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Re: Invited Article: Changing concepts in Parkinson disease: Moving beyond the Decade of the Brain

I congratulate Marras and Lang on their article concerning the changing concepts in Parkinson disease (PD). [1] They provide three alternatives to define PD: 1) A clinical syndrome dominated by levodopa responsive parkinsonism; 2) A neuropathological entity characterized by degeneration of the substantia nigra and formation of Lewy bodies; or 3) levodopa responsive parkinsonism associated with Lewy bodies.

They opt for “an adult onset progressive disorder dominated by parkinsonism responsive to levodopa and commonly associated with motor complications”. [1] The authors had previously termed this ‘classic parkinsonism’.

I agree with Marras and Lang’s implicit view that clinicians need an accurate, non-speculative, working definition for what can be observed. Thus current definitions based on pathological findings (2 and 3 above) are outside in vivo clinical practice.

As evidence for multiple etiologies for PD(s) increase it is clear that clinically it is a syndrome. Clinical terminology needs to evolve to avoid speculation about underlying pathology and to encompass advancing knowledge.

Acknowledging these issues, I have used the term ‘parkinsonism’ at the initial diagnosis. Subsequently, when the natural history and responsiveness to dopaminergic treatment is apparent, I switch to the term ‘typical parkinsonism’ for what Marras and Lang deemed ‘classic parkinsonism.’ However, neither label can be applied initially. This approach, although honest—particularly in the light of the Scans Without Evidence of Dopaminergic Deficit (SWEDDs) findings [2]—has disadvantages.

By using the term parkinsonism and not Parkinson disease, patients may think that an atypical parkinsonism is being implied. However, this is probably not the case and the term should be carefully explained. Furthermore, time is required to observe whether the condition follows a typical course including response to treatment, and that no atypical features develop. In addition, patients and their families may conclude that the neurologist does not even know how to diagnose Parkinson disease.

References

1. Marras C, Lang A. Changing concepts in Parkinson’s disease. Moving beyond the decade of the brain. Neurology 2008;70:1996-2003.

2. Schneider SA, Edwards MJ, Mir P et al. Patients with adult-onset dystonic tremor resembling parkinsonian tremor have scans without evidence of dopaminergic deficit (SWEDDs). Mov Dis 2007;22:2210-2215.

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Re: Reply from the authors

We thank Dr. Bain for his comments. We also regularly use the term ‘parkinsonism’ when seeing patients initially and admit to them that, although Parkinson disease is the most common cause of this syndrome, there is potential for confusion between this and other causes especially in the early years, even in the absence of "red flags" suggesting an alternative diagnosis.

Like Dr. Bain, we have witnessed the skepticism that patients and families convey when a definitive diagnosis is not made. However, we agree that it is important to present these uncertainties using an honest and open approach to patients and their families. A concern about their belief that we are incapable of making a diagnosis of Parkinson disease should not be a reason for presenting a level of diagnostic certainty that is not justified.

Importantly, when we are incorrect about our initial suspicions that the patient has PD, their resentment can be considerable and understandable if they are actually suffering from a disease with a much graver prognosis.