Accelerometer based analysis of gait initiation failure in advanced juvenile parkinsonism: a single subject study.

[Purpose] This study used an accelerometer placed close to the center of gravity to quantitatively investigate whether unexpected gait initiation aggravates start hesitation (freezing of gait in gait initiation). [Subject and Methods] The subject was a 53-year-old female who had been suffering from juvenile parkinsonism since she was aged 21 years. An alternating-treatment design was used to compare acceleration characteristics under two gait initiation conditions, which were 1) deliberate gait initiation and 2) gait initiation on a sudden "go" verbal command (sudden gait initiation), in the "on" state of the medication cycle. [Results] In six out of eight sessions, a combination of reduced peak positive anterior accelerations and large power percentage in the high frequency band was consistently observed in the sudden gait initiation compared with deliberate gait initiation. In the other two sessions, although a large acceleration just after the "go" signal was observed, subsequent acceleration signals were blocked by sudden gait initiation. [Conclusion] The results suggest that, even in the "on" state, start hesitation is apparent without increased reliance on frontal cortical attentional mechanisms to compensate for impaired automaticity. In advanced juvenile parkinsonism, sudden gait initiation may be an effective paradigm as a provoking test for start hesitation.