Repeater F-waves are signs of motor unit pathology in polio survivors.

INTRODUCTION

The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors.

METHODS

Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE).

RESULTS

A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE.

CONCLUSIONS

These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology.