Objective: The purpose of this study was therefore to develop a fully automatic video-based hypomimia assessment tool and estimate the prevalence and characteristics of hypomimia facial bradykinesia in de-novo Parkinson’s disease (PD). The relationships between hypomimia features and dopamine transporter imaging markers were also surveyed.

Background: Even though, the facial bradykinesia, also termed hypomimia, is the hallmark of PD [1], automatic objective tools to evaluate the disruption of spontaneous and emotional moves are lacking. The current advances in image processing and facial landmark detection technology enable for fast and objective analysis of facial movements.

Method: One-minute video recordings of freely spoken monologues provided by 91 newly diagnosed, untreated PD (61.0 ± 12.3 years old, 54 men) and 75 age- and gender-matched healthy control (60.8 ± 8.8 years old, 45 men) participants were analysed by an automatic algorithm detecting 68 facial landmarks [2] describing the dynamic of eight different facial regions including forehead, nose root, eyebrows, eyes, lateral canthal areas, cheeks, mouth, and jaw. Based on these landmarks, the analysis of facial geometry and movement was performed, yielding 12 features. The extent of hypomimia from simultaneous video recordings was also rated by speech-language pathologist expert in movement disorders.

Results: The discrimination between PD and healthy controls was achieved with area under the curve of 0.87. The prevalence of hypomimia in de-novo PD was 57%, mainly related to dysfunction of mouth and jaw movements, and decreased variability in forehead and nose root wrinkles (p < 0.001). The strongest correlation was observed between reduction of lower lip movements and nigro-putaminal dopaminergic loss (r = 0.32, p = 0.002). In addition, the correlation analysis also revealed significant relationships between expert rating and all the significantly altered features revealed by automated video-based method (r = -0.54, p < 0.001).

Conclusion: Hypomimia represents a frequent, early marker of motor impairment in PD that can be robustly automatically captured and described by the current image processing technology. Our results also confirmed the critical role of striatal dopaminergic deficit in development of hypomimia in PD. This study was supported by the Ministry of Health of the Czech Republic, grant nr. NV19-04-00120.

References: [1] Bologna M, Fabbrini G, Marsili L, Defazio G, Thompson PD, Berardelli A. Facial bradykinesia. J Neurol Neurosurg Psychiatry. 2013;84(6):681‐5.
[2] Nirkin Y, Masi I, Tran AT, Hassner T, Medioni G. On Face Segmentation, Face Swapping, and Face Perception, arXiv preprint arXiv:1704.06729, 22 Apr 2017.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/automated-quantification-of-facial-bradykinesia-through-video-in-de-novo-parkinsons-disease/