Article

After cerebral ischemia, disruption and subsequent reorganization of
functional connections occur both locally and remote to the lesion. Recently,
complexity of brain connectivity has been described using graph theory, a
mathematical approach that depicts important properties of complex systems by
quantifying topologies of network representations. Functional and dynamic changes
of brain connectivity can be reliably analyzed via electroencephalography (EEG)
recordings even when they are not yet reflected in structural changes of
connections. Objective We tested whether and how ischemic stroke in the acute
stage may determine changes in small-worldness of cortical networks as measured
by cortical sources of EEG. Methods Graph characteristics of EEG of 30
consecutive stroke patients in acute stage (no more than 5 days after the event)
were examined. Connectivity analysis was performed using eLORETA in both
hemispheres. Results Network rearrangements were mainly detected in delta, theta,
and alpha bands when patients were compared with healthy subjects. In delta and
alpha bands similar findings were observed in both hemispheres regardless of the
side of ischemic lesion: bilaterally decreased small-worldness in the delta band
and bilaterally increased small-worldness in the alpha2 band.
In the theta band,
bilaterally decreased small-worldness was observed only in patients with stroke
in the left hemisphere. Conclusions After an acute stroke, brain cortex
rearranges its network connections diffusely, in a frequency-dependent modality
probably in order to face the new anatomical and functional frame.
CI - (c) The Author(s) 2016.

Langue : ANGLAIS