TABLE 1.
Axonal motor loss in the patient with Hirayama disease
| Motor nerves | Latency (ms) | Amplitude (mV) | Conduction velocity (m/s) |
|---|---|---|---|
| Right median‐APB | |||
| Wrist | 3.4 | 8.3 | |
| Elbow | 7.9 | 7.9 | 55.6 |
| Left median‐APB | |||
| Wrist | 4.25 | 5.6 | |
| Elbow | 8.1 | 6.1 | 59.7 |
| Left ulnar‐ADM | |||
| Wrist | 4 | 0.3 | |
| B. Elbow | 7.35 | 0.5 | 59.7 |
| A. Elbow | 9.9 | 0.3 | 35.3 |
| Axilla | 13.45 | 0.4 | 47.9 |
| Right ulnar‐ADM | |||
| Wrist | 2.8 | 4.7 | |
| B. Elbow | 6.8 | 4.5 | 57.5 |
| A. Elbow | 8.45 | 3.8 | 54.5 |
| Left radial‐EIP | |||
| Forearm | 3.95 | 8.1 | |
| Right common peroneal‐EDB | |||
| Ankle | 3.05 | 8.9 | |
| Fibular head | 10.55 | 8.1 | 40.0 |
| Knee | 11.9 | 8 | 59.3 |
| Left common peroneal‐EDB | |||
| Ankle | 3.9 | 12.8 | |
| Fibular head | 10.75 | 11.7 | 43.8 |
| Knee | 12.55 | 12 | 44.4 |
| Left tibial knee‐AH | |||
| Ankle | 3.7 | 7.1 | |
| Knee | 12 | 7.9 | 43.4 |
| Sensory nerves | Latency (ms) | Amplitude (μV) | Conduction velocity (m/s) |
|---|---|---|---|
| Right median‐Digit II | |||
| 1 | 2.6 | 30.5 | 61.7 |
| 2 | 6.65 | 15.5 | N/A |
| Left ulnar‐Digit V | |||
| Wrist | 2.25 | 19.7 | N/A |
| Before elbow | 5.3 | 19.3 | 75.4 |
| After elbow | 6.8 | 18.2 | 53.3 |
| Axilla | 8.45 | 15.7 | 90.9 |
| Left radial‐thumb | |||
| Forearm | 2.45 | 14.7 | N/A |
| Left sural‐lateral malleolus | 44.8 | ||
| Calf | 2.9 | 14.3 | 61.7 |
Note: Nerve conduction studies show a low‐amplitude left ulnar compound motor action potential and a reduced ratio (<0.6) between the abductor digit minimi and abductor pollicis brevis, bilaterally, supporting the diagnosis.
Abbreviations: ADM, abductor digiti minimi; AH, abductor hallucis; APB, abductor pollicis brevis; EDB, extensor digiti brevis; EIP, extensor indicis proprius; ms, milliseconds; m/s, meters per second; mV, millivolts; N/A, not available; μV, microvolts.