Article

Understanding mechanisms of recovery may result in new treatment
strategies to improve motor outcome after stroke. Imaging techniques such as
functional magnetic resonance imaging (fMRI) and positron emission tomography
(PET) allow changes in brain activity after stroke recovery to be identified.
OBJECTIVE: To systematically review serial imaging studies on recovery within 6
months poststroke, assess their methodological quality, and identify trends in
the association between task-related brain activation patterns and functional
upper limb recovery. METHODS: A literature search was performed using Medline,
PICARTA, and EMBASE databases. Studies were appraised using binary weighted
methodological criteria for internal, statistical, and external validity.
RESULTS: Twenty-two of the 869 identified studies met the inclusion criteria.
Studies showed methodological weaknesses with respect to controlling for task
performance, selecting appropriate outcome measures, and adequate presentation
and execution of statistical analysis. After stroke, motor task performance shows
unilateral overactivation of motor and nonmotor areas, a posterior shift in
activity in the primary motor cortex, and bilateral recruitment of associated
motor and nonmotor areas. Concomitant with neurological recovery, overactivation
appears to diminish longitudinally, but not in all patients. CONCLUSION: Despite
methodological shortcomings and heterogeneity, trends can be discerned. However,
statistically sound associations with recovery are not consistent. The challenges
in future research will be, controlling for confounding factors, finding outcomes
that specifically measure dexterity of the paretic limb, to control for the
extent of white matter damage and changes in perfusion in order to establish the
longitudinal construct validity of fMRI and PET with regard to upper limb
recovery after stroke.

Langue : ANGLAIS