Usefulness of assessing repeater F-waves in routine studies

Repeater F-waves are sometimes seen in routine studies.

We retrospectively reviewed the clinical significance of repeater F-waves in median, ulnar, and fibular nerve recordings in 50 healthy subjects and groups of 50 patients each with diabetic polyneuropathy, amyotrophic lateral sclerosis, carpal tunnel syndrome, ulnar mononeuropathy, and L5 root lesion. The number of identical F-waves and their repetitions in samples of 20 stimuli were estimated.

Repeater F-waves occurred significantly more frequently in all nerves and patient groups than in healthy individuals. Their persistence was negatively correlated with that of non-repeater F-waves.

Based on the presented material and recording condition it appears that repeater F-waves differentiate between health and disease but not between different types of pathology of motor neurons or their axons. Even in routinely recorded samples of 20 traces, the index of repeater all F-waves could be used as a sign of nerve pathology.