Inconsistent primary motor cortex glucose hypometabolism in primary lateral sclerosis

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Primary lateral sclerosis (PLS) is a rare neurodegenerative disorder characterized by upper motor neuron degeneration.
• It is often modeled to originate in the primary motor cortex.
• Clinical observations suggest variability in primary motor cortex hypometabolism in PLS patients.

Purpose of the Study:

• To evaluate the reliability of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) in detecting motor cortex hypometabolism throughout the disease course in PLS patients.
• To assess the consistency of primary motor cortex hypometabolism as a diagnostic marker for PLS.

Main Methods:

• Analysis of baseline FDG-PET data from nine consecutive PLS patients.
• Inclusion of follow-up assessments for five patients.
• Extraction of average FDG-PET signals from motor regions and calculation of covariate-corrected z scores using data from healthy controls (ADNI cohort).

Main Results:

• Only four out of nine PLS patients exhibited primary motor cortex hypometabolism across all available assessments.
• Glucose metabolism in motor regions showed decline over time in some patients.
• Other patients maintained stable metabolism despite disease progression and increased symptom severity.

Conclusions:

• Primary motor cortex hypometabolism is less consistently observed in PLS patients than previously thought.
• The absence of FDG-PET detected hypometabolism should not rule out a PLS diagnosis.
• The study underscores the heterogeneity of PLS and the need for improved diagnostic methods for earlier confirmation.