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Changes in cerebral activity after decreased upper-limb hypertonus: an EMG-fMRI study
Paolo Manganotti1, Michele Acler, Emanuela Formaggio
1Department of Neurological and Visual Sciences, University of Verona, Clinic Hospital Gianbattista Rossi, Verona, Italy. paolo.manganotti@univr.it
Magnetic Resonance Imaging
|February 2, 2010
Summary
Botulinum toxin (BoNT-A) therapy for post-stroke upper-limb hypertonus reduced widespread brain activation, leading to more focused motor control. This neurorehabilitation approach improved active movements and brain activity patterns in stroke survivors.
Area of Science:
- Neuroscience
- Rehabilitation Medicine
- Medical Imaging
Background:
- Stroke often results in hemiparesis and upper-limb hypertonus, impacting motor recovery.
- The central nervous system's motor control adaptations following hypertonus treatment remain incompletely understood.
- Functional magnetic resonance imaging (fMRI) combined with electromyography (EMG) offers a method to investigate brain activity during movement.
Purpose of the Study:
- To investigate changes in central motor patterns using continuous EMG-fMRI in chronic stroke patients treated with Botulinum toxin type A (BoNT-A) for hand-muscle hypertonus.
- To determine if BoNT-A therapy alters brain activation related to motor control after stroke.
Main Methods:
- Eight stroke patients with hemiparesis and upper-limb hypertonus underwent fMRI-EMG recording and clinical assessment before and 5 weeks after BoNT-A treatment.
- A standardized handgrip motor task, controlled for movement amplitude and force using an orthosis and dynamometer, was performed during fMRI-EMG.
- An age-matched control group of healthy volunteers underwent the same fMRI-EMG recording procedure.
Main Results:
- Before BoNT-A, fMRI revealed widespread bilateral activation in sensorymotor areas (SM1), supplementary motor area (SMA), and cerebellum during paretic hand movement.
- Following BoNT-A treatment, blood oxygenation level-dependent (BOLD) activation decreased in both ipsilateral and contralateral motor areas, becoming more lateralized.
- A reduction in BOLD activation was also observed in ipsilateral cerebellar regions and the SMA after BoNT-A therapy.
Conclusions:
- Treatment with BoNT-A for upper-limb hypertonus in chronic stroke patients is associated with improved active movements.
- BoNT-A therapy leads to more lateralized and focalized activation of motor areas, suggesting a refinement of central motor patterns.
- The integrated EMG-fMRI technique is valuable for studying hypertonus and guiding neurorehabilitation strategies post-stroke.
