From: Electrophysiological differences between Hirayama disease, amyotrophic lateral sclerosis and cervical spondylotic amyotrophy
U/M CMAP ratio
<0.6
0.6-1.7
>1.7
HD
Affected limb
62
28
10
Healthy limb
0
78
ALS
3
54
33
37
CSA
1
27
2
22
Normal controls
35