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White matter lesions and cognitive deficits: relevance of lesion pattern?
M S Damian1, G Schilling, G Bachmann
1Department of Neurology, Justus-Liebig-University, Giessen, Germany.
Abstract:
Magnetic resonance imaging (MRI) permits efficient visualization of white matter lesions (WML). A growing body of literature deals with the correlation of WML and cognitive dysfunction with conflicting results. We studied the influence of lesion pattern as well as size by analyzing MRI and psychometric test performance in 2 patient collectives with different WML patterns. 22 patients with myotonic dystrophy (MD) and mainly subcortical WML were compared with 39 patients with multiple sclerosis (MS) and mainly periventricular lesions. 73% of MD patients had WML, the extent of which correlated with cognitive deficits. Severely impaired patients had psychometric findings compatible with "subcortical" dementia. In MS the extent of WML alone did not correlate significantly with cognitive deficits. Significant cognitive dysfunction was observed with extension of WML to areas of white matter immediately underlying cortex, but not with exclusively periventricular lesions. Cerebral atrophy had less impact. Comparison of MD and MS indicates that WML immediately subjacent to cortex are likely to cause significant cognitive deficits, whereas extensive periventricular demyelination may cause no major dysfunction. This may relate to early disturbance of associative fibers by subcortical lesions. Our results emphasize the significance of pattern as well as total extent of WML. Myotonic dystrophy is a useful model to study the effect of subcortical lesions, due to a typical lesion pattern unusual in other conditions.
Insights
White matter lesion (WML) patterns significantly impact cognitive function. Subcortical WML, seen in myotonic dystrophy, strongly correlate with cognitive deficits, unlike periventricular lesions in multiple sclerosis.
Area of Science:
- Neuroimaging
- Neurology
- Cognitive Science
Background:
- White matter lesions (WML) are visible on Magnetic Resonance Imaging (MRI).
- The relationship between WML and cognitive dysfunction is debated, with conflicting research findings.
- Understanding the impact of WML requires considering both their location and extent.
Purpose of the Study:
- To investigate how WML patterns and size influence cognitive function.
- To compare the effects of subcortical WML (myotonic dystrophy) versus periventricular WML (multiple sclerosis).
Main Methods:
- Analysis of MRI scans and psychometric test performance.
- Comparison of two patient groups: 22 with myotonic dystrophy (MD) and 39 with multiple sclerosis (MS).
- Assessment of WML patterns, focusing on subcortical vs. periventricular distribution.
Main Results:
- 73% of MD patients exhibited WML, with extent correlating to cognitive deficits, suggesting "subcortical" dementia.
- In MS patients, WML extent alone did not significantly correlate with cognitive deficits.
- Cognitive dysfunction in MS was linked to WML near the cortex, not exclusively periventricular lesions. Cerebral atrophy had minimal impact.
Conclusions:
- WML immediately below the cortex likely cause significant cognitive deficits.
- Extensive periventricular demyelination may not lead to major dysfunction.
- The pattern, not just the extent, of WML is crucial for cognitive outcomes. Myotonic dystrophy serves as a model for studying subcortical lesion effects.