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

Ioannis Liampas; Dimitra Veltsista; Alexandra Germeni; Paraskevi Batzikosta; Emilia Michou; Zinovia Kefalopoulou; Elisabeth Chroni

doi:10.1016/j.neucli.2025.103061

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

Neurophysiol Clin. 2025 Mar 13;55(4):103061. doi: 10.1016/j.neucli.2025.103061. Online ahead of print.

Authors

Ioannis Liampas¹, Dimitra Veltsista², Alexandra Germeni³, Paraskevi Batzikosta⁴, Emilia Michou⁵, Zinovia Kefalopoulou⁶, Elisabeth Chroni⁷

Affiliations

¹ Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece; Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa 41100, Greece. Electronic address: iliampas@uth.gr.
² Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece. Electronic address: dveltsista@yahoo.gr.
³ Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece. Electronic address: alexgermeni@hotmail.com.
⁴ Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece. Electronic address: vivi.batzikosta@gmail.com.
⁵ Department of Speech and Language Therapy, School of Health Rehabilitation Sciences, University of Patras, Patras 26504, Greece. Electronic address: emiliamichou@upatras.gr.
⁶ Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece. Electronic address: zkefalopoulou@gmail.com.
⁷ Department of Neurology, University Hospital of Patras, School of Medicine, University of Patras, Patras, Rio 26504, Greece. Electronic address: echroni@upatras.gr.

PMID: 40086112
DOI: 10.1016/j.neucli.2025.103061

Abstract

Objective: This systematic review and meta-analysis aimed to determine the pattern of F-wave abnormalities and their potential utility in the early diagnosis of amyotrophic lateral sclerosis (ALS).

Methods: Medline and Embase were thoroughly searched. We primarily emphasized F-wave recordings from the abductor digiti minimi, following stimulation of the ulnar nerve at the wrist. Data from case-control studies involving individuals with ALS versus healthy controls (HC) or other well-defined patient groups were reviewed and -if appropriate- quantitatively synthesized.

Results: Twenty-nine studies were included in this systematic review and 17 of them in the analytic part. The pattern of F-abnormalities in ALS compared to HC was as follows: decreased persistence (MD=20.25 %,15.67-24.84 %), mildly prolonged minimum latency (MD=1.59msec,1.11-2.06msec), increased maximum amplitude (MD=196μV,106-287μV) and elevated Index total Freps (MD=33.9 %,26.0-41.8 %). Affected limbs (with substantial weakness in clinical examination and/or muscle wasting and/or abnormal nerve conduction studies) exhibited more marked abnormalities in persistence, minimum latency, and Index total Freps, whereas abnormalities in these parameters were very mild in clinically unaffected limbs. More prominent increases in maximum amplitude accompanied pyramidal dysfunction. Of note, isolated upper motor neuron (UMN) disorders exhibited a comparable increase in Index total Freps without a decrease in persistence.

Conclusions: The pattern of F wave abnormalities may raise suspicion of involvement of the under-study lower motor neuron (LMN) pool in ALS. These findings may identify LMN dysfunction even at a preclinical stage and prompt extensive electromyographic investigations. UMN involvement may to some extent differentiate the profile of F wave abnormalities in ALS.

Keywords: Lower motor neuron; Motor neuron disease; Neuropathies; Neurophysiology; Upper motor neuron.

Publication types

Review