http://nnr.sagepub.com/content/early/2012/09/14/1545968312457827.abstract
Abstract
Background. Functional magnetic
resonance imaging (fMRI) of motor impairment after stroke strongly
depends on patient effort and capacity
to make a movement. Hence fMRI has had limited use
in clinical management. Alternatively, resting-state fMRI (ie, with no
task) can elucidate the brain’s functional
connections by determining temporal synchrony between brain regions. Objective.
The authors examined whether resting-state fMRI can elucidate the
disruption of functional connections within hours of ischemic
stroke as well as during recovery. Methods.
A total of 51 ischemic stroke patients—31 with mild-to-moderate hand
deficits (National Institutes of Health Stroke Scale
[NIHSS] motor score ≥1) and 20 with NIHSS score of
0—underwent resting-state fMRI at less than 24 hours, 7 days, and 90 days poststroke;
15 age-matched healthy individuals participated in 1
session. Using the resting-state fMRI signal from the ipsilesional
motor
cortex, the strength of functional connections with
the contralesional motor cortex was computed. Whole-brain maps of the
resting-state motor network were also generated and
compared between groups and sessions. Results. Within hours poststroke, patients with motor deficits exhibited significantly lower connectivity than controls (P = .02) and patients with no motor impairment (P
= .03). Connectivity was reestablished after 7 days in recovered (ie,
NIHSS score = 0) participants. After 90 days, recovered
patients exhibited normal motor connectivity;
however, reduced connectivity with subcortical regions associated with
effort
and cognitive processing remained. Conclusion.
Resting-state fMRI within hours of ischemic stroke can demonstrate the
impact of stroke on functional connections throughout
the brain. This tool has the potential to help
select appropriate stroke therapies in an acute imaging setting and to
monitor
the efficacy of rehabilitation.
Results
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