F waves in amyotrophic lateral sclerosis: A systematic review and meta-analysis

Area of Science:

• Neurology
• Neurophysiology

Background:

• Amyotrophic lateral sclerosis (ALS) diagnosis relies on identifying both upper and lower motor neuron (UMN and LMN) dysfunction.
• Early detection of LMN involvement is crucial for timely intervention and management of ALS.

Purpose of the Study:

• To systematically review and meta-analyze F-wave abnormalities in ALS.
• To assess the utility of F-wave patterns in the early diagnosis of ALS.

Main Methods:

• Systematic review and meta-analysis of studies from Medline and Embase.
• Focus on F-wave recordings from abductor digiti minimi after ulnar nerve stimulation.
• Inclusion of case-control studies comparing ALS patients with healthy controls (HC) and other patient groups.

Main Results:

• ALS patients showed decreased F-wave persistence, prolonged minimum latency, increased maximum amplitude, and elevated Index total Freps compared to HC.
• Abnormalities were more pronounced in clinically affected limbs.
• Pyramidal dysfunction correlated with increased maximum amplitude; isolated UMN disorders showed increased Index total Freps without decreased persistence.

Conclusions:

• F-wave abnormality patterns suggest LMN pool involvement in ALS.
• These findings may aid in identifying preclinical LMN dysfunction and guide further electromyographic investigations.
• UMN involvement can differentiate F-wave abnormality profiles in ALS.