hoehn and yahr scale hoehn and yahr scale the hoehn and yahr scale is a commonly used system for describing how the symptoms of parkinson's disease progress. it was originally published in 1967 in the journal neurology by margaret hoehn and melvin yahr and included stages 1 through 5. since then, a modified hoehn and yahr scale was proposed with the addition of stages 1.5 and 2.5 to help describe the intermediate course of the disease. it has been shown that hy stage discrimination can be automated, even with patients who cannot support themselves. stagehoehn and yahr scalemodified hoehn and yahr scale 1unilateral involvement only usually with minimal or no functional disabilityunilateral involvement only 1.5-unilateral and axial involvement 2bilateral or midline involvement without impairment of balancebilateral involvement without impairment of balance 2.5-mild bilateral disease with recovery on pull test 3bilateral disease: mild to moderate disability with impaired postural reflexes; physically independentmild to moderate bilateral disease; some postural instability; physically independent 4severely disabling disease; still able to walk or stand unassistedsevere disability; still able to walk or stand unassisted 5confinement to bed or wheelchair unless aidedwheelchair bound or bedridden unless aided this rating system has been largely supplanted by the unified parkinson's disease rating scale, which assesses limitation of daily activities and non-motor symptoms in more detail. time between stages a 2010 study of 695 patients (mean age: 65.2, male: 57.3%) found the median time taken to transit h&y stages as shown below: stagemedian time to transit (months) 1- 220 2.562 325 424 526