Here we determine if instrumenting timed functional tasks (TFTs) with wireless inertial motion sensors improves sensitivity to disease progression and movement pattern changes in facioscapulohumeral muscular dystrophy (FSHD).

We performed a longitudinal study in 10 genetically confirmed, clinically affected individuals at the University of Kansas Medical Center.  At each visit an instrumented timed up and go (iTUG) was performed with participants wearing 6 wireless inertial sensors (OPAL, APDM, Portland, OR).  We determined the average monthly slope of progression and estimated 12-month change for temporal and spatial motion parameters and compared to the TFT duration. We created a summary iTUG Z-score made up of stride velocity and trunk sagittal range of motion.

Participants were followed on average for 20.6 months, were middle aged and spanned a full range of ambulatory severities.  The average iTUG duration stayed constant; whereas stride length, stride velocity, and trunk sagittal range of motion changed indicating poorer performance over time.  Arm swing changed in a compensatory direction towards the normative means.  The iTUG Z score declined an estimated 48% at one year (95% confidence limit -75, -18) indicating poorer performance over time.

The iTUG motion parameters were more sensitive to FSHD progression than the traditional TFT which supports the iTUG approach for future FSHD clinical trials or other muscular dystrophies.