| Hoehn and Yahr Scale | Â Modified Hoehn and Yahr Scale | |
|---|---|---|
| 1 | Unilateral involvement only usually with minimal or no functional disability | Unilateral involvement only |
| 1.5 | – | Unilateral and axial involvement |
| 2 | Bilateral or midline involvement without impairment of balance | Bilateral involvement without impairment of balance |
| 2.5 | – | Mild bilateral disease with recovery on pull test |
| 3 | Bilateral disease: mild to moderate disability with impaired postural reflexes; physically independent | Mild to moderate bilateral disease; some postural instability; physically independent |
| 4 | Severely disabling disease; still able to walk or stand unassisted | Severe disability; still able to walk or stand unassisted |
| 5 | Confinement to bed or wheelchair unless aided | Wheelchair bound or bedridden unless aided |