Fatigue leads to gait changes in spinal muscular atrophy.

INTRODUCTION: Impaired mobility and fatigue are common in ambulatory spinal muscular atrophy (SMA) patients. The 6-minute walk test (6MWT) is a reliable measure of fatigue in SMA patients. To further evaluate fatigue, we used quantitative gait analysis during the 6MWT.

METHODS: Nine subjects with SMA and 9 age- and gender-matched, healthy controls were evaluated. Gait parameters of speed and dynamic balance were correlated with 6MWT distance. Performance during the first and last 25 meters of the 6MWT was compared.

RESULTS: Speed-related gait parameters and support base correlated with 6MWT distance. Walking performance was worse for SMA patients. The deterioration in stride length during the 6MWT was greater in SMA patients than in controls.

CONCLUSIONS: Gait analysis detects fatigue, and the decrement in stride length may reflect selective muscle involvement in SMA. Further understanding of the mechanisms underlying fatigue may suggest additional targets for future therapeutic interventions.