Establishing clinical stages of diseases—particularly for those of degenerative nature—is important for understanding disease progression for a given patient depending on specific symptoms and abilities. Staging in Parkinson’s disease helps healthcare providers understand how well a patient can function, determine whether or not specific drugs or therapies are likely to be effective, and monitor response to medications. Staging scales can also allow caregivers to better understand a patient’s changing care needs.
So, what are the stages of Parkinson’s disease? While there is no single staging scale used in practice, two of the most common and highly regarded Parkinson’s disease staging scales are Hoehn and Yahr (H-Y) and the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS).
The H-Y staging scale was first described in 1967 by Hoehn and Yahr based on the level of clinical disability and included five stages (1-5). A modified version of this staging scale has been widely adopted and includes the additional stages of 0, 1.5, and 2.5. The stages of Parkinson's disease, as described by the original and modified H-Y staging scale, are detailed below.
| Stage | Description | Symptoms |
|---|---|---|
| 0 | No clinical signs of Parkinson’s disease | n/a |
| 1 | Unilateral involvement only | During stage one, patients have mild symptoms that usually do not interfere with Activities of Daily Living (ADLs). Movement symptoms, such as tremor, occur unilaterally, meaning on one side of the body only. |
| 2 | Bilateral involvement without impairment of balance | During stage two, movement symptoms—such as tremor, rigidity, and loss of facial expressions—become more severe and affect both sides of the body or the midline (trunk and neck). Speech abnormalities and slowness in ADLs are common during this stage. |
| 3 | Mild to moderate bilateral disease; some postural instability; physically independent | Loss of balance and slowed movement are hallmarks of stage three. Motor symptoms continue to become more severe, and falls become more common. |
| 4 | Severe disability; still able to walk or stand unassisted | During stage four, symptoms are severe, and significant assistance with ADLs is typically required, though the patient may still be able to walk or stand without assistance. |
| 5 | Wheelchair-bound or bedridden unless aided | Stage five is the most advanced stage and is characterized by confinement to a wheelchair or bed. Patients in this stage require around-the-clock care for all ADLs. |
| Stage | Description |
|---|---|
| 0 | No clinical signs of Parkinson’s disease |
| 1 | Unilateral involvement only |
| 1.5 | Unilateral and axial involvement |
| 2 | Bilateral involvement without impairment of balance |
| 2.5 | Mild bilateral disease with recovery on pull test |
| 3 | Mild to moderate bilateral disease; some postural instability; physically independent |
| 4 | Severe disability; still able to walk or stand unassisted |
| 5 | Wheelchair-bound or bedridden unless aided |
The UPDRS was developed in 1987 to incorporate elements from existing scales and provide a more comprehensive tool to assess the vast range of symptoms, both motor- and non-motor-related. In 2001, the Movement Disorder Society updated the rating scale. This scale is referred to as the MDS-UPDRS and is commonly used by neurologists to monitor response to medications and decrease the signs of Parkinson’s disease.
The MDS-UPDRS consists of four parts:
| Part | Symptoms Analyzed |
|---|---|
| 1 | |
| 2 | |
| 3 | |
| 4 |
Each category within each part is scored on a five-point scale to indicate severity:
Scores are tallied up to provide insight into disease severity, with 199 points being total disability and zero points being no disability.
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