The synkinetic mentalis muscle and its negative effect on the smile: pathomechanism and treatment with mentalis targeted selective neurectomies.

BACKGROUND: The treatment of post-paretic facial synkinesis is based on a combination of nonsurgical and surgical strategies. Even if improvements towards the restoration of a natural smile have been obtained with selective neurectomies (SN) and depressor anguli oris (DAO) myectomy, the lower lip frequently remains asymmetric and cranially displaced. The aim of this study was to evaluate the effect of the mentalis muscle on the position and symmetry of the lower lip in patients with synkinesis and to assess the added benefit of neurectomies of nerves innervating the mentalis muscle in improving the lower lip configuration and mandibular teeth show. METHODS: A retrospective cohort study on all patients affected by post-paretic synkinesis at our Institution was performed. A Non-mentalis Neurectomy Group including twelve patients treated with SN without targeting the branches to mentalis muscle was compared to a Mentalis Neurectomy Group, including sixteen patients who underwent additional specific mentalis branches neurectomies. All patients underwent DAO myectomy. Analyses of standardized images were performed with ImageJ software. RESULTS: Post-operative comparisons between the two groups showed superior and significant improvements in the Mentalis Neurectomy Group across all measures, including lower and upper border deviation (p=0.035 and p=.004, respectively), inclination of the lower lip (p=.019), and lower quadrant dental show (p=.004). CONCLUSIONS: The addition of targeted selective neurectomies to the branches innervating mentalis muscle significantly improved dental show and caudal position and symmetry of the lower lip during open mouth smile.

Effect of Lower Extremity Nerve Decompression in Patients with Painful Diabetic Peripheral Neuropathy: The DNND Randomized, Observation Group- and Placebo Surgery-controlled Clinical Trial.

OBJECTIVE: Evaluate the effect of nerve decompression on pain in patients with lower extremity painful Diabetic Peripheral Neuropathy (DPN). SUMMARY BACKGROUND DATA: Currently, no treatment provides lasting relief for patients with DPN. Benefits of nerve decompression remain inconclusive. METHODS: This double-blinded, observation- and same-patient sham surgery-controlled randomized trial enrolled patients aged 18-80 years with lower extremity painful DPN who failed one-year of medical treatment. Patients were randomized to nerve decompression- or observation-group (2:1). Decompression-group patients were further randomized and blinded to nerve decompression in either right or left leg and sham surgery in the opposite leg. Pain (11-point Likert score) was compared between decompression and observation groups and between decompressed versus sham legs at 12 and 56 months. RESULTS: Of 2987 screened patients, 78 were randomized. At 12 months, compared with controls (n=37), both right-decompression-group (n=22) and left-decompression-group (n=18) reported lower pain (mean difference for both, -4.46; [95% CI, -6.34 to -2.58 and -6.48 to -2.45 respectively]; P<0.0001). Decompressed and sham legs equally improved. At 56 months, compared with controls (n=14), pain was lower in both the right-decompression-group (n=20) (mean difference, -7.65; [95% CI, -9.87 to -5.44]; P<0.0001) and left-decompression-group (n=16) (mean difference, -7.26; [95% CI, -9.60 to -4.91]; P<0.0001). Mean pain score was lower in decompressed versus sham legs (mean difference, 1.57 [95% CI, 0.46 to 2.67]; P=0.0002). CONCLUSION: Although nerve decompression was associated with reduced pain, the benefit of surgical decompression needs further investigation since a placebo effect may be responsible for part or all of these effects.

Polyetheretherketone Implant Cranioplasty for Large Cranial Defects: A Seven-Year Follow-Up.

BACKGROUND: Goals of a cranioplasty include protection of the brain, restoration of normal appearance, and neurological function improvement. Although choice of materials for cranial remodeling has changed through the years, computer-designed polyetheretherketone (PEEK) implant has gained traction as a preferred material used for cranioplasty. However, long-term outcomes and complications of PEEK implants remain limited. The goal of this study was to report long-term clinical outcomes after PEEK implant cranioplasty. METHODS: A retrospective chart review was performed on patients undergoing PEEK cranioplasty between January 2007 and February 2023. Preoperative, intraoperative, and postoperative data were collected and analyzed. RESULTS: Twenty-two patients were included in this study. Mean postoperative follow-up time was 83.45 months (range: 35.47-173.87). Before PEEK implant cranioplasty, patients with multiple cranial procedures had undergone a mean of 2.95 procedures. PEEK implant cranioplasty indications were prior implant infection (14) and secondary reconstruction of cranial defect (8). The mean implant size was 180.43 cm2 (range: 68.00-333.06). Four patients received a 2-piece implant. Postoperative complications included: perioperative subgaleal self-resolving fluid collection in 1 patient, hematoma in another, and 3 infections resulting in explantations with successful reinsertion in 2 patients. Four of 5 patients with preoperative history of seizures reported improved seizures and all 4 patients with preoperative syndrome of the trephined reported improved symptoms and neurological function. CONCLUSION: At a mean follow-up of 7 years, most PEEK implants continued to provide protection to the brain and consistent symptom relief in patients suffering from prior postcraniectomy/craniotomy sequelae of seizures and syndrome of the trephined.

Post-Paretic Synkinesis: Objective & Subjective Comparisons of Depressor Anguli Oris (DAO) Myectomies vs DAO & Buccinator Myectomies.

BACKGROUND: Muscles affected by post-paretic synkinesis have imbalanced tonicity that limit peri-oral mimetic movement and inhibit the ability to smile. The depressor anguli oris (DAO) muscle has been a common myectomy target for the treatment of peri-oral synkinesis. While addition of buccinator myectomies to DAO myectomies has risen, no studies have analyzed the effects of buccinator myectomies. The goal of this study was to evaluate and compare the effects of a DAO myectomy with and without concomitant buccinator myectomy through objective facial metrics and subjective patient reported outcomes. METHODS: This study is a retrospective review of patients with post-paretic synkinesis who underwent DAO myectomy (DAO myectomy group) or DAO myectomy with buccinator myectomy (DAO+Buccinator myectomies group). Outcomes included post-operative differences in objective smile measures (smile angle, excursion, and dental show) using validated software, and patient reported outcomes using the Facial Disability Index (FDI) questionnaire and a myectomy-specific questionnaire. RESULTS: After chart review, 18 patients were included in the DAO myectomy group and 19 in the DAO+Buccinator myectomies group. There were no significant post-operative differences between the groups in 1. smile excursion, angle, or dental show at resting, closed smile, or open smile (p>.05), 2. FDI physical and social scores, p=.198 and p=.932, respectively, or 3. myectomy-specific questionnaire responses (p>.05). CONCLUSION: The addition of a buccinator myectomy to a DAO myectomy does not provide significant clinical benefit when compared with an isolated DAO myectomy, based on objective measures and subjective patient reported outcomes.

Dual-Innervated Gracilis Free Functional Muscle Transfers in Facial Palsy Patients: Comparing Long-Term Outcomes between One- versus Two-Stage Procedures.

BACKGROUND: In facial reanimation, dual-innervated gracilis free functional muscle transfers (FFMTs) may have amalgamated increases in tone, excursion, synchroneity, and potentially spontaneity when compared with single innervation. The ideal staging of dual-innervated gracilis FFMTs has not been investigated. We aim to compare objective long-term outcomes following one- and two-stage dual-innervated gracilis FFMTs. METHODS: Included were adult patients with facial paralysis who underwent either one- (one-stage group) or two-stage (two-stage group) dual-innervated gracilis FFMT with ≥1 year of postoperative follow-up. Facial measurements were obtained from standardized photographs of patients in repose, closed-mouth smile, and open-mouth smile taken preoperatively, 1 year postoperatively, and 3 years postoperatively. Symmetry was calculated from the absolute difference between the paralyzed and healthy hemiface; a lower value indicates greater symmetry. RESULTS: Of 553 facial paralysis patients, 14 were included. Five and nine patients were in the one- and two-stage groups, with mean follow-up time, respectively, being 2.5 and 2.6 years. Within-group analysis of both groups, most paralyzed-side and symmetry measurements significantly improved over time with maintained significance at 3 years postoperatively in closed and open-mouth smile (all p ≤ 0.05). However, only the two-stage group had maintained significance in improvements at 3 years postoperatively in paralyzed-side and symmetry measurements in repose with commissure position (median change [interquartile range, IQR], 7.62 [6.00-10.56] mm), commissure angle (median change [IQR], 8.92 [6.18-13.69] degrees), commissure position symmetry (median change [IQR], -5.18 [-10.48 to -1.80] mm), commissure angle symmetry (median change [IQR], -9.78 [-11.73 to -7.32] degrees), and commissure height deviation (median change [IQR], -5.70 [-7.19 to -1.64] mm; all p ≤ 0.05). In the between-group analysis, all measurements were comparable in repose, closed-mouth smile, and open-mouth smile (all p > 0.05). CONCLUSION: Long-term outcomes demonstrate that both one- and two-stage dual-innervated gracilis FFMTs significantly improve excursion, but only two-stage reconstruction significantly improves resting tone.

Lateral Tarsal Strip versus Tensor Fascia Lata Sling for Paralytic Ectropion: Comparison and Long-Term Outcomes.

BACKGROUND: Paralytic ectropion increases risk for corneal injury in facial palsy patients. Although a lateral tarsal strip (LTS) provides corneal coverage through superolateral lower eyelid pull, the unopposed lateral force may result in lateral displacement of the lower eyelid punctum and overall worsening asymmetry. A tensor fascia lata (TFL) lower eyelid sling may overcome some of these limitations. This study quantitatively compares scleral show, punctum deviation, lower marginal reflex distance, and periorbital symmetry between the two techniques. METHODS: Retrospective review was performed on facial paralysis patients who underwent LTS or TFL sling surgery with no prior lower lid suspension procedures. Standardized preoperative and postoperative images in primary gaze position were used to measure scleral show and lower punctum deviation using ImageJ, and lower marginal reflex distance using Emotrics. RESULTS: Of 449 facial paralysis patients, 79 met inclusion criteria. Fifty-seven underwent LTS surgery and 22 underwent TFL sling surgery. Compared with preoperatively, lower medial scleral show improved significantly with both LTS (10.9 mm 2 ; P < 0.01) and TFL (14.7 mm 2 ; P < 0.01). The LTS group showed significant worsening of horizontal and vertical lower punctum deviation when compared with the TFL group (both P < 0.01). The LTS group was unable to achieve periorbital symmetry between the healthy and paralytic eye across all parameters measured postoperatively ( P < 0.01); and the TFL group achieved symmetry in medial scleral show, lateral scleral show, and lower punctum deviation. CONCLUSION: In patients with paralytic ectropion, TFL sling provides similar outcomes to LTS, with the added advantages of symmetry without lateralization or caudalization of the lower medial punctum. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Neurofibromatosis Type II and Facial Paralysis: Clinical Evaluation and Management.

BACKGROUND: Facial paralysis secondary to neurofibromatosis type 2 (NF2) presents the reconstructive surgeon with unique challenges because of its pathognomonic feature of bilateral acoustic neuromas, involvement of multiple cranial nerves, use of antineoplastic agents, and management. Facial reanimation literature on managing this patient population is scant. METHODS: A comprehensive literature review was performed. All patients with NF2-related facial paralysis who presented in the past 13 years were reviewed retrospectively for type and degree of paralysis, NF2 sequelae, number of cranial nerves involved, interventional modalities, and surgical notes. RESULTS: Twelve patients with NF2-related facial paralysis were identified. All patients presented after resection of vestibular schwannoma. Mean duration of weakness before surgical intervention was 8 months. On presentation, one patient had bilateral facial weakness, 11 had multiple cranial nerve involvement, and seven were treated with antineoplastic agents. Two patients underwent gracilis free functional muscle transfer, five underwent masseteric-to-facial nerve transfer (of whom two were dually innervated with a crossfacial nerve graft), and one patient underwent depressor anguli oris myectomy. Trigeminal schwannomas did not affect reconstructive outcomes if trigeminal nerve motor function on clinical examination was normal. In addition, antineoplastic agents such as bevacizumab and temsirolimus did not affect outcomes if stopped in the perioperative period. CONCLUSIONS: Effectively managing patients with NF2-related facial paralysis necessitates understanding the progressive and systemic nature of the disease, bilateral facial nerve and multiple cranial nerve involvement, and common antineoplastic treatments. Neither antineoplastic agents nor trigeminal nerve schwannomas associated with normal examination affected outcomes. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Optimizing Facial Function in Patients With High-Risk Recurrent Pleomorphic Adenoma and a History of Facial Nerve Injury.

BACKGROUND: Parotid pleomorphic adenoma (PA) patients present significant diagnostic and surgical challenges rendering them high risk for facial nerve injury. Recurrent PA patients often present with history of facial nerve injury or previous reanimations making salvage of the facial nerve or previous reanimations significantly more complex. The study aim is to share our experience with this high risk for facial nerve injury population and review the literature. METHODS: Adult patients with recurrent PA and history of facial nerve injury with at least 3 months of follow-up were analyzed for demographics, facial palsy history, previous head and neck surgeries, previous facial paralysis reconstruction, preoperative imaging, surgical approach, and postoperative outcomes. RESULTS: Four female patients were identified with an average age of 62 years. All patients underwent an initial protective dissection of the facial nerve or previous reanimation reconstruction by the facial nerve reconstructive team followed by the extirpative team. The average number of previous head and neck surgeries was 5, the number of recurrences was 2, and follow-up was 20 months. Half had prior dynamic facial reanimation. Two patients underwent complete preextirpative dissection of the facial nerve resulting in neuropraxia, which recovered completely after an average of 143 days. A third patient presented with 2 recurrences, both during and after reanimation with a dually innervated free functional muscle transfer. The reconstruction was salvaged, and motion was achieved. A fourth patient presented with benign preoperative findings, but intraoperative findings confirmed malignancy, necessitating facial nerve sacrifice, followed by immediate intratemporal grafting of the facial nerve and masseteric nerve transfer. Motion appeared 139 days postoperatively. CONCLUSIONS: A multidisciplinary effort should be implemented in this high risk for facial nerve injury population with the primary goal of protecting the facial nerve or any previous reanimation procedures, yet with preparedness to apply any reconstructive strategy based on intraoperative findings.

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

BACKGROUND: Comparing long-term tone and excursion between single- versus dual-innervated free functional muscle transfer (FFMT) in patients with longstanding facial paralysis. METHODS: Longstanding facial palsy patients treated with a FFMT innervated either by a nerve-to-masseter (single-innervation group) or by nerve-to-masseter and cross-facial-nerve graft (dual-innervation group) were included. One year minimal follow up was required. Outcome measures, based on standardized photos, 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 (Massachusetts Eye and Ear Infirmary, Boston, MA) and ImageJ (Rasband, W.S., ImageJ, U.S, National Institutes of Health, Bethesda, MD) were used for measurements. Between group and within group longitudinal comparisons were analyzed. RESULTS: At three years (single=24, dual=13), significance was found between groups in commissure position (single=26.42mm, dual=31.51mm, p<0.0001) and excursion with open mouth smile (single=31.32mm, dual=26.59mm, 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, while dual-innervation group revealed significant improvements (3.67mm and p<0.001, 3.17mm and p<0.001 respectively). Teeth exposure revealed an increase in the dual-innervation group (single=35.753 mm 2, dual=64.177 mm 2), albeit significance was not observed. CONCLUSIONS: Dually innervated FFMT revealed improvements in resting tone and teeth exposure with minimal decrease in smile excursion compared with single innervated FFMT.

Facial Nerve High-Resolution Microanatomy Analysis of the Distal Intratemporal to Extracranial Pes Segment: Reconstructive Implications.

BACKGROUND: Current knowledge of facial nerve topography between the stylomastoid foramen to the pes anserinus is very limited. Elucidating this segment's intraneural microanatomy may be advantageous in certain clinical settings: the planning of nerve grafts for gaps extending from the proximal facial nerve trunk to distal branches or in determining coaptation sites for hypoglossal jump grafts to provide selective upper and lower facial tone. This study is the first to provide high-definition intraneural topography of the aforementioned segment to optimize reconstructive outcomes. METHODS: Sixteen facial nerves extending from the second genu to the pes anserinus were harvested from eight cadavers en bloc to preserve orientation. Specimens were imaged by micro-computed tomography using a serial 6-µm protocol and digitally reconstructed three-dimensionally to be analyzed using bioinformatic tools. RESULTS: No clinically significant fascicular separation was noted between 14.4 mm proximal to the stylomastoid foramen until 4.4 mm distal to the foramen. Fascicles remained separate throughout the remainder of the specimen and were found to undergo a mean rotation of 45.5 degrees ( P = 0.0002) between 8.9 and 13.7 mm distal to the stylomastoid foramen. This reliable clockwise rotation in left nerves and counterclockwise rotation in right nerves resulted in superficially oriented fascicles entering the upper division of the pes anserinus, whereas deep-oriented fascicles entered the lower division. CONCLUSION: Intraneural facial nerve topography and rotation are consistent from 4 to 14 mm distal to the stylomastoid foramen, enabling surgeons to accurately place grafts targeted to either the upper or lower face, thus optimizing functional accuracy and minimizing synkinesis.

Selective Myectomies Alone vs Selective Myectomies Combined with Selective Neurectomies in Patients with Post-paretic Synkinesis - Comparing Outcomes.

BACKGROUND: In post-paretic synkinesis, muscle tone imbalance between upper and lower lip depressors and elevators, results in the inability to produce an effective smile. Surgical treatments to improve smile, focus on restoring tonicity balance between peri-oral muscles by weakening hyper-toned muscles through selective myectomies or selective neurectomies. The goal of this study was to compare objective outcomes between selective myectomies alone with those of selective myectomies combined with selective neurectomies. METHODS: Retrospective cohort study performed on post-paretic synkinesis patients who underwent depressor anguli oris (DAO) myectomies or DAO and platysma myectomies with selective neurectomies. Objective outcomes included pre- and post-operative analyses of smile measures (excursion, angle, and dental show) and Botox administration (periorbital and platysmal). RESULTS: Thirty-seven pa tients underwent DAO myectomies only (myectomy group) and eighteen patients underwent DAO and platysma myectomies with selective neurectomies (myectomy-neurectomy group). Within group analyses showed significant angle improvement in both groups (p<.05) and improved smile excursion in the myectomy-neurectomy group (p<.05). Between group comparisons showed significant closed mouth smile excursion improvement (difference in means: -1.14 millimeters; 95% CI -2.19 to -0.09; p=.034) and significant decrease in platysmal Botox administration (difference in means: 27.36 Botox units ; 95% CI 18.72 to 36.00; p<.001) in the myectomy-neurectomy group compared to the myectomy group. CONCLUSIONS: This study suggests that selective myectomies and selective myectomies with selective neurectomies provide overlapping and differing benefits to peri-oral synkinesis. Selective neurectomies and platysma myectomy provided slightly improved excursion and significantly decreased botulinum injections to the platysma.

Cross Facial Nerve Grafting for Smile Restoration: Thoughts on Improving Graft Inset.

Cross facial nerve grafts (CFNGs) are one of the most ubiquitous and time-honored surgical tools used in facial reanimation. They may be used for targeting different mimetic muscles in the subacute setting as well as to innervate newly placed muscle flaps in varied facial subunits. In our experience, when used specifically for smile reanimation in two-stage strategies with either traditional "babysitting" approaches in nerve transfers or free functional muscle transfers, the second stage may present some challenges in CFNG identification as well as injury to the previously banked nerve graft. We present some technical modifications in the first-stage CFNG inset that can make the second stage easier and safer. These modifications include: (1) marking the course of the nerve graft with surgical metal clips and inserting loose circumferential sutures throughout the distal course of the nerve in the recipient area to avoid displacement; (2) transferring the nerve graft through the nasal sills rather than lips, protecting it from damage during insertion of free functional muscle transfer; and (3) routing the nerve from the lateral nose to the preauricular area over the zygomatic arch, allowing easier dissection and banking of adequate graft length to provide tension-free coaptation with the flexibility of nerve coaptation in variable positions.

Do Preoperative Depressor Anguli Oris Muscle Blocks Predict Myectomy Outcomes? A Single-Cohort Comparison in Postparetic Facial Synkinesis.

SUMMARY: The complexity of facial synkinesis will likely benefit from an individualized approach to intervene on discrete synkinetic facial subunits. This overarching treatment algorithm requires understanding each synkinetic mimetic subunit. The depressor anguli oris muscle, because of its antagonistic relationship to the zygomaticus major, is of particular interest. This study aims to provide outcomes of depressor anguli oris muscle myectomies and the predictive value of preoperative lidocaine blocks. Preoperative depressor anguli oris muscle lidocaine blocks were administered to patients with postparetic facial synkinesis, and subsequent isolated depressor anguli oris muscle myectomies were performed on those who showed improvement and elected to proceed. Twenty synkinetic patients underwent isolated depressor anguli oris myectomies after lidocaine blockade, with an average follow-up of 9 months. Facial mimetic parameters and measurements were recorded and analyzed by Massachusetts Eye and Ear Infirmary Emotrics and National Institutes of Health ImageJ software to compare results from both blocks and myectomies. Both lidocaine block and depressor anguli oris myectomy improved dental show by 14.42 mm 2 and 23.012 mm 2 , respectively, and open mouth smile angles above a horizontal plane by 4.66 and 3.32 degrees, respectively. There was no statistical difference between the groups in terms of improvements noted in closed and open mouth smile angles above a horizontal plane, or in dental show ( p = 0.695, p = 0.351, and p = 0.242, respectively). Preoperative lidocaine blockade accurately predicts the improvement in dental show and modiolus smile angle that is provided by isolated depressor anguli oris muscle myectomy. This furthers our understanding of depressor anguli oris muscle abnormality in the overall spectrum of facial synkinesis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Depressor Anguli Oris Myectomy versus Transfer to Depressor Labii Inferioris for Facial Symmetry in Synkinetic Facial Paralysis.

BACKGROUND: Postparalytic synkinesis presents with a combination of hypo- and hypertonic muscles, leading to facial asynchrony with animation and at rest. One ubiquitous finding is a hypertonic depressor anguli oris (DAO) muscle and a weak depressor labii inferioris (DLI) muscle. The goal of this study was to evaluate the utility of DAO myectomy with or without its transfer to the weakened DLI in improving critical components of the dynamic smile. METHODS: From 2018 to 2020, this single-center, prospective study included of postparetic facial synkinetic patients with evidence of DAO hypertonicity who underwent DAO myectomy with or without transfer to DLI. Objective facial measurements were used to compare the effectiveness of DAO to DLI transfer to pure DAO myectomy in improving asymmetry of the synkinetic hemiface. RESULTS: Twenty-one patients with unilateral postparetic facial synkinesis with DAO hypertonicity were included; 11 underwent DAO myectomy, while 10 underwent DAO to DLI transfer. Baseline demographics and facial measurements were similar between the groups. DAO myectomy resulted in increased modiolus resting position, closed-mouth smile modiolus angle and excursion, open-mouth smile modiolus angle, excursion, dental show, and decreased lower lip height deviation. DAO to DLI transfer demonstrated similar findings but lacked significant increase in excursion and resulted in worsened lower lip height deviation. CONCLUSION: These findings illustrate the utility of DAO myectomy in improving imbalance in the synkinetic patient and necessitate further technical refinements for DAO transfers or a different approach for improving lower lip depression in this subgroup of patients.

The Effect of Depressor Anguli Oris Muscle Block on Facial Symmetry in Synkinetic Facial Paralysis Patients and Its Role in Preoperative Assessment.

BACKGROUND: Depressor anguli oris muscle hypertonicity in synkinetic facial paralysis patients may have an overpowering antagonistic effect on facial symmetry. Depressor anguli oris muscle block is a crucial diagnostic test before any treatment planning. Presented is the largest patient cohort analysis to date on static and dynamic facial symmetry changes after depressor anguli oris muscle block. METHODS: Unilateral synkinetic patients with depressor anguli oris muscle hypertonicity were included. Resting symmetry and smile modiolus angle, excursion, and exposure of teeth were measured on both synkinetic and healthy hemifaces before and after depressor anguli oris muscle block using Emotrics and FaceGram photographic analyses. RESULTS: Thirty-six patients were included. Before depressor anguli oris block, resting modiolus height was elevated on the synkinetic side (p = 0.047). During open-mouth smile, reduced modiolus angle (p < 0.0001), modiolus excursion (p < 0.0001), and exposure of teeth (p < 0.0001) were observed on the synkinetic hemiface. After depressor anguli oris block, resting modiolus height became symmetric (p = 0.64). During open-mouth smile, modiolus angle and exposure of teeth significantly increased (both p < 0.0001); excursion did not improve on the synkinetic side (p = 0.13) but unexpectedly improved in open-mouth smile on the healthy side (p = 0.0068). CONCLUSIONS: Depressor anguli oris muscle block improved resting symmetry and modiolus angle and exposure of teeth during smile, demonstrating the inhibitory mimetic role of a hypertonic depressor anguli oris muscle in synkinesis. It is a critical diagnostic and communication tool in the assessment and treatment planning of depressor anguli oris muscle hypertonicity, suggesting the potential effects of future depressor anguli oris myectomy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Topographic and Neural Anatomy of the Depressor Anguli Oris Muscle and Implications for Treatment of Synkinetic Facial Paralysis.

BACKGROUND: Synkinetic patients often fail to produce a satisfactory smile because of antagonistic action of a hypertonic depressor anguli oris muscle and concomitantly weak depressor labii inferioris muscle. This study investigated their neurovascular anatomy to partially explain this paradoxical depressor anguli oris hypertonicity and depressor labii inferioris hypotonicity and delineated consistent anatomical landmarks to assist in depressor anguli oris muscle injection and myectomy. METHODS: Ten hemifaces from five fresh human cadavers were dissected to delineate the neurovascular supply of the depressor anguli oris and depressor labii inferioris muscles in addition to the depressor anguli oris muscle relation to consistent anatomical landmarks. RESULTS: The depressor anguli oris muscle received innervation from both lower buccal and marginal mandibular facial nerve branches, whereas the depressor labii inferioris muscle was solely innervated by marginal mandibular branches. The mandibular depressor anguli oris origin was on average 39 mm wide, and its medial and lateral borders were located 17 mm from the symphysis and 41 mm from the mandibular angle, respectively. The depressor anguli oris fibers consistently passed anterior to the first mandibular molar toward their insertion into the modiolus, which was located 10 mm lateral and 10 mm caudal to the oral commissure. CONCLUSIONS: Depressor anguli oris muscle dual innervation versus depressor labii inferioris single innervation may explain why depressor anguli oris hypertonicity and depressor labii inferioris weakness are commonly observed concomitantly in synkinetic patients. Based on treatment goals, diagnostic percutaneous injection with lidocaine can be performed on the depressor anguli oris muscle along a cutaneous line from the modiolus to the mandibular first molar border, and an intraoral depressor anguli oris myectomy can be performed along that same transmucosal line.

Orbicularis Oculi Muscle Reinnervation Confers Corneal Protective Advantages over Static Interventions Alone in the Subacute Facial Palsy Patient.

BACKGROUND: Corneal protection is a priority in flaccid facial palsy patients. Denervation of the orbicularis oculi muscle results in weak palpebral closure and predisposes patients to severe corneal sequelae. While periorbital static procedures enhance corneal coverage in repose, voluntary closure is only regained through dynamic reinnervation of the muscle. This study aims to elucidate the added effect of dynamic reinnervation of the orbicularis oculi muscle on long-term corneal integrity as well as on dynamic closure of the palpebral aperture. METHODS: Retrospective review was performed on two groups of complete palsy patients: those who received solely periorbital static procedures and those who underwent concomitant orbicularis oculi muscle reinnervation and static lid procedures. Only patients with complete ophthalmic examinations were included. Corneal punctate epithelial erosions in addition to static and dynamic palpebral measurements were serially assessed preoperatively and postoperatively. RESULTS: Of 272 facial palsy patients, 26 fit the inclusion criteria. Eleven patients underwent combined muscle reinnervation involving facial-to-masseteric nerve coaptation in addition to static eye procedures, and 15 patients underwent solely static interventions. Analysis revealed a 65.3 percent lower mean punctate epithelial erosion score in reinnervation patients as compared with static patients when evaluated at more than 9 months postoperatively (p < 0.01). Reinnervation patients were also found to have 25.3 percent greater palpebral aperture closure (p < 0.05) and 32.8 percent higher closure velocity (p < 0.01) compared with static patients. CONCLUSION: In patients with subacute facial palsy, dynamic reanimation of the orbicularis oculi muscle with concomitant static interventions provides lasting corneal protection not seen in patients who receive solely static interventions. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.