Amplitude of the F wave: a potential means of documenting spasticity.
The amplitude of 32 averaged F responses (F32) recorded with surface electrodes was 1 percent of the amplitude of the M wave. The largest F response (Fmax) was 4.5 percent of the M wave. In spasticity, Fmax did not increase in amplitude but became more persistent, resulting in a significant increase of F32. There was a positive correlation between the amplitude of F32 and the M wave, and this relationship was abnormal in 60 percent of the studies of patients with spasticity.
D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D000368:Aged; D004576:Electromyography; D005071:Evoked Potentials; D006801:Humans; D008875:Middle Aged; D009128:Muscle Spasticity / Q000503:physiopathology*