Hoehn and Yahr Scale Overview
The Hoehn and Yahr scale is an internationally recognized clinical system used to describe and stage the progression of Parkinson's disease (PD) symptoms. Originally published in 1967, it remains one of the most fundamentally important tools in neurology for categorizing the overall functional disability of a PD patient.
The Five Stages of Progression
The scale focuses heavily on motor impairment and the patient's balance (postural stability):
- Stage 1: Symptoms are strictly unilateral (affecting only one side of the body). Minor tremor or stiffness.
- Stage 1.5: Unilateral and axial (central body/neck) involvement.
- Stage 2: Bilateral symptoms (both sides of the body) but balance is completely intact.
- Stage 2.5: Mild bilateral disease with recovery on the pull test (able to catch themselves if pushed).
- Stage 3: Mild to moderate bilateral disease; postural instability is present, but the patient remains physically independent.
- Stage 4: Severe disability; the patient can still walk or stand unassisted but is highly impaired.
- Stage 5: Wheelchair-bound or bedridden unless physically aided by a caregiver.
Staging = Qualitative clinical observation assigned from 1.0 to 5.0