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The evolution of motor cortical dysfunction in amyotrophic lateral sclerosis
Kazumoto Shibuya1, Neil G Simon2, Nimeshan Geevasinga3
1Brain and Mind Centre, University of Sydney, Australia.
Summary
Cortical function in amyotrophic lateral sclerosis (ALS) declines with disease progression, evidenced by reduced short interval intracortical inhibition (SICI). This suggests inhibitory interneuron dysfunction as ALS advances.
Area of Science:
- Neuroscience
- Neurology
- Motor Neuron Diseases
Background:
- Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
- Understanding cortical function alterations in ALS is crucial for tracking disease progression and developing interventions.
Purpose of the Study:
- To investigate changes in cortical function in amyotrophic lateral sclerosis (ALS) patients as the disease progresses.
- To correlate neurophysiological markers with disease stage in ALS.
Main Methods:
- Evaluated 189 ALS patients using clinical assessments and threshold tracking transcranial magnetic stimulation (TMS) to assess cortical function.
- Defined disease stage by proportion of disease duration, time from onset, and ALS rating scale-revised (ALSFRS-R).
Main Results:
- Demonstrated decreased neurophysiological index and compound muscle action potential (CMAP) in ALS patients.
- Observed prolonged central motor conduction time (CMCT) and decreased short interval intracortical inhibition (SICI) with disease progression.
- Found that decreased SICI correlated with disease duration and ALSFRS-R decline.
Conclusions:
- Cortical function, specifically SICI, decreases progressively in ALS patients.
- Findings suggest potential dysfunction of inhibitory interneurons in ALS progression.