MDS 2021 | Diagnosing parkinsonism with atypical features: a classification system
Oscar Gershanik, MD, Favaloro University, Buenos Aires, Argentina, outlines the details of a proposed diagnostic classification system and a roadmap to correct diagnosis in patients with parkinsonian syndromes. The lack of objective, specific biomarkers for the differential diagnosis of Parkinson’s disease means that patients are typically diagnosed using clinically defined criteria. Recognizing the challenges in the diagnosis of parkinsonism with atypical features, Prof. Gershanik shares a systematic approach to the diagnosis of parkinsonism, based on 5 categories. Firstly, cases can be classified as typical parkinsonism (classical presentation of idiopathic Parkinson’s disease) or atypical-typical parkinsonism (atypical presentation of typical parkinsonism). The next groups are typical-atypical parkinsonism (progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophy) and atypical-typical-atypical (atypical presentation of typical-atypical parkinsonism). Finally, atypical-atypical parkinsonism includes all presentations that do not fit into the above categories. This interview took place during the 2021 International Congress of Parkinson’s Disease and Movement Disorders.
Transcript (edited for clarity)
The title of my presidential lecture is opening the Pandora’s box of parkinsonism, and the concept of the Pandora’s box is that when Zeus gave the Pandora box as a present, anybody that would open that box would just free a lot of trouble that was inside the box. And I make an analogy with that because every time we face a patient with a parkinsonian syndrome or with parkinsonian symptoms, it really is the start of trouble because we are never sure if we are facing a case of Parkinson’s disease, some of the atypical parkinsonisms, the classical forms like MSA or PSP or corticobasal degeneration; or the more difficult to diagnose, the very atypical cases that are thousands caused by different etiologies like mitochondrial disease, genetic forms of parkinsonism, even some of the ataxias or the paraplegias can present with parkinsonism...
The title of my presidential lecture is opening the Pandora’s box of parkinsonism, and the concept of the Pandora’s box is that when Zeus gave the Pandora box as a present, anybody that would open that box would just free a lot of trouble that was inside the box. And I make an analogy with that because every time we face a patient with a parkinsonian syndrome or with parkinsonian symptoms, it really is the start of trouble because we are never sure if we are facing a case of Parkinson’s disease, some of the atypical parkinsonisms, the classical forms like MSA or PSP or corticobasal degeneration; or the more difficult to diagnose, the very atypical cases that are thousands caused by different etiologies like mitochondrial disease, genetic forms of parkinsonism, even some of the ataxias or the paraplegias can present with parkinsonism. So we are really faced with a significant problem every time we see a patient with parkinsonian syndrome.
And the major limitation we have at present is that we don’t have a definitive biomarker to differentiate all these disorders. We cannot even differentiate between Parkinson’s disease and some of the atypical parkinsonisms because of the lack of these biomarkers, so we have to use clinically defined criteria. We have to analyze the phenomenology of a patient. We have to take a very detailed clinical history, the family history, the existence of atypical manifestations, the use of auxiliary methods of investigation like MRI and some of the functional neuroimaging techniques in order to try to tease out all these different types of parkinsonism.
And the other significant problem is that we know for a fact that when we see a patient with Parkinson’s, or with what we believe is Parkinson’s disease, for the first time, this can change in the course of the disease. And I propose to apply the five-year rule; that means that for the first five years in the course of a person that has something that we believe is Parkinson’s disease may change. After five years, once the disease has consolidated and we have a significant response to the treatment, we have sorted out that the patient doesn’t have any atypical symptoms in the clinical examination, then we can be significantly sure that we are facing a case of Parkinson’s disease.
And I’m proposing a classification of parkinsonism that includes several categories and a roadmap to analyze these different categories. And the categories are the typical parkinsonian syndromes, the atypical presentations of the typical parkinsonism or Parkinson’s disease, the typical atypical parkinsonisms, like MSA or PSP, and then we have the atypical presentations of these disorders. And finally, we have this huge box of the atypical atypicals. So, that’s the skeleton of my presentation.
The basis is on the clinical features of the patients. It’s clinically oriented because we don’t have any other indicator or clue to lead us into a certain diagnosis. So we have to base in a very careful, comprehensive clinical examination and follow-up of the patient.
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