MD, PhD student Section Cerebrovascular Disorders
Department of Neurology and Neurosurgery
email
c.a.m.oers@umcutrecht.nltel +31-88 75 59111, pacer 3555
ProjectRecovery from Aphasia after Stroke. A functional MRI study
SupervisorsL.J.Kappelle, H.B.Van der Worp, R.Dijkhuizen
Aim of project
To relate the spatio-temporal activation pattern measured using fMRI with the functional recovery from aphasia after Stroke. This might give a better insight into the neural processes responsible for functional recovery and possibly make it possible to predict outcome of individual patients based on their brain activation pattern.
SummaryBackground: About 40% of stroke patients suffer from language disturbances (aphasia). Most of these patients show a certain, albeit variable, degree of functional recovery over time. A clinical measure that can predict functional outcome in the early stage and that can aid in the selection of optimal therapeutic intervention is not available. Functional recovery after stroke has been associated with cerebral reorganization. Rearrangement of functional fields a such as peri- and contralesional shifts of representational areas may play an important role in the recovery of language disturbances. These processes can be investigated with functional magnetic resonance imaging (fMRI) allowing whole-brain mapping of cerebral activity during task execution.
Hypothesis: 1) The right, nondominant hemisphere contributes to language function of patients with aphasia caused by a stroke more than 2 years ago. 2.1) Initial recovery from aphasia (i.e., in the first 3 months after stroke) is correlated with the degree of activation in the left, dominant hemisphere, whereas subsequent functional improvement is mostly related to increase of activity in the right, nondominant hemisphere. 2.2) Activation in the right, nondominant hemisphere in the early phase of stroke predicts poor recovery of function.
Study objectives: To investigate the relationship between spatio-temporal alterations in brain activation patterns and functional recovery of language disturbances caused by ischemic stroke.
Methods: Patients with aphasia due to stroke 2 years earlier (n = 14; Study 1) and patients with aphasia due to stroke in the previous 2 weeks (n = 14; Study 2) will undergo neuropsychological examination and fMRI. Healthy subjects will serve as controls (n = 2 ´ 14; Study 1 & 2). Brain activation patterns will be assessed during execution of different neurocognitive language tasks. In Study 1, investigations will be repeated after 3, 6 and 18 months. The fMRI data will be analyzed using high-resolution cortical surface-based analysis tools. T2-weighted MRI and perfusion MRI will be performed to assess ischemic tissue and perfusion damage, respectively. First, 16 healthy volunteers will serve to optimize language tasks and MRI protocols.
Expected results: We expect that these studies will demonstrate that recovery from aphasia is accompanied by a multiphasic change in brain activation. Good, initial recovery is expected to correlate best with preservation or redistribution of left, dominant hemisphere activation, whereas late supplementary activity in the right, nondominant hemisphere would contribute to chronic improvements. Finally, we anticipate that functional MRI in acute stroke patients is able to provide prognostic information on recovery from aphasia.