Modified dynamic gait index and limits of stability in myotonic dystrophy type 1.

INTRODUCTION: The purpose of this study was to describe and compare the performance of balance and walking tests in relation to self-reported fall history in adults with myotonic dystrophy type 1 (DM1). METHODS: Twenty-two (13 male) participants with DM1 completed, a 6-month fall history questionnaire, the modified Dynamic Gait Index (mDGI), limits of stability (LoS) testing, and 10-m walking tests. RESULTS: Mean (SD) falls in 6 months was 3.7 (3.1), and 19 (86%) participants reported at least 1 fall. Significant differences in mDGI scores (P = 0.006) and 10-m fast walking gait velocity (P = 0.02) were found between those who had been classified as "fallers" and those who had been classified as "nonfallers." Significant correlations were found between mDGI scores and 10-m walking time. DISCUSSION: Falls are common in DM1, and the mDGI may have potential to distinguish fallers from nonfallers, whereas the LoS failed to detect such impairment. Future studies should further explore use of the mDGI in DM1. Muscle Nerve 58: 694-699, 2018.

Stepping Activity in Children With Congenital Myotonic Dystrophy.

PURPOSE: The purpose of this study was to investigate the physical activity levels in children with congenital myotonic dystrophy (CDM), and to examine whether patient clinical and functional characteristics correlated to physical activity. METHODS: Twenty-five children with CDM were assessed on functional measures, clinical measures, and physical activity levels. RESULTS: Results support that children with CDM spend the majority of their time inactive. There was a negative correlation between inactivity and cytosine-thymine-guanine repeats, suggesting increased inactivity with increased CDM severity. Age, body mass index, and lean muscle mass may be factors influencing activity levels. CONCLUSIONS: Children in this study received one-third the recommended steps per day. The number of steps per day is not correlated with clinical measures.

Physical function and mobility in children with congenital myotonic dystrophy.

INTRODUCTION: Congenital myotonic dystrophy (CDM) occurs when symptoms of myotonic dystrophy present at birth. In this study we evaluated the relationship between physical function, muscle mass, and age to provide an assessment of the disease and help prepare for therapeutic trials. METHODS: CDM participants performed timed functional tests (TFTs), the first 2 minutes of 6-minute walk tests (2/6MWTs), and myometry tests, and also performed dual-energy X-ray absorption (DEXA) scans. Healthy controls (HCs) performed TFTs, 6MWTs, and myometry. RESULTS: Thirty-seven children with CDM and 27 HCs (age range 3-13 years) participated in the study. There were significant differences in the 10-meter walk (11.3 seconds in CDM vs. 6.8 seconds in HC) and 2MWT (91 meters in CDM vs. 193 meters in HCs). DEXA lean mass of the right arm correlated with grip strength (r = 0.91), and lean mass of the right leg correlated with 6MWT (r = 0.62). CONCLUSION: Children with CDM have significant limitations in strength and mobility. The tests performed were reliable, and lean muscle mass may serve as a useful biomarker. Muscle Nerve 56: 224-229, 2017.

Disease burden and functional outcomes in congenital myotonic dystrophy: A cross-sectional study.

OBJECTIVE: Herein, we describe the disease burden and age-related changes of congenital-onset myotonic dystrophy (CDM) in childhood. METHODS: Children with CDM and age-matched controls aged 0 to 13 years were enrolled. Participants were divided into cohorts based on the following age groups: 0-2, 3-6, and 7-13 years. Each cohort received age-appropriate evaluations including functional testing, oral facial strength testing, neuropsychological testing, quality-of-life measurements, and ECG. Independent-samples t test or Wilcoxon 2-sample test was used to compare the differences between children with CDM and controls. Probability values less than 0.05 are reported as significant. RESULTS: Forty-one participants with CDM and 29 healthy controls were enrolled. The 6-minute walk was significantly different between CDM (258.3 m [SD 176.0]) and control participants (568.2 m [SD 73.2]). The mean lip force strength was significantly different in CDM (2.1 N [SD 2.8)] compared to control participants (17.8 N [SD 7.6]). In participants with CDM, the mean IQ (65.8; SD 18.4) was 3 SDs below the mean compared to standardized norms. Measurements of grip strength, sleep quality, and quality of life were also significantly different. Strength measures (oral facial strength, grip strength, and 6-minute walk) correlated with each other but not with participant IQ. CONCLUSIONS: This work identifies important phenotypes associated with CDM during childhood. Several measures of strength and function were significantly different between participants with CDM and controls and may be useful during future therapeutic trials.