Changes in cerebral activity after decreased upper-limb hypertonus: an EMG-fMRI study.
OBJECTIVE
Whereas 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.


METHODS
We 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.


RESULTS
Before 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.


CONCLUSIONS
Changes 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.
Manganotti
Paolo
P
Department of Neurological and Visual Sciences, University of Verona, Clinic Hospital Gianbattista Rossi, Verona, Italy. paolo.manganotti@univr.it
Acler
Michele
M
Formaggio
Emanuela
E
Avesani
Mirko
M
Milanese
Franco
F
Baraldo
Andrea
A
Storti
Silvia Francesca
SF
Gasparini
Anna
A
Cerini
Roberto
R
Mucelli
Roberto Pozzi
RP
Fiaschi
Antonio
A
D000368:Aged; D001132:Arm / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods*; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D009122:Muscle Hypertonia / Q000175:diagnosis / Q000503:physiopathology*