F-wave for assessment of segmental motoneurone excitability

The purpose of this study was to evaluate alterations in F-wave parameters in spasticity and the possibility for using them as a method for assessment of segmental motoneurone excitability. Clinical and electromyographical examinations were performed on 120 patients with varying degrees of spasticity after cerebrovascular lesions. The F-wave was determined after supramaximal electrostimulation of the median, ulnar, fibular and tibial nerves in the distal points. As all patients were with hemiparesis, the healthy side was used as a control. The F-wave was found to be increased in amplitude (mean and maximal), duration and persistence on the spastic side. The number of F-wave phases and the Fmax/M, Fmean/M, Fmean/Fmax amplitude ratios were also increased on the involved side. We can conclude that alterations in F-wave parameters in spasticity are more complex than it has been known. They are more precise for assessment of segmental motoneurone excitability than the well known T and H-reflexes.