Table 1.
Characteristics of motor units in the direct (CMAP) and the recurrent motor response (recCMAP) in regenerated median nerves at times >900 d after repair
| Procedure | Motor unit no. | Motor unit amplitude (mV) | |||
|---|---|---|---|---|---|
| CMAP: no. of motor units (mean ± SD) | No. of motor units in CMAP vs expected | recCMAP: no. of motor units (mean ± SEM) | CMAP* (mean ± SEM) | recCMAP** (mean ± SEM) | |
| Normal, closed hand (n = 64; 16) | 147 ± 14 | 0.2 ± 0.1 | |||
| Normal, open surgery (n = 1) | 155 | 0.17 ± 0.05 | |||
| Direct suture (n = 19; 4) | 18.4 ± 3.2 | p < 0.001 | 2.7 ± 0.5 | 1.5 ± 0.2 | 0.9 ± 0.3 |
| Graft, 20 mm (n = 29; 8) | 14.9 ± 1.9 | p < 0.02 | 3.1 ± 0.3 | 1.3 ± 0.1 | 0.5 ± 0.1 |
| Graft, 50 mm (n = 25; 6) | 16.3 ± 2.9 | p < 0.01 | 3.5 ± 0.5 | 0.7 ± 0.1 | 0.4 ± 0.1 |
| Tube, 20 mm (n = 38; 8) | 12.5 ± 1.9 | NS | 2.3 ± 0.4 | 1.2 ± 0.1 | 0.9 ± 0.3 |
| Tube, 50 mm (n = 15; 3) | 9.7 ± 2 | NS | 1.7 ± 0.5 | 0.9 ± 0.1 | 0.7 ± 0.1 |
| Expected | 8.8 ± 2.9 | ||||
The number of independent physiological assessments as well as the number of nerves sampled for this period (>900 d) is shown for each repair group (e.g., for the normal baseline measurements 64 independent assessments were made from 16 different nerves). The expected number of regenerated motor units was derived from calculations using binomial statistics to model “random” motor axon regeneration (see Results and Discussion for details).
*Compared with the amplitude of motor units in normal muscle (0.2 ± 0.1 mV), the amplitude of the direct CMAP motor units was significantly greater for all repair groups (ANOVA, p< 0.05).
**Within each of the repair groups, the motor unit amplitude of recCMAPs was significantly smaller than that of the direct CMAP (p < 0.001, paired t tests).