The Duchenne Video Assessment (DVA) was developed to assess ease of movement in patients with Duchenne muscular dystrophy. The outcome measure uses at-home video capture to quantify the compensatory movements necessary for patients to perform daily activities and maintain independence. A majority of patients with Primary Mitochondrial Myopathy (PMM) identify muscular weakness as a bothersome symptom, suggesting the utility of the DVA to assess ease of movement in patients with PMM.
The applicability of the DVA tasks to PMM was assessed in consultation with expert clinicians, and 5 tasks were identified as appropriate for feasibility testing in PMM patients: sit up from supine, stand up from floor, stand from couch, climb 5 stairs, and walk. In a recorded telehealth visits, participants were given standardized instructions to complete each task (N=10). A physical therapist certified in DVA scoring assessed each video using the DVA scorecards.
For three activities, stairs, sit from supine, and stand from floor, compromised movement was observed in 60-80% of participants. For stand from couch, two patients (20%) exhibited compensated movement. For the walk activity, initial review indicated an ataxic gait rather than a gait exhibiting muscle weakness, and a modified scorecard was developed to assess ataxia, which assessed 50% of patients with an ataxic gait. In one participant, random factors resulted in a capture of repeat attempts in the climb stairs task, which evidenced the importance of fatigue on the magnitude of compensatory movements employed during the task.
The results indicated that at-home video captures could be used to rigorously assess muscle weakness as evidenced by ease of movement in patients’ with PMM. Further, review of the videos indicated that fatiguability could be captured and scored, which can help assess an additional important aspect of the patient experience of PMM.