staging of Parkinson's disease (Hoehn-Yahr scale)

Hoehn-Yahr staging scale: - stage 0: no signs of disease - stage 1: - unilateral disease - generally minimal or no functional impairment - stage 2: - bilateral or midline involvement - no impairment of balance - stage 3: - stage 2 + impaired balance - mild postural instablilty - 1st sign of impaired righting reflexes - unsteadiness as the patient turns - stage 4: - severe disability, still able to walk - bilateral disease - moderate to marked instability - fully developed, severely disabling disease - stage 5: wheelchair-bound/bedridden

References

Hoehn & Yar, Neurology 17:427, 1967