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Brain MRI shows white matter sparing in Kennedy's disease and slow-progressing lower motor neuron disease
Edoardo G Spinelli1,2, Federica Agosta1, Pilar M Ferraro1
1Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
Abstract:
The extent of central nervous system involvement in Kennedy's disease (KD) relative to other motor neuron disease (MND) phenotypes still needs to be clarified. In this study, we investigated cortical and white matter (WM) MRI alterations in 25 patients with KD, compared with 24 healthy subjects, 25 patients with sporadic amyotrophic lateral sclerosis (ALS), and 35 cases with lower motor neuron-predominant disease (LMND). LMND patients were clinically differentiated into 24 fast and 11 slow progressors. Whole-brain cortical thickness, WM tract-based spatial statistics and corticospinal tract (CST) tractography analyses were performed. No significant difference in terms of cortical thickness was found between groups. ALS patients showed widespread decreased fractional anisotropy and increased mean (MD) and radial diffusivity (radD) in the CST, corpus callosum and fronto-temporal extra-motor tracts, compared with healthy controls and other patient groups. CST tractography showed significant alterations of DT MRI metrics in ALS and LMND-fast patients whereas KD and LMND-slow patients were comparable with healthy controls. Our study demonstrated the absence of WM abnormalities in patients with KD and LMND-slow, in contrast with diffuse WM damage in ALS and focal CST degeneration in LMND-fast, supporting the use of DT MRI measures as powerful tools to differentiate fast- and slow-progressing MND syndromes, including KD.
Insights
Kennedy
Area of Science:
- Neuroscience
- Neurology
- Radiology
Background:
- Central nervous system (CNS) involvement varies across motor neuron diseases (MND).
- Kennedy's disease (KD) CNS involvement requires further clarification relative to other MND phenotypes.
- Distinguishing between fast and slow progressing MND is crucial for patient management.
Purpose of the Study:
- To investigate and compare cortical and white matter (WM) MRI alterations in Kennedy's disease (KD) versus other motor neuron diseases (MND).
- To assess the utility of diffusion tensor (DT) MRI metrics in differentiating MND subtypes and progression rates.
Main Methods:
- Compared MRI data (cortical thickness, WM tract-based spatial statistics, CST tractography) from 25 KD patients with 24 healthy controls, 25 ALS patients, and 35 LMND patients.
- LMND patients were classified into fast and slow progressors.
- Analyzed diffusion MRI metrics including fractional anisotropy, mean diffusivity (MD), and radial diffusivity (radD).
Main Results:
- No significant cortical thickness differences were observed between groups.
- Amyotrophic lateral sclerosis (ALS) patients exhibited widespread WM abnormalities in CST, corpus callosum, and fronto-temporal tracts.
- KD and slow-progressing LMND patients showed no significant WM abnormalities, unlike fast-progressing LMND and ALS patients.
Conclusions:
- Kennedy's disease (KD) and slow-progressing lower motor neuron disease (LMND) lack white matter (WM) abnormalities.
- Diffuse WM damage is characteristic of ALS, while focal CST degeneration is seen in fast-progressing LMND.
- Diffusion tensor (DT) MRI metrics effectively differentiate fast- and slow-progressing MND syndromes, including KD.