Brain Advance Access originally published online on May 11, 2009
Brain 2009 132(8):2151-2160; doi:10.1093/brain/awp053
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Gait freezing in Parkinson's disease and the stride length sequence effect interaction
1 School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, Victoria, Australia 2 Clinical Research Centre for Movement Disorders & Gait, Kingston Centre Southern Health, Melbourne, Australia 3 Monash Ageing Research Centre, Kingston Centre Southern Health, Melbourne, Australia 4 National Parkinson Foundation Centre of Excellence, Kingston Centre Southern Health, Melbourne, Australia
Correspondence to: Prof. Robert Iansek, Clinical Research Centre for Movement Disorders & Gait, Kingston Centre Southern Health, Melbourne, Victoria 3192, Australia E-mail: robert.iansek{at}med.monash.edu.au
Freezing of gait (FOG) has been identified as one of the main contributors to gait disturbances in Parkinson's disease. While the pathophysiology remains enigmatic, several factors such as step length and the sequence effect (step to step reduction in amplitude) may lead to the occurrence of FOG. It was hypothesized that by reducing step length, FOG episodes would present more frequently if a significant sequence effect (measured as a regression slope) was co-existent in the subject. Twenty-six participants with Parkinson's disease were separated clinically into a freezing (PD + FOG, n = 16) and non-freezing (PD – FOG, n = 10) group, with 10 age-matched control participants. Testing involved walking trials where preferred step length was set at 100%, 75%, 50% and 25% of normalized step length. The number of FOG episodes increased in the 50% condition and further increased in the 25% condition compared to other conditions. The participants with FOG also demonstrated a larger average regression slope, with significant differences in the 75%, 50% and 25% conditions when compared to the PD – FOG and control groups. There were no significant differences when comparing the slope of the PD – FOG and control group, indicating the reduced step length and the sequence effect may have led to the occurrence of FOG. These findings support the possible dual requirement of a reduced step length and a successive step to step amplitude reduction to lead to FOG.
Key Words: Parkinson's disease; freezing of gait; sequence effect
Abbreviations: FOG, freezing of gait; FOG-Q, freezing of gait questionnaire; GDS, Geriatric Depression Scale; MMSE, Mini Mental State Examination
Received July 30, 2008. Revised January 14, 2009. Accepted February 4, 2009.