Residual Upper Arm Motor Function Primes Innervation of Paretic Forearm Muscles in Chronic Stroke after Brain-Machine Interface (BMI) Training.
BACKGROUND
Abnormal upper arm-forearm muscle synergies after stroke are poorly understood. We investigated whether upper arm function primes paralyzed forearm muscles in chronic stroke patients after Brain-Machine Interface (BMI)-based rehabilitation. Shaping upper arm-forearm muscle synergies may support individualized motor rehabilitation strategies.


METHODS
Thirty-two chronic stroke patients with no active finger extensions were randomly assigned to experimental or sham groups and underwent daily BMI training followed by physiotherapy during four weeks. BMI sessions included desynchronization of ipsilesional brain activity and a robotic orthosis to move the paretic limb (experimental group, n = 16). In the sham group (n = 16) orthosis movements were random. Motor function was evaluated with electromyography (EMG) of forearm extensors, and upper arm and hand Fugl-Meyer assessment (FMA) scores. Patients performed distinct upper arm (e.g., shoulder flexion) and hand movements (finger extensions). Forearm EMG activity significantly higher during upper arm movements as compared to finger extensions was considered facilitation of forearm EMG activity. Intraclass correlation coefficient (ICC) was used to test inter-session reliability of facilitation of forearm EMG activity.


RESULTS
Facilitation of forearm EMG activity ICC ranges from 0.52 to 0.83, indicating fair to high reliability before intervention in both limbs. Facilitation of forearm muscles is higher in the paretic as compared to the healthy limb (p<0.001). Upper arm FMA scores predict facilitation of forearm muscles after intervention in both groups (significant correlations ranged from R = 0.752, p = 0.002 to R = 0.779, p = 0.001), but only in the experimental group upper arm FMA scores predict changes in facilitation of forearm muscles after intervention (R = 0.709, p = 0.002; R = 0.827, p<0.001).


CONCLUSIONS
Residual upper arm motor function primes recruitment of paralyzed forearm muscles in chronic stroke patients and predicts changes in their recruitment after BMI training. This study suggests that changes in upper arm-forearm synergies contribute to stroke motor recovery, and provides candidacy guidelines for similar BMI-based clinical practice.
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany; International Max Planck Research School for Neural & Behavioral Sciences, Tübingen, Germany.
Marco Rocha
MR
Curado
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany; International Max Planck Research School for Neural & Behavioral Sciences, Tübingen, Germany.
Eliana Garcia
EG
Cossio
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany.
Doris
D
Broetz
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany.
Manuel
M
Agostini
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany.
Woosang
W
Cho
Edmond and Lily Safra International Institute of Neuroscience, Institute Santos Dumond, Natal, Brazil.
Fabricio Lima
FL
Brasil
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany; International Max Planck Research School for Neural & Behavioral Sciences, Tübingen, Germany.
Oezge
O
Yilmaz
Institute of Neuroscience, Université catholique de Louvain, Louvain la Neuve, Belgium.
Giulia
G
Liberati
Department of Neurology, University of São Paulo, São Paulo, Brazil; Department of Neurosurgery, University of Tübingen, Tübingen, Germany.
Guilherme
G
Lepski
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany; Ospedale San Camillo, IRCCS, Venice, Italy; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany.
Niels
N
Birbaumer
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Silcherstr. 5, 72076, Tübingen, Germany; TECNALIA Health Technologies, San Sebastian, Spain.
Ander
A
Ramos-Murguialday
D000328:Adult; D000368:Aged; D001132:Arm / Q000503:physiopathology*; D062207:Brain-Computer Interfaces; D002908:Chronic Disease; D004576:Electromyography; D005260:Female; D005542:Forearm / Q000294:innervation / Q000503:physiopathology*; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D010291:Paresis / Q000503:physiopathology / Q000534:rehabilitation*; D026741:Physical Therapy Modalities; D012782:Shoulder / Q000503:physiopathology; D020521:Stroke / Q000503:physiopathology; D000071939:Stroke Rehabilitation; D016896:Treatment Outcome