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PubMed This is a summary of 17 peer-reviewed journal articles Updated
Neurology · Progressive Supranuclear Palsy

Getting the Right Diagnosis: Criteria and Imaging

At a Glance

Progressive Supranuclear Palsy (PSP) is diagnosed using the 2017 MDS criteria and specific MRI findings. Doctors look for vertical eye movement issues, early backward falls, and brain shrinkage (like the Hummingbird sign) to distinguish atypical PSP from Parkinson's disease.

Diagnosing Progressive Supranuclear Palsy (PSP) is often a “process of elimination” because its early symptoms frequently overlap with other conditions like Parkinson’s disease or Alzheimer’s [1][2]. However, modern medical guidelines and imaging techniques have made it much easier to identify the specific “atypical” variants of PSP early on [3].

The Gold Standard: 2017 MDS Criteria

The Movement Disorder Society (MDS) established the current international standards for diagnosing PSP in 2017 [3]. These criteria move away from looking only for the “classic” symptoms and instead focus on four key areas:

  1. Ocular Motor Dysfunction: Problems with eye movement, specifically difficulty looking up or down (vertical gaze palsy) [4].
  2. Postural Instability: A tendency to lose balance and fall, often backwards [4].
  3. Akinesia: Slowness of movement or “freezing” of gait [4].
  4. Cognitive Dysfunction: Changes in personality, speech, or the ability to plan and organize [4].

Under these guidelines, a doctor will assign a level of certainty to the diagnosis [5]:

  • Probable PSP: High certainty; the patient shows classic, well-defined symptoms [6].
  • Possible PSP: Symptoms are present but may be less severe or missing the classic eye movement issues [7].
  • Suggestive of PSP: Used for very early cases where subtle signs hint at PSP rather than another condition [7].

The Role of Brain Imaging (MRI)

While a diagnosis is primarily based on a physical exam, Magnetic Resonance Imaging (MRI) provides crucial “biomarkers”—physical evidence in the brain that supports the diagnosis [8].

An Important Note on Early MRIs: It is very common for an MRI to look completely normal in the early stages of PSP. Do not panic or assume a misdiagnosis if your initial brain scan is clear; the classic visible changes often take time to develop [8].

The Midbrain-to-Pons (M/P) Ratio

In PSP, the midbrain (a small area at the top of the brainstem) often shrinks, while the pons (the area just below it) remains a normal size [9]. Radiologists measure the size of these two areas and calculate the M/P ratio [10]. A significantly low ratio is a strong indicator of PSP and helps distinguish it from Parkinson’s disease [10][11].

Visual Signs

You may hear your doctor mention two famous visual patterns seen on an MRI:

  • The Hummingbird Sign: On a side-view (sagittal) image, the shrunken midbrain and normal pons look like the head and body of a hummingbird [11].
  • The Morning Glory Sign: On a cross-section (axial) image, the specific way the midbrain shrinks resembles the morning glory flower [11].

Why is it Hard to Tell Apart from Parkinson’s?

The variant PSP-Parkinsonism (PSP-P) is notoriously difficult to distinguish from Parkinson’s disease early on because both cause slowness, stiffness, and sometimes tremors [1].

Here is a quick look at the “red flags” that point toward PSP-P rather than Parkinson’s disease [12]:

Feature Typical Parkinson’s Disease Atypical PSP (PSP-P)
Response to Levodopa Excellent and sustained Poor, partial, or only temporary [13]
Falls Rare in the first few years Common early on, frequently backward [12]
Posture Stooped or bent forward Stiff, straight, leaning backward [12]
Sense of Smell Frequently lost early on Usually remains normal [12]

Diagnostic Checklist: What to Expect

If you are currently in the evaluation process, you should expect (or ask for) the following:

  • [ ] Comprehensive Neurological Exam: Testing “saccades” (fast eye movements). This also includes the “pull test,” where the doctor will stand behind you and give a quick, unexpected pull on your shoulders to see how well you recover your balance [14].
  • [ ] High-Resolution MRI: To look for midbrain atrophy and calculate the MRPI (Magnetic Resonance Parkinsonism Index) [15].
  • [ ] Levodopa Challenge: Taking standard Parkinson’s medication for a period of time to see if symptoms improve [13].
  • [ ] Cognitive and Speech Assessment: To identify executive dysfunction or specific language “hesitancy” [16].
  • [ ] FDG-PET Scan (Optional): Used if the diagnosis is still unclear to look for specific patterns of low metabolism in the frontal lobes [17].

Common questions in this guide

What is the Hummingbird sign on an MRI?
The Hummingbird sign is a specific visual pattern seen on a side-view MRI of the brain. It occurs when the midbrain shrinks while the pons remains a normal size, making the structure look like a hummingbird. This is a strong indicator of PSP.
How is atypical PSP different from Parkinson's disease?
Doctors look for 'red flags' that differentiate PSP from Parkinson's disease. Patients with PSP often experience early backward falls, maintain a stiff upright posture, keep their normal sense of smell, and respond poorly to standard Parkinson's medications like Levodopa.
What are the MDS criteria for diagnosing PSP?
The 2017 Movement Disorder Society (MDS) criteria focus on four main areas to diagnose PSP. These include ocular motor dysfunction (trouble moving eyes up and down), postural instability, akinesia (slowness or freezing of movement), and cognitive or speech changes.
Is it normal for my first MRI to be clear if I have PSP?
Yes, it is very common for an initial MRI to appear completely normal during the early stages of PSP. The visible physical changes in the brain, such as midbrain shrinkage, often take time to develop as the condition progresses.
What is the pull test?
The pull test is a physical exam used to check for postural instability and balance issues. The doctor stands behind you and gives a quick, unexpected tug on your shoulders to see how well you can catch your balance and prevent yourself from falling backward.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does the MRI report mention specific measurements like the midbrain-to-pons (M/P) ratio or the Magnetic Resonance Parkinsonism Index (MRPI)?
  2. 2.Is there evidence of the 'Hummingbird sign' or 'Morning Glory sign' on the brain imaging, or is it still too early to see these?
  3. 3.Based on the MDS criteria, which level of diagnostic certainty applies to my situation—'probable,' 'possible,' or 'suggestive'?
  4. 4.If the symptoms resemble Parkinson's, what specific 'red flags' led you to rule out idiopathic Parkinson's disease?
  5. 5.Would an FDG-PET scan be helpful to check for frontal hypometabolism to further clarify the subtype?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (17)
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    Development and Validation of Automated Magnetic Resonance Parkinsonism Index 2.0 to Distinguish Progressive Supranuclear Palsy-Parkinsonism From Parkinson's Disease.

    Quattrone A, Bianco MG, Antonini A, et al.

    Movement disorders : official journal of the Movement Disorder Society 2022; (37(6)):1272-1281 doi:10.1002/mds.28992.

    PMID: 35403258
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    Epidemiology of Progressive Supranuclear Palsy: Real World Data from the Second Largest Health Plan in Israel.

    Barer Y, Chodick G, Cohen R, et al.

    Brain sciences 2022; (12(9)) doi:10.3390/brainsci12091126.

    PMID: 36138862
  3. 3

    Graphic Summary of Movement Disorders Society Criteria for Progressive Supranuclear Palsy and Multiple Allocations eXtinction Rules.

    Ogawa T, Hatano T, Oyama G, et al.

    Movement disorders clinical practice 2020; (7(2)):240-242 doi:10.1002/mdc3.12894.

    PMID: 32071951
  4. 4

    Clinical diagnosis of progressive supranuclear palsy: The movement disorder society criteria.

    Höglinger GU, Respondek G, Stamelou M, et al.

    Movement disorders : official journal of the Movement Disorder Society 2017; (32(6)):853-864 doi:10.1002/mds.26987.

    PMID: 28467028
  5. 5

    An Evaluation of the Progressive Supranuclear Palsy Speech/Language Variant.

    Whitwell JL, Stevens CA, Duffy JR, et al.

    Movement disorders clinical practice 2019; (6(6)):452-461 doi:10.1002/mdc3.12796.

    PMID: 31392246
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    Video-tutorial for the Movement Disorder Society criteria for progressive supranuclear palsy.

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    Parkinsonism & related disorders 2020; (78()):200-203 doi:10.1016/j.parkreldis.2020.06.030.

    PMID: 32988736
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    Clinical Conditions "Suggestive of Progressive Supranuclear Palsy"-Diagnostic Performance.

    Grimm MJ, Respondek G, Stamelou M, et al.

    Movement disorders : official journal of the Movement Disorder Society 2020; (35(12)):2301-2313 doi:10.1002/mds.28263.

    PMID: 32914550
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    Brainstem Biomarkers of Clinical Variant and Pathology in Progressive Supranuclear Palsy.

    Grijalva RM, Pham NTT, Huang Q, et al.

    Movement disorders : official journal of the Movement Disorder Society 2022; (37(4)):702-712 doi:10.1002/mds.28901.

    PMID: 34970796
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    Midbrain area and the hummingbird sign from brain MRI in progressive supranuclear palsy and idiopathic normal pressure hydrocephalus.

    Virhammar J, Blohmé H, Nyholm D, et al.

    Journal of neuroimaging : official journal of the American Society of Neuroimaging 2022; (32(1)):90-96 doi:10.1111/jon.12932.

    PMID: 34520581
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    Highly specific radiographic marker predates clinical diagnosis in progressive supranuclear palsy.

    Owens E, Krecke K, Ahlskog JE, et al.

    Parkinsonism & related disorders 2016; (28()):107-11.

    PMID: 27160570
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    Accuracy of MR markers for differentiating Progressive Supranuclear Palsy from Parkinson's disease.

    Zanigni S, Calandra-Buonaura G, Manners DN, et al.

    NeuroImage. Clinical 2016; (11()):736-742 doi:10.1016/j.nicl.2016.05.016.

    PMID: 27330973
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    Diagnosis Across the Spectrum of Progressive Supranuclear Palsy and Corticobasal Syndrome.

    Jabbari E, Holland N, Chelban V, et al.

    JAMA neurology 2020; (77(3)):377-387 doi:10.1001/jamaneurol.2019.4347.

    PMID: 31860007
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    Tau in Atypical Parkinsonisms: A Meta-Analysis of in Vivo PET Imaging Findings.

    Mena AM, Chen R, Graff-Guerrero A, et al.

    Movement disorders clinical practice 2023; (10(12)):1725-1737 doi:10.1002/mdc3.13885.

    PMID: 38094644
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    Refining initial diagnosis of Parkinson's disease after follow-up: A 4-year prospective clinical and magnetic resonance imaging study.

    Quattrone A, Morelli M, Vescio B, et al.

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    PMID: 30759325
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    Accuracy of Magnetic Resonance Parkinsonism Index in Differentiating Progressive Supranuclear Palsy from Parkinson's Disease among South Indian Population: A Retrospective Case Control Study.

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    A 15-Item modification of the PSP rating scale to improve clinical meaningfulness and statistical performance.

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    Frontal hypometabolism in the diagnosis of progressive supranuclear palsy clinical variants.

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    PMID: 38632125

This page provides educational information about diagnosing progressive supranuclear palsy. Always consult a neurologist to properly evaluate your specific symptoms and imaging results.

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