White matter lesions and cognitive deficits: relevance of lesion pattern?

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 werecompared 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.

Cerebral involvement in myotonic dystrophies

“…Some authors do not find a clinical correlate to the neuroimaging profile, 14 whereas others find a correlation between neuropsychological data and the distribution and severity of white matter abnormalities. 24,45,111 We found no correlation between the degree of cerebral involvement on traditional MRI studies and cognitive and behavioral profiles. 72 Other authors suggest an evolution of white matter abnormalities during the disease.…”

“…Several authors tried to correlate neuropsychological and neuroimaging findings. 6,24,27,28,45,62,101 Meola et al 71,72 confirmed a selective impairment on tests of frontal lobe function in DM1 and suggested that this type of deficit does not correlate with cortical atrophy and white matter hyperintense lesions, but might be associated with fronto-temporal lobe hypoperfusion on PET studies.…”

“…Frontal lobe motor areas and the prefrontal cortex are involved in strategic planning tasks. Earlier reports had documented a significant impairment of frontal lobe function, 14,24 as is typical of a dysexecutive syndrome. Several authors tried to correlate neuropsychological and neuroimaging findings.…”

“…98 Conventional MRI Studies. Several reports have documented cortical atrophy and white matter hyperintense lesions 15,24,27,28,45,52,72,76,79 in patients with DM1. Fiorelli et al 31 documented an increased frequency of subarachnoid cysts in DM1.…”

Relationship between pulmonary and cognitive functions in myotonic dystrophy type 1: a preliminary study

“…Neuropsychological studies has shown especially executive functions on frontal lobe has been deterioted at DM1 2 . While on imaging studies with magnetic resonance imaging (MRI) brain atrophy is detected at particularly anterior temporal lobe 3 , on brain positron emission tomography (PET) studies hypometabolism was observed on frontal and temporal lobes 4,5 . Also intraneural neurofibrillary tangles and tau protein accumulation in DM1 were same as frontotemporal dementia on pathological studies 6 .…”