The Role of the Cross Face Nerve Graft in Facial Reanimation and Endoscopic Harvest of the Sural Nerve.

Cross-face nerve grafting (CFNG) allows for spontaneous, involuntary facial movement for patients with irreversible hemifacial paralysis. This technique uses an intact contralateral facial nucleus and nerve as an input and axon source, allowing donor neural input to be routed through a nerve graft across the face. The sural nerve is well equipped for use as a nerve graft due to its length and minimal donor site morbidity. Endoscopic nerve harvest techniques allow for efficient, minimally invasive dissection that improves the integrity of the harvested nerve.

Lower Eyelid Sling for Primary and Revision Correction of Paralytic Lagophthalmos.

Background: Lateral tarsal techniques alone for lower eyelid correction in paralytic lagophthalmos may yield suboptimal outcomes. Objective: To describe a lower eyelid sling technique for primary and revision correction of lower eyelid ptosis and ectropion and evaluate outcomes as measured by margin reflex distance 2 (MRD2). Methods: A retrospective review of patients with long-standing unilateral paralytic lagophthalmos who underwent primary or revision lower eyelid ptosis correction by sling suspension between January 2016 and August 2020 at a tertiary medical center was performed. Surgical technique is illustrated with video and technical considerations are discussed. Pre- and postoperative MRD2 values were quantified from databased photographs. Results: Thirty-eight patients were included. Eighteen patients had undergone prior procedures for ptosis correction. Lower eyelid symmetry and paralyzed side MRD2 significantly improved after lower lid sling for primary and revision cases (p < 0.05), and improvement was sustained over the study period (mean follow-up duration 13.3 months, range 1-33 months). No postoperative complications occurred. Conclusion: Lower eyelid sling yielded safe, effective, and durable correction of lower eyelid position in a cohort of patients with paralytic lagophthalmos.

Facial Nerve Exploration for Known or Suspected Transection: The Massachusetts Eye and Ear Experience.

Background: There is no ideal test to determine likelihood of spontaneous recovery after post-traumatic and postsurgical facial palsy (FP). Objective: Among patients with unexpected FP undergoing facial nerve (FN) exploration for suspected discontinuity, we endeavored to discern whether intraoperative findings, repair type, and time to exploration impact FN recovery, as measured by electronic Facial Clinimetric Evaluation (eFACE) and FaCE scales. Methods: Retrospective cohort study of 42 adult patients who underwent FN exploration. Results: FN injury resulted from either surgery (n = 29) or trauma (n = 13). Average time to repair was 68.4 (standard deviation 79.6) days. Postoperative improvements were observed in total eFACE (73.3-86.5; p < 0.0001) and FaCE (21.5-38.1; p = 0.0214) scores. Distal FN injuries were most common (n = 29) and had best recovery (percentage change in eFACE 57.2% vs. 34.3% main trunk, p = 0.0306). Discontinuity injuries (n = 33) repaired with primary coaptation (n = 18) had noninferior outcomes compared with cable graft repair (n = 16; percentage change in eFACE 49.6% vs. 39.2%, p = 0.3470). Denervation times <3 months yielded better recovery using percentage change in eFACE score (56.9% vs. 33.1%, p = 0.0270). Conclusions: Surgical exploration for unexpected FP allows for direct visualization of anatomical nerve status and timely repair.

Embellishing Emotrics for a More Complete Emotion Analysis: Addition of the Nasolabial Fold.

Background: The nasolabial fold (NLF) greatly contributes to facial aesthetics; changes to NLF depth and vector are disfiguring in patients with facial paralysis (FP). NLF parameters are integral to clinician-graded outcomes, but automated programs currently lack NLF identification capabilities. Objective: To incorporate an automated NLF identification and quantification function into the facial landmark program, Emotrics, and to compare new Emotrics-derived NLF data to clinician-graded electronic facial paralysis assessment (eFACE) data for accuracy. Methods: Photographs of 135 patients with FP were marked bilaterally, using identification markers manually placed on each NLF. A machine learning model was trained to automatically localize the markers using these data. Once Emotrics accurately identified the NLF and its corresponding vector, photographs of 20 additional patients who underwent facial reanimation procedures were assessed by the algorithm. Results: The enhanced Emotrics algorithm successfully identified the NLF, and measured the vector from midline, in a series of patients with FP. NLF vector data closely matched corresponding eFACE parameters. Furthermore, changes in NLF presence and vector were detected following facial reanimation procedures. Conclusion: The Emotrics program now provides critical NLF data, providing objective parameters for clinicians interested in changing NLF dynamics after FP.

Haller's Ansa: An Unrecognized Route of Facial Movement After Skull Base Surgery.

A direct communication between the glossopharyngeal and facial nerves known as Haller's ansa exists in a minority of patients. Clinical manifestations of this anastomosis are not commonly observed. We describe post-operative facial movement with swallowing after facial nerve sacrifice in two patients who underwent surgery for skull base tumors. Patient 1, a 49-year-old male, received a transcochlear approach for resection of endolymphatic sac tumor and intratemporal facial nerve sacrifice without nerve reconstruction. Patient 2, a 23-year-old female, underwent surgery for left jugular paraganglioma, requiring facial nerve sacrifice and cable graft. Both patients had preoperative facial weakness and intraoperative preservation of the glossopharyngeal nerve. A literature review related to Haller's ansa was performed using PubMed, EMBASE, and Scopus from 1920-2021. Post-operatively, both patients demonstrated oral commissure movement with swallowing, suggesting a communication between the glossopharyngeal nerve and the facial nerve (Haller's ansa). Although anatomical references to Haller's ansa exist, there are no reported clinical manifestations of this neural anastomosis. Glossopharyngeal-facial nerve communications may contribute to facial tone and movement. Pre- and post-operative assessment of facial nerve movement with swallowing may help assess for the presence of Haller's ansa. Better understanding of this neural anastomosis may have implications for facial reanimation surgery. Laryngoscope, 132:1750-1752, 2022.

Effect of age, electrode array, and time on cochlear implant impedances.

Objectives: To determine the impact of age, electrode array, and time on impedance patterns in cochlear implant (CI) patients. Methods: A retrospective case review was performed on 98 patients implanted with the CI24RE perimodiolar (PM) and CI422 lateral wall (LW) arrays between 2010 and 2014 to assess impedances at the 1 week and 3-6 month visit after initial stimulation (IS). Results: With respect to age, impedances were higher in young patients compared to older patients in the middle and apical turns. With time, there were significant reductions in impedances across most electrodes. Electrode array type also had a significant impact on impedance measurements with PM and LW arrays having higher impedances in the basal turn and apical turns, respectively. Furthermore, PM arrays demonstrated significantly lower impedances in the middle and apical turn with time, when compared to LW arrays. Conclusions: Age, electrode array, and time can independently affect CI impedances. Moreover, we show that PM arrays may be advantageous to LW arrays, due to demonstrated lower impedances in the middle and apical turns long term. Understanding the impact of impedance on speech discrimination and determining the intracochlear processes that contribute to differences in impedance are future research directions.

Update on anterior skull base reconstruction.

PURPOSE OF REVIEW: Anterior skull base reconstruction has rapidly evolved over the past few years as endoscopic approaches to resect tumors in this region have become more established. The present review evaluates the robust amount of new literature on this topic over the past year with particular attention to minimally invasive methods for reconstruction. RECENT FINDINGS: Although vascularized local flaps remain the mainstay reconstructive choice when available for the anterior skull base, innovative techniques for all types of reconstruction, ranging from free grafts to free flaps continue to emerge. SUMMARY: Because of the unique challenges and wide variety of options available to repair the anterior skull base with the goal to prevent or treat cerebrospinal fluid leaks, surgical expertise and experience in this field is of utmost importance.

Controversies in free tissue transfer for head and neck cancer: A review of the literature.

BACKGROUND: Microvascular free tissue transfer provides superior functional outcomes when reconstructing head and neck cancer defects. Careful patient selection and surgical planning is necessary to ensure success, as many preoperative, intraoperative, and postoperative patient and technical factors may affect outcome. AIMS: To provide a concise, yet thorough, review of the current literature regarding free flap patient selection and management for the patient with head and neck. MATERIALS AND METHODS: PubMed and Cochrane databases were queried for publications pertaining to free tissue transfer management and outcomes. RESULTS: Malnutrition and tobacco use are modifiable patient factors that negatively impact surgical outcomes. The use of postoperative antiplatelet medications and perioperative antibiotics for greater than 24 hours have not been shown to improve outcomes, although the use of clindamycin alone has been shown to have a higher risk of flap failure. Liberal blood transfusion should be avoided due to higher risk of wound infection and medical complications. DISCUSSION: There is a wide range of beliefs regarding proper management of patients undergoing free tissue transfer. While there is some data to support these practices, much of the data is conflicting and common practices are often continued out of habit or dogma. CONCLUSION: Free flap reconstruction remains a highly successful surgery overall despite as many different approaches to patient care as there are free flap surgeons. Close patient monitoring remains a cornerstone of surgical success.

Modulation of BDNF-TRKB Interactions on Schwann Cell-induced Oral Squamous Cell Carcinoma Dispersion In Vitro.

BACKGROUND/AIM: Perineural invasion (PNI) is a significant pathological feature in head and neck cancer. The molecular mechanisms of PNI are poorly understood. Contrary to the previous belief that cancer cells invade nerves, recent studies have shown that Schwann cells (SC) can dedifferentiate, intercalate between cancer cells, and promote cancer dispersion. Communication between cells through brain-derived neurotrophic factor (BDNF) activation of its receptor tropomyosin receptor kinase B (TRKB) may contribute to these cellular events. We aimed to determine the effect of TRKB inhibitor ANA-12 on the direction of cell migration and degree of SC-induced oral cancer cell dispersion. MATERIALS AND METHODS: Cell migration and dispersion assays were performed in vitro using murine SC and oral carcinoma cell lines. Assays were performed with and without ANA-12. RESULTS: Although SCs preferentially migrated towards cancer cells in control medium, there was minimal SC-associated cancer cell dispersion. In contrast, treatment with ANA-12 reduced migration of SCs and cancer cells towards each other and initiated more SC-associated cancer cell dispersion. CONCLUSION: This pilot study shows that BDNF-TRKB signaling may have a role in regulating interactions between SC and oral cancer cells that affect cell migration, intercalation, and cancer cell dispersion. Further research into these interactions may provide important clues about the molecular and cellular mechanisms of PNI.

Inhibition of tropomyosine receptor kinase B on the migration of human Schwann cell and dispersion of oral tongue squamous cell carcinoma in vitro.

BACKGROUND: Schwann cells (SC) may play an important role in perineural invasion (PNI) by promoting cancer cell dispersion. Brain-derived neurotrophic factor (BDNF) may contribute to these cellular events by activating tropomyosine receptor kinase B (TrkB). This study examines the effect of TrkB inhibition on SC migration and oral cancer cell dispersion in vitro. METHODS: Human tongue squamous cell carcinoma (SCC-9) and human SCs were cocultured in three different conditioned mediums: control, BDNF, and TrkB inhibitor. Cell migration, cancer cell dispersion, and SC dedifferentiation were measured on time-lapse and immunofluorescence images. RESULTS: Cancer cell migration exceeded SC migration in all conditions. TrkB inhibition promoted SC dedifferentiation and significantly increased SC migration, when compared to BDNF conditions. TrkB inhibition also reduced cancer cell dispersion, when compared to control and BDNF-treated cultures. CONCLUSION: SCs may have importance in the pathophysiology of PNI. TrkB inhibition may be a potential avenue for therapeutic intervention.

Fluorescent Detection of Merlin-deficient Schwann Cells and Primary Human Vestibular Schwannoma Cells Using Sodium Fluorescein.

HYPOTHESIS: Merlin-deficient Schwann cells (MD-SC) and primary human vestibular schwannoma (VS) cells exhibit selective uptake of sodium-fluorescein (SF), allowing for fluorescent detection and improved visualization of tumor cells, when compared with Schwann cells (SC). BACKGROUND: SF is a fluorescent compound used for fluorescence-guided resection of gliomas. The utility of SF for VS surgery has not been assessed. METHODS: Mouse MD-SCs and rat SCs were cultured on 96-well plates at different cell densities and treated with SF at several drug concentrations and durations. Relative fluorescence units (RFU) were measured using a fluorometer to determine optimal treatment parameters in vitro. Subsequently, a four-point Likert scale for fluorescence visualization of pelleted cells was created and validated. Blinded observers rated SF-treated primary human VS and SC cultures, which were developed from deidentified specimens obtained from live and cadaveric donors, respectively. RESULTS: In contrast to SCs that showed low levels of fluorescence, MD-SCs demonstrated dose-dependent increases in RFUs when treated with incremental dosages of SF as well as longer treatment and fluorescent excitation times. In addition, RFUs were higher at greater MD-SC densities. The Likert scale for fluorescence visualization was validated using nine blinded observers and there were excellent inter- and intrarater reliabilities (intraclass coefficients of 0.989 and >0.858, respectively). Using the Likert scale, human VS treated with SF received higher scores than human SCs (p < 0.001). CONCLUSION: Mouse MD-SC and human VS cells demonstrate preferential uptake of SF when compared with normal primary SCs. Observers detected differences in fluorescence using the validated Likert scale. Further investigations into the utility of SF-guidance in VS surgery are warranted.