Fig 1.
(A) Positions of the active EMG electrode used for mapping maximal CMAPs from 9 sites (site 0 to site 8). Site 0 is located at the approximate EDB mid-belly, and sites 1 to 8 are located at the designated target positions about the perimeter of a 2 cm x 2 cm square drawn on the skin. Also shown are 2 ink marks (one over the lateral malleolus and the other at the 5th toe cleft) for determining the one-third distance to the EDB mid-belly (B) Overlay of CMAP waveforms in one participant. Single maximal CMAPs from sites 0 to 8, and repeat recordings from sites 0, 3 and 4, are displayed. In this case, site 4 was the optimal recording site.
Fig 2.
Maximum CMAP waveforms, MScans, nerve conduction and MScanFit results in 3 subjects.
(A, D) Male 36 y. (B, E) Male 30 y. (C, F) Female 36 y. Maximum CMAPs evoked by nerve stimulation at the knee and ankle are overlayed in 30 ms windows in A, B, and C. (D-F) MScan recording (left) and corresponding modeled MScan (right) for each person. (G) Nerve conduction and MScanFit study results in the 3 subjects.
Table 1.
Nerve conduction study and MScanFit results for all subjects.
Fig 3.
Correlations between MScanFit parameters in all subjects.
Data points for males are black symbols (N = 15) and females are white symbols (N = 6). (A) SMUP amplitude was positively correlated with maximal CMAP amplitude. (B) MUNE was negatively correlated with SMUP amplitude. (C) MUNE was not significantly correlated with maximum CMAP amplitude. Lines of best fit are shown only for correlations that were statistically significant. Circled data points correspond to the 3 subjects in Fig 2. Data points surrounded by a triangle are two subjects with similar CMAP maximum but different MUNE.
Table 2.
Estimation of numbers and size parameters of extensor digitorum brevis motor units in young adults reported in the literature.