PSP and CBD folks –
This is further evidence that the “applause sign” is not a very useful tool when diagnosing PSP or, by inference, CBD. This research shows that the applause sign can occur in FTD (only the behavioral variant of FTD was included) and AD. (Previously others have argued that it is unique to PSP. More recently, researchers have argued that it is specific to parkinsonian disorders.)
Here’s a description of the applause sign from the article: “The applause sign was detected using the three clap test which was administered and scored according to the literature: subjects were asked ‘to clap three times as quickly as possible after demonstration of the examiner’. The subject’s performance was considered normal when he/she clapped three times (score=3), abnormal when the subject clapped more than three times (2=four times, 1=five to ten times; 0= more than 10 times).”
“An abnormal applause sign was present in all patient groups (80% in PSP, 70% in FTD and 31% in AD) while it was absent in normal controls. …[P]oor specificity and low positive predictive value of the applause sign should raise questions about its diagnostic usefulness.”
Robin
Journal of Neurology, Neurosurgery and Psychiatry. 2011 Jan 18. [Epub ahead of print]
Applause sign: is it really specific for Parkinsonian disorders? Evidence from cortical dementias.
Luzzi S, Fabi K, Pesallaccia M, Silvestrini M, Provinciali L.
Department of Neuroscience, Polytechnic University of Marche, Ancona, Italy.
Abstract
Objective
The applause sign, originally reported as a specific sign of progressive supranuclear palsy (PSP), has recently been found in several parkinsonian disorders. Its nature is still uncertain. It has been interpreted as a motor perseveration or a form of apraxia.
The present study aims to: (a) verify the specificity of the applause sign for parkinsonian disorders, examining the presence of the applause sign in cortical dementias which should be error free and (b) clarify the nature of the applause sign (resulting or not from apraxia).
Methods
77 subjects were included: 10 PSP, 15 frontotemporal dementia (FTD), 29 Alzheimer’s disease (AD) and 23 normal
controls. The presence of apraxia was an exclusion criterion. All patients underwent a detailed neuropsychological examination, and cognitive performance was correlated to the applause sign.
Results
All patient groups showed the applause sign and differed significantly from normal subjects who were error free.
No difference was found when comparing PSP with FTD and FTD with AD.
AD differed significantly from PSP but they were not error free (31% of patients with AD showed the applause sign).
The only correlation with background neuropsychology was found for measures of executive functions.
Conclusions
The presence of the applause sign in cortical dementia does not confirm the specificity of the applause sign for parkinsonian disorders. The applause sign should be interpreted as a sign of frontal lobe dysfunction rather than a form of apraxia, and can likely be detected in any kind of disease which involves frontal lobe structures to some extent.
Pub Med ID#: 21245475 (see pubmed.gov for this abstract only)