Arquivos de neuro-psiquiatria
The whistle-smile reflex in Parkinson's disease: an exploratory case-control study
By Damiani Monteiro M, Carvalho Neto EG, Fernandez LL and 2 others.
Abstract
Background
Parkinson's disease (PD) is a well-known neurodegenerative disease characterized by tremors, rigidity, and bradykinesia. In 1943, Frederic Hanes described the whistle-smile reflex (WSR), noting its absence in PD patients due to reduced facial movements.
Objective
To assess the WSR's diagnostic performance.
Methods
In the current cross-sectional study, we selected PD patients and healthy controls. They were filmed while asked to whistle, and a blinded physician assessed if the individuals smiled or not. Absence of smiling after whistling was considered a positive test. We stratified the smiling intensity into 4 groups. We calculated the odds ratio (OR) of the positive WSR in PD and asymptomatic patients, which was reported with CIs, sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and we plotted a receiver operating characteristic (ROC) curve.