Differential diagnosis - PSP, CBD, MSA, DLB, and PD
The recent issue of the journal Swiss Medical Weekly offers a great overview of the terms "parkinsonism" and "atypical parkinsonism."
The article also offers very detailed explanations of how to differentially diagnose the atypical parkinsonism disorders (PSP, CBD, MSA, and DLB) and Parkinson's Disease. The authors give three reasons why they believe it's important to identify the subtype of parkinsonism at the time of diagnosis:
* "the prognosis can be estimated."
* "some of the atypical features such as autonomous or cognitive problems may be targeted by pharmacological treatment"
* because "identification of atypical parkinsonism may prevent unnecessary iatrogenic harm from ineffective drugs, to which these patients typically react very sensitively."
The full article is available in English at no charge on the Swiss Medical Weekly's website:http://www.smw.ch/content/smw-2011-13293/
Note that the authors use the acronym "LBD" to designate Dementia with Lewy Bodies, in the full paper.
I've copied the abstract below with an excerpt.
Swiss Medical Wkly. 2011 Nov 1;141.
Parkinsonism: heterogeneity of a common neurological syndrome.
Bohlhalter S, Kaegi G.
Division of Restorative and Behavioral Neurology, Department of Internal Medicine, Luerner Kantonsspital, Luzern, Switzerland
Parkinsonism refers to a neurological syndrome embracing bradykinesia, muscle rigidity, tremor at rest and impaired postural reflexes, and involving a broad differential diagnosis.
Having ruled out secondary causes (most importantly drugs), distinguishing levodopa-responsive idiopathic parkinson's disease (PD) from chiefly treatment-resistant and hence atypical parkinsonism is essential.
Recent clinico-pathological studies using data-driven approaches have refined the traditional classifications of parkinsonism by identifying a spectrum of subtypes with different prognoses. For example, progressive supranuclear palsy (PSP), characterised by early vertical gaze limitation and falls, probably has a milder variant with predominant parkinsonism (PSP-P) which may respond quite well to levodopa before converting to the classical disease, relabelled Richardson syndrome (PSP-RS).
Analysis of PD subcategories has shown that tremor-dominant forms are probably less benign than was hitherto thought and that in mild cases dystonia should rather be considered. In addition, life expectancy in early onset PD may be shortened.
Despite the clinical and pathological overlap of the various subtypes, appreciating the heterogeneity of parkinsonism also includes identifying non-motor features such as early autonomous or cognitive problems which are potentially amenable to pharmacological treatment. Not least, non-motor symptoms, along with postural instability, render the patient particularly vulnerable to side effects, and hence avoiding unnecessary treatment is equally important in the management of parkinsonian disorders.
PubMed ID#: 22052571
Here are excerpts:
"Parkinsonism arising with early dementia is a core feature of DLB, which is likely in the spectrum of PD dementia (PDD). To delineate DLB from PDD, the somewhat arbitrary 1-year rule has been advocated, i.e. the emergence of a prominent cognitive decline within 12 months of disease onset. Essential for the diagnosis of DLB is the presence of additional neuropsychiatric features such marked diurnal fluctuations in cognition and unprovoked visual hallucinations (often with children or hunting scenes). DLB should not be confused with diffuse Lewy body disease, which is a rapidly progressive dementia leading to death within 18 months, and considered rather in the differential diagnosis of Creutzfeld Jakob Disease."
[Robin's note: I've never heard of a clinical diagnosis of "diffuse Lewy body disease."]