Table 2.
Nerve conduction studies of patients with PMP22 point mutations.
| Patient | A | B | C | D | E |
|---|---|---|---|---|---|
| PMP22 mutation | c.124 T > C, p.C42R | c.256 C > T, p.Q86X | c.256 C > T, p.Q86X | c.310delA, p.I104FfsX7 | c.319 + 1G > A |
| Median nerve | |||||
| DML (ms) | 8.3 | NR | NR | 18.2 | 10.8 |
| MNCV (m/s) | 42.0 | NR | NR | 4 | 21.6 |
| CMAP (mV) | 10.2 | NR | NR | 0.4 | 4.4 |
| F-wave L (ms) | 36.3 | NR | NR | NR | NR |
| DSL (ms) | 3.9 | NR | NR | NR | NR |
| SNAP (uV) | 10 | NR | NR | NR | NR |
| Ulnar nerve | |||||
| DML (ms) | 5.8 | 18.2 | 22.1 | NR | 7.0 |
| MNCV (m/s) | 48.9 | 5.9 | 7.6 | NR | 20.5 |
| CMAP (mV) | 7.5 | 0.4 | 0.2 | NR | 6.1 |
| F-wave L (ms) | 37.6 | NR | NR | NR | NR |
| DSL (ms) | 3.9 | NR | NR | NR | NR |
| SNAP (uV) | 10 | NR | NR | NR | NR |
| Tibial nerve | |||||
| DML (ms) | 5.4 | NR | NR | NR | NR |
| MNCV (m/s) | 34.9 | NR | NR | NR | NR |
| CMAP (mV) | 11.5 | NR | NR | NR | NR |
| F-wave L (ms) | 61.8 | NR | NR | NR | NR |
| Sural nerve | |||||
| DSL (ms) | 4.5 | NR | NR | NR | NR |
| SNAP (uV) | 12.6 | NR | NR | NR | NR |
Abbreviation:
DML = distal motor latency; MNCV = motor nerve conduction velocity; CMAP = compound motor action potential amplitude; F-wave L = F-wave latency; DSL = distal sensory latency; SNAP = sensory nerve action potential (antidromic); NR = no response.
Normal values:
Median nerve: DML ≤ 4.4 ms; MNCV ≥ 51.9 m/s; CMAP ≥ 6.4 mV; F-wave L ≤ 29 ms; DSL ≤ 3.2 ms; SNAP ≥ 17μV.
Ulnar nerve: DML ≤ 3.5 ms; MNCV ≥ 56.1 m/s; CMAP ≥ 7.0 mV; F-wave L ≤ 29 ms; DSL ≤ 3.0 ms; SNAP ≥ 8 μV.
Tibial nerve: DML ≤ 6.4 ms; MNCV ≥ 42.9 m/s; CMAP ≥ 4.1 mV; F-wave L ≤ 53 ms;
Sural nerve: DSL ≤ 3.5 ms; SNAP ≥ 12 μV.