Changes in motor unit numbers in patients with ALS: a longitudinal study using the adapted multiple point stimulation...

Area of Science:

• Neurology
• Electrophysiology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
• Monitoring disease progression and treatment effects in ALS is crucial for patient management.

Purpose of the Study:

• To evaluate the utility of the adapted multiple point stimulation (AMPS) method for quantifying changes in motor unit number (MUNE) and related electrophysiological parameters in ALS patients undergoing riluzole therapy.
• To assess the correlation between MUNE, compound muscle action potential (CMAP) size, and surface motor unit potential (SMUP) size over a 12-month period.

Main Methods:

• The AMPS method was employed to measure MUNE, CMAP size, and SMUP size in 12 ALS patients.
• Measurements were taken at baseline (T(0)) and at 4, 8, and 12 months after initiating riluzole treatment.
• Patients were categorized into two groups based on the rate of motor unit loss at 4 months.

Main Results:

• A significant decrease in thenar MUNE and CMAP size was observed over the 12 months, while SMUP size remained stable.
• Patients with rapid motor unit loss (>20% at 4 months) showed a dramatic reduction in CMAP size compared to those with slower loss.
• Percent changes in MUNE and CMAP size were significantly different between the rapid and slow motor unit loss groups.

Conclusions:

• The AMPS technique is valuable for documenting longitudinal changes in MUNE, SMUP size, and CMAP size in ALS patients.
• AMPS can help differentiate disease progression rates and may aid in monitoring therapeutic responses.
• The study highlights the utility of AMPS in clinical trials and patient management for ALS.