Progressive Supranuclear Palsy (PSP) is a progressive parkinsonian disease that is often misdiagnosed as Parkinson's disease or Alzheimer's disease due to the overlap of its symptoms. PSP is the most common atypical parkinsonian disorder. It gets its name from the brain lesions that occur that control the eye movement.
Symptoms of PSP vary depending on the areas of the brain that are affected by the disease. Accordingly, there are variable clinical syndromes (presentations) of the disease.
Progressive supranuclear palsy: Richardson syndrome (PSP-RS)
This syndrome is the most common form of PSP that typically starts above age 50 with balance disturbances that lead to unexplained falls, often backward without loss of consciousness. Patients may develop gait instability with broad-based steps. Slowness (bradykinesia) and stiffness (rigidity) are Parkinsonian symptoms that occur in all disorders that mimick Parkinson's disease.
Slowness in daily activities is another feature of PSP. For example, PSP patients often take longer to eat, dress, and bathe. Those with Richardson syndrome tend to walk, turn and sit as a "block" because of stiffness in their trunk.They also usually develop slowness and stiffness more in their neck and trunk than in their limbs.
Most of the important symptoms of PSP that lead to its name are found in the eye movements. Vertical supranuclear gaze paresis is a movement limitation of the eyes that results in the inability to aim the eyes properly looking up and down, with the ocular reflexes preserved.
Light sensitivity (photophobia) is another symptom related of PSP that can be explained in part by a decrease in eye blinking. It can be associated with redness of the eyes and increased tearing and patients may need to wear sunglasses even indoors to avoid the irritating light. Due to the severely decreased blinking and diminished facial expressions (mask face), PSP patients may have an "astonished" or "surprise" face.
Patients with PSP-RS usually have some degree of apathy (loss of interest) and slowness of thought (bradyphrenia) associated with impaired attention. Other symptoms related to mental dysfunction are forgetfulness, difficulty in making decisions, impaired abstract thought, and occasionally disinhibition (executive dysfunction).
Dysarthria (poor articulation of speech) and dysphagia (swallowing) are also frequently affected relatively early in the course of the disease. The disease progresses relatively slowly, but PSP-RS patients have a shortened survival rate than in the general population.