Three-dimensional objective evaluation of facial palsy and follow-up of recovery with a handheld scanner

Correlation of 3D Morphometric Changes, Kinematics, and Muscle Activity During Smile

OBJECTIVE

Knowing the morphological, kinematic, and electrophysiological parameters of the smile in healthy individuals may contribute to evaluating, planning, and monitoring the smile reanimation. This study aimed to determine the correlation between 3D morphometric changes, movement kinematics, and muscle activity in the facial soft tissue of healthy individuals.

METHOD

In this cohort study, 20 volunteers were selected from healthy individuals with no facial disorders. During smiling, three-dimensional face scanning, facial motion capture, and surface electromyography (sEMG) were performed. The average displacement, velocity, and acceleration during facial movements were measured. The mean change in 3D surface morphometry and activation of the zygomaticus major were determined.

RESULTS

The volunteers, comprising 10 males and 10 females, had a mean age of 24 ± 10 years; for female, mean age was 23 ± 5 years and for men 26 ± 13 years. Significant correlations were found between kinematic and morphometric data (r = 0.51, p < 0.001), sEMG and morphometric (r = 0.50, p < 0.001) data, and sEMG and kinematic data (r = 0.49, p < 0.002). The maximum acceleration occurred during approximately 65% of the muscle activation time and 64% of the peak muscle activation value. Additionally, the maximum velocity was reached at around 73% of the muscle activation time and 67% of the peak muscle activation value. Furthermore, the maximum displacement values were observed at approximately 88% of the muscle activation time and 76% of the peak muscle activation value.

CONCLUSION

The findings may provide insights into the smile's functional parameters, contribute to understanding facial muscle-related disorders, and aid in improving the diagnosis and treatment of the smile.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:3112-3119, 2024.

Validation of the Spanish version of the Electronic Facial Palsy Assessment (eFACE)

PURPOSE

The clinician-graded electronic facial paralysis assessment (eFACE) is a relatively new digital tool for assessing facial palsy. The present study aimed to determine the validity and reliability of the Spanish version of the eFACE.

METHODS

Forward-backward translation from the original English version was performed. Videos and photographs from 65 adult patients with unilateral facial paralysis (any severity, time course, and etiology) were evaluated twice by five otolaryngologists with varying levels of experience in facial palsy evaluation. Internal consistency was measured using Cronbach's α and the intra- and inter-rater reliability were measured using intraclass correlation coefficient. Concurrent validity was established by calculating Spearman's rho correlation (ρ) between the eFACE and the House-Brackmann scale (H-B) and Pearson's correlation (r) between the eFACE and the Sunnybrook Facial Grading System (SFGS).

RESULTS

The Spanish version of the eFACE showed good internal consistency (Cronbach's α > 0.8). The intra-rater reliability was nearly perfect for the total score (intraclass correlation coefficient: 0.95-0.99), static score (0.92-0.96), and dynamic score (0.96-0.99) and important-to-excellent for synkinesis score (0.79-0.96). The inter-rater reliability was excellent for the total score (0.85-0.93), static score (0.80-0.90), and dynamic score (0.90-0.95) and moderate-to-important for the synkinesis score (0.55-0.78). The eFACE had a very strong correlation with the H-B (ρ =  - 0.88 and  - 0.85 for each evaluation, p < 0.001) and the SFGS (r = 0.92 and 0.91 each evaluation, p < 0.001).

CONCLUSION

The Spanish version of the eFACE is a reliable and valid instrument for assessment of facial function in the diagnosis and treatment of patients with facial paralysis.

Three-dimensional evaluation of symmetry in facial palsy reanimation using stereophotogrammetric devices: A series of 15 cases

Facial palsy can severely compromise quality of life, significantly altering the harmony and symmetry of the face, which can be restored by surgical rehabilitation. The aim of the study was the quantification of facial symmetry following facial reanimation. Fifteen consecutive adult patients were surgically treated through triple innervation for reanimation of flaccid unilateral facial paralysis (contralateral facial nerve, masseteric nerve, and hypoglossal nerve) and fascia lata graft for definition of the nasolabial sulcus. In the preoperative stage and at least 11 months after the surgical treatment, three-dimensional facial images were recorded through stereophotogrammetry in a neutral (rest) position, and with Mona Lisa and full-denture (maximum) smiles. Labial commissure inclination relative to the interpupillary axis, and a surface assessment of local facial asymmetry at rest and while smiling were obtained for the upper, middle, and lower facial thirds. The angle between the interpupillary axis and the labial commissure significantly improved in post-surgical acquisitions, regaining symmetry at rest (t-test; p < 0.001). Facial symmetry increased significantly when passing from pre-to postsurgical facial scans, from the lower to the upper facial third, and from the full smile to the rest position (ANOVA; p < 0.001). After treatment, the full smile recovered more symmetry than the other two expressions. In summary, surgical treatment significantly reduced facial asymmetry, but this reduction differed significantly among the various animations and facial thirds. The results of this study confirmed clinical findings of significant static and dynamic improvements in facial symmetry after triple innervation reanimation surgery.

The Emerging Role of Artificial Intelligence Tools for Outcome Measurement in Facial Reanimation Surgery: A Review

Importance: Surgeons treating facial paralysis with reanimation surgery measure the outcomes of surgery and adjust treatment to each patient's needs. Our objective is to review the current subjective facial paralysis assessment tools and the emerging computer-based objective analysis, which may involve artificial intelligence. Observations: In recent years, many new automated approaches to outcome measurement in facial reanimation surgery have been developed. Most of these tools utilize artificial intelligence to analyze emotional expression and symmetry of facial landmarks. Other tools have provided automated approaches to existing clinician-guided scales. Conclusions: Newly developed computer-based tools using artificial intelligence have been developed to both improve existing clinician-graded scales and provide new approaches to facial symmetry and emotional expressivity analysis.

Identification of Stable Anatomical Landmarks During Facial Expressions

Background: Identifying stable anatomical landmarks during facial expressions is necessary to register and align three-dimensional (3D) data, determine the common origin and motion axis, and calculate displacement, velocity, and acceleration of relative motion. Objective: Our study aimed to determine the stable anatomical landmarks during facial expressions. Methods: We included 30 volunteers in our study and asked them to perform resting, mouth opening, showing teeth, clenching teeth, eye closure, smiling, whistling, eyebrow raising, and disgusted facial expressions. We recorded the 3D movements of passive reflective markers with optoelectronic cameras, which we attached to 10 bilateral and 8 midline landmarks. Results: We determined that the inner corner of the eye while mouth opening, the hairline superior while showing teeth, the infraorbital rim while clenching teeth, the alare while eye closure, the inner corner of the eye while smiling, the mideyebrow while whistling, corners of the mouth while eyebrow raising, and hairline superior while disgust are the most stable anatomical landmarks. Conclusions: Our study identified immobile soft tissue landmarks specific to facial expression.