Changes in cerebral activity after decreased upper-limb hypertonus: an EMG-fMRI study |
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Authors: | Paolo Manganotti Michele Acler Emanuela Formaggio Mirko Avesani Franco Milanese Andrea Baraldo Silvia Francesca Storti Anna Gasparini Roberto Cerini Roberto Pozzi Mucelli Antonio Fiaschi |
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Affiliation: | 1. Department of Neurological and Visual Sciences, Section of Rehabilitative Neurology, University of Verona, Clinic Hospital “Gianbattista Rossi”, P.zz.le LA Scuro, 37100 Verona, Italy;2. IRCCS, Instituto di Ricovero e Cura a carattere Scientifico, S. Camillo Hospital, Venice, Italy;3. Department of Morphological and Biomedical Sciences, Institute of Radiology, University of Verona, 37100 Verona, Italy |
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Abstract: |
ObjectiveWhereas several studies have used functional magnetic resonance imaging (fMRI) to investigate motor recovery, whether therapy to decrease post-stroke hypertonus alters central motor patterns remains unclear. In this study, we used continuous electromyography (EMG)-fMRI to investigate possible changes in movement-related brain activation in patients receiving Botulinum toxin (BoNT-A) for hand-muscle hypertonus after chronic stroke.MethodsWe studied eight stroke patients all of whom had hemiparesis and associated upper-limb hypertonus. All patients underwent an fMRI-EMG recording and clinical-neurological assessment before BoNT-A and 5 weeks thereafter. The handgrip motor task during imaging was fixed across both patients and controls. The movements were metronome paced, movement amplitude and force were controlled with a plastic orthosis, dynamometer and EMG recording. An age-matched control group was recruited from among healthy volunteers underwent the same fMRI-EMG recording.ResultsBefore BoNT-A, while patients moved the paretic hand, fMRI detected wide bilateral activation in the sensorymotor areas (SM1), in the supplementary motor area (SMA) and cerebellum. After BoNT-A blood oxygenation level-dependent (BOLD) activation decreased in ipsilateral and contralateral motor areas and became more lateralized. BOLD activation decreased also in ipsilateral cerebellar regions and in the SMA.ConclusionChanges in peripheral upper-limb hypertonus after BoNT-A were associated to an improvement in active movements and more lateralized and focalized activation of motor areas. The clinical and EMG-fMRI coregistration technique we used to study hand-muscle hypertonus in patients receiving BoNT-A after chronic stroke should be useful in future studies seeking improved strategies for post-stroke neurorehabilitation. |
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Keywords: | Stroke Spasticity fMRI EMG Botulinum toxin |
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