Functional reorganization and prediction of motor recovery after a stroke: A graph theoretical analysis of functional networks.
OBJECTIVE
This study investigated the changes in the network topological configuration of the ipsilesional and contralesional hemispheres after a stroke and the indicators for the prediction of motor recovery using a graph theoretical approach in networks obtained from functional magnetic resonance imaging (fMRI).


METHODS
A longitudinal observational experiments (2 weeks and 1, 3, and 6 months after onset) were conducted on 12 patients after a stroke. We investigated the network reorganization during recovery in the ipsilesional and contralesional hemispheres by examining changes of graph indices related to network randomization. We predicted the recovery of motor function by examining the relationship between specific network measures and improved motor function scores.


RESULTS
The ipsilesional hemispheric network showed active reorganization during recovery after a stroke. The randomness of the network significantly increased for 3 months post-stroke. We described an indicator for the prediction of the recovery of motor function from graph indices: the characteristic path length. As the path length of the ipsilesional network was lower immediately after onset, the better recovery could be expected after 3 months.


CONCLUSIONS
This approach were helpful for understanding dynamic reorganizations of both hemispheric networks after a stroke and finding the implication for recovery.
Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea.
Jungsoo
J
Lee
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Irwon-ro, Gangnam-gu, Seoul, Republic of Korea.
Minji
M
Lee
Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea.
Dae-Shik
DS
Kim
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Irwon-ro, Gangnam-gu, Seoul, Republic of Korea.|Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-ro, Gangnam-gu, Seoul, Republic of Korea.
Yun-Hee
YH
Kim
D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D002545:Brain Ischemia / Q000175:diagnosis / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009434:Neural Pathways / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D012146:Rest; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology*
Stroke; functional reorganization; graph theoretical analysis; motor recovery