Efficacy of EMG-triggered electrical arm stimulation in chronic hemiparetic stroke patients.
OBJECTIVE
EMG-triggered electrostimulation (EMG-ES) may improve the motor performance of affected limbs of hemiparetic stroke patients even in the chronic stage. This study was designed to characterize cortical activation changes following intensified EMG-ES in chronic stroke patients and to identify predictors for successful rehabilitation depending on disease severity.


METHODS
We studied 9 patients with severe residual hemiparesis, who underwent 8 weeks of daily task-orientated multi-channel EMG-ES of the paretic arm. Before and after treatment, arm function was evaluated clinically and cortical activation patterns were assessed with functional MRI (fMRI) and/or transcranial magnetic stimulation (TMS).


RESULTS
As response to therapy, arm function improved in a subset of patients with more capacity in less affected subjects, but there was no significant gain for those with Box & Block test values below 4 at inception. The clinical improvement, if any, was accompanied by an ipsilesional increase in the sensorimotor cortex (SMC) activation area in fMRI and enhanced intracortical facilitation (ICF) as revealed by paired TMS. The SMC activation change in fMRI was predicted by the presence or absence of motor-evoked potentials (MEPs) on the affected side.


CONCLUSIONS
The present findings support the notion that intensified EMG-ES may improve the arm function in individual chronic hemiparetic stroke patients but not in more severely impaired individuals. Functional improvements are paralleled by increased ipsilesional SMC activation and enhanced ICF supporting neuroplasticity as contributor to rehabilitation. The clinical score at inception and the presence of MEPs have the best predictive potential.
von Lewinski
Friederike
F
Abteilung Klinische Neurophysiologie, Georg-August Universität Göttingen, Göttingen 37075, Germany.
Hofer
Sabine
S
Kaus
Jürgen
J
Merboldt
Klaus-Dietmar
KD
Rothkegel
Holger
H
Schweizer
Renate
R
Liebetanz
David
D
Frahm
Jens
J
Paulus
Walter
W
D000293:Adolescent; D000368:Aged; D000704:Analysis of Variance; D001132:Arm / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000098:blood supply; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010291:Paresis / Q000473:pathology / Q000534:rehabilitation*; D020521:Stroke / Q000473:pathology; D000071939:Stroke Rehabilitation
D010100:Oxygen