From the Guidelines
Progressive Supranuclear Palsy (PSP) is diagnosed primarily through clinical evaluation, including a thorough neurological examination and imaging tests such as brain MRI, which may show midbrain atrophy and thinning of the superior cerebellar peduncles 1.
Key Diagnostic Tests
- A comprehensive clinical examination including vital signs, basic cardiovascular exam, and basic neurological examination helps inform the appropriate investigations or explore alternative diagnoses 1.
- The neurological examination aims to identify motor signs that may be associated with FTD or FTD-related disorders, such as parkinsonism, oculomotor disorders, or ALS 1.
- Testing for parkinsonism, including bradykinesia/akinesia, parkinsonian gait/posture, or rigidity, is essential 1.
- Smooth pursuit and saccadic eye movements should be tested for vertical eye-gaze palsy (downward and upward) 1.
- Brain MRI is the most useful imaging test, which may show midbrain atrophy (the "hummingbird" or "penguin" sign) and thinning of the superior cerebellar peduncles.
- PET or SPECT scans can help by showing reduced glucose metabolism or blood flow in specific brain regions.
- Neuropsychological testing often reveals frontal lobe dysfunction.
- Blood tests are performed mainly to rule out other conditions.
- In some cases, cerebrospinal fluid analysis may be done to exclude other disorders.
Importance of Clinical Evaluation
Diagnosis of PSP often takes time and may require evaluation by movement disorder specialists, as it shares symptoms with other neurodegenerative disorders 1.
Recent Recommendations
Recent studies recommend a detailed neurological examination, including additional signs such as decreased velocity of saccades, unilateral dystonia, stimulus-sensitive myoclonus, cortical sensory deficits, ideomotor apraxia, and alien limb phenomenon 1.
Limitations and Future Directions
Currently, definitive diagnosis can only be confirmed through brain autopsy showing tau protein deposits, though researchers are developing tau PET tracers that may eventually allow visualization of these deposits in living patients 1.
From the Research
Diagnostic Tests for Progressive Supranuclear Palsy (PSP)
- The diagnosis of PSP remains clinical, although various tests can aid in the diagnostic process 2, 3, 4, 5.
- The following tests are used to diagnose PSP:
- Clinical diagnostic criteria with excellent specificity and a clinical rating scale sensitive to progression 2.
- Magnetic resonance imaging (MRI) as an early-stage screening tool 2, 5.
- Cerebrospinal fluid (CSF) measures as an early-stage screening tool 2, 4, 5.
- The 2017 International Parkinson and Movement Disorder Society PSP criteria, which outline 14 core clinical features and 4 clinical clues to diagnose one of eight PSP phenotypes with probable, possible, or suggestive certainty 3.
- Select imaging approaches, such as positron emission tomography (PET), in the classic PSP-Richardson syndrome phenotype 3, 5.
- These tests can help differentiate PSP from other atypical parkinsonian disorders, such as multiple system atrophy (MSA) and corticobasal syndrome (CBS) 4.
- The use of CSF biomarkers, although still in development, may contribute to the differential diagnosis of PSP, particularly in the early stages of the disease 4, 5.