Brain Advance Access published online on May 29, 2009
Brain, doi:10.1093/brain/awp133
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Reduced medial temporal lobe functionality in stroke patients: a functional magnetic resonance imaging study
1 Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience, Medical Centre, Radboud University Nijmegen, The Netherlands 2 Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, The Netherlands
Correspondence to:
Frank-Erik de Leeuw, Department of Neurology, Radboud University Nijmegen, Medical Centre, PO Box 9101, 6500 HB Nijmegen (HP 935), The Netherlands E-mail: H.deLeeuw{at}neuro.umcn.nl
Stroke is a leading cause of disability, not only because of motor limitations, but also because of the frequent occurrence of post-stroke cognitive impairment. This is illustrated by the fact that the risk of post-stroke dementia is reportedly higher than a recurrent stroke. The loss of subcortical and cortical functions in the post-stroke cognitive dysfunction spectrum is usually well explained by the size and location of the infarction. However, this does not apply for post-stroke memory dysfunction (especially episodic memory dysfunction), as there is almost never an infarction in the medial temporal lobe. Involvement of the medial temporal lobe in post-stroke memory dysfunction seems likely since this structure is essential for memory encoding and retrieval. For a proper episodic memory function, the medial temporal lobe depends on intact connections with virtually the whole brain. Disconnection from other brain areas due to the infarction could lead to a reduced medial temporal lobe function and the attendant reduced episodic memory function. We investigated medial temporal lobe functionality in 28 ‘first-ever’ stroke patients and 22 healthy controls with the aid of functional magnetic resonance imaging. Stroke patients with a reduced episodic memory function 6–8 weeks after infarction had reduced medial temporal lobe functionality. Post-stroke reduced medial temporal lobe functionality may be responsible for the frequent observation of impaired post-stroke episodic memory function. Insight into this mechanism could be helpful in identifying which stroke patients may be at increased risk for developing post-stroke dementia and those who could benefit from early cognitive rehabilitation.
Key Words: stroke; fMRI; MTL; imaging; n-back task
Abbreviations: fMRI, functional magnetic resonance imaging; MMSE, mini mental state examination; MTL, medial temporal lobe; NIHSS, National Institute of Health Stroke Scale
Received June 25, 2008. Revised April 19, 2009. Accepted April 22, 2009.