| Value | Code Name | Code | Code System | Code Description |
|---|---|---|---|---|
| Stage 0 | Stage 0 | No signs of disease | ||
| Stage 1 | Stage 1 | Unilateral disease | ||
| Stage 1.5 | Stage 1.5 | Unilateral plus axial involvement | ||
| Stage 2 | Stage 2 | Bilateral disease, without impairment of balance | ||
| Stage 2.5 | Stage 2.5 | Mild bilateral disease, with recovery on pull test | ||
| Stage 3 | Stage 3 | Mild to moderate bilateral disease| some postural instability| physically independent | ||
| Stage 4 | Stage 4 | Severe disability| still able to walk or stand unassisted | ||
| Stage 5 | Stage 5 | Wheelchair bound or bedridden unless aided |