Progressive Supranuclear Palsy (PSP) is a rare neurodegenerative disorder characterized by early postural instability, leading to falls, and a characteristic vertical supranuclear-gaze palsy on physical exam. It is classified as an atypical parkinsonian syndrome (or Parkinson's Plus).
The “classic” form of PSP is also called Richardson PSP phenotype (PSP-RS) (also known as Steele-Richardson-Olszewski syndrome). Patients report early difficulties with vertical gaze and pseudobulbar palsy, nuchal dystonia, and dementia. The National Institute of Neurological Disorders and Stroke and Society for PSP (NINDS-SPSP) criteria are the most widely used criteria for the diagnosis of PSP.[4]
Symptoms | |
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Probable PSP | Vertical supranuclear gaze palsy plus postural instability and falls within the first year of symptom onset to diagnosis. |
Possible PSP | Supranuclear gaze palsy or a combination of slow vertical saccades and postural instability with falls within the first year. |
The International Parkinson and Movement Disorder Society (MDS)-endorsed PSP Study Group set out to provide an evidence and consensus-based revision of the NINDS-SPSP criteria in 2017, with a much more comprehensive set of criteria.[5]
Mandatory inclusion criteria | 1. Sporadic occurrence 2. Age 40 or older at onset of first PSP-related symptom 3. Gradual progression of PSP-related symptoms |
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Mandatory exclusion criteria | Clinical findings 1. Predominant, otherwise unexplained impairment of episodic memory, suggestive of Alzheimer's Disease (AD) 2. Predominant, otherwise unexplained autonomic failure, e.g., orthostatic hypotension (orthostatic reduction in blood pressure after 3 minutes standing 30 mm Hg systolic or 15 mm Hg diastolic), suggestive of multiple system atrophy or Lewy body disease 3. Predominant, otherwise unexplained visual hallucinations or fluctuations in alertness, suggestive of dementia with Lewy bodies 4. Predominant, otherwise unexplained multisegmental upper and lower motor neuron signs, suggestive of motor neuron disease (pure upper motor neuron signs are not an exclusion criterion) 5. Sudden onset or step-wise or rapid progression of symptoms, in conjunction with corresponding imaging or laboratory findings, suggestive of vascular etiology, autoimmune encephalitis, metabolic encephalopathies, or prion disease 6. History of encephalitis 7. Prominent appendicular ataxia 8. Identifiable cause of postural instability, e.g., primary sensory deficit, vestibular dysfunction, severe spasticity, or lower motor neuron syndrome Imaging findings 1. Severe leukoencephalopathy, evidenced by cerebral imaging 2. Relevant structural abnormality, e.g., normal pressure or obstructive hydrocephalus; basal ganglia, diencephalic, mesencephalic, pontine or medullary infarctions, hemorrhages, hypoxic-ischemic lesions, tumors, or malformations |
Levels of Certainty | Ocular Motor Dysfunction | Postural Instability | Akinesia | Cognitive Dysfunction |
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Level 1 | O1: Vertical supranuclear gaze palsy | P1: Repeated unprovoked falls within 3 years | A1: Progressive gait freezing within 3 years | C1: Speech/language disorder (i.e. - nonfluent/agrammatic variant of primary progressive aphasia or progressive apraxia of speech) |
Level 2 | O2: Slow velocity of vertical saccades | P2: Tendency to fall on the pull-test within 3 year | A2: Parkinsonism, akinetic-rigid, predominantly axial, and levodopa resistant | C2: Frontal cognitive/behavioural presentation |
Level 3 | O3: Frequent macro square wave jerks or “eyelid opening apraxia” | P3: More than two steps backward on the pull-test within 3 years | A3: Parkinsonism, with tremor and/or asymmetric and/or levodopa responsive | C3: Corticobasal syndrome |
The differential diagnosis for PSP is very broad and includes:[12]
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times. If they clap more than 3 times, it is a positive sign.[14]Differentiation of PSP from Parkinson's disease (PD) and Multiple System Atrophy (MSA) can be difficult, particularly in the early stages of the disease. The hummingbird sign (also known as the penguin sign) refers to the appearance of the midbrain in patients with progressive supranuclear palsy (PSP).[16][17][18][19]