Normal brain activation in hemiatrophy due to multiple sclerosis: a functional MRI case study.

Area of Science:

• Neuroscience
• Clinical Neurology
• Neuroimaging

Background:

• Adaptive cortical changes, or plasticity, are hypothesized to maintain function in multiple sclerosis (MS).
• Functional magnetic resonance imaging (fMRI) studies explore brain plasticity in MS.
• Understanding the relationship between brain atrophy and cortical activation is crucial for MS management.

Observation:

• A single patient with relapsing-remitting MS and left-sided hemiparesis (EDSS 2.0) presented with right hemisphere hemiatrophy (15% volume reduction).
• The clinical presentation was linked to a corona radiata lesion affecting corticospinal fibers.
• Motor-evoked potential recordings indicated significant axonal damage in the pyramidal tract of the affected hemisphere.

Findings:

• Despite hemispheric asymmetries in atrophy and axonal damage, the patient exhibited normal brain activation for both hand and foot movements on both sides.
• Brain atrophy, even with mild disability, did not necessarily induce compensatory cortical adaptive changes in this case.
• This suggests that significant clinical disability, potentially from other lesion locations like the spinal cord, may be a stronger driver of cortical changes.

Implications:

• Brain atrophy alone may not be sufficient to trigger cortical reorganization in multiple sclerosis.
• The extent and location of clinical disability might be more critical than focal brain atrophy in driving adaptive brain changes.
• Further longitudinal studies are needed to elucidate the complex interplay between atrophy, disability, and cortical plasticity in MS.