Die Augen sagen alles! - Die motorische Verbesserung und Impulsivität nach STN-THS bei Parkinson-Syndrom kann anhand der Aktivität von periokulären Gesichtsmuskeln bestimmt werden

We observed changes in lid fissure width related to motor improvement and impulsivity in patients after deep brain stimulation (DBS) in the subthalamic nucleus (STN) for Parkinson's disease in clinical practice. Here we aim to analyze whether this phenomenon can be corroborated by analyzing the activity of Action Units (AU) of the face.

12 patients who received STN-DBS at our department and gave their informed consent were included. Each patient was examined at least twice in the timespan of a few days prior to surgery, to a year after surgery. Participants were filmed during an emotional imagination task with randomized topics of positive, neutral and negative valence (10 of each) in medication OFF state and at follow-ups ≥ 3 months postoperatively in stimulation ON, medication OFF state.
The activity of facial AUs as defined by Ekman et al. (2002) was extracted with the FaceReader 9 software (Noldus Information Technology bv., Wageningen, The Netherlands) (Fig. 1).
We analyzed how activity of AUs surrounding the eyes correlated with simultaneously collected scores for the motor part of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS III), Self-Report Manic Inventory (SRMI) and the Barratt Impulsiveness Scale (BIS-11).

We found a significant correlation (p = 0.002) between the alleviation of motor symptoms (i.e. reduced UPDRS III scores) and the activity of the upper lid raiser muscle (Fig. 2A).
Furthermore, we found significant associations of the SRMI score with the activity of the inner brow raiser muscle (p = 0.025) and the BIS-11 attentional subscore with the brow lowerer muscle (p = 0.0002) (Fig. 2B+C).

We found that specifically the activity of AUs surrounding the eyes were indicative of motor status and measures of impulsivity and might therefore serve as suitable markers that could be analyzed during intraoperative test stimulation and DBS programming.

References: Ekman P. and W. V. Friesen (1978). Facial Action Coding System: A Technique for the Measurement of Facial Movement. Consulting Psychologists Press, Palo Alto.