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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... more
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 thes...
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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;... more
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. 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. 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. These results may help surgeons to prognosticate postoperative neural function and intraoperative decision-mak...
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Glottal dysplasia is likely the most common laryngeal disease with a discernible lesion; however, investigations describing its initial anatomic geographic presentation are rare. To examine this, we identified 52 patients who did not have... more
Glottal dysplasia is likely the most common laryngeal disease with a discernible lesion; however, investigations describing its initial anatomic geographic presentation are rare. To examine this, we identified 52 patients who did not have significant prior treatment or glottal cancer. Thirty-one patients had bilateral disease, so there were 83 vocal folds with precancerous dysplasia. The phonatory mucosa was the dominant disease site in all; the epicenter was on the superior surface in 65 of the 83 folds and on the medial surface in 18 of the 83 folds. The arytenoid mucosa was involved in 8 of the 83 folds. Nineteen of the 52 patients had direct anterior-commissure involvement, and none had interarytenoid mucosal disease. The investigation established the commonly held principle that glottal dysplasia occurs primarily on phonatory mucosa. Given the frequent occurrence and recurrence of glottal dysplasia, treatment goals should focus on disease control to prevent malignant degenerati...
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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... more
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.
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Objectives/Hypothesis: Fat preparation for vocal‐fold injection medialization is typically done by scraping of excised fat or by lipo‐aspiration; however, lipo‐aspiration is substantially more efficient. Considering this, we compared... more
Objectives/Hypothesis: Fat preparation for vocal‐fold injection medialization is typically done by scraping of excised fat or by lipo‐aspiration; however, lipo‐aspiration is substantially more efficient. Considering this, we compared viability of fat tissues obtained by these two techniques. We also examined whether basic fibroblast growth factor (bFGF) would increase cell proliferation in samples harvested by these methods.Study Design: Harvesting techniques (scraping and lipo‐aspiration) were compared using both human and ferret fat. In vitro assays were used to assess tissue viability and cell proliferation.Methods: Human (n = 5) and ferret (n = 15) abdominal fat specimens were harvested by scraping and lipo‐aspiration, for a total of 40 specimens. Alamar Blue and glycerol‐3‐phosphate dehydrogenase assays were used to quantitatively assess metabolic activity and cellular damage immediately after harvest. PicoGreen assays assessed cell proliferation by quantifying total DNA in har...
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Intraoperative assessment of vocal fold vibration during phonomicrosurgery performed under general anesthesia may enhance surgical decision-making. We therefore developed and bench-tested a new device we refer to as the aerodynamic vocal... more
Intraoperative assessment of vocal fold vibration during phonomicrosurgery performed under general anesthesia may enhance surgical decision-making. We therefore developed and bench-tested a new device we refer to as the aerodynamic vocal fold driver (AVFD). The AVFD comprises a hand-held probe that uses airflow to drive individual vocal folds into phonatory-like vibration. This permits stroboscopic visualization of mucosal waves with simultaneous control of subglottal air pressure. In initial experiments to validate the technique, AVFD driven phonation and conventional whole-larynx phonation were compared using excised canine larynges (n = 14). Single vocal fold phonation using the AVFD and whole larynx phonation yielded similar, positive correlations between subglottal pressure and both amplitude and frequency of vibration. Experiments simulating vocal fold scar-related mucosal stiffening by subepithelial injection of fixative showed the expected elevation of phonation threshold pressures as measured with the AVFD. Likewise, unilateral tissue compression injury disrupted vocal fold vibration, and the AVFD was useful for quantifying improvement in the damaged vocal fold after repair with injection of cross-linked hyaluronic acid gel. These results show that this new instrument has the potential to provide novel and useful information for laryngeal experimentation and to improve phonosurgery.
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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... more
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 a...
Research Interests: Microsurgery, Medicine, Massage, Prospective studies, Female, and 13 moreAnimals, Anesthesia, Transcutaneous Electrical Nerve Stimulation, Nerve Regeneration, Clinical Sciences, Facial Nerve, Mechanical Stress, Rats, Stimulation, Wistar Rats, Random Allocation, Recovery of Function, and Electric stimulation
Lesions were placed in either nucleus basalis (Bas) or the primary thalamorecipient portion of Field 'L' (i.e. centered in Field L2a) in budgerigars at 3-5 weeks posthatching and as adults. The calls of birds sustaining... more
Lesions were placed in either nucleus basalis (Bas) or the primary thalamorecipient portion of Field 'L' (i.e. centered in Field L2a) in budgerigars at 3-5 weeks posthatching and as adults. The calls of birds sustaining Bas lesions before fledging, or as adults, were markedly abnormal in that they showed little frequency modulation and individual distinctiveness. Call durations, however, were similar for lesioned and unlesioned birds. In contrast, the calls of Field 'L' lesioned birds were similar to those of siblings and cagemates. This implies that the roles of the isthmofrontal (i.e., direct projections from the ventrolateral nucleus of the lateral lemniscus to Bas) and thalamotelencephalic (i.e., direct projections from nucleus ovoidalis thalami to Field L2a) auditory pathways in providing auditory feedback during vocal learning and performance are different and that the isthmofrontal pathway plays an essential role in these processes throughout the life of the animal.
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Objectives: The goal of this study was to determine whether speech breathing changes over time in laryngectomy patients who use an electrolarynx, to explore the potential of using respiratory signals to control an artificial voice source.... more
Objectives: The goal of this study was to determine whether speech breathing changes over time in laryngectomy patients who use an electrolarynx, to explore the potential of using respiratory signals to control an artificial voice source. Methods: Respiratory patterns during serial speech tasks (counting, days of the week) with an electrolarynx were prospectively studied by inductance plethysmography in 6 individuals across their first 1 to 2 years after total laryngectomy, as well as in an additional 8 individuals who had had a laryngectomy at least 1 year earlier. Results: In contrast to normal speech that is only produced during exhalation, all individuals were found to engage in inhalation during speech production, and those studied longitudinally displayed increased occurrences of inhalation during speech production with time after laryngectomy. These trends appear to be stronger for individuals who used an electrolarynx as their primary means of oral communication rather than ...
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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... more
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. 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. A majority of subjects exhibited a significant bias toward overestimating their phonation times, with a...
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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. To establish... more
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. To establish functional recovery parameters after interposition autografting in a rodent facial nerve model. Prospective randomized animal study at a tertiary care facial nerve center using 16 female Wistar Hannover rats. The experimental group received reversed autograft reconstruction of a 20-mm neural gap, and the control group received facial nerve transection and primary repair. Whisker excursion was measured weekly for 70 postoperative days using laser micrometers. 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 ...
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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... more
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. To determine the detection threshold of side-to-side facial movement timing asymmetry and measure its effect on perceived movement naturalness. 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...
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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.... more
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...
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Research Interests: Psychology, Acoustics, Audiology, Adolescent, Phonation, and 15 moreMedicine, Prospective studies, Humans, Female, Male, Formant, Palpation, Electromyography, Clinical Sciences, Observer Variation, Adult, Reproducibility of Results, Neck Muscles, Surface Electromyography, and Predictive value of tests
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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... more
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 ta...
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The occurrence of inappropriate co-contraction (synkinesis) of facially innervated muscles in humans is a common sequela of facial nerve injury and recovery. We have developed a system for studying facial nerve function and synkinesis in... more
The occurrence of inappropriate co-contraction (synkinesis) of facially innervated muscles in humans is a common sequela of facial nerve injury and recovery. We have developed a system for studying facial nerve function and synkinesis in restrained rats using non-contact opto-electronic techniques that enable simultaneous bilateral monitoring of eyelid and whisker movements. Whisking is monitored in high spatio-temporal resolution using laser micrometers, and eyelid movements are detected using infrared diode and phototransistor pairs that respond to the increased reflection when the eyelids cover the cornea. To validate the system, 8 rats were tested with multiple 5-min sessions that included corneal air puffs to elicit blink and scented air flows to elicit robust whisking. Four rats then received unilateral facial nerve section and were tested at weeks 3-6. Whisking and eye blink behavior occurred both spontaneously and under stimulus control, with no detectable difference from pu...
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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... more
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 ...
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The sniffing position is traditionally considered optimal for direct laryngoscopic examination of the vocal folds. This study examined head and neck positions associated with ideal exposure of the anterior glottal commissure with a... more
The sniffing position is traditionally considered optimal for direct laryngoscopic examination of the vocal folds. This study examined head and neck positions associated with ideal exposure of the anterior glottal commissure with a variety of laryngoscopes. A prospective investigation was done in 20 patients by comparing the force required to expose the anterior vocal folds by utilizing 3 head and neck positions with 3 different-sized tubular laryngoscopes. The completeness of anterior glottal exposure was rated and the force required to achieve this exposure was measured with a strain gauge. Three positions relating the atlanto-occipital and cervicothoracic vertebrae were analyzed: 1) extension-extension, 2) sniffing: extension-flexion, and 3) flexion-flexion. Head and neck position and laryngoscope size were both statistically significant factors for achieving complete anterior vocal fold exposure. Regardless of the laryngoscope, the number of patients in whom complete exposure co...
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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... more
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. 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. The pattern of DN innervation matched that of the intrinsic whisker pad musculature (ie, via the buccal and marginal mandibular branches of the facia...
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To describe denervation features of facial musculature following facial nerve injury in a rodent model. Six Wistar-Hannover rats underwent unilateral transection and immediate repair of the facial nerve. After 8 weeks, muscular bundles... more
To describe denervation features of facial musculature following facial nerve injury in a rodent model. 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. 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...
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Our society depends on communication, the most natural form of which is speech. Trauma, disease and the normal aging process will cause many to suffer degraded or lost vocal fold function, and it has been observed that this number is... more
Our society depends on communication, the most natural form of which is speech. Trauma, disease and the normal aging process will cause many to suffer degraded or lost vocal fold function, and it has been observed that this number is growing [1]. The vocal folds are the vibrating structures in the larynx that enable us to generate voice, from speech to opera singing. The vibrating portions of the folds consist of an external 0.1mm thick layer of epithelial cells, a soft, gel-like 0.5mm thick layer called the lamina propria (LP), a 0.3mm thick vocal ligament and an underlying thyroarytenoid muscle [2]. The fundamental frequency of speech in men is in the 100–150Hz range, and between 200 and 300Hz in women [3].