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Updated: Mar 8, 2026
Assessing Cortical Cerebral Microinfarcts on High Resolution MR Images
Published on: November 20, 2015
Functional deficits induced by cortical microinfarcts
Philipp M Summers1, David A Hartmann1, Edward S Hui2
11 Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA.
Abstract:
Clinical studies have revealed a strong link between increased burden of cerebral microinfarcts and risk for cognitive impairment. Since the sum of tissue damage incurred by microinfarcts is a miniscule percentage of total brain volume, we hypothesized that microinfarcts disrupt brain function beyond the injury site visible to histological or radiological examination. We tested this idea using a mouse model of microinfarcts, where single penetrating vessels that supply mouse cortex were occluded by targeted photothrombosis. We found that in vivo structural and diffusion MRI reliably reported the acute microinfarct core, based on spatial co-registrations with post-mortem stains of neuronal viability. Consistent with our hypothesis, c-Fos assays for neuronal activity and in vivo imaging of single vessel hemodynamics both reported functional deficits in viable peri-lesional tissues beyond the microinfarct core. We estimated that the volume of tissue with functional deficit in cortex was at least 12-fold greater than the volume of the microinfarct core. Impaired hemodynamic responses in peri-lesional tissues persisted at least 14 days, and were attributed to lasting deficits in neuronal circuitry or neurovascular coupling. These data show how individually miniscule microinfarcts could contribute to broader brain dysfunction during vascular cognitive impairment and dementia.
Insights
Tiny cerebral microinfarcts cause widespread brain dysfunction, impacting brain function far beyond visible damage. This study reveals how these small injuries contribute to cognitive impairment in vascular dementia.
Area of Science:
- Neuroscience
- Vascular Biology
- Medical Imaging
Background:
- Cerebral microinfarcts are linked to cognitive impairment.
- The extent of functional disruption by microinfarcts is not fully understood.
- Microinfarcts represent a small percentage of total brain volume.
Purpose of the Study:
- To investigate if microinfarcts cause functional deficits beyond visible tissue damage.
- To quantify the extent of functional disruption caused by microinfarcts.
- To explore the persistence of these functional deficits.
Main Methods:
- Utilized a mouse model with targeted photothrombosis to induce single microinfarcts.
- Employed in vivo structural and diffusion MRI for acute microinfarct core detection.
- Used c-Fos assays and in vivo hemodynamic imaging to assess neuronal activity and blood flow.
- Validated MRI findings with post-mortem neuronal viability stains.
Main Results:
- In vivo MRI accurately identified acute microinfarct cores.
- Functional deficits, including impaired neuronal activity and hemodynamics, were observed in viable tissue surrounding microinfarcts.
- The volume of functionally impaired tissue was estimated to be at least 12-fold larger than the microinfarct core.
- Hemodynamic deficits persisted for at least 14 days, suggesting lasting neuronal circuitry or neurovascular coupling issues.
Conclusions:
- Microinfarcts disrupt brain function in areas significantly larger than the visible lesion.
- These widespread functional deficits contribute to cognitive impairment seen in vascular dementia.
- Understanding the broader impact of microinfarcts is crucial for developing effective treatments for cognitive decline.
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