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Objectives: Endoscopic microlaryngeal laser surgery performed with general anesthesia through a laryngoscope speculum generates heat that accumulates at the distal lumen, creating an "oven" effect and potentially causing bystander thermal damage to nontarget tissue such as the contralateral vocal fold. We report the effects of cooling on air and tissue temperatures that occurred during simulated laryngeal laser surgery with KTP and thulium lasers in an ex vivo calf model. Methods: Ten fresh excised calf larynges were studied at room temperature. Laser energy was applied to one vocal fold for 2 minutes, with or without cooling, while temperatures were monitored with sensors placed within the glottal lumen or inserted superficially into the contralateral vocal fold. A pulsed KTP laser (525 mJ) was used for 5 larynges, and a thulium laser (7 W, continuous) was used for the other 5 larynges. Results: Heating was slightly greater for the KTP laser than for the thulium laser with use of these parameters. The lumen temperatures for both lasers increased an average of 13.2° C without cooling, but only 6.7° C with cooling (p < 0.05). The contralateral vocal fold (subepithelial space) temperature increased an average of 6.8° C without cooling, but only 4.2° C with cooling (p> 0.05). Conclusions: Cooling with room-temperature air during laryngeal laser surgery reduces luminal air and contralateral vocal fold temperatures. This effect is believed to be due to elimination of the plume of steam and smoke that significantly heats surrounding structures. [ABSTRACT FROM AUTHOR]

Purpose: Medialization procedures for unilateral vocal fold (VF) paralysis generally improve voice but do not fully replace dynamic VF adduction. Paralyzed VFs typically experience synkinetic reinnervation, which makes it feasible to elicit movement through electrical stimulation. We tested a novel laryngeal pacing implant capable of providing closed-loop (automatic) stimulation of a VF triggered by electromyography (EMG) potentials from the contralateral VF., Method: A custom, battery-powered, microprocessor-based stimulator was tested in eight dogs with bipolar electrodes implanted for recording EMG from the left VF and stimulating adduction of the right VF. A cuff electrode on the left recurrent laryngeal nerve (RLN) stimulated unilateral VF adduction, modeling voluntary control in anesthetized animals. Closed-loop stimulation was tested in both acute and chronic experiments. Synkinetic reinnervation was created in two animals by right RLN transection and suture repair to model unilateral VF paralysis., Results: In all animals, left VF activation through RLN stimulation generated a robust EMG response that rapidly triggered stimulation of contralateral thyroarytenoid and lateral cricoarytenoid muscles, causing nearly simultaneous bilateral adduction. Optimal triggering of VF stimulation from elicited EMG was achieved using independent onset and offset thresholds. Real-time artifact blanking allowed closed-loop stimulation without self-perpetuating feedback, despite the proximity of recording and stimulation electrodes., Conclusions: Using a custom implant system, we demonstrated real-time closed-loop stimulation of one VF triggered by the activation of the contralateral VF. This approach could potentially restore dynamic glottic closure for reflexive behaviors or phonation in cases of unilateral VF paralysis with synkinetic reinnervation., Supplemental Material: https://doi.org/10.23641/asha.24492133.

Objectives: The 2 µm-wavelength thulium laser is an effective cutter during partial arytenoidectomy, but thermal trauma can damage adjacent laryngeal tissue. Pulsing laser energy may reduce trauma when compared to continuous-wave cutting. This study measured temperature changes, thermal trauma, and time to complete partial arytenoidectomy, with and without pulsing, in an ex-vivo calf model., Methods: Tissue temperature and time to complete a trans-cartilaginous cut were measured during partial arytenoidectomy on ex-vivo calf vocal folds (N = 24) using a thulium laser in continuous-wave (CW, N = 12) and pulsed-wave (PW, N = 12) modes. Energy was 5 W for CW and PW cuts; pulse-widths were 250, 500, and 750 ms. Thermal damage was analyzed histologically by measuring the depth of lactate dehydrogenase (LDH) inactivation perpendicular to the laser-cut edge at the vocal process. Paired t-tests compared CW and PW modes., Results: Change in temperature was lower using CW (6.5°C) compared to PW modes (250 ms = 18°; 500 ms = 16°; 750 = 19°; P  < .05). Trans-cartilaginous cuts were completed faster using CW (37 seconds) compared to PW (250 ms = 136 seconds; 500 ms = 61 seconds; 750 = 44 seconds; P  < .05), and both modes delivered the same total Joules. The average depth of LDH depletion (thermal damage) was similar for all cuts., Conclusions: 1. Thulium laser cuts in continuous-mode unexpectedly produced less tissue heating yet created similar thermal damage than pulsed-mode cuts during simulated partial arytenoidectomy. 2. Trans-cartilaginous cuts were completed significantly faster in continuous-mode as compared to pulsed-mode cutting. 3. Pulsing the thulium laser does not minimize thermal damage compared to continuous wave cutting during thulium laser-assisted partial arytenoidectomy.

Objectives: While it is acknowledged that otolaryngologists performing microlaryngeal surgery can develop musculoskeletal symptoms due to suboptimal body positioning relative to the patient, flexible laryngoscopy and awake laryngeal surgeries (ALSs) can also pose ergonomic risk. This prospective study measured the effects of posture during ergonomically good and bad positions during laryngoscopy using ergonomic analysis, skin-surface electromyography (EMG), and self-reported pain ratings., Study Design: Prospective cohort study., Methods: Eight participants trained in laryngoscopy assumed four ergonomically distinct standing positions (side/near, side/far, front/near, front/far) at three different heights (neutral-top of patient's head in line with examiner's shoulder, high-6 inches above neutral, and low-6 inches below neutral) in relation to a simulated patient. Participants' postures were analyzed using the validated Rapid Upper Limb Assessment (RULA, 1 [best] to 7 [worst]) tool for the 12 positions. Participants then simulated ALS for 10 minutes in a bad position (low-side-far) and a good position (neutral-front-near) with 12 EMG sensors positioned on the limbs and torso., Results: The position with the worst RULA score was the side/near/high (7.0), and the best was the front/near/neutral (4.5). EMG measurements revealed significant differences between simulated surgery in the bad and good positions, with bad position eliciting an average of 206% greater EMG root-mean-squared magnitude across all sampled muscles compared to the good posture (paired t-test, df = 7, P < .01), consistent with self-reported fatigue/pain when positioned poorly., Conclusion: Quantitative and qualitative measurements demonstrate the impact of surgeon posture during simulated laryngoscopy and suggest ergonomically beneficial posture that should facilitate ALSs., Level of Evidence: 3 Laryngoscope, 131:2752-2758, 2021., (© 2021 The American Laryngological, Rhinological and Otological Society, Inc.)

Purpose This study aimed to evaluate a novel communication system designed to translate surface electromyographic (sEMG) signals from articulatory muscles into speech using a personalized, digital voice. The system was evaluated for word recognition, prosodic classification, and listener perception of synthesized speech. Method sEMG signals were recorded from the face and neck as speakers with ( n  = 4) and without ( n  = 4) laryngectomy subvocally recited (silently mouthed) a speech corpus comprising 750 phrases (150 phrases with variable phrase-level stress). Corpus tokens were then translated into speech via personalized voice synthesis ( n  = 8 synthetic voices) and compared against phrases produced by each speaker when using their typical mode of communication ( n  = 4 natural voices, n  = 4 electrolaryngeal [EL] voices). Naïve listeners ( n  = 12) evaluated synthetic, natural, and EL speech for acceptability and intelligibility in a visual sort-and-rate task, as well as phrasal stress discriminability via a classification mechanism. Results Recorded sEMG signals were processed to translate sEMG muscle activity into lexical content and categorize variations in phrase-level stress, achieving a mean accuracy of 96.3% ( SD  = 3.10%) and 91.2% ( SD  = 4.46%), respectively. Synthetic speech was significantly higher in acceptability and intelligibility than EL speech, also leading to greater phrasal stress classification accuracy, whereas natural speech was rated as the most acceptable and intelligible, with the greatest phrasal stress classification accuracy. Conclusion This proof-of-concept study establishes the feasibility of using subvocal sEMG-based alternative communication not only for lexical recognition but also for prosodic communication in healthy individuals, as well as those living with vocal impairments and residual articulatory function. Supplemental Material https://doi.org/10.23641/asha.14558481.

Objective: Tracking recovery after nerve injury may require many intermittent assessments over long periods, preferably with non- or minimally invasive methods. We developed subcutaneous electrical connection ports (ECPs) for repeated connection to nerve cuff or intramuscular electrodes via transdermal needles and evaluated them during studies of laryngeal reinnervation., Study Design: Animal experiment., Setting: Laboratory., Methods: ECPs were designed and 3-dimensionally printed for connection to bipolar electrodes with biocompatible polymers. Dual compartments filled with conductive silicone capped with nonconductive silicone were used to make the connections between electrode leads and transdermally inserted needles. Ten dogs (19-29 kg) were implanted with 22 ECPs. In 7 dogs, 11 electrodes were placed on recurrent laryngeal nerves proximal to transection and suture repair to track laryngeal reinnervation. In 6 dogs, 8 spinal accessory nerve cuff electrodes were used to stimulate neck muscle contraction. In 2 dogs, 3 electrodes were implanted in the thyroarytenoid muscle. Stimulation thresholds, electromyography, and videolaryngoscopic imaging were obtained in 156 tests over survival periods up to 32 months. Stimulation data provided information about ECP performance., Results: ECPs added negligible resistance to electrodes (mean ± SD, 2.14 ± 0.9 Ω). Despite some electrode leads breaking distally, ECPs were reliable and well tolerated at implant sites and enabled periodic assessment of nerve and muscle function over the time course of laryngeal reinnervation. Histology showed ECP encapsulation as thin layers of connective tissue and minimal acute inflammation., Conclusion: Custom ECPs are easily fabricated and cause little tissue reaction over months to years of subcutaneous implantation, facilitating long-term physiologic studies.

Objectives/hypothesis: We previously developed an instrument called the Aerodynamic Vocal Fold Driver (AVFD) for intraoperative magnified assessment of vocal fold (VF) vibration during microlaryngoscopy under general anesthesia. Excised larynx testing showed that the AVFD could provide useful information about the vibratory characteristics of each VF independently. The present investigation expands those findings by testing new iterations of the AVFD during microlaryngoscopy in the canine model., Study Design: Animal model., Methods: The AVFD is a handheld instrument that is positioned to contact the phonatory mucosa of either VF during microlaryngoscopy. Airflow delivered through the AVFD shaft to the subglottis drives the VF into phonation-like vibration, which enables magnified observation of mucosal-wave function with stroboscopy or high-speed video. AVFD-driven phonation was tested intraoperatively (n = 26 VFs) using either the original instrument design or smaller and larger versions three-dimensionally printed from a medical grade polymer. A high-fidelity pressure sensor embedded within the AVFD measured VF contact pressure. Characteristics of individual VF phonation were compared with typical two-fold phonation and compared for VFs scarred by electrocautery (n = 4) versus controls (n = 22)., Results: Phonation was successful in all 26 VFs, even when scar prevented conventional bilateral phonation. The 15-mm-wide AVFD fits best within the anteroposterior dimension of the musculo-membranous VF, and VF contact pressure correlated with acoustic output, driving pressures, and visible modes of vibration., Conclusions: The AVFD can reveal magnified vibratory characteristics of individual VFs during microlaryngoscopy (e.g., without needing patient participation), potentially providing information that is not apparent or available during conventional awake phonation, which might facilitate phonosurgical decision making., Level of Evidence: NA Laryngoscope, 130: 1980-1988, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective:: The goal of this work was to create implantable stimulator systems that could be used in animal experiments on laryngeal paralysis, including "closed-loop" stimulation of impaired muscles triggered by electromyographic (EMG) potentials from healthy muscles., Study Design:: Iterative device design and testing., Methods:: A series of microcontroller-based implantable devices were built that incorporated increasingly sophisticated features for stimulation, EMG recording, and communication across the skin. Specific engineering challenges included minimizing power consumption, achieving charge-balanced and relatively high stimulation capacity, implementing noninvasive communication across the skin, providing real-time processing of EMG signals, and mitigating effects of shock artifacts. Bench testing was used to verify performance., Results:: Two prototypes are described in detail. Each system is based on an "implant" and an external "communication adapter" that interfaces both with the implant and with external computers for adjustments and monitoring. The first version described is inductively powered and referred to as the "inductive laryngeal stimulator." It uses inductive coupling for both power and communication and performs EMG processing in the communication adapter module. The second version, a "battery-powered laryngeal stimulator," consists of an autonomous battery-powered implant with onboard EMG processing and artifact control; it communicates by infrared light with the external communication adapter for setup and monitoring., Conclusions:: The devices met design and performance specifications and have proved useful in the animal experiments that are described in Part 2 of this series. Detailed descriptions of the circuits and their firmware are made available in the Appendix. Level of Evidence: NA.

Objective:: Laryngeal paralysis of central or peripheral origin can potentially be treated using functional electrical stimulation (FES) of laryngeal muscles. Experiments in canines (dogs) were performed using implant prototypes capable of closed-loop FES to refine engineering designs and specifications, test surgical approaches for implantation, and better understand the in vivo effects of laryngeal muscle stimulation on short- and long-term glottic function., Study Design:: Prospective, laboratory., Methods:: We designed and tested a series of microprocessor-based implantable devices that can stimulate glottic opening or closing based on input from physiological control signals (real-time processing of electromyographic [EMG] signals). After acute device testing experiments, 2 dogs were implanted for 8 and 24 months, with periodic testing of closed-loop laryngeal muscle stimulation triggered from EMG signals. In total, 5 dogs were tested for the effects of laryngeal muscle stimulation on vocal fold (VF) posturing in larynges with nerve supplies that were intact (7 VFs), synkinetically reinnervated (2 VFs), or chronically denervated (1 VF). In 3 cases, the stimulation was combined with airflow-driven phonation to study the consequent modulation of phonatory parameters., Results:: Initial device prototypes used inductive coupling for power and communication, while later iterations used battery power and infrared light communication (detailed descriptions are provided in the Part 1 companion paper). Two animals were successfully implanted with the inductively powered units, which operated until removed at 8 months in 1 animal or for more than 16 months in the second animal. Surgically, the encapsulated implants were well tolerated, and procedures for placing, attaching, and connecting the devices were developed. To simulate EMG control signals in anesthetized animals, we created 2 types of nerve/muscle signal sources. In one approach, a neck muscle had a cuff electrode placed on its motor nerve that was connected to transdermal electrical connection ports for periodic testing. In the second approach, the recurrent laryngeal nerve on one side of the larynx was stimulated to generate a VF EMG signal, which was then used to trigger FES of the paralyzed contralateral side (eg, restoring VF movement symmetry). Implant testing identified effective stimulation parameters and closed-loop stimulation artifact rejection techniques for FES of both healthy and paralyzed VFs. Stimulation levels effective for VF adduction did not cause signs of discomfort during awake testing., Conclusion:: Our inductive and battery-powered prototypes performed effectively during in vivo testing, and the 2 units that were implanted for long-term evaluation held up well. As a proof of concept, we demonstrated that elicited neck strap muscle or laryngeal EMG potentials could be used as a control signal for closed-loop stimulation of laryngeal adduction and vocal pitch modulation, depending on electrode positioning, and that VFs were stimulable in the presence of synkinetic reinnervation or chronic denervation.

Objectives:: Gels composed of carboxymethylcellulose (CMC) and cross-linked hyaluronic acid are commonly used as temporary or resorbable injectable materials for vocal fold medialization. However, there is limited information about tissue injection patterns, soft tissue reaction, degradation, and residence time, particularly for the newer CMC gels., Study Design:: Prospective, laboratory., Methods:: Ten canines underwent paraglottic (deep to the vocal ligament) microlaryngoscopic injection with about 100 µL (0.1 mL) of cross-linked hyaluronic acid (Restylane) in the right vocal fold and about 100 µl (0.1 mL) of CMC gel in the left vocal fold. Two commercial CMC gels of similar formulation (Prolaryn Gel and Renú Gel) were used in 5 animals each. Two subjects were sacrificed for histologic analysis at 3, 13, 29, 42, and 55 days., Results:: Histology showed that injected Restylane formed cohesive ovoid-shaped aggregated implants with minimal dispersion, inflammation, or cellular invasion in all subjects. Approximately 86% of Restylane injected remained at 8 weeks, as estimated from postmortem, high-resolution magnetic resonance imaging scans. In contrast, histology showed that both CMC gels dispersed widely through fascial planes during and after injection within and outside the thyroarytenoid muscle fascicles. There was a robust macrophage and histiocyte phagocytic response, with moderate to severe inflammation noted around residual CMC gel at early time points, and at 6 to 8 weeks, very little free gel was observed., Conclusions:: None of the studied materials induced a clinical inflammatory reaction on laryngoscopy such that they would be considered problematic or dangerous. Restylane demonstrated superior injection localization, tissue compatibility, and residence time. Both CMC gels did not localize well in the paraglottic region, and there was a robust inflammatory response, with clearance by macrophages and short residence time. These results suggest that CMC gels may have a more limited application than previously thought for vocal fold medialization in patients in whom the injection is being used to achieve voice enhancement while awaiting reinnervation. Level of Evidence: NA.

Introduction:: Endotracheal (ET) intubation is a common cause of acquired glottic stenosis. Severe cases often require an irreversible arytenoidectomy/cordectomy, which typically results in poor voice quality. Adult human cadaver larynges were studied to gain insights about ET tube-induced posterior glottic injuries, hoping to create a less invasive remedy., Study Design:: Human cadaver investigation and case reports., Methods:: Microlaryngeal assessments were done on 10 human cadaver larynges (5 men, 5 women) with and without ET tubes. After supracricoid soft tissue resection, measurements were obtained, including the distance between the outer diameter of the ET tube and the medial aspect of the cricoarytenoid joint facet. Additionally, measurements of the circumferential arc of differently sized ET tubes were made alongside both cricoarytenoid joint capsules. This information was used to design a silastic stent that would function as a self-retaining interarytenoid spring to treat posterior glottic stenosis in 5 patients. Four of 5 patients included in the clinical study were tracheotomy dependent, primarily because of glottic stenosis. The human surgical technique is described in detail., Results:: The shortest distance between the outer diameter of the ET tube to the medial cricoid facet averaged 5.02 mm in men and 3.62 mm in women. On the basis of the diameter of the intralaryngeal component of the initially round stent, and the position of the cricoarytenoid joint facets, the interarytenoid spring would have a subtended arc between 110° and 175°. These data helped fashion parameters for modifying a conventional T-tube to form a new self-retaining silastic interarytenoid spring. The first 5 human cases have been successful, allowing effective tracheotomy tube decannulation and excellent voice quality., Conclusions:: The anatomic investigation herein provided key insights into ET tube-induced glottic stenosis and facilitated a new straightforward procedure to surgically improve the airway yet preserve excellent vocal function in patients with acquired glottic stenosis. Level of Evidence: NA.

Objective: The purpose of this study was to determine (a) which factors may affect singers' completing voice therapy, and (b) develop predictive profiles to capture those singers at risk for dropping out of voice therapy., Study Design: A case-control study was conducted comparing singers who completed voice therapy to singers who dropped out of voice therapy., Methods: Six factors, including age, gender, diagnosis, length of time between laryngology referral and commencement of therapy, type of singer, and referral source were investigated in relation to voice therapy completion using the medical records of 409 singers in the Massachusetts General Hospital Voice Center database., Results: Referral source and type of singer were demonstrated to be the most robust predictor of singers' completion of therapy., Conclusions: Forty-seven percent of singers who were referred to voice therapy completed their course of treatment. Sixty percent of singers who dropped out of voice therapy were reliably identified based on what types of music they sing (type of singer) and who referred them for laryngology evaluation (referral source), aiding in early identification of those singers who may need additional support to reach their therapy goals. Identifying specific characteristics of singers completing or dropping out of voice therapy may allow medical professionals to better serve the specialized needs of singers who use their voices professionally and recreationally., (Copyright © 2018 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: Speech is among the most natural forms of human communication, thereby offering an attractive modality for human-machine interaction through automatic speech recognition (ASR). However, the limitations of ASR-including degradation in the presence of ambient noise, limited privacy and poor accessibility for those with significant speech disorders-have motivated the need for alternative non-acoustic modalities of subvocal or silent speech recognition (SSR)., Approach: We have developed a new system of face- and neck-worn sensors and signal processing algorithms that are capable of recognizing silently mouthed words and phrases entirely from the surface electromyographic (sEMG) signals recorded from muscles of the face and neck that are involved in the production of speech. The algorithms were strategically developed by evolving speech recognition models: first for recognizing isolated words by extracting speech-related features from sEMG signals, then for recognizing sequences of words from patterns of sEMG signals using grammar models, and finally for recognizing a vocabulary of previously untrained words using phoneme-based models. The final recognition algorithms were integrated with specially designed multi-point, miniaturized sensors that can be arranged in flexible geometries to record high-fidelity sEMG signal measurements from small articulator muscles of the face and neck., Main Results: We tested the system of sensors and algorithms during a series of subvocal speech experiments involving more than 1200 phrases generated from a 2200-word vocabulary and achieved an 8.9%-word error rate (91.1% recognition rate), far surpassing previous attempts in the field., Significance: These results demonstrate the viability of our system as an alternative modality of communication for a multitude of applications including: persons with speech impairments following a laryngectomy; military personnel requiring hands-free covert communication; or the consumer in need of privacy while speaking on a mobile phone in public.

Each year thousands of individuals require surgical removal of their larynx (voice box) due to trauma or disease, and thereby require an alternative voice source or assistive device to verbally communicate. Although natural voice is lost after laryngectomy, most muscles controlling speech articulation remain intact. Surface electromyographic (sEMG) activity of speech musculature can be recorded from the neck and face, and used for automatic speech recognition to provide speech-to-text or synthesized speech as an alternative means of communication. This is true even when speech is mouthed or spoken in a silent (subvocal) manner, making it an appropriate communication platform after laryngectomy. In this study, 8 individuals at least 6 months after total laryngectomy were recorded using 8 sEMG sensors on their face (4) and neck (4) while reading phrases constructed from a 2,500-word vocabulary. A unique set of phrases were used for training phoneme-based recognition models for each of the 39 commonly used phonemes in English, and the remaining phrases were used for testing word recognition of the models based on phoneme identification from running speech. Word error rates were on average 10.3% for the full 8-sensor set (averaging 9.5% for the top 4 participants), and 13.6% when reducing the sensor set to 4 locations per individual (n=7). This study provides a compelling proof-of-concept for sEMG-based alaryngeal speech recognition, with the strong potential to further improve recognition performance.

Objectives: Low-level light therapy (LLLT) is effective in reducing inflammation, promoting wound healing, and preventing tissue damage, but has not yet been studied in the treatment of voice disorders. The objective of this study was to investigate the possible effectiveness of LLLT in attenuating symptoms of vocal fatigue created by a vocal loading task as measured by acoustic, aerodynamic, and self-reported vocal effort., Methods: In a randomized, prospective study, 16 vocally healthy adults divided into four groups underwent a 1-hour vocal loading procedure, followed by infrared wavelength LLLT (828 nm), red wavelength LLLT (628 nm), heat, or no heat-light (control) treatment targeting the laryngeal region of the ventral neck surface. Phonation threshold pressure (PTP), relative fundamental frequency (RFF), and the inability to produce soft voice (IPSV) self-perceptual rating scale were recorded (1) at baseline, (2) immediately after vocal loading, (3) after treatment, and (4) 1 hour after treatment., Results: Vocal loading significantly increased PTP and IPSV and decreased onset and offset RFFs, consistent with a shift toward vocal dysfunction. Red light significantly normalized the combination of PTP, IPSV, and RFF measures compared to other conditions., Conclusions: RFF is sensitive to a vocal loading task in conjunction with PTP and IPSV, and red LLLT may have a normalizing effect on objective and subjective measures of vocal fatigue. The results of this study lay the groundwork and rationale for future research to optimize LLLT wavelength combinations and overall dose., (Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives/hypothesis: Injury to the recurrent laryngeal nerve (RLN) is a dreaded complication of endocrine surgery. Intraoperative neural monitoring (IONM) has been increasingly utilized to assess the functional status of the RLN. Although the posterior cricoarytenoid muscle (PCA) is innervated by the RLN as the abductor of the larynx, PCA electromyography (EMG) is infrequently recorded during IONM and PCA activity after RLN compressive injury remains poorly characterized., Study Design: Single-subject prospective animal study., Methods: We employed a canine model to identify postcricoid EMG correlates of postoperative vocal cord paralysis (VCP). Postcricoid electrode recordings were obtained before and after compressive RLN injury associated with VCP., Results: Normative postcricoid recordings revealed mean amplitude of 1288 microvolt (μV) and latency of 8.2 millisecond (ms) with maximum (1 milliamp [mA]) vagal stimulation, and mean amplitude of 1807 μV and latency of 3.5 ms with maximum (1 mA) RLN stimulation. Following injury that was associated with VCP, there was 62.1% decrement in postcricoid EMG amplitude with maximum vagal stimulation and 80% decrement with maximum RLN stimulation. Threshold stimulation of the vagus increased by 23%, and there was a corresponding 42% decrease in amplitude. For RLN stimulation, latency increased by 17.3% following injury, whereas threshold stimulation increased by 61% with 35.5% decrement in EMG amplitude. Thus, if RLN amplitude decreases by ≥ 80%, with absolute amplitude of ≤ 300 μV or less and latency increase of ≥ 10%, RLN injury is likely associated with VCP., Conclusion: Our results predict postoperative VCP based on postcricoid electromyographic IONM and may guide surgical decision making., Level of Evidence: NA Laryngoscope, 126:2744-2751, 2016., (© 2016 The American Laryngological, Rhinological and Otological Society, Inc.)

Purpose: Accurate estimation of daily patterns of vocal behavior is essential to understanding the role of voice use in voice disorders. Given that clinicians currently rely on patient self-report to assess daily vocal behaviors, this study sought to assess the accuracy with which adults with and without voice disorders can estimate their amount of daily voice use in terms of phonation time., Method: Eighteen subjects (6 patients, 6 matched members of a control group without voice disorders, 6 low voice users) wore the accelerometer-based Ambulatory Phonation Monitor (APM; model 3200, KayPENTAX, Montvale, NJ) for at least 5 workdays. Subjects were instructed to provide hourly self-reports of time spent talking using a visual analog scale. Spearman correlation coefficients and errors between self-reported and APM-based estimates of phonation time revealed subject- and group-specific characteristics., Results: A majority of subjects exhibited a significant bias toward overestimating their phonation times, with an average absolute error of 113%. Correlation coefficients between self-reported and APM-based estimates of phonation time ranged from statistically nonsignificant to .91, reflecting large intersubject variability., Conclusions: Subjects in all 3 groups were moderately accurate at estimating their hourly voice use, with a consistent bias toward overestimation. The results support the potential role that ambulatory monitoring could play in improving the clinical assessment of voice disorders.

An electrolarynx (EL) is a valuable rehabilitative option for individuals who have undergone laryngectomy, but current monotone ELs do not support controlled variations in fundamental frequency for producing tonal languages. The present study examined the production and perception of Mandarin Chinese using a customized hand-held EL driven by computer software to generate tonal distinctions (tonal EL). Four native Mandarin speakers were trained to articulate their speech coincidentally with preprogrammed tonal patterns in order to produce mono- and di-syllabic words with a monotone EL and tonal EL. Three native Mandarin speakers later transcribed and rated the speech samples for intelligibility and acceptability. Results indicated that words produced using the tonal EL were significantly more intelligible and acceptable than those produced using the monotone EL.

Background: Recurrent laryngeal nerve (RLN) injury is a known complication of thyroid/parathyroid surgery. Intraoperative nerve monitoring (IONM) has been used to gain more information regarding the functional status of the RLN intraoperatively; however, the electromyography (EMG) parameters of RLN after nontransection neuropraxic compressive injury remain unknown., Methods: We developed a canine model to identify IONM EMG correlates of postoperative vocal cord paralysis (VCP) using a standardized method to simulate surgical RLN compression sufficient to cause VCP., Results: Compression nerve injury decreased EMG amplitude and increased EMG latency, with a 60% increase in RLN threshold stimulation compared to preinjury values. If RLN amplitude decreases by 80% with an absolute amplitude of 300 μV or less in combination with a latency increase of 10% or more, then nerve injury and associated VCP is likely., Conclusion: These results may help surgeons to prognosticate postoperative neural function and intraoperative decision-making regarding contralateral thyroid surgery. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1341-E1350, 2016., (© 2015 Wiley Periodicals, Inc.)

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.

Background: Elicitation of eye closure and other movements via electrical stimulation may provide effective treatment for facial paralysis. The authors performed a human feasibility study to determine whether transcutaneous neural stimulation can elicit a blink in individuals with acute facial palsy and to obtain feedback from participants regarding the tolerability of surface electrical stimulation for daily blink restoration., Methods: Forty individuals with acute unilateral facial paralysis, HB grades 4 through 6, were prospectively studied between 6 and 60 days of onset. Unilateral stimulation of zygomatic facial nerve branches to elicit eye blink was achieved with brief bipolar, charge-balanced pulse trains, delivered transcutaneously by adhesive electrode placement; results were recorded on a high-speed video camera. The relationship between stimulation parameters and cutaneous sensation was analyzed using the Wong-Baker Faces Pain Rating Scale., Results: Complete eye closure was achieved in 55 percent of participants using stimulation parameters reported as tolerable. In those individuals, initial eye twitch was observed at an average current of 4.6 mA (±1.7; average pulse width of 0.7 ms, 100 to 150 Hz), with complete closure requiring a mean of 7.2 mA (±2.6)., Conclusions: Transcutaneous facial nerve stimulation may artificially elicit eye blink in a majority of patients with acute facial paralysis. Although individuals varied widely in their reported degrees of discomfort from blink-eliciting stimulation, most of them indicated that such stimulation would be tolerable if it could restore eye closure. These patients would therefore benefit from a biomimetic device to facilitate eye closure until the recovery process is complete., Clinical Question/level of Evidence: Therapeutic, IV.

Background: Obesity is a major risk factor for the development of diabetes. Limb ischemia-reperfusion injury (IR) is a common clinical problem in diabetics who have compromised lower extremity perfusion. This study compared the histologic, metabolic, and functional outcomes after hind limb IR in diet-induced obese (DIO) and non-diabetic (ND) mice during the acute and the regenerative phases of IR., Methods: DIO and ND mice were subjected to 1.5 h unilateral hind limb ischemia followed by 1- or 28-d IR. Muscle morphology, metabolic, and genomic stress were evaluated at days 1 and 28 IR; Acute inflammation and thrombosis were only measured at day-1 IR. At day 28, IR, skeletal muscle contractility, and maturation were also assessed., Results: At day-1 IR, similar levels of acute muscle fiber necrosis were seen in both groups. DIO mice demonstrated substantially greater inflammatory, prothrombotic, and genomic stress responses, which were also associated with a greater reduction in energy substrates and Akt phosphorylation. At 28d, there was no difference in the peak forces generated in the hind limbs for the two groups. DIO mice had reduced fatigue resistance compared with ND and larger areas of fat accumulation although there was no significant difference in muscle fiber maturation., Conclusions: DIO mice had an exacerbated acute response to IR with enhanced metabolic deficit, fat accumulation, and defective functional recovery during the regenerative phase of IR. These changes in fatigue resistance reflect compromised functional recovery after IR injury and have relevance for the functional recovery of patients with metabolic syndrome and insulin resistance., (Copyright © 2014 Elsevier Inc. All rights reserved.)

IMPORTANCE Facial paralysis remains one of the most challenging conditions to effectively manage, often causing life-altering deficits in both function and appearance. Facial rehabilitation via pacing and robotic technology has great yet unmet potential. A critical first step toward reanimating symmetrical facial movement in cases of unilateral paralysis is the detection of healthy movement to use as a trigger for stimulated movement. OBJECTIVE To test a blink detection system that can be attached to standard eyeglasses and used as part of a closed-loop facial pacing system. DESIGN, SETTING, AND PARTICIPANTS Standard safety glasses were equipped with an infrared (IR) emitter-detector unit, oriented horizontally across the palpebral fissure, creating a monitored IR beam that became interrupted when the eyelids closed, and were tested in 24 healthy volunteers from a tertiary care facial nerve center community. MAIN OUTCOMES AND MEASURES Video-quantified blinking was compared with both IR sensor signal magnitude and rate of change in healthy participants with their gaze in repose, while they shifted their gaze from central to far-peripheral positions, and during the production of particular facial expressions. RESULTS Blink detection based on signal magnitude achieved 100% sensitivity in forward gaze but generated false detections on downward gaze. Calculations of peak rate of signal change (first derivative) typically distinguished blinks from gaze-related eyelid movements. During forward gaze, 87% of detected blink events were true positives, 11% were false positives, and 2% were false negatives. Of the 11% false positives, 6% were associated with partial eyelid closures. During gaze changes, false blink detection occurred 6% of the time during lateral eye movements, 10% of the time during upward movements, 47% of the time during downward movements, and 6% of the time for movements from an upward or downward gaze back to the primary gaze. Facial expressions disrupted sensor output if they caused substantial squinting or shifted the glasses. CONCLUSIONS AND RELEVANCE Our blink detection system provides a reliable, noninvasive indication of eyelid closure using an invisible light beam passing in front of the eye. Future versions will aim to mitigate detection errors by using multiple IR emitter-detector units mounted on glasses, and alternative frame designs may reduce shifting of the sensors relative to the eye during facial movements.

Vibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic denervation was from autonomic, cholinergic axons traveling within the infraorbital branch of the trigeminal nerve (ION). Rats underwent unilateral facial nerve transection with repair (N=7) or resection without repair (N=11). Post-operative whisking amplitude was measured weekly across 10weeks, and during intraoperative stimulation of the ION and facial nerves at ⩾18weeks. Whisking was also measured after subsequent ION transection (N=6) or pharmacologic blocking of the autonomic ganglia using hexamethonium (N=3), and after snout cooling intended to elicit a vasodilation reflex (N=3). Whisking recovered more quickly and with greater amplitude in rats that underwent facial nerve repair compared to resection (P<0.05), but individual rats overlapped in whisking amplitude across both groups. In the resected rats, non-facial-nerve-mediated whisking was elicited by electrical stimulation of the ION, temporarily diminished following hexamethonium injection, abolished by transection of the ION, and rapidly and significantly (P<0.05) increased by snout cooling. Moreover, fibrillation-related whisker movements decreased in all rats during the initial recovery period (indicative of reinnervation), but re-appeared in the resected rats after undergoing ION transection (indicative of motor denervation). Cholinergic, parasympathetic axons traveling within the ION innervate whisker pad vasculature, and immunohistochemistry for vasoactive intestinal peptide revealed these axons branching extensively over whisker pad muscles and contacting neuromuscular junctions after facial nerve resection. This study provides the first behavioral and anatomical evidence of spontaneous autonomic innervation of skeletal muscle after motor nerve lesion, which not only has implications for interpreting facial nerve reinnervation results, but also calls into question whether autonomic-mediated innervation of striated muscle occurs naturally in other forms of neuropathy., (Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.)

Objectives/hypothesis: To quantify the threshold for human perception of asymmetry for eyebrow elevation, eye closure, and smile, and to ascertain whether asymmetry detection thresholds and perceived severity of asymmetry differ in distinct facial zones., Study Design: Online survey., Methods: Photographs of a female volunteer performing eyebrow elevation, eye closure, and smile were digitally manipulated to introduce left-to-right asymmetry in 1-mm increments from 0 mm to 6 mm. One hundred and forty-five participants viewed these photographs using an online survey, measuring accuracy of asymmetry detection and perceived expression unnaturalness (on a scale of 1-5)., Results: Photographs of facial asymmetries were correctly judged as asymmetrical over 90% of the time for 2 mm or more of asymmetry in eyelid closure, and 3 mm or more of asymmetry during smiling. Identification of eyebrow elevation asymmetry gradually rose from 23% correct to 97% correct across the range of 1 mm to 6 mm of asymmetry. Greater degrees of asymmetry were ranked as significantly more unnatural across all expressions (3 tests; X(2) (6, N = 145) = 405.52 to 656.27, all P <0.001)., Conclusion: Thresholds for asymmetry detection vary across different zones of the face; once detected, asymmetry in eyelid position is perceived as more unnatural than asymmetries in either brow elevation or smile. These data will inform counseling of patients with segmental facial weakness and may provide more objective goals for facial reanimation procedures., Level of Evidence: 4., (© 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

IMPORTANCE Recovery from facial nerve transection is typically poor, but daily mechanical stimulation of the face in rats has been reported to remarkably enhance functional recovery after facial nerve transection and suture repair. This phenomenon needs additional investigation because of its important clinical implications. OBJECTIVE To determine whether automated mechanical stimulation of the whisker pad improves whisking recovery after facial nerve transection and repair in a rat model. DESIGN AND SETTING Sixty-one rats underwent unilateral facial nerve transection and suture repair and were randomized into 8 groups. Six groups received daily automated whisker or whisker pad mechanical stimulation including 0.5-, 1.5-, and 8.0-Hz patterns. Two control groups received restraint without stimulation. Treatment started on postoperative day 8, occurred 5 days per week, and lasted throughout 15 weeks of recovery. Whisking amplitude, velocity, and acceleration were quantified weekly for 15 weeks. INTERVENTIONS Unilateral facial nerve transection, suture repair, and, for 6 groups, daily automated whisker or whisker pad mechanical stimulation. MAIN OUTCOMES AND MEASURES Quantification of whisking amplitude, velocity, and acceleration. RESULTS Rats receiving the low frequencies of stimulation of the whiskers or whisker pad did not demonstrate enhanced whisking recovery, and rats receiving stimulation at 8.0 Hz showed significantly worse whisking recovery compared with controls and previously published groups receiving lower dose manual stimulation. CONCLUSIONS AND RELEVANCE Although daily manual whisker pad stimulation has been shown to enhance whisking recovery, rats in this study did not demonstrate improved whisking recovery after automated mechanical stimulation across a wide range of driving frequencies. Moreover, faster stimulation (8.0 Hz) was actually detrimental to recovery. Further work is needed to understand the relationship between stimulation patterns and the physiologic mechanisms underlying improved or worsened functional outcomes after facial nerve transection and repair.

Importance: Cable grafting is widely considered to be the preferred alternative to primary repair of the injured facial nerve; however, quantitative comparison of the 2 techniques has not been previously undertaken in a rodent model., Objective: To establish functional recovery parameters after interposition autografting in a rodent facial nerve model., Design, Setting, and Participants: Prospective randomized animal study at a tertiary care facial nerve center using 16 female Wistar Hannover rats., Intervention: The experimental group received reversed autograft reconstruction of a 20-mm neural gap, and the control group received facial nerve transection and primary repair., Main Outcome and Measure: Whisker excursion was measured weekly for 70 postoperative days using laser micrometers., Results: The control group exhibited the most rapid recovery, with substantial return of whisker movement occurring during the third postoperative week. The experimental group demonstrated return of function beginning in the fourth postoperative week, eventually achieving a degree of function comparable to that of the control group by the sixth postoperative week (P = .68)., Conclusions and Relevance: Recovery of facial function after cable grafting seems to be slower than, but eventually similar to, recovery after primary neurorrhaphy in a rodent model. In the present study we have established a benchmark for recovery of whisker movement across a 20-mm rodent facial nerve gap, which will be used for comparison of different facial nerve gap bridging materials in future studies., Level of Evidence: NA.

Importance: In this study, we examined whether specific facial movements have different time-delay detection thresholds, and to what extent such side-to-side facial movement asymmetry affects subjective ratings of movement naturalness. Ratings of dynamic asymmetry in experimentally manipulated video recordings demonstrate that there are different side-to-side time-delay thresholds for distinct regions of the face, with a strong inverse correlation between naturalness rating and the length-of-time delay. These findings will be helpful for counseling patients with unilateral facial paralysis and guide the design of neural interfaces for facial reanimation., Objective: To determine the detection threshold of side-to-side facial movement timing asymmetry and measure its effect on perceived movement naturalness., Design, Setting, and Participants: Videos of 5 symmetrical facial movements (eye blink, rapid eyebrow raising, slow eyebrow raising, smiling, and lip depression) were edited to introduce 6 levels of side-to-side timing asymmetry, ranging from 33 to 267 milliseconds. Participants (N = 58) viewed video clips through an online survey service, indicating whether they noticed side-to-side asymmetry and judging movement naturalness on a 5-point scale., Results: There was a significant difference among facial movements in asymmetry detection threshold. There was a strong correlation between naturalness ratings and amount of delay across movements (R = 0.823), with greater asymmetry being judged as progressively less natural. Blink was judged as less natural at 33, 67, 100, and 133 milliseconds of side-to-side delay compared with all other movements (P < .005)., Conclusions and Relevance: Side-to-side asymmetry in blink timing is detected sooner and viewed as less natural compared with asymmetry of the eyebrow and lips. At 100 milliseconds of delay, nearly all movements are detected as asymmetric, although blink is judged as the least natural. These findings will help set timing goals for facial pacing technologies treating unilateral paralysis., Level of Evidence: NA.

Functional recovery is typically poor after facial nerve transection and surgical repair. In rats, whisking amplitude remains greatly diminished after facial nerve regeneration, but can recover more completely if the whiskers are periodically mechanically stimulated during recovery. Here we present a robotic "whisk assist" system for mechanically driving whisker movement after facial nerve injury. Movement patterns were either preprogrammed to reflect natural amplitudes and frequencies, or movements of the contralateral (healthy) side of the face were detected and used to control real-time mirror-like motion on the denervated side. In a pilot study, 20 rats were divided into nine groups and administered one of eight different whisk assist driving patterns (or control) for 5-20 minutes, five days per week, across eight weeks of recovery after unilateral facial nerve cut and suture repair. All rats tolerated the mechanical stimulation well. Seven of the eight treatment groups recovered average whisking amplitudes that exceeded controls, although small group sizes precluded statistical confirmation of group differences. The potential to substantially improve facial nerve recovery through mechanical stimulation has important clinical implications, and we have developed a system to control the pattern and dose of stimulation in the rat facial nerve model.

Objectives/hypothesis: Repair of the transected facial nerve has traditionally been accomplished with microsurgical neurorrhaphy; however, fibrin adhesive coaptation (FAC) of peripheral nerves has become increasingly popular over the past decade. We compared functional recovery following suture neurorrhaphy to FAC in a rodent facial nerve model., Study Design: Prospective, randomized animal study., Methods: Sixteen rats underwent transection and repair of the facial nerve proximal to the pes anserinus. Eight animals underwent epineurial suture (ES) neurorrhaphy, and eight underwent repair with fibrin adhesive (FA). Surgical times were documented for all procedures. Whisking function was analyzed on a weekly basis for both groups across 15 weeks of recovery., Results: Rats experienced whisking recovery consistent in time course and degree with prior studies of rodent facial nerve transection and repair. There were no significant differences in whisking amplitude, velocity, or acceleration between suture and FA groups. However, the neurorrhaphy time with FA was 70% shorter than for ES (P < 0.05)., Conclusion: Although we found no difference in whisking recovery between suture and FA repair of the main trunk of the rat facial nerve, the significantly shorter operative time for FA repair makes this technique an attractive option. The relative advantages of both techniques are discussed., (Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.)

Objective: To describe denervation features of facial musculature following facial nerve injury in a rodent model., Methods: Six Wistar-Hannover rats underwent unilateral transection and immediate repair of the facial nerve. After 8 weeks, muscular bundles consisting of dilator naris and levator labii superioris from both sides were analyzed for mean muscle cell diameter and the percentage of muscle cell cross-sectional area using image processing software. The atrophic features of facial muscles were quantified and compared with the contralateral, healthy side of the face., Results: Weekly postoperative whisking assessment demonstrated the anticipated course of recovery. We observed significant differences between the normal side and the manipulated side, respectively, in the percentage of muscle specimen cross-sectional area attributable to muscle cell profiles (57% vs 29%; P = .006) and total fiber counts (1346 vs 794; P = .02). The mean cross-sectional area of individual muscle fibers was higher on the normal side (1129 vs 928 μm2; P = .39); however, this difference was statistically nonsignificant., Conclusion: The objective, quantitative measures of muscle microstructure used in this report provide a valuable point of comparison for whisking function and electrophysiologic measures and can be used in future studies to assess muscle atrophic features associated with facial nerve injury and repair techniques.

Objectives/hypothesis: Vocal fold (VF) injections of viscous materials are typically performed using hand-operated syringes or injection guns; however, these methods can be imprecise due to accumulation of pressure, effort-related tremor, and poor feedback regarding injection volume and rate., Study Design: Apparatus development with laboratory bench-top and animal model testing., Methods: A foot pedal-triggered device for dispensing viscous materials was modified by adding a linear transducer and display for monitoring dispensed volume. In bench tests, bovine VFs were injected with fluids/materials of different viscosities (saline, glycerol, hydrogel, and liposuctioned fat) through narrow-bore needles using a range of driving pressures and air pulse durations. The device was further evaluated in >50 in vivo VF injection experiments., Results: Device function was repeatable, with high correlations (typically R(2) > 0.98) between the readout and direct measures of volume, even for small volumes (<5 μL/pulse). Foot pedal control enabled surgeons to make steady, accurate injections into ferret and dog VFs during phonosurgery, and, because the dispenser released all driving pressure between pulses, there were no instances of clog-related overinjection when the obstruction cleared., Conclusions: This VF injection system shows promise for development to enhance human phonosurgery by increasing injection control and precision., (Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.)

Objectives: Minimizing collateral thermal damage during endoscopic laryngeal laser surgery remains a priority, and tissue cooling is one way to achieve this goal. Cooling systems utilizing compressed air have been shown to reduce the extent of thermal trauma on the vocal folds, but these units are not ideal for endoscopic applications because cooling is inefficient at the low airflows needed. We examined whether a novel vortex cooling device that generates cooled air at low flow rates would provide a cooling benefit beyond that which could be obtained by using room-temperature air for cooling tissue or by using no cooling during simulated laryngeal laser surgery., Methods: A continuous-wave thulium laser was used to incise glottic tissue in 12 calf vocal folds. Cooling was achieved with a prototype vortex cooler (9 degrees C air output; flow rate, 3 L/min), and tissue temperature measurements were compared to those with room-air cooling and no cooling. Thermal damage was analyzed histologically by measuring the depth of lactate dehydrogenase inactivation surrounding the mucosal incision. The cooling conditions were tested during time-constant cuts (8 seconds) and depth-constant cuts (into the thyroarytenoid muscle)., Results: During time-constant cuts, comparison between vortex cooling and room-air cooling revealed that vortex cooling resulted in a thermal damage zone that was 14% smaller (519 versus 603 microm; p < 0.05). During depth-constant cuts, vortex cooling created a thermal damage zone that was 32% smaller than that created with no cooling (p <0.01) and 9% smaller than that created with room-air cooling (p < 0.01)., Conclusions: Vortex cooling reduces thermal damage more effectively than room-air cooling or no cooling during both time-constant and depth-constant thulium laser cuts.

Introduction: Rodent whisking behavior is supported by the buccal and mandibular branches of the facial nerve, but a description of how these branches converge and contribute to whisker movement is lacking., Methods: Eight rats underwent isolated transection of either the buccal or mandibular branch and subsequent opposite branch transection. Whisking function was analyzed after both transections. Anatomical measurements, and video recording of stimulation to individual branches, were taken from both facial nerves in 10 rats., Results: Normal to near-normal whisking was demonstrated after isolated branch transection. Whisking was eliminated after transection of both branches. The buccal and mandibular branches form a convergence just proximal to the whisker pad, herein called "distal pes." Distal to this convergence, we identified consistent anatomy that demonstrated cross-innervation., Conclusion: The overlap of efferent supply to the whisker pad must be considered when studying facial nerve regeneration in the rat facial nerve model., (Copyright © 2012 Wiley Periodicals, Inc.)

Purpose: The goals of this study were to determine if there were significant differences between singers and nonsingers in the morphology of vocal nodules and the associated impact on vocal function., Method: Participants were 10 professionally trained singers with nodules, eight nonsingers with nodules, and 10 individuals with healthy normal voice (controls). Surface electromyography (sEMG) from three anterior neck locations and acoustic rise times for vowels /a/ and /i/ were measured in all the participants. In individuals with nodules, dB SPL/cm H(2)O, glottal airflow, and nodule location and size were also measured., Results: There were no significant differences between singers and nonsingers with nodules in terms of airflow, dB SPL/cm H(2)O, nodule size, or nodule location. In nonsingers with nodules, airflow and nodule size were significantly correlated, but were not significantly correlated in singers. Vowel rise times and sEMG during vocal tasks did not differentiate among nodule and control groups. Sternocleidomastoid sEMG during initiation of the vowel /a/ was statistically significantly stronger in nonsingers with nodules relative to singers with nodules and controls., Conclusions: Nodule morphology did not differ between singers and nonsingers, although some behavioral aspects of phonation differed between the groups., (Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Purpose: The purpose of this study was to determine whether the relative fundamental frequency (RFF) surrounding a voiceless consonant in patients with hyperfunctionally related voice disorders would normalize after a successful course of voice therapy., Method: Pre- and posttherapy measurements of RFF were compared in 16 subjects undergoing voice therapy for voice disorders associated with vocal hyperfunction., Results: A 2-way analysis of variance showed a statistically significant effect of both cycle of vibration near the consonant and therapy phase (pre- vs. post-), with p < .001. A post hoc paired Student's t test showed that posttherapy RFF measurements were significantly higher (more typical; p < .0001) than pretherapy measurements., Conclusions: Prior to therapy, participants exhibited lowered RFF values, similar to those found previously (Stepp, Hillman, & Heaton, 2010). After successful completion of voice therapy, RFF values increased toward patterns seen previously in individuals with healthy typical voice. The goal of voice therapy in these patients was to reduce laryngeal muscle tension; therefore, the increase of RFF toward more typical values may be indicative of decreased baseline laryngeal muscle tension resulting from therapy. Results are discussed further in terms of necessary research to incorporate RFF as a clinical measure of vocal hyperfunction.

Purpose: The purpose of this study was to better understand neck intermuscular beta coherence (15-35 Hz; NIBcoh) in healthy individuals, with respect to modulation by behavioral tasks., Method: Mean NIBcoh was measured using surface electromyography at 2 anterior neck locations in 10 individuals during normal speech, static nonspeech maneuvers, "clear" speech (intentionally produced to maximize intelligibility), divided-attention speech, singing, and mimicked hyperfunctional speech., Results: An analysis of variance showed significant effects of both individual and condition (p = .001) on the mean beta-band intermuscular coherence. Dunnett's simultaneous paired t tests found decreased NIBcoh during low-attention speech, singing, and hyperfunctional speech (p(adj) < .05), but no significant difference in NIBcoh during nonspeech tasks or clear speech production relative to normal speech., Conclusions: Compared with normal speech, mean NIBcoh was decreased in a divided-attention speech task, but clear speech did not result in increased mean coherence relative to normal speech, possibly due to ceiling effects caused by heightened attention and precision during experimental recording. Mimicking a strained, hyperfunctional voice resulted in a reduction in mean beta intermuscular coherence quantitatively and qualitatively similar to the lowered values of mean beta coherence seen in individuals with vocal nodules relative to individuals with normal voice.

Objectives: Most cases of irresolvable hoarseness are due to deficiencies in the pliability and volume of the superficial lamina propria of the phonatory mucosa. By using a US Food and Drug Administration-approved polymer, polyethylene glycol (PEG), we created a novel hydrogel (PEG30) and investigated its effects on multiple vocal fold structural and functional parameters., Methods: We injected PEG30 unilaterally into 16 normal canine vocal folds with survival times of 1 to 4 months. High-speed videos of vocal fold vibration, induced by intratracheal airflow, and phonation threshold pressures were recorded at 4 time points per subject. Three-dimensional reconstruction analysis of 11.7 T magnetic resonance images and histologic analysis identified 3 cases wherein PEG30 injections were the most superficial, so as to maximally impact vibratory function. These cases were subjected to in-depth analyses., Results: High-speed video analysis of the 3 selected cases showed minimal to no reduction in the maximum vibratory amplitudes of vocal folds injected with PEG30 compared to the non-injected, contralateral vocal fold. All PEG30-injected vocal folds displayed mucosal wave activity with low average phonation threshold pressures. No significant inflammation was observed on microlaryngoscopic examination. Magnetic resonance imaging and histologic analyses revealed time-dependent resorption of the PEG30 hydrogel by phagocytosis with minimal tissue reaction or fibrosis., Conclusions: The PEG30 hydrogel is a promising biocompatible candidate biomaterial to restore form and function to deficient phonatory mucosa, while not mechanically impeding residual endogenous superficial lamina propria.

The most common artificial voice source for post-laryngectomy speech rehabilitation is the handheld buzzer or electrolarynx (EL). EL speech is often described as mechanical-sounding (robotic), and typically lacks pitch variation, making it monotone and unnatural. Prior studies have shown improved perceptual ratings of speech naturalness when pitch variation is added to EL speech, and a proof-of-concept EL prosthesis has been developed to provide pitch variation and voice on/off control in relation to neck muscle electromyographic (EMG) signals. The goal of the present study was to design a new wireless version of the EMG-controlled EL (EMG-EL) that could provide a flexible mixture of manual (push button) and automatic (EMG-based) control options for voice onset/offset and pitch, and that could be manufactured at a reasonable cost for widespread patient use. This paper describes both technical and human factors considered while designing the new EMG-EL voice prosthesis.

The purpose of this study was to evaluate current neck tension palpation rating systems to determine interrater reliability and possible correlation with necksurface electromyography (sEMG, collected from three electrode recording locations) and to measure the third formant for /a/ during various vocal behaviors. This prospective study examined the neck muscle tension of 16 participants before and after a single session of voice therapy. Interrater reliability and relationships between palpation ratings and objective measures of sEMG (anterior neck) and the third formant for /a/ were assessed using Pearson's correlations (r). Interrater reliability was relatively low as measured by Pearson's correlations, although Wilcoxon signed-rank test results were similar as those in a previous study. Correlations between palpation ratings and sEMG and between ratings of laryngeal height and the third formant for /a/ were generally low. Correlations increased between anterior neck sEMG and ratings of suprahyoid muscle tension when examined in a reduced set of individuals with higher interrater reliability. Palpation rating scales do not reliably capture changes that may occur in neck muscle tension of typical voice therapy patients over one session. Consequently, little can be concluded from correlations between sEMG and palpation ratings., (Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Objective: To evaluate whether a series of pharmacologic agents with potential neuroprotective effects accelerate and/or improve facial function recovery after facial nerve crush injury., Study Design: Randomized animal study., Setting: Tertiary care facility., Methods: Eighty female Wistar-Hannover rats underwent head restraint implantation and daily conditioning. Animals then underwent unilateral crush injury to the main trunk of the facial nerve and were randomized to receive treatment with atorvastatin (n = 10), sildenafil (n = 10), darbepoetin (n = 20), or a corresponding control agent (n = 40). The return of whisking function was tracked throughout the recovery period., Results: All rats initiated the return of whisking function from nerve crush by day 12. Darbepoetin-treated rats (n = 20) showed significantly improved whisking amplitude and velocity across the recovery period, with several days of significant pairwise differences vs comparable control rats (n = 16) across the first 2 weeks of whisking function return. In contrast, rats treated with sildenafil (n = 10) and atorvastatin (n = 10) did not show significant improvement in whisking function recovery after facial nerve crush compared to controls. By week 8, all darbepoetin-treated animals and comparable nerve crush control animals fully recovered whisking function and were statistically indistinguishable., Conclusion: Among the 3 potentially neuroprotective agents evaluated, only darbepoetin administration resulted in accelerated recovery of whisking parameters after facial nerve crush injury. Further efforts to define the mechanism of action and translate these findings to the use of darbepoetin in the care of patients with traumatic facial paralysis are needed.

sEMG based silent speech recognition systems seek to bypass the limitations of acoustic speech recognition by measuring and interpreting muscle activity of the facial and neck musculature involved in speech production. However, this speech recognition modality introduces unique challenges of its own. This paper describes signal acquisition and processing strategies that we have employed to address these challenges during our development of a silent speech recognition system.

Purpose: This study tested the hypothesis that individuals with vocal hyperfunction would show decreases in relative fundamental frequency (RFF) surrounding a voiceless consonant., Method: This retrospective study of 2 clinical databases used speech samples from 15 control participants and women with hyperfunction-related voice disorders: 82 prior to treatment (muscle tension dysphonia, n=22; vocal fold nodules, n=30; vocal fold polyps, N=30) and 18 before and after surgical removal of vocal fold nodules or polyps. Acoustic samples were analyzed with respect to the RFF at the offset and onset of voicing surrounding a voiceless consonant., Results: Individuals with vocal hyperfunction in a large clinical sample showed significant lowering of offset and onset RFF compared with controls. Voicing offset and onset RFFs were not significantly changed by the removal of vocal fold lesions in the surgical group., Conclusions: Altered offset and onset RFF in patients with hyperfunction-related voice disorders can be interpreted as a by-product of heightened levels of laryngeal muscle tension. Measurement of RFF during voice offset and onset has potential for use as a simple, noninvasive measure of vocal hyperfunction.

Objectives: To evaluate whether the timing of early (≤6 months from time of nerve injury) vs. late (>6 months) injection medialization laryngoplasty impacts the need for subsequent open-neck reconstruction to restore vocal function in patients with unilateral vocal cord paralysis., Study Design: Retrospective chart review., Methods: A total of 112 outpatient or hospitalized adults with dysphonia resulting from postsurgical or idiopathic unilateral vocal cord paralysis were identified who were injected as initial treatment within 1 year of onset of their paralysis. All subjects underwent awake, transoral, paraglottic injection with absorbable hyaluronic-acid gel. Patients with documented recovery of vocal cord mobility (22), active disease directly affecting the recurrent laryngeal nerve (8), <3 months of follow-up after injection (time for gel to be reabsorbed) (34), or deaths within 1 year after the onset of paralysis (13) were excluded, leaving a study population of 35 patients., Results: Twenty of 32 (62.5%) patients with early injection medialization maintained an adequate voice, obviating the need for open-neck phonosurgical reconstruction; their follow-up from onset of paralysis ranged from 4.0 to 41.8 months (mean 15.2). None of the three patients undergoing late injection (>6 months postparalysis) avoided phonosurgical reconstruction (P = .03, χ2 test)., Conclusions: Patients receiving early injection medialization for vocal cord paralysis were less likely to require transcervical reconstruction. We believe that early medialization creates a more favorable vocal cord position for phonation that can be maintained by synkinetic reinnervation, in contrast to the final position of a lateralized vocal cord being determined solely by reinnervation.

Objectives: The goal of this preliminary study was to determine whether neck surface electromyography (sEMG) is sensitive to possible changes in vocal hyperfunction associated with injection laryngoplasty, particularly with respect to alterations in the degree of vocal hyperfunction., Methods: Thirteen individuals undergoing office-based injection laryngoplasty for glottal phonatory insufficiency were prospectively studied with a battery of acoustic, aerodynamic, endoscopic, and anterior neck sEMG assessments before the procedure and approximately 1 week afterward., Results: Anterior neck sEMG values were not significantly reduced (p < 0.05) after the procedure; however, perceptual ratings of strain and false vocal fold compression were both significantly reduced, reflecting a decrease in vocal hyperfunction., Conclusions: The results do not support the use of anterior neck sEMG measures to assess vocal hyperfunction, and place into question the use of some other measures (estimates of anterior-posterior supraglottic compression, quantitative measures of anterior-posterior and false vocal fold supraglottic compression, and acoustic vowel rise times) that have been considered reflective of vocal hyperfunction.

Intermuscular coherence in the beta band was explored as a possible indicator of vocal hyperfunction, a common condition associated with many voice disorders. Surface electromyography (sEMG) was measured from two electrodes on the anterior neck surface of 18 individuals with vocal nodules and 18 individuals with healthy normal voice. Coherence was calculated from sEMG activity gathered while participants produced both read and spontaneous speech. There was no significant effect of speech type on average coherence. Individuals with vocal nodules showed significantly lower mean coherence in the beta band (15-35 Hz) when compared to controls. Results suggest that bilateral EMG-EMG beta coherence in neck strap muscle during speech production shows promise as an indicator of vocal hyperfunction.

Objectives/hypothesis: Investigators have long sought realistic methods to accelerate regeneration following nerve injury. Herein, we investigated the degree to which manual target muscle manipulation and brief electrical stimulation of the facial nerve, alone or in combination, affects recovery following rat facial nerve injury., Study Design: Prospective, randomized animal study., Methods: Sixty rats were randomized to three groups: brief electrical stimulation (BES), mechanical stimulation of the whisker pad (MEC), or both (COMBO). Animals underwent facial nerve transection and immediate microsurgical repair. In BES and COMBO groups, transection was preceded by 1-hour (3 V, 20 Hz square wave) electrical stimulation. Animals were tested weekly, with 5-minute recording sessions of whisker movement. In the MEC and COMBO groups, animals received 5 minutes of daily massage to the left whisker pad throughout the recovery period. Whisking behavior was analyzed for comparisons., Results: The BES and MEC groups demonstrated improved functional recovery in all whisking parameters compared with the COMBO group or historical controls at most time points between postoperative weeks 1 and 7. After 12 weeks, functional recovery remained superior in the BES and MEC groups compared with the COMBO and control groups, although the effect was no longer statistically significant., Conclusions: We observed an accelerative recovery effect of either electrical nerve stimulation or massage of the whisker pad on whisking behavior. The combination of both interventions had a negating effect on the acceleration of recovery. The potential clinical utility of these modalities bears consideration, and their negating interaction warrants further study.