Peripheral and central motor conduction in amyotrophic lateral sclerosis

Area of Science:

• Neuroscience
• Neurology
• Clinical Electrophysiology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
• Understanding the neurophysiological underpinnings of ALS is crucial for diagnosis and management.
• Peripheral and central motor conduction studies offer insights into motor pathway integrity.

Purpose of the Study:

• To investigate neurophysiological abnormalities in patients with amyotrophic lateral sclerosis (ALS).
• To correlate electrophysiological findings with clinical signs of lower motor neurone (LMN) and upper motor neurone (UMN) involvement.
• To assess the utility of central motor conduction time (CMCT) in ALS.

Main Methods:

• Conventional peripheral motor conduction studies and transcranial magnetic stimulation (TMS) were performed on 65 ALS patients.
• Hands were classified based on LMN and/or UMN involvement.
• Results were compared to established normal values and a control group of 53 subjects.

Main Results:

• Abnormalities in compound muscle action potential (CMAP) amplitude, distal motor latency (DML), and F wave latency were observed in 36%, 34%, and 19% of hands, respectively.
• These peripheral abnormalities were more frequent in hands exhibiting LMN signs.
• Central motor conduction time (CMCT) abnormalities were found in 17% of ALS patients, with no clear correlation to physical signs.

Conclusions:

• Peripheral neurophysiological abnormalities are common in ALS and are associated with LMN involvement.
• Prolongation of DML can occur even without overt muscle wasting or weakness.
• CMCT abnormalities are less frequent and do not reliably correlate with the clinical presentation in ALS.