Detecting neuronal dysfunction of hand motor cortex in ALS: A MRSI study.

Area of Science:

• Neuroimaging
• Neuroscience
• Biomarkers

Background:

• Hand motor cortex (HMC) is crucial for motor control and has established clinic-anatomic correlations.
• Previous magnetic resonance spectroscopy (MRS) studies in amyotrophic lateral sclerosis (ALS) have not independently assessed HMC neurochemical profiles.
• HMC's consistent location and functional relevance suggest its potential as a diagnostic region of interest in ALS.

Purpose of the Study:

• To investigate the neurochemical profile of the HMC in patients with ALS.
• To determine if HMC can serve as a diagnostic biomarker for ALS.
• To assess the utility of the N-acetyl aspartate (NAA)/creatine (Cr) ratio in HMC for differentiating ALS patients from healthy controls.

Main Methods:

• Recruited 14 ALS patients and 14 age/gender-matched healthy controls (HC).
• Utilized an optimized magnetic resonance spectroscopic imaging (MRSI) method to scan bilateral HMC areas (0.56 cm³ voxels).
• Measured the NAA/Cr ratio in HMC and the adjacent postcentral gyrus for all subjects.

Main Results:

• ALS patients showed significantly reduced NAA/Cr ratios in HMC and postcentral gyrus compared to HC.
• No significant difference in NAA/Cr ratios between HMC and postcentral gyrus within either group.
• Asymmetrical NAA/Cr ratios in HMC correlated with hand strength, suggesting potential for individual-level ALS diagnosis.

Conclusions:

• Reduced NAA/Cr ratios in HMC effectively differentiate ALS patients from HC, indicating HMC neuronal dysfunction.
• The postcentral gyrus is not a suitable internal reference tissue for ALS diagnosis.
• Asymmetrical NAA/Cr ratios in bilateral HMC show promise as a diagnostic biomarker for ALS at the individual level.