An Automatic Procedure For The Determination Of F-Wave Latency And End Intervals During FES

The F-wave is a recurrent discharge of an antidromically activated motor neurone and has received little attention in the FES literature. It though may have important influence on the design of neural prosthesis. It is found in the myoelectric signal from the 16Hz stimulated tibialis anterior muscle with a mean latency (tFstart) of 35ms and an end interval (tFend) of 55ms. Since the F-wave is normally used for diagnostics it is measured at very low frequency and latency is evaluated manually. The elevated frequency used for FES purpose together with the need to analyse long term effects has created a need for an automatically method to characterise F-wave. Such a method to determine latency and end interval has been developed and tested in 5*20 trials on five neurological normal male subjects. Results show a low intra-subject standard deviation (SD). Hypothesising that latency do not change for a subject during and between experimental sessions, the low SD is proof of robustness of this method. Higher inter-subject SD values imply that an F-wave latency period has to be calculated for each subject.