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Injury of the mammillothalamic tract in patients with thalamic hemorrhage
Hyeok Gyu Kwon1, Han Do Lee1, Sung Ho Jang1
1Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University , Daegu , South Korea.
Objective:
Injury of the mammillothalamic tract (MTT) has been suggested as one of the plausible pathogenic mechanisms of memory impairment in patients with thalamic hemorrhage; however, it has not been clearly demonstrated so far. We attempted to investigate whether injury of the MTT documented by diffusion tensor tractography following thalamic hemorrhage correlates with cognitive impairment.
Methods:
We recruited 22 patients with a thalamic hemorrhage and 20 control subjects. MTTs were reconstructed using the probabilistic tractography method. Patients were classified into two subgroups: reconstructed group, patients whose MTT was reconstructed in the affected hemisphere, and non-reconstructed group, patients whose MTT was not reconstructed.
Results:
Mammillothalamic tract was reconstructed in 5 (22.7%, reconstructed group) patients in the affected hemisphere and was not reconstructed in the remaining 17 patients (77.3%, non-reconstructed group). In addition, the MTT was not reconstructed even in the unaffected hemisphere in four patients (23.5%) in non-reconstructed group. Fractional anisotropy and mean diffusivity values of the affected hemisphere in reconstructed group also did not show significant differences from those in the unaffected hemisphere of reconstructed group and the control group (p > 0.05). However, the tract volume of the affected hemisphere in reconstructed group was significantly lower than that of the unaffected hemisphere in reconstructed group and the control group (p < 0.05).
Conclusion:
A large portion of patients with thalamic hemorrhage appeared to suffer severe injury of the ipsilesional MTT (77.3%) and 18.2% of them appeared to suffer severe injury even in the contralesional MTT. In addition, the remaining 22.7% of patients who had preserved integrity of the ipsilesional MTT appeared to suffer partial injury of the ipsilesional MTT.
Insights
Thalamic hemorrhage frequently causes severe injury to the mammillothalamic tract (MTT), potentially leading to memory impairment. Diffusion tensor tractography revealed significant MTT damage in most patients, correlating with cognitive deficits.
Area of Science:
- Neuroscience
- Neurology
- Radiology
Background:
- Thalamic hemorrhage is linked to memory deficits.
- Injury to the mammillothalamic tract (MTT) is a suspected cause.
- Direct evidence linking MTT injury to cognitive impairment in thalamic hemorrhage is lacking.
Purpose of the Study:
- To investigate the correlation between MTT injury and cognitive impairment in thalamic hemorrhage.
- To assess MTT integrity using diffusion tensor tractography (DTT).
Main Methods:
- 22 patients with thalamic hemorrhage and 20 controls underwent DTT.
- Mammillothalamic tracts (MTTs) were reconstructed using probabilistic tractography.
- Patients were categorized based on MTT reconstruction in the affected hemisphere.
Main Results:
- Mammillothalamic tract (MTT) reconstruction was unsuccessful in 77.3% of patients in the affected hemisphere.
- Severe ipsilesional MTT injury was observed in 77.3% of patients.
- Partial MTT injury was noted in 22.7% of patients, even with preserved integrity.
- Significant reduction in tract volume was observed in the affected hemisphere.
Conclusions:
- A high prevalence of severe ipsilesional MTT injury exists in thalamic hemorrhage patients.
- Some patients also exhibit contralesional MTT injury.
- MTT injury, documented by DTT, is a significant factor in cognitive impairment following thalamic hemorrhage.
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