Automated Spontaneity Assessment after Smile Reanimation: A Machine Learning Approach

Dual versus Single Innervation of Gracilis Free Functional Muscle Transfer in Facial Paralysis: Long-Term Resting and Dynamic Outcomes

BACKGROUND

The purpose of this study was to compare long-term tone and excursion in single- versus dual-innervated free functional muscle transfer (FFMT) in patients with longstanding facial paralysis.

METHODS

Patients with longstanding facial palsy treated with an FFMT innervated either by a nerve-to-masseter graft (single-innervation group) or nerve-to-masseter and cross-facial-nerve grafts (dual-innervation group) were included. One-year minimum follow-up was required. Outcome measures, based on standardized photographs, included excursion, smile angle, teeth exposure, commissure height deviation, and upper lip height deviation in repose and in closed and open-teeth smile preoperatively and at 3 months, 1 year, and 3 years postoperatively. Emotrics software and ImageJ software were used to take measurements. Between-group and within-group longitudinal comparisons were analyzed.

RESULTS

At 3 years (single, n = 24; dual, n = 13), significance was found between groups in commissure position (single, 26.42 mm versus dual, 31.51 mm; P < 0.0001) and excursion with open-mouth smile (single, 31.32 mm versus dual, 26.59 mm; P < 0.001). Single-innervation FFMT within-group analysis lacked significant improvement in commissure height deviation and upper lip height deviation at 3 years in repose, whereas the dual-innervation group revealed significant improvements (3.67 mm [ P < 0.001], 3.17 mm [ P < 0.001], respectively). Teeth exposure revealed an increase in the dual-innervation group (single, 35.753 mm 2 versus dual, 64.177 mm 2 ), but significance was not observed.

CONCLUSION

Dual-innervated FFMT revealed improvements in resting tone and teeth exposure with minimal decrease in smile excursion compared with single-innervated FFMT.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Applications of artificial intelligence in facial plastic and reconstructive surgery: a systematic review

PURPOSE OF REVIEW

Arguably one of the most disruptive innovations in medicine of the past decade, artificial intelligence is dramatically changing how healthcare is practiced today. A systematic review of the most recent artificial intelligence advances in facial plastic surgery is presented for surgeons to stay abreast of the latest in our field.

RECENT FINDINGS

Artificial intelligence applications developed for use in perioperative patient evaluation and management, education, and research in facial plastic surgery are highlighted. Selected themes include automated facial analysis with landmark detection, automated facial palsy grading and emotional assessment, generation of artificial facial profiles for testing and model training, automated postoperative patient communications, and improving ethnicity-sensitive facial morphometry norms. Inherent bias can exist in artificial intelligence models, and care must be taken to utilize algorithms trained with diverse datasets.

SUMMARY

Artificial intelligence tools are helping clinicians provide more standardized, objective, and efficient care to their patients. Increasing surgeon awareness of available tools, and their widespread implementation into clinical workflows are the next frontier. Ethical considerations must also shape the adoption of any artificial intelligence functionality. As artificial intelligence applications become a fixture in medicine, surgeons must employ them effectively to stay at the vanguard of modern medicine.

Facial nerve reconstruction for flaccid facial paralysis: a systematic review and meta-analysis

Objectives

To determine the functional outcome after facial nerve reconstruction surgery in patients with flaccid facial paralysis.

Methods

A systematic review and meta-analysis was performed on studies reporting outcomes after direct facial nerve suture (DFS), facial nerve interpositional graft suture (FIGS), hypoglossal-facial nerve suture (HFS), masseteric-facial nerve suture (MFS), and cross-face nerve suture (CFS). These studies were identified from PubMed/MEDLINE, Embase, and Web of Science databases. Two independent reviewers performed two-stage screening and data extraction. A favorable result was defined as a final House-Brackmann grade I-III and is presented as a ratio of all patients in percentage. Pooled proportions were calculated using random-effects models.

Results

From 4,932 screened records, 54 studies with 1,358 patients were included. A favorable result was achieved after DFS in 42.67% of the patients [confidence interval (CI): 26.05%-61.12%], after FIGS in 66.43% (CI: 55.99%-75.47%), after HFS in 63.89% (95% CI: 54.83%-72.05%), after MFS in 63.11% (CI: 38.53%-82.37%), and after CFS in 46.67% (CI: 24.09%-70.70%). There was no statistically significant difference between the techniques (Q = 6.56, degrees of freedom = 4, p = 0.1611).

Conclusions

The established facial nerve reconstruction techniques including the single nerve cross-transfer techniques produce satisfactory results in most of the patients with permanent flaccid facial paralysis. An international consensus on standardized outcome measures would improve the comparability of facial reanimation techniques.

Functional Outcome of Dual Reinnervation with Cross-Facial Nerve Graft and Masseteric Nerve Transfer for Facial Paralysis

BACKGROUND

The combination of cross-facial nerve graft (CFNG) and masseteric nerve transfer (MNT) for reinnervation of facial paralysis may provide advantages of both neural sources. However, quantitative functional outcome reports with a larger number of patients are lacking in the literature. Here, the authors describe their 8-year experience with this surgical technique.

METHODS

Twenty patients who presented with complete facial paralysis (duration, <12 months) received dual reinnervation with CFNG and MNT. The functional outcome of the procedure was evaluated with the physician-graded outcome metric eFACE scale. The objective artificial intelligence-driven software Emotrics and FaceReader were used for oral commissure measurements and emotional expression assessment, respectively.

RESULTS

The mean follow-up was 31.75 ± 23.32 months. In the eFACE score, the nasolabial fold depth and oral commissure at rest improved significantly ( P < 0.05) toward a more balanced state after surgery. Postoperatively, there was a significant decrease in oral commissure asymmetry while smiling (from 19.22 ± 6.1 mm to 12.19 ± 7.52 mm). For emotional expression, the median intensity score of happiness, as measured by the FaceReader software, increased significantly while smiling (0.28; interquartile range, 0.13 to 0.64). In five patients (25%), a secondary static midface suspension with fascia lata strip had to be performed because of unsatisfactory resting symmetry. Older patients and patients with greater preoperative resting asymmetry were more likely to receive static midface suspension.

CONCLUSION

The authors' results suggest that the combination of MNT and CFNG for reinnervation of facial paralysis provides good voluntary motion and may lessen the use of static midface suspension in the majority of patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Restoring the spontaneous smile through free functional muscle transfer. A systematic review and meta-analysis of the last twenty years' experience

BACKGROUND

The recovery of the spontaneous smile has become a primary focus in facial reanimation surgery and its major determinant is the selected neurotizer. We aimed to compare the spontaneity outcomes of the most preferred neurotization methods in free functional muscle transfer for long-standing facial paralysis.

METHODS

The Embase, Ovid Medline, and PubMed databases were queried with 21 keywords. All clinical studies from the last 20 years reporting the postoperative spontaneity rate for specified neurotization strategies [cross-face nerve graft (CFNG), contralateral facial nerve (CLFN), motor nerve to the masseter (MNM), and dual innervation (DI)] were included. A meta-analysis of prevalence was performed using Freeman-Tukey double arcsine transformation, I2 statistic, and generic inverse variance with a random-effects model. Risk Of Bias In Non-randomized Studies of Interventions and Newcastle-Ottawa scale were used to assess bias and study quality.

RESULTS

The literature search produced 2613 results and 473 unique citations for facial reanimation. Twenty-nine studies including 2046 patients were included in the systematic review. A meta-analysis of eligible data (1952 observations from 23 studies) showed statistically significant differences between the groups (CFNG: 0.94; 95% confidence interval [CI], 0.76-1.00, CLFN: 0.91; 95% CI, 0.49-1.00, MNM: 0.26; 95% CI, 0.05-0.54, DI: 0.98; 95% CI, 0.90-1.00, P < 0.001). In pairwise comparisons, statistically significant differences were found between MNM and other neurotization strategies (P < 0.001 in CFNG compared with MNM, P = 0.013 for CLFN compared with MNM, P < 0.001 for DI compared with MNM).

CONCLUSIONS

DI- and CLFN-driven strategies achieved the most promising outcomes, whereas MNM showed the potential to elicit spontaneous smile at a lower extent. Our meta-analysis was limited primarily by incongruency between spontaneity assessment systems. Consensus on a standardized tool would enable more effective comparisons of the outcomes.

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.

Evidence-Based Medicine: Facial Reanimation

This article provides a brief historical overview of the assessment instruments that have been developed to categorize the severity of disease in patients with facial palsy. Important advances in the quality of these instruments are discussed. The modern-day instruments that are commonly required for evidence-based patient assessment are then presented, with emphasis on the level of evidence of the studies that describe these instruments.

The evolution of facial reanimation techniques

This review article provides an updated discussion on evidence-based practices related to the evaluation and management of facial paralysis. Ultimately, the goals of facial reanimation include obtaining facial symmetry at rest, providing corneal protection, restoring smile symmetry and facial movement for functional and aesthetic purposes. The treatment of facial nerve injury is highly individualized, especially given the wide heterogeneity regarding the degree of initial neuronal insult and eventual functional outcome. Recent advancements in facial reanimation techniques have better equipped clinicians to approach challenging patient scenarios with reliable, effective strategies. We discuss how technology such as machine learning software has revolutionized pre- and post-intervention assessments and provide an overview of current controversies including timing of intervention, choice of donor nerve, and management of nonflaccid facial palsy with synkinesis. We highlight novel considerations to mainstay conservative management strategies and examine innovations in modern surgical techniques with a focus on gracilis free muscle transfer. Innervation sources, procedural staging, coaptation patterns, and multi-vector and multi-muscle paddle design are modifications that have significantly evolved over the past decade.

The Facial Graft: A Graft of Emotions? (About the Reanimation of the Facial Allotransplantation)

Although there have been numerous scientific papers reporting on composite allotransplantation of the face, few have been about assessment and evolution of the functional benefit for patients in terms of soft tissue mobility, movement coordination, and face expressions, even fewer on the choice of the surgical procedures to restore motricity. On some videos and interviews, it is possible to analyze significative motricity. Of course that has been voluntary motricity, not emotional motricity. The data confirmed that the result on the complexity of the expression of the face is not great, providing opportunity to reflect on the question of nerve regeneration.