Brainstem reflex excitability changes in patients with amyotrophic lateral sclerosis

Area of Science:

• Neuroscience
• Neurology
• Clinical Electrophysiology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
• Investigating brainstem reflex excitability offers insights into ALS pathophysiology.

Purpose of the Study:

• To evaluate changes in brainstem reflex excitability, specifically blink reflex recovery cycles (BRRCs) and masseter inhibitory reflexes (MIRs), in ALS patients.
• To compare these neurophysiological measures between ALS patients and healthy controls.

Main Methods:

• Recruited 14 ALS patients and 14 healthy controls.
• Measured BRRCs at various interstimulus intervals (ISIs) from 100 to 600 ms.
• Assessed latencies and durations of silent period 1 (SP1) and silent period 2 (SP2) of MIRs.

Main Results:

• ALS patients exhibited significantly decreased R2 area suppression at 200, 300, and 400 ms ISIs compared to controls.
• No significant differences in BRRCs were found at 100, 500, and 600 ms ISIs between groups.
• The duration of SP2 in MIRs was significantly prolonged in ALS patients.

Conclusions:

• Brainstem inhibitory and excitatory interneuronal activity is altered in ALS.
• These alterations may stem from cortical or bulbar level physiological and morphological changes.
• Neurophysiological assessments like BRRCs and MIRs can reveal underlying brainstem dysfunction in ALS.