Upper Extremity Motor Impairments and Microstructural Changes in Bulbospinal Pathways in Chronic Hemiparetic Stroke
Meriel Owen1,2, Carson Ingo1, Julius P A Dewald1,2,3
1Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
Frontiers in Neurology
|June 30, 2017
Summary
Stroke survivors with severe arm and hand impairments show increased white matter integrity in the contralesional reticulospinal tract (RetST). This suggests neuroplastic reorganization may underlie abnormal limb synergies after stroke.
Area of Science:
- Neuroscience
- Neurology
- Biomedical Engineering
Background:
- Hemiparetic stroke often leads to abnormal limb synergies, replacing precise joint control and impairing arm function.
- The reticulospinal (RetST) and rubrospinal (RubST) tracts are hypothesized to mediate these synergies due to their multi-muscle activation patterns.
Purpose of the Study:
- To investigate the relationship between white matter microstructure of the RetST and RubST tracts and the severity of upper extremity (UE) synergy and hand motor impairments post-stroke.
- To explore potential neuroplastic changes in these pathways.
Main Methods:
- High-resolution diffusion tensor imaging (DTI) was used to assess white matter integrity.
- DTI data were collected from 19 chronic stroke individuals with moderate to severe UE impairment and 15 healthy controls.
- Fractional anisotropy (FA) and diffusivity measures were analyzed in relation to clinical assessments of synergy and hand function.
Main Results:
- Stroke individuals exhibited reduced FA and increased diffusivity in the corona radiata and corpus callosum compared to controls.
- Contralesional RetST FA significantly correlated with both UE synergy severity (r=-0.606) and hand impairment (r=-0.609).
- Ipsilesional RubST FA correlated significantly with hand impairment severity (r=-0.590).
Conclusions:
- Increased FA in the contralesional RetST in stroke survivors with severe impairments suggests increased myelination and neuroplastic reorganization.
- Reticulospinal tract microstructure is sensitive to abnormal joint coupling and hand impairment, offering a potential biomarker for evaluating anti-synergy rehabilitation strategies.
