Work

The whistle-smile reflex in Parkinson's disease: an exploratory case-control study

Year: 2026

Type: article

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. Results: We identified 43 patients with PD (mean age = 63 ± 10 years; 30% of female subjects) and 44 asymptomatic controls (mean age = 64 ± 10 years; 51% of female subjects). The WSR test was positive in 35/43 PD cases versus 7/44 in the asymptomatic group (OR = 23.1; 95%CI = 7.6-70.5; SE = 81.4%; SP = 84.1%; PPV = 83.3%; NPV = 82.2%). When stratified considering the group with the least intense smile as a positive test, the test was positive in 42/43 PD cases versus 23/44 in the asymptomatic group (OR = 38.3; 95%CI = 4.8-303.7; SE = 97.7%; SP = 47.7%; PPV = 64.6%; NPV = 95.4%). Conclusion: The WSR test showed a good performance in identifying PD patients; it may complement the physical examination, and its result may be a useful finding during the assessment of a patient with PD.

Source: Arquivos de Neuro-Psiquiatria

DOI: 10.1055/s-0046-1829023

Authors: Mateus Damiani Monteiro, Eurípedes Gomes de Carvalho Neto, Liana Lisboa Fernandez, Arlete Hilbig, Carlos Roberto de Mello Rieder

Institution: Universidade Federal de Ciências da Saúde de Porto Alegre

Language: English

Topic: Parkinson's Disease Mechanisms and Treatments

Subfield: Clinical Neurology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $200