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Postural inflexibility in parkinsonian subjects.
F B Horak1, J G Nutt, L M Nashner
1R.S. Dow Neurological Sciences Institute of Good Samaritan Hospital, Portland, OR 97209.
Journal of the Neurological Sciences
|August 1, 1992
Summary
Parkinsonian patients exhibit postural instability due to abnormal movement patterns, not sensory issues. While levodopa aids coordination, it doesn't improve adaptation to changing support conditions in Parkinson's disease.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Movement Science
Background:
- Parkinson's disease (PD) is characterized by motor deficits, including postural instability.
- Understanding the specific postural control deficits in PD is crucial for developing targeted interventions.
Purpose of the Study:
- To identify the specific types of postural deficits contributing to postural instability in parkinsonian patients.
- To compare postural control in parkinsonian subjects with young and old healthy controls.
Main Methods:
- Assessed three aspects of postural control: sensory information use, movement pattern coordination during surface displacements, and adaptation to changing support conditions.
- Compared parkinsonian subjects with young and old control groups.
Main Results:
- Parkinsonian subjects showed reduced sway but abnormal postural response patterns, including excessive antagonist activity and inflexibility in adapting to altered support.
- Response latencies were normal, but movement appeared stiffer with a reduced rate-of-change of sway.
- Levodopa improved postural coordination but not the ability to adapt to changing support conditions.
Conclusions:
- Postural instability in Parkinson's disease stems from abnormal motor execution and adaptation, rather than impaired sensory processing or delayed responses.
- Deficits include difficulty sequencing motor programs and inflexibility in adapting postural responses.
- Levodopa shows potential for improving some aspects of postural control in PD.