHODS: MetS was diagnosed using 2009 consensus criteria. Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), Fatigue Severity Scale (FSS), Beck Depression Inventory (BDI), and 36-Item Short Form Health Survey (SF-36) were recorded and correlations between muscle function, depression, fatigue, QoL, and MetS were analyzed. RESULTS: We included 36 individuals (18 males; mean age: 38.7 ± 14.6 years). MetS was present in 25.0%. The most common component of MetS was central obesity (69.7%). Nearly half of the SMA individuals exhibited at least one abnormal lipid level result. Individuals with MetS more frequently were SMA type 3 (77.8% vs. 37.0%, p = .02) and had higher levels of fatigue (48.4 ± 6.7 vs. 39.5 ± 11.6, p = .03) than those without MetS. No associations of the presence of MetS with ambulatory status or HFMSE/RULM scores were observed. SMA individuals with MetS scored significantly lower in mental and social domains of QoL and total SF-36 score (p = .04). We observed weak to moderate correlations between the presence of MetS and SMA type, presence of comorbidities, QoL, and fatigue. DISCUSSION: The frequency of MetS was modestly higher among adults with SMA than in the general population, particularly in SMA type 3. MetS was associated with reduced QoL and increased fatigue. Larger studies are needed to fully understand the significance of MetS in adults with SMA.

Assessing the Swallowing Function in Children with Spinal Muscular Atrophy: An Easily Accessible and Objective Multidimensional Approach.

Background: Spinal muscular atrophy (SMA), a genetic neuromuscular disease caused by lack of survival of motor neuron (SMN) protein, is characterized by muscular atrophy and respiratory and bulbar dysfunction. While swallowing disorders are common, they remain poorly studied. Objectives: Our study aimed to explore 1) intraoral pressure measurements with the Iowa Oral Performance Instrument system and the reliability of a Swallowing Function Assessment Questionnaire (SFAQ) in healthy controls, and 2) evaluate their use as swallowing function biomarkers and the evolution of swallowing function over time in children with SMA. Methods: We recruited 53 healthy children and 27 SMA patients all treated with SMN gene modulator therapy. Participants completed the SFAQ and underwent at least one measurement of maximal oral pressures (lingual, labial, and masseter). Results: Mean oral normalized pressure index were lower (all sites p < 0.001) and mean SFAQ scores were higher (p < 0.001) in patients compared with healthy controls. Pressure evolution over 1 year in SMA patients for all three oral sites did not show significant differences. SFAQ scores correlated negatively with oral pressures at all three sites in patients. Conclusions: Both tools provided new insights on the oral and pharyngeal phase of swallowing in SMA patients. In SMA patients, muscle strength in certain crucial anatomical regions during swallowing is weaker than in healthy children.

Relationship Between Hand Strength and Function in Duchenne Muscular Dystrophy and Spinal Muscular Atrophy: Implications for Clinical Trials.

Background: Measurement of muscle strength and motor function is recommended in clinical trials of neuromuscular diseases, but the loss of hand strength at which motor function is impacted is not documented. Objectives: To establish the relationship between hand strength and function, and to determine the strength threshold that differentiates normal and abnormal hand function in individuals with Duchenne Muscular Dystrophy (DMD) or Spinal Muscular Atrophy (SMA). Methods: Maximal handgrip and key pinch strength were measured with the MyoGrip and MyoPinch dynamometers, respectively. Hand function was assessed using the MoviPlate, the Motor Function Measure items for distal upper limb (MFM-D3-UL) and the Cochin Hand Function Scale (CHFS). Results: Data from 168 participants (91 DMD and 77 SMA, age 6-31 years) were analyzed. Relationships between strength and function were significant (P < 0.001). Hand function was generally preserved when strength was above the strength threshold determined by Receiver-Operating Characteristic (ROC) analysis: For MFM-D3-UL, the calculated handgrip strength thresholds were 41 and 13% of the predicted strength for a healthy subject (% pred) and the key pinch strength thresholds were 42 and 26% pred for DMD and SMA, respectively. For the MoviPlate, handgrip strength thresholds were 11 and 8% pred and key pinch strength thresholds were 21 and 11% pred for DMD and SMA, respectively. For participants with sub-threshold strength, hand function scores decreased with decreasing strength. At equal % pred strength, individuals with SMA had better functional scores than those with DMD. Conclusions: Hand function is strength-dependent for most motor tasks. It declines only when strength falls below a disease-specific threshold. Therefore, therapies capable of maintaining strength above this threshold should preserve hand function.

Subclinical spinal muscular atrophy in a 60-year-old man.

Spinal muscular atrophy is an autosomal recessive genetic disease that can manifest with different phenotypes, classified as types 1 to 4, being type 4 the mildest form. We report a case of a 60-year-old man presenting with sudden onset of numbness in the right upper limb and with a family history of a 48-year-old brother with progressive weakness. At the first visit, his exam was unremarkable, except for a mild paresis of the right elbow extension and reduced right bicipital and tricipital reflexes. Electromyography revealed chronic motor neuronopathy and the genetic study confirmed a diagnosis of spinal muscular atrophy. At the follow-up visit his complains improved and his neurologic exam returned to normal. To our knowledge, this patient is the oldest asymptomatic SMA individual ever reported. This case highlights the need to exclude late onset spinal muscular atrophy in patients with indolent motor neuronopathy.

Polysomnography findings and respiratory muscle function in infants with early onset spinal muscular atrophy after gene replacement as monotherapy: A prospective study.

BACKGROUND: Gene replacement therapy (onasemnogene abeparvovec) is associated with an improvement of the prognosis of children with spinal muscular atrophy, but information on long-term respiratory outcome is scarce. The aim of this study was to report the polysomnography findings and respiratory muscle function of infants with treatment-naive spinal muscular atrophy type 1 and 2 up to 24 months after onasemnogene abeparvovec monotherapy. METHODS: A clinical and motor evaluation, respiratory muscle function testing, and polysomnography were performed repeatedly. RESULTS: Fifteen spinal muscular atrophy patients (1 presymptomatic, 7 type 1b, 6 type 1c, and 1 type 2) were included at a median age of 8.6 months (range 3.8-12.6) and followed for 24 months. The thoracic over head circumference ratio was close to normal at baseline (median 1.00 (range 0.90-1.05)) and increased significantly over time. All polysomnography and nocturnal gas exchange parameters were within normal ranges at baseline (median apnea-hypopnea index 2.5 events/hour (range 0.4-5.3)) and follow-up. The inspiratory muscle strength was normal at baseline but tended to slightly decrease over time and the expiratory muscle strength was low at any time especially for patients with recurrent respiratory infections (median (range) at baseline in cmH2O: crying esophageal pressure 54 (30-110), crying transdiaphragmatic pressure 65 (35-107), gastric pressure during maximal cough 26 (10-130), esophageal pressure during maximal cough 61 (38-150)). Only 3 patients required noninvasive ventilation. CONCLUSION: A continuous respiratory monitoring of spinal muscular atrophy patients during the first years of life following onasemnogene abeparvovec monotherapy seems recommended despite the normality of polysomnography parameters.

Cardiac function evaluation in children with spinal muscular atrophy: A case-control study.

BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by degeneration of lower motor neurons, resulting in progressive muscle weakness and atrophy. However, little is known regarding the cardiac function of children with SMA. METHODS: We recruited SMA patients younger than 18 years of age from January 1, 2022, to April 1, 2022, in the First Affiliated Hospital of Sun Yat-sen University. All patients underwent a comprehensive cardiac evaluation before treatment, including history taking, physical examination, blood tests of cardiac biomarkers, assessment of echocardiography and electrocardiogram. Age/gender-matched healthy volunteers were recruited as controls. RESULTS: A total of 36 SMA patients (26 with SMA type 2 and 10 with SMA type 3) and 40 controls were enrolled in the study. No patient was clinically diagnosed with heart failure. Blood tests showed elevated values of creatine kinase isoenzyme M and isoenzyme B (CK-MB) mass and high-sensitivity cardiac troponin T (hs-cTnT) in spinal muscular atrophy (SMA) patients. Regarding echocardiographic parameters, SMA children were detected with lower global left and right ventricular longitudinal strain, abnormal diastolic filling velocities of trans-mitral and trans-tricuspid flow. The results revealed no clinical heart dysfunction in SMA patients, but subclinical ventricular dysfunction was seen in SMA children including the diastolic function and myocardial performance. Some patients presented with elevated heart rate and abnormal echogenicity of aortic valve or wall. Among these SMA patients, seven patients (19.4%) had scoliosis. The Cobb's angles showed a significant negative correlation with LVEDd/BSA, but no correlation with other parameters, suggesting that mild scoliosis did not lead to significant cardiac dysfunction. CONCLUSIONS: Our findings warrant increased attention to the cardiac status and highlight the need to investigate cardiac interventions in SMA children.

Determining minimal clinically important differences in the Hammersmith Functional Motor Scale Expanded for untreated spinal muscular atrophy patients: An international study.

BACKGROUND AND PURPOSE: Spinal muscular atrophy (SMA) is a rare and progressive neuromuscular disorder with varying severity levels. The aim of the study was to calculate minimal clinically important difference (MCID), minimal detectable change (MDC), and values for the Hammersmith Functional Motor Scale Expanded (HFMSE) in an untreated international SMA cohort. METHODS: The study employed two distinct methods. MDC was calculated using distribution-based approaches to consider standard error of measurement and effect size change in a population of 321 patients (176 SMA II and 145 SMA III), allowing for stratification based on age and function. MCID was assessed using anchor-based methods (receiver operating characteristic [ROC] curve analysis and standard error) on 76 patients (52 SMA II and 24 SMA III) for whom the 12-month HFMSE could be anchored to a caregiver-reported clinical perception questionnaire. RESULTS: With both approaches, SMA type II and type III patients had different profiles. The MCID, using ROC analysis, identified optimal cutoff points of -2 for type II and -4 for type III patients, whereas using the standard error we found the optimal cutoff points to be 1.5 for improvement and -3.2 for deterioration. Furthermore, distribution-based methods uncovered varying values across age and functional status subgroups within each SMA type. CONCLUSIONS: These results emphasize that the interpretation of a single MCID or MDC value obtained in large cohorts with different functional status needs to be made with caution, especially when these may be used to assess possible responses to new therapies.

Exploring variability in cognitive functioning in patients with spinal muscular atrophy: a scoping review.

The cognitive functioning of individuals with spinal muscular atrophy (SMA) is not well understood, prompting a call for more research to better grasp cognitive involvement in SMA. This study aims to explore recent findings regarding cognitive outcomes in SMA patients, including correlations between clinical features and cognitive abilities. The investigation seeks to identify commonly used measures for assessing cognitive function in this patient population. A scoping review following the Joanna Briggs Institute methodology examined literature until December 2023. Two databases were searched along with relevant article references using specific terms such as "spinal muscular atrophy," "SMA," "cognitive," "abilities," "functions," "intellective," or "intellectual." Screening focused on titles and abstracts from English language peer-reviewed journals. After the initial research, 1452 articles were identified. Subsequent screening and selection led to the inclusion of 13 articles in the review. Among these studies, four indicated a cognitive trend within the normal range for SMA patients. In four other studies, the majority of patients fell within the normal range. However, smaller proportions were observed to be either above or below the norm compared to the controls. Three studies reported noted cognitive performance below the average, while two showed above-average scores. The scoping review suggests that most SMA patients have cognitive abilities similar to the general population, with types II and III showing even lesser impact. However, certain cognitive domains may be affected in type I patients, highlighting the need for further research to fully understand cognitive involvement in SMA.

Motor unit number estimation via MScanFit MUNE in spinal muscular atrophy.

INTRODUCTION/AIMS: MScanFit MUNE (MScanFit) is a novel tool to derive motor unit number estimates (MUNEs) from compound muscle action potential (CMAP) scans. Few studies have explored its utility in 5q spinal muscular atrophy (SMA5q) patients, assessing only the abductor pollicis brevis (APB) muscle. We aimed to assess different distal muscles in pediatric and adult SMA5q patients, further evaluating clinical-electrophysiological correlations. METHODS: We analyzed MScanFit parameters reflecting the extent of denervation (MUNE; N50) and parameters of collateral reinnervation in APB, abductor digiti minimi (ADM), and tibialis anterior (TA) muscles. SMA patients were clinically evaluated using standardized motor function clinical scales, including the Hammersmith Functional Motor Scale - Expanded and the Revised Upper Limb Module. RESULTS: A total of 23 SMA5q (9 SMA type 2 and 14 SMA type 3) and 12 age-matched healthy controls (HCs) were enrolled. SMA patients showed lower MUNE and N50 values and higher parameters of collateral sprouting in all muscles compared to HC (p < .001). SMA type 2 patients demonstrated lower MUNE and higher collateral reinnervation values in APB and TA compared to SMA type 3 (p < .05). Walker patients showed higher values of MUNE and N50, and lower parameters of reinnervation in all muscles compared to sitters (p < .05). MScanFit parameters showed strong correlations (Rho-values ranging from .72 to .83) with clinical measurements. MUNE values were abnormal in muscles that were not clinically affected. DISCUSSION: MScanFit parameters showed promise as an outcome measure. Further studies, particularly longitudinal ones, are needed to evaluate MScanFit in measuring response to treatments.

Reliability and Validity of the Turkish Translation of the PedsQL™ 3.0 Neuromuscular Module for 2-to 4-Year-Olds in Spinal Muscular Atrophy.

BACKGROUND: The Pediatric Quality of Life Inventory™ (PedsQL™) Neuromuscular Module (PedsQL™ 3.0 NM) evaluates the health-related quality of life in children who are affected by neuromuscular diseases. This study's aim is to assess the adaptation of the PedsQL™ 3.0 NM Turkish version (PedsQL™ 3.0 NM-TR) for 2- to 4-year-olds in spinal muscular atrophy (SMA). METHODS: The procedure of translating the PedsQL™ 3.0 NM into Turkish was conducted in accordance with the translation methodology outlined by the PedsQL™ measurement model. The PedsQL™ 3.0 NM-TR was administered to 54 parents of children with SMA aged 2 to 4 years. The test-retest reliability and intraclass correlation coefficient (ICC) were measured for reliability analysis. Cronbach's α coefficient and item score correlations were calculated for internal consistency. Concurrent construct validity was evaluated by Pearson correlations between the outcomes of the PedsQL™ 4.0 Generic Core Scale (PedsQL™ 4.0 GCS) and the PedsQL™ 3.0 NM. RESULTS: The PedsQL™ 3.0 NM-TR total score shows excellent reliability. The Cronbach's α values for the PedsQL™ 3.0 NM ranged between 0.871 and 0.906, while those for the PedsQL™ 4.0 GCS ranged between 0.843 and 0.897. Test-retest ICC values for the PedsQL™ 3.0 NM-TR ranged between 0.812 and 0.917, and for the PedsQL™ 4.0 GCS ranged between 0.773 and 0.899. The relationship between the PedsQL™ 3.0 NM-TR and the subscores of the PedsQL™ 4.0 GCS demonstrated a range of correlations from excellent to fair, indicating the interplay between two scales. CONCLUSION: This study established the PedsQL™ 3.0 NM-TR as reliable, valid, and feasible for use in children aged 2 to 4 years with SMA.

Risdiplam improves subjective swallowing quality in non-ambulatory adult patients with 5q-spinal muscular atrophy despite advanced motor impairment.

BACKGROUND: 5q-associated spinal muscular atrophy (SMA) is characterized by the progressive loss of motor neurons with consecutive weakness and atrophy of the limb, respiratory, and bulbar muscles. While trunk and limb motor function improve or stabilize in adults with SMA under nusinersen and risdiplam treatment, the efficacy on bulbar function in this age group of patients remains uncertain. However, it is important to assess bulbar dysfunction, which frequently occurs in the disease course and is associated with increased morbidity and mortality. METHODS: Bulbar function was evaluated prospectively in 25 non-ambulatory adults with type 2 and 3 SMA before and 4 and 12 months after risdiplam treatment initiation using the Sydney Swallow Questionnaire (SSQ) and the bulbar subscore of the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (b-ALSFRS-R). Extremity function was assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM). RESULTS: Subjective swallowing quality, measured with the SSQ, improved after 12 months of therapy with risdiplam. For the b-ALSFRS-R, a non-significant trend towards improvement was observed. The RULM score improved after 12 months of risdiplam therapy, but not the HFMSE score. HFMSE and RULM scores did not correlate with the SSQ but the b-ALSFRS-R score at baseline. CONCLUSIONS: The improvement in subjective swallowing quality under risdiplam treatment, despite an advanced disease stage with severe motor deficits, strengthens the importance of a standardized bulbar assessment in addition to established motor scores. This may reveal relevant treatment effects and help individualize treatment decisions in the future.

Longitudinal changes of swallowing safety and efficiency in infants with spinal muscular atrophy who received disease modifying therapies.

BACKGROUND: Dysphagia is a common feature of the natural history of patients with spinal muscular atrophy (SMA). Literature regarding swallowing safety and efficiency is scarce in patients with SMA, particularly in the era of newborn screening programs and disease-modifying therapies. OBJECTIVE: To describe the longitudinal changes of swallowing safety and efficiency in children with SMA who received one or more disease modifying therapies METHODS: Case series of patients with SMA followed at the University of Florida from 1 May 2019 to 31 December 2022 who had two or more videofluoroscopy swallowing studies (VFSS), with the first being within 30 days of their first treatment. Data extracted from the electronic health record included: neuromotor outcomes, VFSS penetration aspiration scores (PAS), presence of abrnormal oral or pharyngeal residue, clinical history, and timing of disease-modifying therapies administration. RESULTS: Seven subjects were included (five male); three were diagnosed via newborn screen. Median age at diagnosis was 10 days (range: 4-250). Median age at initial VFSS was 29 days (range: 9-246), and age at the last VFSS was 26.1 months (range: 18.2-36.2). All subjects received onasemnogene-abeparvovec (OA); four received additional therapies. PAS at diagnosis was abnormal in four subjects. Six subjects required feeding modifications after VFSS results. Of these, three had silent aspiration (PAS 8) and three of them improved after treatment. CONCLUSIONS: Swallowing safety and efficiency can be impaired in patients with SMA despite early treatment. Larger, prospective studies are needed to define optimal timiing of longitudinal instrumental evaluations.

Patient Reported Outcome Measures in Adult Spinal Muscular Atrophy: A Scoping Review and Graphical Visualization of the Evidence.

BACKGROUND: Spinal Muscular Atrophy (SMA) is a hereditary neuromuscular disease with an estimated prevalence of 1/10 000 births. SMA is increasingly recognized as a multi-system disease with a need to study additional under-recognized health domains such as quality of life, fatigue, bulbar function, respiratory function, and independence. OBJECTIVE: Identify and assess reported evidence from the literature investigating Patient Reported Outcome Measures (PROMs) in adults with SMA. Develop a novel method drawing from network theory to graphically depict the literature, PROMs, and supporting psychometric evidence. METHODS: A scoping review was completed following PRISM-ScR, COSMIN and JBI scoping review guidelines. Literature investigating PROMs in adult SMA or neuromuscular disease was identified from peer-reviewed and grey databases. A network graph was derived from extracted data. RESULTS: 5292 articles were retrieved, 81 articles met inclusion criteria; corresponding to 31 unique PROMs. Only two PROMs were developed specifically for SMA. Few PROMs covered multiple domains of health. Most PROMs were incompletely validated, focusing on concurrent validity, and few assessed responsiveness or internal consistency. CONCLUSIONS: PROMs are emerging tools for monitoring and assessing adults with SMA. Despite their potential benefits, additional validation studies should be completed prior to their use for clinical decision-making. Network graphics may represent a technique to aid in the visualization of evidence supporting a scoping review.

Effect of lumbar muscle atrophy on the mechanical loading change on lumbar intervertebral discs.

The objective of this study was to quantitatively analyze the effect of lumbar spinal muscle atrophy on the compressive (perpendicular to the upper surface of the disc) and shear (parallel to the upper surface of the disc in the anterior-posterior direction) forces change on lumbar intervertebral discs using a full body musculoskeletal modeling approach. Muscles atrophy was modeled with reduction of the functional cross-sectional area (FCSA) of the muscles. Compressive and shear forces under two levels of lumbar muscle atrophy (20% and 40%) at eight daily postures (lying on back, seating slouched, seating straight, standing, standing flexed (36°), standing lift a 20 kg weight close to chest, standing lift a 20 kg weight flexed (38°), and standing lift a 20 kg weight with arm stretched) were analyzed. There was small increase in compressive forces on lumbar discs with muscle atrophy at most postures except lying and sitting straight. The maximum increase of compressive forces on lumbar discs were 23 N (6%), 28 N (5%), 34 N (2%), 71 N (6%), 89 N (4%), and 190 N (10%) with 20% atrophy, and 66 N (19%), 77 N (12%), 98 N (6%), 169 N (14%), 256 N (12%), 501 N (24%) with 40% atrophy at seating slouched, standing, standing flexed, standing lift close, standing lift flexed, and standing stretched arm, respectively. The shear force did not change significantly on lumbar discs with muscle atrophy. This study is important for understanding the biomechanical mechanisms of how lumbar muscle atrophy may affect the lumbar IVD health.

Induction of Survival of Motor Neuron (SMN) Protein Deficiency in Spinal Astrocytes by Small Interfering RNA as an In Vitro Model of Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is a motor neuron disorder leading to progressive loss of ventral horn neurons resulting in muscle wasting. Here we investigate the contribution of spinal astrocytes to the pathogenesis of late-onset SMA forms using a mouse model. Furthermore, we generated SMA-like astrocytes using survival of motor neuron (SMN) siRNA transfection techniques. In the SMA mouse model, the activation of spinal astrocytes and the reduction of the inward rectifier potassium channel Kir4.1 and excitatory amino acid transporter 1 (EAAT1) were observed at postnatal day (P) 28, preceding the loss of spinal motor neurons appearing earliest at P42. Using SMA-like astrocytes, we could mimic the modulation of spinal astrocytes of the mouse model in a dish and perform electrophysiological assessments and functional assays. In SMA-like astrocytes, glutamate uptake was diminished due to a reduction in EAAT1. Furthermore, patch-clamp measurements revealed reduced potassium uptake into astrocytes with membrane depolarization. Additionally, exposure of healthy spinal motor neurons to a conditioned medium of SMA-like astrocytes resulted in increased firing frequency. These data demonstrate spinal astrocytes' crucial role in the late-onset SMA forms' pathogenesis.

Spinal muscular atrophy with predominant lower extremity (SMA-LED) with no signs other than pure motor symptoms at the intersection of multiple overlap syndrome.

BACKGROUND: Mutations in the cytoplasmic dynein 1 heavy chain gene (DYNC1H1) have been associated with spinal muscular atrophy with predominant lower extremity involvement (SMA-LED), Charcot-Marie-Tooth 2O (CMT2O) disease, cortical migration anomalies, and autosomal dominant mental retardation13. SMA-LED phenotype-related mutation was found in the DYNC1H1 gene in the patient who applied with the complaint of gait disturbance. METHODS: Pathogenic heterozygous c.1678G > A (p.Val560Met) mutation was detected in the DYNC1H1 gene by next-generation targeted gene analysis in the patient who had no phenotypic findings except delayed motor milestones, lumbar lordosis, and lower extremity muscle weakness. The patient's creatinine phosphokinase enzyme level and brain magnetic resonance imaging (MRI) were normal. Electromyography (EMG) had pure motor findings. CONCLUSION: It should be kept in mind that DYNC1H1 mutation, which we are accustomed to seeing with accompanying findings such as orthopedic and ocular dysmorphic findings, sensorineural EMG findings, and intellectual disability, can also observe with pure motor findings such as muscular dystrophy examination findings.

Revised upper limb module in type II and III spinal muscular atrophy: 24-month changes.

The aim of the study was to establish 24-month changes in a large cohort of type II and III spinal muscular atrophy (SMA) patients assessed with the Revised Upper Limb Module (RULM), a tool specifically developed to assess upper limb function in SMA. We included 107 patients (54 type II and 53 type III) with at least 24-months follow up. The overall RULM 24-month changes showed a mean decline of -0.79 points. The difference between baseline and 24 months was significant in type II but not in type III patients. There was also a difference among functional subgroups but not in relation to age. Most patients had 24-month mean changes within 2 points, with 23% decreasing more than 2 points and 7% improving by >2 points. Our results suggest an overall progressive decline in upper limb function over 24 months. The negative changes were most notable in type II, in non-ambulant type III and with a different pattern of progression, also in non-sitter type II. In contrast, ambulant type III showed relative stability within the 24-month follow up. These findings will help in the interpretation of the real world data collected following the availability of new therapeutic approaches.

Quantitative Motion Measurements Based on Markerless 3D Full-Body Tracking in Children with SMA Highly Correlate with Standardized Motor Assessments.

BACKGROUND: Spinal Muscular Atrophy (SMA) is the most common neurodegenerative disease in childhood. New therapeutic interventions have been developed to interrupt rapid motor deterioration. The current standard of clinical evaluation for severely weak infants is the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND), originally developed for SMA type 1. This test however, remains subjective and requires extensive training to be performed reliably. OBJECTIVE: Proof of principle of the motion tracking method for capturing complex movement patterns in ten children with SMA. METHODS: We have developed a system for tracking full-body motion in infants (KineMAT) using a commercially available, low-cost RGB-depth sensor. Ten patients with SMA (2-46 months of age; CHOP INTEND score 10-50) were recorded for 2 minutes during unperturbed spontaneous whole-body activity. Five predefined motion parameters representing 56 degrees of freedom of upper, lower extremities and trunk joints were correlated with CHOP INTEND scores using Pearson product momentum correlation (r). Test-retest analysis in two patients used descriptive statistics. RESULTS: 4/5 preselected motion parameters highly correlated with CHOP INTEND: 1. Standard deviation of joint angles (r = 0.959, test-retest range 1.3-1.9%), 2. Standard deviation of joint position (r = 0.933, test-retest range 2.9%), 3. Absolute distance of hand/foot travelled (r = 0.937, test-retest range 6-10.5%), 4. Absolute distance of hand/foot travelled against gravity (r = 0.923; test-retest range 4.8-8.5%). CONCLUSIONS: Markerless whole-body motion capture using the KineMAT proved to objectively capture motor performance in infants and children with SMA across different severity and ages.

Organotypic spinal cord cultures: An in vitro 3D model to preliminary screen treatments for spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a severe neuromuscular disease affecting children, due to mutation/deletion of survival motor neuron 1 (SMN1) gene. The lack of functional protein SMN determines motor neuron (MN) degeneration and skeletal muscle atrophy, leading to premature death due to respiratory failure. Nowadays, the Food and Drug Administration approved the administration of three drugs, aiming at increasing the SMN production: although assuring noteworthy results, all these therapies show some non-negligible limitations, making essential the identification of alternative/synergistic therapeutic strategies. To offer a valuable in vitro experimental model for easily performing preliminary screenings of alternative promising treatments, we optimized an organotypic spinal cord culture (derived from murine spinal cord slices), which well recapitulates the pathogenetic features of SMA. Then, to validate the model, we tested the effects of human Mesenchymal Stem Cells (hMSCs) or murine C2C12 cells (a mouse skeletal myoblast cell line) conditioned media: 1/3 of conditioned medium (obtained from either hMSCs or C2C12 cells) was added to the conventional medium of the organotypic culture and maintained for 7 days. Then the slices were fixed and immunoreacted to evaluate the MN survival. In particular we observed that the C2C12 and hMSCs conditioned media positively influenced the MN soma size and the axonal length respectively, without modulating the glial activation. These data suggest that trophic factors released by MSCs or muscular cells can exert beneficial effects, by acting on different targets, and confirm the reliability of the model. Overall, we propose the organotypic spinal cord culture as an excellent tool to preliminarily screen molecules and drugs before moving to in vivo models, in this way partly reducing the use of animals and the costs.

Models for IGHMBP2-associated diseases: an overview and a roadmap for the future.

Models are practical tools with which to establish the basic aspects of a diseases. They allow systematic research into the significance of mutations, of cellular and molecular pathomechanisms, of therapeutic options and of functions of diseases associated proteins. Thus, disease models are an integral part of the study of enigmatic proteins such as immunoglobulin mu-binding protein 2 (IGHMBP2). IGHMBP2 has been well defined as a helicase, however there is little known about its role in cellular processes. Notably, it is unclear why changes in such an abundant protein lead to specific neuronal disorders including spinal muscular atrophy with respiratory distress type 1 (SMARD1) and Charcot-Marie-Tooth type 2S (CMT2S). SMARD1 is caused by a loss of motor neurons in the spinal cord that results in muscle atrophy and is accompanied by rapid respiratory failure. In contrast, CMT2S manifests as a severe neuropathy, but typically without critical breathing problems. Here, we present the clinical manifestation of IGHMBP2 mutations, function of protein and models that may be used for the study of IGHMBP2-associated disorders. We highlight the strengths and weaknesses of specific models and discuss the orthologs of IGHMBP2 that are found in different systems with regard to their similarity to human IGHMBP2.