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Published on: January 23, 2019
Longitudinal thalamic diffusion changes after middle cerebral artery infarcts
Background:
Cerebral infarcts are responsible for functional alterations and microscopic tissue damage at distance from the ischaemic area. Such remote effects have been involved in stroke recovery. Thalamic hypometabolism is related to motor recovery in middle cerebral artery (MCA) infarcts but little is known concerning the tissue changes underlying these metabolic changes. Diffusion tensor imaging (DTI) is highly sensitive to microstructural tissue alterations and can be used to quantify in vivo the longitudinal microscopic tissue changes occurring in the thalamus after MCA infarcts in humans.
Methods:
Nine patients underwent DTI after an isolated MCA infarct. Mean diffusivity (MD), fractional anisotropy (FA), and thalamic region volume were measured from the first week to the sixth month after stroke onset in these patients and in 10 age matched controls.
Results:
MD significantly increased in the ipsilateral thalamus between the first and the sixth month (0.766 x 10(-3) mm(2)/s first month; 0.792 x 10(-3) mm(2)/s third month; 0.806 x 10(-3) mm(2)/s sixth month). No significant modification of FA was detected. In six patients, the ipsilateral/contralateral index of MD was higher than the upper limit of the 95% CI calculated in 10 age matched controls. An early decrease of MD preceded the increase of ipsilateral thalamic diffusion in one patient at the first week and in two other patients at the first month.
Conclusion:
After MCA infarcts, an increase in diffusion is observed with DTI in the ipsilateral thalamus later than 1 month after the stroke onset. This is presumably because of the progressive loss of neurons and/or glial cells. In some patients, this increase is preceded by a transient decrease in diffusion possibly related to an early swelling of these cells or to microglial activation. Further studies in larger series are needed to assess the clinical correlates of these findings.
Insights
Diffusion tensor imaging reveals progressive thalamic diffusion increase after middle cerebral artery (MCA) infarcts, indicating remote tissue changes. This may reflect neuronal loss and is crucial for understanding stroke recovery.
Area of Science:
- Neuroimaging
- Stroke research
- Diffusion Tensor Imaging (DTI)
Background:
- Cerebral infarcts cause remote functional and microstructural damage.
- Thalamic hypometabolism correlates with motor recovery after middle cerebral artery (MCA) infarcts.
- Tissue changes underlying thalamic hypometabolism post-MCA infarct are poorly understood.
Purpose of the Study:
- To quantify in vivo longitudinal microstructural changes in the thalamus after MCA infarcts using DTI.
- To investigate the relationship between DTI metrics and remote effects of MCA infarcts.
Main Methods:
- Diffusion tensor imaging (DTI) was performed on nine patients with isolated MCA infarcts.
- Mean diffusivity (MD) and fractional anisotropy (FA) of the thalamus were measured from 1 week to 6 months post-stroke.
- Thalamic region volume and ipsilateral/contralateral MD indices were analyzed.
Main Results:
- Mean diffusivity (MD) significantly increased in the ipsilateral thalamus between 1 and 6 months post-stroke.
- No significant changes in fractional anisotropy (FA) were observed.
- In most patients, ipsilateral/contralateral MD indices exceeded control values, with some showing an early transient decrease in MD.
Conclusions:
- An increase in thalamic diffusion post-MCA infarct occurs after the first month, likely due to neuronal and glial cell loss.
- Transient decreases in diffusion may indicate early cellular swelling or microglial activation.
- Further research is needed to correlate these DTI findings with clinical outcomes in stroke recovery.
