Abstract
Background and purposeMemory impairment after stroke is poorly understood as stroke rarely occurs in the hippocampus. Previous studies have observed smaller ipsilateral hippocampal volumes after stroke compared with controls. Possibly, these findings on macroscopic level are not the first occurrence of structural damage and are preceded by microscopic changes that may already be associated with a worse memory function. We therefore examined the relationship between hippocampal integrity, volume, and memory performance long after first-ever ischemic stroke in young adults.MethodsWe included all consecutive first-ever ischemic stroke patients, without hippocampal strokes or recurrent stroke/TIA, aged 18–50 years, admitted to our academic hospital between 1980 and 2010. One hundred and forty-six patients underwent T1 MPRAGE, DTI scanning and completed the Rey Auditory Verbal Learning Test and were compared with 84 stroke-free controls. After manual correction of hippocampal automatic segmentation, we calculated mean hippocampal fractional anisotropy (FA) and diffusivity (MD).ResultsOn average 10 years after ischemic stroke, lesion volume was associated with lower ipsilateral hippocampal integrity (p<0.05), independent of hippocampal volume. In patients with a normal ipsilateral hippocampal volume (volume is less than or equal to 1.5 SD below the mean volume of controls) significant differences in ipsilateral hippocampal MD were observed (p<0.0001). However, patients with a normal hippocampal volume and high hippocampal MD did not show a worse memory performance compared with patients with a normal volume and low hippocampal MD (p>0.05).ConclusionsPatients with average ipsilateral hippocampal volume could already have lower ipsilateral hippocampal integrity, although at present with no attendant worse memory performance compared with patients with high hippocampal integrity. Longitudinal studies are needed to investigate whether a low hippocampal integrity after stroke might lead to exacerbated memory decline with increasing age.
Highlights
Episodic memory dysfunction frequently occurs after ischemic stroke at young age (18 through 50 years), it's underlying mechanism is poorly understood
On average 10 years after ischemic stroke, lesion volume was associated with lower ipsilateral hippocampal integrity (p
Patients with average ipsilateral hippocampal volume could already have lower ipsilateral hippocampal integrity, at present with no attendant worse memory performance compared with patients with high hippocampal integrity
Summary
Episodic memory dysfunction frequently occurs after ischemic stroke at young age (18 through 50 years), it's underlying mechanism is poorly understood. Recent studies started to unravel potential underlying mechanisms by demonstrating smaller ipsilateral hippocampal volumes in patients who experienced an ischemic stroke outside the medial temporal lobe at young age, with an accompanying worse memory performance [2]. Most likely, these findings on the macroscopic level are not the first manifestation of structural damage of the hippocampus after ischemic stroke as they are presumably preceded by microstructural changes with already (subtle) cognitive correlates. We examined the relationship between hippocampal integrity, volume, and memory performance long after first-ever ischemic stroke in young adults
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