Muscle force, balance and falls in muscular impaired individuals with myotonic dystrophy type 1: A five-year prospective cohort study

- 43 patients with myotonic dystrophy type 1 were followed prospectively.
- Natural history in muscle force, gait, balance and falls was assessed during five years.
- We found a significant decrease in muscle force, gait and balance for the whole group.
- A larger muscle force decrease and more falls were found in males.
- More patients had fallen and had more serious injuries after five years.

Individuals with myotonic dystrophy type 1 (DM1) have progressive muscle weakness with gait and balance impairments. We explored prospectively the natural history of muscle force, gait, balance, balance confidence and walking ability in muscular affected individuals with DM1. After five years data from 43 individuals (m/f:18/25) were analysed. All measures of balance showed statistically significant deterioration (p < 0.001) with averaged yearly loss of function by 3-4%. In the group as a whole, loss of muscle force was statistically significant in all lower limb muscles measured after five years: changes relative to baseline force were median −6% to −18%. For males muscle force loss was statistically significant in all leg muscles, but only in hip flexors for women. After five years 100% of the men had fallen during the previous year and 67% three times or more, in contrast only 60% of the women had fallen in the previous year and 36% three times or more. The proportion of individuals seeking medical care the previous year, after falling, was more than doubled after five years, albeit the number of falls had not changed. Awareness of this increased risk of falls is important for caregivers and patients.