PSP is a tauopathy, meaning that the condition is caused by a build-up of the toxic form of tau. This is distinguished from Parkinson’s disease, which is caused by a build-up of the toxic form of alpha-synuclein. Other diseases that are also tauopathies include corticobasal degeneration (CBD) and frontotemporal dementia (FTD).
Progressive supranuclear palsy (PSP) should be considered when a patient with parkinsonism has frequent, early falls; dementia; difficulty moving the eyes (especially in the vertical direction); eyelid opening apraxia (trouble coordinating the eyelids) and emotional lability and freezing of gait.
Freezing refers to patients having difficulty initiating gait, the feet appearing to be stuck to the floor, then improving after a few steps. Freezing is often brought on by turning, walking in crowded areas, or walking through doorways. In some patients the primary symptom is gait freezing without associated symptoms, called primary freezing of gait (FOG). FOG is felt to be caused by various conditions and not believed to represent a discrete disease. FOG can be caused by PSP, but also vascular parkinsonism, normal pressure hydrocephalus, and Parkinson’s Disease.
There are various findings on brain MRI that can help establish the diagnosis of PSP in combination with the clinical findings. This includes midbrain atrophy (shrinking) and bright signals (hyperintensities) in the pontine tegmentum (a part of the brainstem). Because these findings can be subtle, especially early in the course of the disease, our movement disorders specialists will personally review all imaging in patients suspected of having PSP, freezing of gait, or atypical parkinsonism. DaTscan cannot distinguish between PSP and PD but can help distinguish between AD and parkinsonian conditions.
PSP symptoms may improve marginally and temporarily with PD medications and physical or speech therapy. Unfortunately there is no cure for PSP, nor medications which slow the progression of PSP. There are small studies that are enrolling to modify the tau protein but are in very early stages.