Reference values for motor NCS parameters in the upper and lower limbs.
| Nerve | Age | Amplitude (mV) | DML (ms) | Conduction velocity (m/s) | Conduction velocity across elbow or FH (m/s) | % amplitude drop in the forearm or leg segment | % amplitude drop across elbow or FH |
|---|---|---|---|---|---|---|---|
| 2nd percentile (LLN) † | 97th percentile (ULN) ‡ | 3rd percentile (LLN) † | 3rd percentile (LLN) † | 97th percentile (ULN) ‡ | 97th percentile (ULN) ‡ | ||
| Median motor N=119β0* = 2.129 (2.006), β1* = –0.004 (–0.008) | |||||||
| 20 | 7.8 (6.3) | 3.7 (3.8) | 50 (50) | ___ | 21.8 (31.4) | ___ | |
| 40 | 7.2 (5.4) | ||||||
| 60 | 6.6 (4.6) | ||||||
| Ulnar motor N=119β0* = 2.212 (2.048), β1=–0.004 (–0.008) | |||||||
| 20 | 8.4 (6.6) § | 3.3 (3.5) | 50 (49) | 52 (52); slowing compared with the forearm segment = 8 m/s (maximum = 9 m/s) | 20.4 (23.8) | 11.3 (16.3) | |
| 40 | 7.8 (5.6) § | ||||||
| 60 | 7.2 (4.8) § | ||||||
| Tibial motor N=134 | |||||||
| 20 – 66 | 7.1 (4.6) | 5.8 (5.9) | 40 (35) | ___ | 58.0 (74.8) ∫ | ___ | |
| Fibular motor N=134β0* = 2.048 (1.841), β1= –0.038 (–0.046) | |||||||
| 20 | 3.6 (2.5) | 5.0 (5.5) | 40 (36) | 43 (38); slowing compared with the leg segment = 5 m/s (maximum = 16 m/s) | 30.0 (44.0) | 14.5 (22.5) | |
| 40 | 1.7 (1.0) | ||||||
| 60 | 0.8 (0.4) | ||||||
↵* Regression coefficients obtained from the quantile regression model: log (predicted value)= β0 + β1 ×(age), † LLN represents the lower limit of the 95% confidence interval at minimum values in the sample, ‡ ULN represents the upper limit of the 95% confidence interval at maximum values in the sample, § Regression model for ulnar CMAP amplitude was estimated at the 5th percentile, as it was not significant at the lower percentiles, ∫ Drop in tibial amplitude with stimulation at popliteal fossa should be interpreted cautiously because supramaximal stimulation may not have been achieved due to pain and technical factors, Data are combined for NCS parameters with no age effect. Age was not significantly associated with tibial CMAP amplitude. Therefore, the reference limit was calculated for the entire group, DML - distal motor latency, FH - fibular head, CMAP - compound muscle action potential, NCS - nerve conduction study