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

The National Institute of Neurological and Communicative Disorders and Stroke developed criteria for progressive supranuclear palsy (PSP) criteria in 1996, which have played an important role in characterizing diagnosis in clinical and pathological research settings. However, patients with PSP exhibit various clinical phenotypes, particularly at an early stage, and a broader disease concept is required. New PSP criteria, included in “Clinical Diagnosis of Progressive Supranuclear Palsy: The Movement Disorder Society Criteria,” were created by the Movement Disorder Society– endorsed PSP Study Group in 2017. The new PSP criteria define the predominance type in detail using 4 core clinical features. Furthermore, sensitivity was improved without lowering specificity when compared with the National Institute of Neurological and Communicative Disorders and Stroke criteria. Grimm and colleagues developed the Multiple Allocations eXtinction (MAX) rules, making it possible for the new PSP criteria to cope with the earlier diagnosis and changes over time from the overlapping predominance type. Applying the MAX rules increases the usefulness of the new PSP criteria. However, owing to the variety of PSP clinical phenotypes, application of the diagnostic criteria is complex. Thus, we created a figure arranged in a hexagon to provide a visual representation of the diagnosis (Fig. 1A). We included the core clinical features and clues, surrounding the items for each predominance type. Each predominance type is indicated by color. Diagnostic levels of “probable” and “possible” are represented by solid lines, “suggestive of” is represented by broken lines, and “or” connects 2 items with diagnosis of the same color. The “or” between ocular motor dysfunction-highest (O1) and -mid (O2) is always an alternative of O1 and O2. We included the MAX rules at the bottom of figure. The inequality sign indicates that the left box has more diagnostic weight and corresponds to MAX Hierarchy (MAX 4). Phenotypic Hierarchy (MAX3) is described in accordance with the items of the PSP with Richardson’s syndrome (PSP-RS), PSP with predominant postural instability (PSP-PI), and PSP with predominant ocular motor dysfunction (PSP-OM) predominance type. An example of applying the MAX rules to the clinical course is shown in Figure 1B. A 72-year-old male developed gait disturbance and asymmetrical parkinsonism without responsiveness to levodopa (year 1: suggestive of PSP with predominant parkinsonism (PSP-P)). Gait freezing with repetitive unprovoked fall was gradually reported (year 2: possible PSP with progressive gait freezing (PSP-PGF)). Later, vertical supranuclear gaze palsy, apraxia, and frontal releasing sign was emerged, and the patient finally showed dysarthria and easy fall, making it impossible for the patient to stand by himself (year 5: probable PSP-RS). Symptoms progressed further until the patient was bedridden. A gastrostomy was conducted for severe dysphagia, and hospitalization for aspiration pneumonia was repeated (years 9–12: probable PSP-RS). Finally, a pathological anatomy revealed diffuse tau deposition (year 12: definite PSP). By including items that correspond to clinical symptoms, the graphic summary can aid the clarity of diagnosis. In addition, embedding the disease progression according to the MAX rules in the diagram increases understanding of the patient’s disease course. Digital applications are useful for various clinical criteria. However, because the clinical criteria for PSP are too complex for current digital applications, our

The National Institute of Neurological and Communicative Disorders and Stroke developed criteria for progressive supranuclear palsy (PSP) criteria in 1996, 1 which have played an important role in characterizing diagnosis in clinical and pathological research settings. However, patients with PSP exhibit various clinical phenotypes, particularly at an early stage, 2 and a broader disease concept is required. New PSP criteria, included in "Clinical Diagnosis of Progressive Supranuclear Palsy: The Movement Disorder Society Criteria," were created by the Movement Disorder Societyendorsed PSP Study Group in 2017. 3 The new PSP criteria define the predominance type in detail using 4 core clinical features. Furthermore, sensitivity was improved without lowering specificity when compared with the National Institute of Neurological and Communicative Disorders and Stroke criteria. 4 Grimm and colleagues 1 developed the Multiple Allocations eXtinction (MAX) rules, making it possible for the new PSP criteria to cope with the earlier diagnosis and changes over time from the overlapping predominance type. 5 Applying the MAX rules increases the usefulness of the new PSP criteria. However, owing to the variety of PSP clinical phenotypes, application of the diagnostic criteria is complex. Thus, we created a figure arranged in a hexagon to provide a visual representation of the diagnosis (Fig. 1A). We included the core clinical features and clues, surrounding the items for each predominance type. Each predominance type is indicated by color. Diagnostic levels of "probable" and "possible" are represented by solid lines, "suggestive of" is represented by broken lines, and "or" connects 2 items with diagnosis of the same color. The "or" between ocular motor dysfunction-highest (O1) and -mid (O2) is always an alternative of O1 and O2. We included the MAX rules at the bottom of figure.
The inequality sign indicates that the left box has more diagnostic weight and corresponds to MAX Hierarchy (MAX 4). Phenotypic Hierarchy (MAX3) is described in accordance with the items of the PSP with Richardson's syndrome (PSP-RS), PSP with predominant postural instability (PSP-PI), and PSP with predominant ocular motor dysfunction (PSP-OM) predominance type.
An example of applying the MAX rules to the clinical course is shown in Figure 1B. A 72-year-old male developed gait disturbance and asymmetrical parkinsonism without responsiveness to levodopa (year 1: suggestive of PSP with predominant parkinsonism (PSP-P)). Gait freezing with repetitive unprovoked fall was gradually reported (year 2: possible PSP with progressive gait freezing (PSP-PGF)). Later, vertical supranuclear gaze palsy, apraxia, and frontal releasing sign was emerged, and the patient finally showed dysarthria and easy fall, making it impossible for the patient to stand by himself (year 5: probable PSP-RS). Symptoms progressed further until the patient was bedridden. A gastrostomy was conducted for severe dysphagia, and hospitalization for aspiration pneumonia was repeated (years 9-12: probable PSP-RS). Finally, a pathological anatomy revealed diffuse tau deposition (year 12: definite PSP).
By including items that correspond to clinical symptoms, the graphic summary can aid the clarity of diagnosis. In addition, embedding the disease progression according to the MAX rules in the diagram increases understanding of the patient's disease course. Digital applications are useful for various clinical criteria. However, because the clinical criteria for PSP are too complex for current digital applications, our graphic summary may be useful as an interim solution. This graphic representation may help neurologists with diagnosis of PSP phenotypes.

Acknowledgments
We thank Benjamin Knight, MSc, from Edanz Group (https:// en-author-services.edanzgroup.com/) for editing a draft of this article.