Progressive Supranuclear Palsy (PSP)

Progressive supranuclear palsy (PSP) is the most common of the atypical parkinsonian disorders. The prevalence of PSP is estimated to be about 6 out of 100,000.

PSP is considered to be a "tauopathy" named for the protein (Tau) which accumulates in the brain of those with PSP. Other tauopathies include Alzheimer's disease, Frontotemporal dementia, Corticobasal degeneration (CBD), and Pick's disease.

Fig. 1: A patient exhibits what is called a staring face, due to her difficulties in moving her eyes, decreased blinking and some facial dystonia 

Usually PSP patients are first diagnosed in their mid 60s; the most common symptom is an instability, or tendency to fall. In general, symptoms and signs apparent early in the course of PSP progress steadily. In the early stages of PSP, blink rate usually becomes profoundly sparse. Later, a vertical gaze abnormality (slowing of vertical eye movement) will occur, with dysarthria, dysphagia, and parkinsonism not responsive to levodopa therapy, as well as cognitive disturbances (impaired abstract thought, decreased verbal fluency, apathy, and disinhibition). 

Fig. 2.1: A patient's difficulty in voluntarily looking upwards.	Fig. 2.2: On moving the head downwards (doll's head maneuver), the patient's eyes go upward, showing that he does not have an involvement of the oculomotor nuclei in the brainstem. The lesion, rather, is above these nuclei, showing the patient's vertical supranuclear gaze palsy.

Differentiation between PSP and CBD can be difficult (and are frequently misdiagnosed as one another), but new diagnostic criteria have helped tremendously. Without a detailed history and examination that include evaluation of speed of rapid eye movements, cognition, behavior, motor, praxis and autonomic functions, a trained clinician will not be able to appropriately apply the set of diagnostic criteria; in general, it is better to see a movement disorders specialist.

The cause of PSP is unknown, but several factors probably contribute to its development, including genetics, environmental exposures, and inflammation. There are no specific laboratory tests for the diagnosis of PSP, but ocular motor studies, electrophysiological studies and magnetic resonance Imaging (MRI).

There are no therapies that slow or completely stop PSP patients' symptoms; instead treatment is based on palliative care (e.g., speech therapy, physical therapy), education, and support. Patients, caregivers, and families are the mainstay of treatment in clinical practice; in our experience we have found that support contributes greatly to the improvement of the quality of life and even life span (through learning techniques to avoid aspiration).

There is no evidence yet that pallidotomy or any other surgical procedure helps PSP patients. 

PSP usually lasts approximately 5-6 years, but it duration varies and is hard to predict in an individual patient. Those with falls, occular and swallowing disturbances have a shorter survival. Death is generally caused by pneumonia or other complications of severe debility such as sepsis.