F-wave: sample size and normative values.
F-waves were recorded from the abductor digiti minimi in 60 healthy subjects aged between 22 and 65 years. F-waves following 80 supramaximal stimuli were recorded. The F with minimal latency (Fmin), the mean latency (Fmean) and chronodispersion (CD) were calculated for each set of ten stimuli. In each subject the values after 10, 20, 30 etc. stimuli were compared with the "true" values obtained examining all responses. After twenty stimuli (16-20 F-waves) a Fmean with latency within 95% of the "true" value was recorded in the 95% of subjects. After twenty stimuli a Fmin with latency within 95% of the "true" latency was recorded in the 88% of subjects. Usually the Fmin after twenty stimuli is little different from the "true" Fmin (mean 1.4 ms), but in one subject the difference was 4.1 ms. The CD increases according to the number of responses examined and a careful evaluation requires 64-80 F-waves.
Raudino
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Neurological Department, Valduce, Hospital, Como, Italy.
D000328:Adult; D000368:Aged; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000502:physiology*; D012016:Reference Values; D018401:Sample Size