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Cortical activation changes in patients suffering from post-stroke arm spasticity and treated with botulinum toxin a
Zuzana Tomášová1, Petr Hluštík, Michal Král
1Department of Neurology, Faculty of Medicine and Dentistry, Palacký University and University Hospital, Olomouc, Czech Republic.
Background And Purpose:
Botulinum toxin (BoNT) treatment relieves focal arm spasticity after stroke, likely acting at several hierarchical levels of the motor system. The central correlate of BoNT-induced spasticity relief may be detected using repeated functional MRI (fMRI) during motor task.
Methods:
Five patients (4 males, 1 female, mean age 67 years) with hemiparesis and distal arm spasticity after chronic ischemic stroke were studied. FMRI was performed while moving the paretic hand in three sessions: before and 4 and 11 weeks after BoNT treatment.
Results:
Arm spasticity significantly decreased following BoNT treatment across the group (mean modified Ashworth scale change .6). FMRI prior to BoNT treatment showed extensive bilateral active networks, whereas post-BoNT activation was limited to midline and contralateral sensorimotor cortices, and the third examination, when the toxin effect has worn off, again showed extensive activation similar to pre-BoNT examination. Post-BoNT session 2 compared to sessions 1 and 3 demonstrated a significantly less activation in contralateral frontoparietal areas including inferior frontal, postcentral, and middle frontal gyri as well as transient crossed cerebellar activation.
Conclusion:
Relief of post-stroke arm spasticity may be associated with changes at several hierarchical levels of the cortical sensorimotor system, including the prefrontal cortex.
