Progressive Supranuclear Palsy (PSP) is a rare brain disorder that gradually worsens over time. This condition impacts a person’s ability to control movement, maintain balance, and coordinate eye movements. It also affects speech and swallowing, leading to various difficulties in daily life. While PSP progresses continuously, its course is often described in stages—early, mid, and late—to provide a framework for understanding the changes individuals may experience.
Early-Stage PSP
The initial signs of progressive supranuclear palsy are often subtle and can be mistaken for other conditions, such as Parkinson’s disease, which can lead to a delayed diagnosis. A frequent early symptom is a loss of balance, resulting in unexplained falls, often backward. Individuals may also experience generalized stiffness, particularly in the neck and trunk, sometimes leading to a characteristic “head-back” posture.
Subtle changes in eye movement are also common, with difficulties looking downward or following objects. This can cause a staring or surprised facial expression due to reduced blinking and constantly raised eyebrows. Early personality and behavioral changes, such as apathy, irritability, or impulsivity, may also appear, sometimes before motor symptoms are fully recognized. These early symptoms, especially falls and eye movement problems, help differentiate PSP from Parkinson’s disease, where such issues typically emerge later in the disease course.
Mid-Stage PSP
In mid-stage PSP, initial symptoms intensify, and more distinctive features become apparent. Balance and gait decline significantly, making walking increasingly difficult and often necessitating the use of walking aids or a wheelchair for mobility. A hallmark of this stage is profound supranuclear ophthalmoplegia, a reduced ability to voluntarily move the eyes, especially downward. This eye movement limitation can severely impact daily activities like reading, eating, or walking down stairs, as individuals struggle to look where they need to.
Speech difficulties, known as dysarthria, become more pronounced, characterized by slow, slurred, or quiet speech that can be challenging to understand. Swallowing problems, or dysphagia, also emerge, increasing the risk of choking and aspiration. Cognitive and behavioral changes, including increased apathy, impaired reasoning, and emotional lability (sudden, uncontrolled laughing or crying), become more noticeable, affecting social interactions and decision-making.
Late-Stage PSP
In late-stage PSP, individuals experience severe disability and become highly dependent on caregivers for most daily activities. Mobility is severely compromised, with many becoming wheelchair-bound or bedridden due to extreme muscle stiffness and frequent falls. Swallowing difficulties become severe, often requiring a feeding tube to ensure adequate nutrition and hydration and prevent aspiration pneumonia.
Communication can become extremely limited or even non-verbal due to profound speech impairments and difficulties organizing thoughts. While cognitive abilities may be significantly impaired, some level of awareness or understanding of their surroundings can remain. The most common causes of death in individuals with late-stage PSP are complications such as aspiration pneumonia or sepsis resulting from infections like bedsores.
How Progression is Measured
Unlike some other diseases, progressive supranuclear palsy does not have a formal, universally adopted numerical staging system with distinct categories like “Stage 1” or “Stage 2”. Instead, the “early, mid, late” framework serves as a descriptive guide used by clinicians to help patients and families understand the general course of the disease.
Neurologists and researchers primarily measure and monitor the progression of PSP using standardized tools, such as the Progressive Supranuclear Palsy Rating Scale (PSPRS). This scale, developed by Dr. Lawrence Golbe, is a quantitative measure of disability that assesses various domains of clinical impairment. It includes 28 items across six main categories:
- Daily activities
- Behavior
- Bulbar function (speech and swallowing)
- Ocular motor function (eye movements)
- Limb motor function
- Gait/midline stability
The PSPRS provides a numerical score, typically ranging from 0 to 100, allowing doctors to track the severity of symptoms and disease progression over time.