Table 1.
Nerve conduction study (NCS) and electromyography (EMG) findings.
| Test | Nerve/muscle | Site | Latency (ms) | Amplitude (mV) | Velocity (m/s) | Findings |
|---|---|---|---|---|---|---|
| Sensory NCS | Median (R) | Digit II—wrist | No response (NR) | NR | NR | NR |
| Ulnar (R) | Digit V—wrist | NR | NR | NR | NR | |
| Sural (R) | Ankle—calf | NR | NR | NR | NR | |
|
| ||||||
| Motor NCS | Median (R) | Wrist—abductor pollicis brevis (APB) | 6.46 | 2.6 | — | Prolonged latency, reduced amplitude |
| Median (R) | Elbow—APB | 17.34 | 1.8 | 17 | Prolonged latency, reduced amplitude, slowed velocity | |
| Median (L) | Wrist—APB | 7.03 | 2.3 | — | Prolonged latency, reduced amplitude | |
| Median (L) | Elbow—APB | 17.08 | 0.6 | 23 | Prolonged latency, reduced amplitude, slowed velocity | |
| Ulnar (R) | Wrist—abductor digiti minimi (ADM) | 8.91 | 0.3 | — | Prolonged latency, low amplitude | |
| Ulnar (R) | B. elbow—ADM | NR | NR | NR | NR | |
| Peroneal (R) | Ankle—extensor digitorum brevis | NR | NR | NR | NR | |
| Tibial (R) | Ankle—abductor hallucis | NR | NR | NR | NR | |
|
| ||||||
| F-wave | Median (R) | APB | NR | — | — | NR |
|
| ||||||
| EMG | Tibialis anterior (R) | L4-L5 | 3+ Fib/PSW | No activity | — | Severe denervation |
Note: EMG and NCS demonstrating severe demyelinating polyneuropathy. Significant slowing in the upper extremity is present, most consistent with a primary demyelinating neuropathy. See supporting Figure 1 for additional interpretation.