Table 2.
Changes in CMAP amplitude and excitability indices following maximal voluntary contraction.
| Normal |
CIDP |
SBMA |
|||
|---|---|---|---|---|---|
| (n = 16) | (n = 17) | (n = 14) | |||
| Median nerve conduction study | |||||
| Distal latency (ms) | 3.5 (0.09) | 6.8 (0.57) *** | 4.4 (0.26) | ||
| CMAP amplitude (mV) | |||||
| Before MVC | 8.3 (0.54) | 5.0 (0.83) ** | 5.1 (0.45) ** | ||
| After MVC | 8.7 (0.54) | 4.6 (0.81) *** | 5.2 (0.50) ** | ||
| Ratio of post/pre MVC (%) | 105 (1.5) | 93 (4.0) ** | 101 (2.6) | ||
| Motor conduction velocity (m/s) | 58 (0.71) | 35 (13) *** | 53 (2.6) | ||
CIDP, chronic inflammatory demyelinating polyradiculoneuropathy; SBMA, spinal and bulbar muscular atrophy; CMAP, compound muscle action potential; MVC, maximal voluntary contraction; data are presented as mean (SEM). *p < 0.05, **p < 0.01, ***p < 0.0001; compared with normal.