Assessment of the F wave technique for motor unit number estimation in normal dogs

Motor unit number estimation (MUNE) is an electrophysiological technique to quantify the number of motor units in a muscle. A previous study examining MUNE in dogs used an incremental method. The purpose of this study was to examine the use of the F wave method in dogs and to provide information about this technique. Seven healthy laboratory dogs were examined using the F wave method by stimulating either a single site or multiple sites. In the multiple site stimulation F wave (MSS-F) method, the nerve was stimulated at several close sites along the deep peroneal nerve innervating the extensor digitorum brevis muscle. Test-retest was performed with a 1 week interval in all dogs using both techniques. In this preliminary study, median MUNE values were 88 (range 27-187) using the single site stimulation F wave (SSS-F) method and 68.5 (range 47-106) using the MSS-F method. The intra-class correlation coefficients between the two sets of data for each method were 0.20 and 0.09 for left and right SSS-F, respectively, and 0.77 and 0.69 for left and right MSS-F, respectively. MSS-F had less intra-individual variability of MUNE values and was more reproducible. These results indicate that MSS-F can be performed in dogs. MUNE using MSS-F might help with quantitative evaluation of motor neurone dysfunction and progression of diseases affecting motor neurones.