Susan Riley

An expanded version of the Hammersmith Functional Motor Scale for SMA II and III patients.

PURPOSE To develop and evaluate an expanded version of the Hammersmith Functional Motor Scale allowing for evaluation of ambulatory SMA patients. PROCEDURES Thirty-eight patients with SMA type II or III were evaluated using the Gross Motor Function Measure and the Hammersmith Functional Motor Scale. Based on statistical and clinical criteria, we selected 13 Gross Motor Function Measure items to develop an expanded HFMS. The expanded Hammersmith Functional Motor Scale was validated by comparison with the Gross Motor Function Measure minus the 13 items (GMFM-75) and an assessment of clinical function. The reliability of the expanded Hammersmith Functional Motor Scale in 36 patients was established. FINDINGS The expanded Hammersmith Functional Motor Scale was highly correlated with the GMFM-75 and the clinical function assessment (p=0.97, and p=0.90). The expanded Hammersmith Functional Motor Scale showed excellent test-retest reliability (International Coordinating Committee = 0.99). CONCLUSIONS The expanded Hammersmith Functional Motor Scale allows assessment of high functioning SMA type II and III patients. Ease of administration and correlation with established motor function measures justify use in future SMA clinical trials.

Observational study of spinal muscular atrophy type I and implications for clinical trials

Objectives: Prospective cohort study to characterize the clinical features and course of spinal muscular atrophy type I (SMA-I). Methods: Patients were enrolled at 3 study sites and followed for up to 36 months with serial clinical, motor function, laboratory, and electrophysiologic outcome assessments. Intervention was determined by published standard of care guidelines. Palliative care options were offered. Results: Thirty-four of 54 eligible subjects with SMA-I (63%) enrolled and 50% of these completed at least 12 months of follow-up. The median age at reaching the combined endpoint of death or requiring at least 16 hours/day of ventilation support was 13.5 months (interquartile range 8.1–22.0 months). Requirement for nutritional support preceded that for ventilation support. The distribution of age at reaching the combined endpoint was similar for subjects with SMA-I who had symptom onset before 3 months and after 3 months of age (p = 0.58). Having 2 SMN2 copies was associated with greater morbidity and mortality than having 3 copies. Baseline electrophysiologic measures indicated substantial motor neuron loss. By comparison, subjects with SMA-II who lost sitting ability (n = 10) had higher motor function, motor unit number estimate and compound motor action potential, longer survival, and later age when feeding or ventilation support was required. The mean rate of decline in The Childrens Hospital of Philadelphia Infant Test for Neuromuscular Disorders motor function scale was 1.27 points/year (95% confidence interval 0.21–2.33, p = 0.02). Conclusions: Infants with SMA-I can be effectively enrolled and retained in a 12-month natural history study until a majority reach the combined endpoint. These outcome data can be used for clinical trial design.

Prospective cohort study of spinal muscular atrophy types 2 and 3

Objective: To characterize the natural history of spinal muscular atrophy type 2 and type 3 (SMA 2/3) beyond 1 year and to report data on clinical and biological outcomes for use in trial planning. Methods: We conducted a prospective observational cohort study of 79 children and young adults with SMA 2/3 who participated in evaluations for up to 48 months. Clinically, we evaluated motor and pulmonary function, quality of life, and muscle strength. We also measured SMN2 copy number, hematologic and biochemical profiles, muscle mass by dual x-ray absorptiometry (DXA), and the compound motor action potential (CMAP) in a hand muscle. Data were analyzed for associations between clinical and biological/laboratory characteristics cross-sectionally, and for change over time in outcomes using all available data. Results: In cross-sectional analyses, certain biological measures (specifically, CMAP, DXA fat-free mass index, and SMN2 copy number) and muscle strength measures were associated with motor function. Motor and pulmonary function declined over time, particularly at time points beyond 12 months of follow-up. Conclusion: The intermediate and mild phenotypes of SMA show slow functional declines when observation periods exceed 1 year. Whole body muscle mass, hand muscle compound motor action potentials, and muscle strength are associated with clinical measures of motor function. The data from this study will be useful for clinical trial planning and suggest that CMAP and DXA warrant further evaluation as potential biomarkers.

Observational Study of Spinal Muscular Atrophy Type 2 and 3: Functional Outcomes Over 1 Year

OBJECTIVE To characterize the short-term course of spinal muscular atrophy (SMA) in a genetically and clinically well-defined cohort of patients with SMA. DESIGN A comprehensive multicenter, longitudinal, observational study. SETTING The Pediatric Neuromuscular Clinical Research Network for SMA, a consortium of clinical investigators at 3 clinical sites. PARTICIPANTS Sixty-five participants with SMA types 2 and 3, aged 20 months to 45 years, were prospectively evaluated. INTERVENTION We collected demographic and medical history information and determined the SMN 2 copy number. MAIN OUTCOME MEASURES Clinical outcomes included measures of motor function (Gross Motor Function Measure and expanded Hammersmith Functional Motor Scale), pulmonary function (forced vital capacity), and muscle strength (myometry). Participants were evaluated every 2 months for the initial 6 months and every 3 months for the subsequent 6 months. We evaluated change over 12 months for all clinical outcomes and examined potential correlates of change over time including age, sex, SMA type, ambulatory status, SMN2 copy number, medication use, and baseline function. RESULTS There were no significant changes over 12 months in motor function, pulmonary function, and muscle strength measures. There was evidence of motor function gain in ambulatory patients, especially in those children younger than 5 years. Scoliosis surgery during the observation period led to a subsequent decline in motor function. CONCLUSIONS Our results confirm previous clinical reports suggesting that SMA types 2 and 3 represent chronic phenotypes that have relatively stable clinical courses. We did not detect any measurable clinical disease progression in SMA types 2 and 3 over 12 months, suggesting that clinical trials will have to be designed to measure improvement rather than stabilization of disease progression.

Six-Minute Walk Test demonstrates motor fatigue in spinal muscular atrophy

Background: In spinal muscular atrophy (SMA), weakness, decreased endurance, and fatigue limit mobility. Scales have been developed to measure function across the wide spectrum of disease severity. However, these scales typically are observer dependent, and scores are based on sums across Likert-scaled items. The Six-Minute Walk Test (6MWT) is an objective, easily administered, and standardized evaluation of functional exercise capacity that has been proven reliable in other neurologic disorders and in children. Methods: To study the performance of the 6MWT in SMA, 18 ambulatory participants were evaluated in a cross-sectional study. Clinical measures were 6MWT, 10-m walk/run, Hammersmith Functional Motor Scale–Expanded (HFMSE), forced vital capacity, and handheld dynamometry. Associations between the 6MWT total distance and other outcomes were analyzed using Spearman correlation coefficients. A paired t test was used to compare the mean distance walked in the first and sixth minutes. Results: The 6MWT was associated with the HFMSE score (r = 0.83, p < 0.0001), 10-m walk/run (r = −0.87, p < 0.0001), and knee flexor strength (r = 0.62, p = 0.01). Gait velocity decreased during successive minutes in nearly all participants. The average first minute distance (57.5 m) was significantly more than the sixth minute distance (48 m) (p = 0.0003). Conclusion: The Six-Minute Walk Test (6MWT) can be safely performed in ambulatory patients with spinal muscular atrophy (SMA), correlates with established outcome measures, and is sensitive to fatigue-related changes. The 6MWT is a promising candidate outcome measure for clinical trials in ambulatory subjects with SMA.

Validation of the Expanded Hammersmith Functional Motor Scale in spinal muscular atrophy type II and III.

The relationships between the Expanded Hammersmith Functional Motor Scale (HFMSE) and genotype and motor and respiratory outcomes were examined in patients with spinal muscular atrophy types II and III (n = 70). The correlation between the HFMSE and Gross Motor Function Measure was r = 0.98. Correlations between HFMSE and forced vital capacity (percentage of predicted normal) (n = 56) and a functional rating (n = 57) were r = 0.87 and r = 0.92, respectively. Correlations with strength were as follows: knee extension, r = 0.74 (n = 60); elbow flexion, r = 0.77 (n = 61); and knee flexion, r = 0.74 (n = 58). The HFMSE differentiated patients by SMN2 copy number (P = .0007); bi-level positive airway pressure use, <8 versus ≥8 hours/day (P < .0001); ambulatory status (P < .0001); and spinal muscular atrophy type (P < .0001). The HFMSE demonstrates significant associations with established measures of function, strength, and genotype, and discriminates patients based on function, diagnostic category, and bi-level positive airway pressure need. Time of administration averaged 12 minutes. The HFMSE is a valid, time-efficient outcome measure for clinical trials in spinal muscular atrophy types II and III.

Motor and cognitive assessment of infants and young boys with Duchenne Muscular Dystrophy: results from the Muscular Dystrophy Association DMD Clinical Research Network

Therapeutic trials in Duchenne Muscular Dystrophy (DMD) exclude young boys because traditional outcome measures rely on cooperation. The Bayley III Scales of Infant and Toddler Development (Bayley III) have been validated in developing children and those with developmental disorders but have not been studied in DMD. Expanded Hammersmith Functional Motor Scale (HFMSE) and North Star Ambulatory Assessment (NSAA) may also be useful in this young DMD population. Clinical evaluators from the MDA-DMD Clinical Research Network were trained in these assessment tools. Infants and boys with DMD (n = 24; 1.9 ± 0.7 years) were assessed. The mean Bayley III motor composite score was low (82.8 ± 8; p ≤ .0001) (normal = 100 ± 15). Mean gross motor and fine motor function scaled scores were low (both p ≤ .0001). The mean cognitive comprehensive (p=.0002), receptive language (p ≤ .0001), and expressive language (p = .0001) were also low compared to normal children. Age was negatively associated with Bayley III gross motor (r = -0.44; p = .02) but not with fine motor, cognitive, or language scores. HFMSE (n=23) showed a mean score of 31 ± 13. NSAA (n = 18 boys; 2.2 ± 0.4 years) showed a mean score of 12 ± 5. Outcome assessments of young boys with DMD are feasible and in this multicenter study were best demonstrated using the Bayley III.

Validation of the Childrenʼs Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND)

Purpose: Preliminary validation of the Childrens Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) for motor skill assessment in spinal muscular atrophy type I. Methods: A total of 27 subjects 3 to 260 months old (mean = 49, SD = 69) with spinal muscular atrophy–I were evaluated with the CHOP INTEND. Subjects were evaluated as part of a multicenter natural history study. Results: CHOP INTEND scores and age were significantly correlated (r = −0.51, P = .007; 2 survival of the motor neuron [SMN] 2 gene copies, n = 16, r = −0.60, 3 SMN2 gene copies, n = 9, r = −0.83). Respiratory support and CHOP INTEND scores were correlated (r = −0.74, P < .0001, n = 26). The CHOP INTEND and age regression in patients with 2 copies versus 3 copies of SMN2 approached significance (P = .0711, n = 25). Subjects who required respiratory support scored significantly lower (mean = 15.5, SD = 10.2 vs mean = 31.2, SD = 4.2, P < .0001, n = 27). Correlation with motor unit number estimation and combined motor unit activation were not significant. Conclusion: The CHOP INTEND reflects measures of disease severity and supports continued exploration of the CHOP INTEND.

Spinal muscular atrophy functional composite score: A functional measure in spinal muscular atrophy.

Introduction: With clinical trials underway, our objective was to construct a composite score of global function that could discriminate among people with spinal muscular atrophy (SMA). Methods: Data were collected from 126 participants with SMA types 2 and 3. Scores from the Hammersmith Functional Motor Scale—Expanded and Upper Limb Module were expressed as a percentage of the maximum score and 6‐minute walk test as percent of predicted normal distance. A principal component analysis was performed on the correlation matrix for the 3 percentage scores. Results: The first principal component yielded a composite score with approximately equal weighting of the 3 components and accounted for 82% of the total variability. The SMA functional composite score, an unweighted average of the 3 individual percentage scores, correlated almost perfectly with the first principal component. Conclusions: This combination of measures broadens the spectrum of ability that can be quantified in type 2 and 3 SMA patients. Muscle Nerve 52: 942–947, 2015

Physical therapy services received by individuals with spinal muscular atrophy (SMA)

PURPOSE The consensus statement for standard of care in SMA recommends multidisciplinary medical care including physical therapy (PT) services. To date there are no reports regarding the implementation of these recommendations and the type of care or services received by individuals with SMA. The purpose of this study is to describe the PT services received by individuals with SMA. METHODS Interviews were conducted with patients or their caregivers at the Pediatric Neuromuscular Clinical Research (PNCR) Network sites from October 2011 to September 2012. Questions included information about clinical status of the patient, sociodemographic profile of the patient or caregiver, and PT services received in the past year, including the setting, frequency, duration and type of PT, and therapies administered by caregivers. RESULTS Eighty-six percent of 105 participants reported receiving PT services, some in multiple settings: 62% in the neuromuscular clinic, 38% at school, 34% at home, and 13% in an outpatient clinic. Greater frequency of PT services received was associated with younger age and inability to walk, but not SMA type. CONCLUSION This is the first multicenter study documenting PT services received by patients with SMA. Further research is needed to better understand the impact of PT services on the natural history of SMA.