The Dilator Naris Muscle as a Reporter of Facial Nerve Regeneration in a Rat Model.

OBJECTIVE: Many investigators study facial nerve regeneration using the rat whisker pad model, although widely standardized outcomes measures of facial nerve regeneration in the rodent have not yet been developed. The intrinsic whisker pad "sling" muscles producing whisker protraction, situated at the base of each individual whisker, are extremely small and difficult to study en bloc. Here, we compare the functional innervation of 2 potential reporter muscles for whisker pad innervation: the dilator naris (DN) and the levator labii superioris (LLS), to characterize facial nerve regeneration. METHODS: Motor supply of the DN and LLS was elucidated by measuring contraction force and compound muscle action potentials during stimulation of individual facial nerve branches, and by measuring whisking amplitude before and after DN distal tendon release. RESULTS: The pattern of DN innervation matched that of the intrinsic whisker pad musculature (ie, via the buccal and marginal mandibular branches of the facial nerve), whereas the LLS seemed to be innervated almost entirely by the zygomatic branch, whose primary target is the orbicularis oculi muscle. CONCLUSIONS: Although the LLS has been commonly used as a reporter muscle of whisker pad innervation, the present data show that its innervation pattern does not overlap substantially with the muscles producing whisker protraction. The DN muscle may serve as a more appropriate reporter for whisker pad innervation because it is innervated by the same facial nerve branches as the intrinsic whisker pad musculature, making structure/function correlations more accurate, and more relevant to investigators studying facial nerve regeneration.

Lower Facial Nerve Nomenclature Clarification: Cervical Branch Controls Smile-Associated Lower Lip Depression and Dental Display.

OBJECTIVE: In head and neck ablative surgery, traditional teaching is that the key facial nerve branch to preserve along the plane of the lower border of the mandible is the marginal mandibular branch (MMb), which is considered to control all lower lip musculature. The depressor labii inferioris (DLI) is the muscle responsible for pleasing lower lip displacement and lower dental display during natural emotive smiling. STUDY DESIGN: To understand the structure/function relationships of the distal lower facial nerve branches and lower lip musculature. SETTING: In vivo extensive facial nerve dissections under general anesthesia. METHODS: Intraoperative mapping was performed in 60 cases, using branch stimulation and simultaneous movement videography. RESULTS: In nearly all cases, the MMb innervated the depressor anguli oris, lower orbicularis oris, and mentalis muscles. The nerve branches controlling DLI function were identified 2 ± 0.5 cm below the angle of the mandible, originating from a cervical branch, separately and inferior to MMb. In half of the cases, we identified at least 2 independent branches activating the DLI, both within the cervical region. CONCLUSION: An appreciation of this anatomical finding may help prevent lower lip weakness following neck surgery. Avoiding the functional and cosmetic consequences that accompany loss of DLI function would have a significant impact on the burden of potentially preventable sequelae that the head and neck surgical patient frequently carries.

Releasing the Smile: Depressor Anguli Oris Excision in the Context of Managing Nonflaccid Facial Palsy.

BACKGROUND: Nonflaccid facial palsy is a debilitating entity characterized by hypertonicity, synkinesis, and hypomobility. Patients with nonflaccid facial palsy often have smile asymmetry and restriction because of disruption of normal vector forces on the modiolus. Excision of the depressor anguli oris can lead to improved oral commissure excursion, smile angle, dental show, and symmetry. METHODS: All depressor anguli oris resection cases between January 8, 2018, and December 26, 2019, were reviewed. Patients with postoperative photographs were included in this cohort study. Preoperative and postoperative photographs were analyzed using the Emotrics software program, and changes in oral commissure excursion, smile angle, and dental show were tracked. Clinician-graded facial palsy assessments and patient-reported outcome measures were compared preoperatively and postoperatively using the Electronic Facial Paralysis Assessment and Facial Clinimetric Evaluation Scale, respectively. RESULTS: Forty-three patients were included in this study; 79 percent of patients underwent isolated depressor anguli oris resection. Depressor anguli oris resection led to a statistically significant increase in oral commissure median excursion, smile angle, and dental show [3.02 mm (p = 0.015), 1.70 degrees (p = 0.002), and 2.36 mm (p < 0.001), respectively]. Median Electronic Facial Paralysis Assessment and Facial Clinimetric Evaluation Scale instrument scores also improved [6.0 (p = 0.001) and 7.5 (p = 0.013), respectively]. Depressor anguli oris resection also led to more symmetric smiles. No correlation was seen between duration of follow-up and change in metrics. CONCLUSION: Depressor anguli oris resection is a minimal-risk procedure that frequently results in improved smile dynamics, smile symmetry, and quality of life in patients with nonflaccid facial palsy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Deep Dive into Denervation: Institutional Experience with Selective Denervation in Nonflaccid Facial Palsy.

Background: Selective denervation of facial nerve branches ("Modified Selective Neurectomy") improves smile dynamics in patients with nonflaccid facial palsy, but functional morbidity such as oral incompetence has been reported. A comprehensive outcomes assessment of selective denervation will help clinicians educate patients regarding risks and benefits, and improve decision making as they incorporate this procedure into treatment algorithms. Methods: Retrospective review identified selective denervation cases performed by the senior author between February 2019 and February 2020. Pre- and postoperative outcomes were assessed using chart review, the facial clinimetric evaluation (FaCE), the electronic clinician-graded facial function tool (eFACE), and an automated computer-aided facial assessment tool (Emotrics). Results: Twenty consecutive selective denervation procedures were performed in 19 patients. Review of patient-reported outcome measures demonstrated mixed results. Favorably, patients reported smile improvement (13/17, 76.5%) and improvements in facial tightness/discomfort (8/17, 47.1%). Seven patients (41.2%) had worse drooling and five patients (29.4%) had increased difficulty chewing after surgery. Clinician-graded evaluation revealed statistically significant improvements in nasolabial fold depth at rest, oral commissure (OC) position at rest, and OC movement with smile. Total, static, and dynamic eFACE scores all demonstrated significant improvements. Computer-aided facial assessment revealed a significant increase in dental display, and an increase in OC excursion that trended toward significance. Conclusions: Selective denervation improves patient-reported, clinician-graded, and automated smile metrics, but some patients experience exacerbations in oral incompetence and articulation difficulties, and must be counseled regarding these possibilities.

Polytetrafluoroethylene granuloma-associated facial palsy following microvascular decompression.

OBJECTIVE: Microvascular decompression (MVD) may be employed in the management of hemifacial spasm (HFS), wherein a pledget of polytetrafluoroethylene (i.e., Teflon, Chemours, Wilmington DE) is sometimes introduced to separate an offending vessel from the cisternal segment of facial nerve. Rarely, Teflon may cause a granulomatous reaction resulting in nerve palsy. We here present the first case series of facial palsy thought to be secondary to Teflon granuloma following MVD for HFS. METHODS: A data repository of 1,312 patients with facial palsy was reviewed to identify individuals who had previously undergone MVD for HFS. Data collected include age at time of MVD, age at onset of facial weakness and at presentation, House-Brackmann scores, clinician-graded facial function using the Electronic Facial Paralysis Assessment scale, imaging findings, and therapeutic interventions and outcomes. RESULTS: Six patients meeting criteria were identified. Average time between MVD with Teflon placement and onset of facial weakness was 16.1 (±4.9) years (range 9.3-23.3 years). Initial House-Brackmann scores were as follows: four patients with V/VI and one each with III/VI and IV/VI. Interventions included eyelid weight placement (n = 3), chemodenervation (n = 2), static suspension with tensor fascia latae (n = 2), dynamic reanimation with cranial nerves V to VII transfer (n = 1), and temporalis muscle transfer (n = 1). CONCLUSION: Teflon granuloma should be considered in the differential diagnosis for patients presenting with new onset facial weakness with a previous history of MVD for HFS. It remains unknown whether early granuloma extirpation is effective. Prompt diagnosis allows consideration of time-sensitive nerve transfer procedures to reanimate facial function. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:1422-1427, 2020.

Bilateral simultaneous free gracilis muscle transfer: a realistic option in management of bilateral facial paralysis.

OBJECTIVES: Bilateral facial paralysis patients have oral incompetence, poor articulation, and dental caries. This problem is frequently addressed by performing staged gracilis transplants without specific oral sphincter reconstruction. The purpose of this study is to describe the technique of bilateral simultaneous free gracilis muscle transfer with oral sphincter reconstruction, for one-stage facial reanimation in patients with bilateral facial paralysis. STUDY DESIGN: Case series. METHODS/RESULTS: One-stage bilateral gracilis transfer was performed in three patients with bilateral facial paralysis. Muscle transplants produced a meaningful smile in all transferred muscles. All patients reported improved speech and decreased drooling. CONCLUSIONS: Bilateral gracilis transplants with reconstruction of the oral commissure is a realistic option in management of the bilaterally paralyzed face. In this small series, it appears to improve oral competence, restore smiling, and contribute favorably to lower lip support. This technique has been made more feasible because the operative time for free tissue transfer has continuously declined with the use of two-team surgery, improved microsurgical techniques, and the advent of venous coupling devices.

Facial mimetic, cosmetic, and functional standardized assessment of the facial artery musculomucosal (FAMM) flap.

OBJECTIVE: To objectively assess donor site morbidity after harvesting the facial artery musculomucosal flap. Use of the FAMM-flap in oral cavity reconstruction remains sporadic. This case series describes our newly developed standardized assessment of this flap in a floor of mouth (FOM) reconstructive setting. METHODS: Standardized postoperative assessment of the FAMM flap for donor site wound complications, functional, facial mimetic and oncologic outcomes. RESULTS: There were no wound complications. Oral competence remained intact, tongue mobility was good to excellent, average word articulation score was 98%, and mimetic function excellent in all patients. Three patients experienced ipsilateral upper lip anesthesia, and five patients were noted to have slight dysfunction of the orbicularis oris resulting in a loss of lip height at rest. CONCLUSION: The FAMM flap is a reliable option for reconstruction of ablative defects of the FOM, and should be considered a workhorse flap for oral cavity defects. Unlike the submental island flap, a complete level I dissection may be concurrently performed without compromising the vascular supply to the FAMM flap.

Photographic Standards for Patients With Facial Palsy and Recommendations by Members of the Sir Charles Bell Society.

IMPORTANCE: There is no widely accepted assessment tool or common language used by clinicians caring for patients with facial palsy, making exchange of information challenging. Standardized photography may represent such a language and is imperative for precise exchange of information and comparison of outcomes in this special patient population. OBJECTIVES: To review the literature to evaluate the use of facial photography in the management of patients with facial palsy and to examine the use of photography in documenting facial nerve function among members of the Sir Charles Bell Society-a group of medical professionals dedicated to care of patients with facial palsy. DESIGN, SETTING, AND PARTICIPANTS: A literature search was performed to review photographic standards in patients with facial palsy. In addition, a cross-sectional survey of members of the Sir Charles Bell Society was conducted to examine use of medical photography in documenting facial nerve function. The literature search and analysis was performed in August and September 2015, and the survey was conducted in August and September 2013. MAIN OUTCOMES AND MEASURES: The literature review searched EMBASE, CINAHL, and MEDLINE databases from inception of each database through September 2015. Additional studies were identified by scanning references from relevant studies. Only English-language articles were eligible for inclusion. Articles that discussed patients with facial palsy and outlined photographic guidelines for this patient population were included in the study. The survey was disseminated to the Sir Charles Bell Society members in electronic form. It consisted of 10 questions related to facial grading scales, patient-reported outcome measures, other psychological assessment tools, and photographic and videographic recordings. RESULTS: In total, 393 articles were identified in the literature search, 7 of which fit the inclusion criteria. Six of the 7 articles discussed or proposed views specific to patients with facial palsy. However, none of the articles specifically focused on photographic standards for the population with facial palsy. Eighty-three of 151 members (55%) of the Sir Charles Bell Society responded to the survey. All survey respondents used photographic documentation, but there was variability in which facial expressions were used. Eighty-two percent (68 of 83) used some form of videography. From these data, we propose a set of minimum photographic standards for patients with facial palsy, including the following 10 static views: at rest or repose, small closed-mouth smile, large smile showing teeth, elevation of eyebrows, closure of eyes gently, closure of eyes tightly, puckering of lips, showing bottom teeth, snarling or wrinkling of the nose, and nasal base view. CONCLUSIONS AND RELEVANCE: There is no consensus on photographic standardization to report outcomes for patients with facial palsy. Minimum photographic standards for facial paralysis publications are proposed. Videography of the dynamic movements of these views should also be recorded. LEVEL OF EVIDENCE: NA.

Facial palsy after dental procedures - Is viral reactivation responsible?

OBJECTIVES: Herpes labialis viral reactivation has been reported following dental procedures, but the incidence, characteristics and outcomes of delayed peripheral facial nerve palsy following dental work is poorly understood. Herein we describe the unique features of delayed facial paresis following dental procedures. MATERIALS AND METHODS: An institutional retrospective review was performed to identify patients diagnosed with delayed facial nerve palsy within 30 days of dental manipulation. Demographics, prodromal signs and symptoms, initial medical treatment and outcomes were assessed. RESULTS: Of 2471 patients with facial palsy, 16 (0.7%) had delayed facial paresis following ipsilateral dental procedures. Average age at presentation was 44 yrs and 56% (9/16) were female. Clinical evaluation was consistent with Bell's palsy in 14 (88%) and Ramsay-Hunt syndrome in 2 patients (12%). Patients developed facial paresis an average of 3.9 days after the dental procedure, with all individuals developing a flaccid paralysis (House Brackmann (HB) grade VI) during the acute stage. 50% of patients developed persistent facial palsy in the form of non-flaccid facial paralysis (HBIII-IV). CONCLUSION: Facial palsy, like herpes labialis, can occur in the days following dental procedures and may also be related to viral reactivation. In this small cohort, long-term facial outcomes appear worse than for spontaneous Bell's palsy.

Biocompatibility analysis of poly(glycerol sebacate) as a nerve guide material.

No satisfactory method currently exists for bridging neural defects. Autografts lead to inadequate functional recovery, and most available artificial neural conduits possess unfavorable swelling and pro-inflammatory characteristics. This study examined the biocompatibility of a novel biodegradable elastomer, poly(glycerol sebacate) (PGS), for neural reconstruction applications, as the material possesses favorable mechanical property and degradation characteristics. The effect of PGS on Schwann cell metabolic activity, attachment, proliferation, and apoptosis were examined in vitro in comparison with poly(lactide-co-glycolide) (PLGA), a biomaterial widely utilized for tissue engineering applications. The in vivo tissue response to PGS was compared with PLGA implanted juxtaposed to the sciatic nerve; the physical changes in the implant material were measured during the degradation process. PGS had no deleterious effect on Schwann cell metabolic activity, attachment, or proliferation, and did not induce apoptosis; the in vitro effects of PGS were similar to or superior to that of PLGA. In vivo, PGS demonstrated a favorable tissue response profile compared with PLGA, with significantly less inflammation and fibrosis and without detectable swelling during degradation. PGS is an excellent candidate material for neural reconstruction applications given its lack of in vitro Schwann cell toxicity and minimal in vivo tissue response.

Biologic activity of nerve growth factor slowly released from microspheres.

Efficient and sustained delivery of neurotrophic factors to the regenerating nerve in biologically active form presents a challenge. Protein delivery in biodegradable microsphere vehicles has been difficult, based on destabilization and breakdown during both the loading and release phases. This study examines the extravasation and stability of Nerve Growth Factor (NGF) in polylactic-co-glycolic acid (PLGA) microspheres, via both ELISA and PC-12 bioassays. PLGA microspheres co-loaded with bovine serum albumin (BSA) and NGF were prepared by a water-in-oil-in-water (W/O/W) technique, using chloroform for the organic phase and 1 percent polyvinyl alcohol (PVA) for the emulsion step. Aliquots of lyophilized microspheres were incubated in double distilled water (dd H2O) at 37 degrees C, and the supernatants assayed over time for NGF activity. ELISA was utilized for quantitative determination of NGF concentration, and a PC-12 cell neurite outgrowth assay assessed biologic activity. Both ELISA and PC-12 assays demonstrated the extravasation of NGF from microspheres. Over time, the predicted concentration of NGF via the two assays differed, suggesting possible preservation of recognizable epitopes for ELISA, but loss of biologic activity. NGF can be stored and released from microspheres. Extravasation studies should include biologically relevant assays for activity.