Conus Elasticus Research Articles

Anatomical morphometry for Cricothyrotomy puncture and incision

PurposeEmergency surgical airway securing techniques include cricothyrotomy, puncture, and incision. While the instruments used for these methods vary in size, no index of laryngeal morphology exists to guide instrument selection. Therefore, we measured the morphology of the cricothyroid ligament in Japanese individuals and assessed its correlations with height.MethodsThis retrospective study used 61 anatomical practice specimens. The cricothyroid ligament of the laryngeal area was dissected, and a frontal image was recorded. Next, images of the midsagittal sections of the larynx and trachea were recorded. The width and height of the cricothyroid ligament were measured from the frontal images, and the depth of the larynx and the angle to the lower edge of the cricothyroid plate were measured from the mid-sagittal cross-sectional images. The height was estimated from the tibial lengths of the specimens and statistically analyzed for correlations. ResultsThe width and depth were significantly greater in males. Overall, there was a slight correlation between the results of each laryngeal measurement and estimated height for all items.ConclusionThe morphology of cricothyrotomy revealed that the width and depth of the laryngeal area varied according to sex. Moreover, the results also showed a correlation with the estimated height. Thus, it is important to predict the morphology of the laryngeal area and cricothyroid ligament by considering factors such as patient sex, weight, and height.

The correct way to deal with the definitivesurgical airway

Dealing with adifficult airway is familiar to emergency care providers in both the prehospital and clinical settings. In anesthesiology and emergency medical care different algorithms almost equal in their wording have been introduced, indicating that an emergency front of neck airway access (eFONA) has to be established in the case of acannot ventilate-cannot oxygenate situation. In asurvey (Surveymonkey®) data concerning the level of experience with eFONA, devices required, previous training and complications were allocated among acute and emergency care providers of different backgrounds (doctors and paramedics). Furthermore, we asked about individual attitudes to and frequency of previous situations, in which an eFONA was not established despite strong indications. Of the respondents 15% (n = 63) answered that they had experienced this type of situation. eFONA had been performed by 28% of the interviewed (n = 117), reflecting the high number of military and EMT (emergency medical team) physicians participating in the survey. The number of experiences are rarely representative for the civilian setting. Different adjuncts may be helpful to detect the cricothyroid ligament. To use ultrasound seems obvious but it doubles the time for the detection of the cricothyroid ligament. Laryngeal masks can be employed as asupraglottic airway device (SAD) during "planB". Stabilizing the airway with aSAD almost doubles the success of identifying laryngeal landmarks in females. The crew resource management (CRM) guidelines are more than essential in threatening situations demanding measures like eFONA. Providers should anticipate emerging problems and whenever feasible call for help and finally speak up. Naming afailed airway should be avoided as it implies afailure of the provider or of the entire airway team. In fact, the term non-accessible airway should be introduced. This might help to avoid the implication of amajor failure. So far, an ideal simulator to train eFONA has not been introduced but it is mandatory to train procedures and algorithms on different types of simulators and manikins to achieve mastery.

The Influence of Fiber Orientation of the Conus Elasticus in Vocal Fold Modeling.

While the conus elasticus is generally considered a part of continuation of the vocal ligament, histological studies have revealed different fiber orientations that fibers are primarily aligned in the superior-inferior direction in the conus elasticus and in the anterior-posterior direction in the vocal ligament. In this work, two continuum vocal fold models are constructed with two different fiber orientations in the conus elasticus: the superior-inferior direction and the anterior-posterior direction. Flow-structure interaction simulations are conducted at different subglottal pressures to investigate the effects of fiber orientation in the conus elasticus on vocal fold vibrations, aerodynamic and acoustic measures of voice production. The results reveal that including the realistic fiber orientation (superior-inferior) in the conus elasticus yields smaller stiffness and larger deflection in the coronal plane at the junction of the conus elasticus and ligament and subsequently leads to a greater vibration amplitude and larger mucosal wave amplitude of the vocal fold. The smaller coronal-plane stiffness also causes a larger peak flow rate and higher skewing quotient. Furthermore, the voice generated by the vocal fold model with a realistic conus elasticus has a lower fundamental frequency, smaller first harmonic amplitude, and smaller spectral slope.

THYROHYOID LIGAMENT CALCIFICATION MIMICKING FOREIGN BODY ESOPHAGUS; A RARE CASE REPORT AND REVIEW OF THE LITERATURE

Background: Foreign body ingestion frequently occurs in the extreme of ages. Meat bolus, fishbone buried in the food, and sharp bone are the common ingested foreign bodies among adults. The normal ligament and bony structure start to ossify after the third decade of life and mimic foreign bodies. Ossified thyrohyoid ligament, cricothyroid ligament, cornu of hyoid bone may be misdiagnosed as a foreign body in the aerodigestive tract. Case presentation: We describe a 54 years female who presented with painful swallowing for two days after eating chicken bone at Emergency Department. X-ray soft tissue neck lateral view showed a radiopaque shadow in front of the C3-C4 region. The patient underwent rigid esophagoscopy, however, a foreign body could not be found at the pharynx. Computerized Tomography (CT) shows the same hyperdense shadow at the same location as seen in the x-ray. Furthermore, Magnetic resonance imaging (MRI) scan was done to localize the exact site of the foreign body, but the patient was a case of thyrohyoid calcification rather than foreign body in the esophagus. Conclusion: Difficulty arises for the surgeons when a foreign body is not found during rigid esophagoscopy. It is important to reassess and locate the foreign body by imaging. The calcified ligament can mimic a foreign body in the neck. MRI confirms the diagnosis which may be misguided by X-ray and CT-scan.

Can thickness of subcutaneous fat tissue limit emergency percutaneous cricothyrotomy?

Introduction: Needle cricothyrotomy is a method of maintaining airways in emergency situations. One of the identified factors that can make this procedure difficult to perform is ‘a difficult neck anatomy’ or a short obese neck. Due to the growing problem of obesity, we decided to estimate the feasibility of a needle cricothyrotomy by measuring the thickness of neck fat tissue in the population. Evaluation of this method is important because it is the only method that can be legally performed by paramedics in Poland. The aim of the study was to estimate the feasibility of needle cricoidectomy by evaluating the percentage of population in which the thickness of subcutaneous fat tissue could potentially limit or complicate such a procedure. Material and methods: In this retrospective study we reviewed computed tomography (CT) scans of the neck from the database at the Department of Radiology, University Hospital in Cracow. 550 CT scans met inclusion criteria: age of patient over 18 years old, lack of any lesions altering the anatomy of measured region of neck, the first CT scan of patient. 50.36% of patients were women. The median age was 61 years (range 18–93). The distance from the skin surface at the level of the lower edge of the thyroid cartilage to the cricothyroid ligament (surface — ligament distance, SLD) was measured. Statistical analysis of the data was performed using R software (R version 4.0.3). Results: Median SLD was 1.41 (1.01–2.04). Subcutaneous fat tissue was thicker than maximal depth of application of cricothyrotomy (3 cm) device in 31 patients (5.64%). Conclusions: Performing needle cricothyrotomy may be limited to a considerable percentage of the population (5.64%).

Endoscopic Wedge Excisions with CO2 Laser for Subglottic Stenosis.

Endoscopic Wedge Excisions with CO2 Laser for Subglottic Stenosis.

Intraoperative neuromonitoring by vagus nerve stimulation in thyroid surgery: Clinical assessment of recurrent and superior laryngeal nerves

Intraoperative neuromonitoring of the laryngeal nerves during thyroidectomy is a reliable method to assess nerve function. After identification of the cricothyroid ligament, a bipolar electrode is selectively inserted through the ligament into the thyroarytenoid muscle (TAM) and cricothyroid muscle (CTM). Vagus nerve stimulation then allows precise monitoring of the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve (EBSLN) in the TAM and CTM, respectively. A significant muscle response (greater than 100μV) is 100% predictive of preserved laryngeal mobility, while the absence of a muscle response is 70% predictive of vocal fold paralysis with 100% sensitivity and 98% specificity. A significant thyroarytenoid muscle response is only recorded ipsilateral to the stimulation with a shorter latency on the right side. A concomitant TAM and CTM response to vagus nerve stimulation or EBSLN stimulation is observed in more than 70% of cases.

Ex-vivo Mechanical Testing of Novel Laryngeal Clamps Used for Laryngeal Advancement Constructs.

Rostral laryngeal advancement, also known as laryngeal tie-forward, is used to treat horses for intermittent dorsal displacement of the soft palate and has a morbidity rate of about 6%. We hypothesized that a novel laryngeal clamp would prevent morbidity associated with the sutures tearing through the thyroid cartilage. Larynges (n = 35 horses) were used for ex vivo testing. For uniaxial testing, 15 equine larynges were tested in one of three laryngeal tie-forward constructs [standard laryngeal tie-forward; modified laryngeal tie-forward using a suture-button; and modified laryngeal tie-forward using a laryngeal clamp]. For biaxial testing, 20 larynges were tested in one of two treatment groups: laryngeal tie-forward and laryngeal tie-forward using a laryngeal clamp. Constructs were tested in single cycle-to-failure. Statistical analyses were performed using ANOVA for uniaxial testing and t-tests for biaxial testing. The laryngeal tie-forward using a laryngeal clamp construct was superior to laryngeal tie-forward and laryngeal tie-forward using a suture-button constructs in resistance to pullout in uniaxial testing. The laryngeal tie-forward using a laryngeal clamp presented a significantly different method of failure than the standard laryngeal tie-forward in the biaxial testing. Failure modes for each construct were primarily by suture failure at the clamp (laryngeal tie-forward using a laryngeal clamp), suture pullout through the thyroid cartilage, or, less commonly, tearing of the cricothyroid ligament (laryngeal tie-forward). In uniaxial testing, the laryngeal tie-forward using a laryngeal clamp failed most commonly due to tearing of the cricothyroid ligament, whereas the standard laryngeal tie-forward and the laryngeal tie-forward using a suture-button failed due to the tearing of the cartilage. The laryngeal clamps provided greater stiffness, load at yield, and tensile stress at yield than did the standard construct. Laryngeal clamps may offer an alternative to standard methods of anchoring the thyroid cartilage when performing the laryngeal tie-forward procedure. Further testing and clinical trials are needed to elucidate the utility of the laryngeal tie-forward using a laryngeal clamp.

Cricothyroidotomy needle length is associated with posterior tracheal wall injury

Background:Cricothyroidotomy is the final strategy in the “cannot intubate, cannot oxygenate” scenario, but half of needle cricothyroidotomy attempts result in failure. The most frequent complication in needle cricothyroidotomy is posterior tracheal wall injury. We hypothesized that needle length is related to posterior wall injury and compared needle cricothyroidotomy with a commercial kit to a modified shorter needle to evaluate success and posterior wall injury rates.Methods:The commercial kit has a needle stopper to prevent posterior wall injury, with a penetrating length of 25 mm. We made long stopper to shorten the length by 5 mm (net 20 mm penetrating length). Residents were recruited, received a lecture about cricothyroidotomy and practiced needle cricothyroidotomy using the commercial kit on a simulator. They then performed cricothyroidotomy using the commercial kit or the shorter needle on an ex-vivo porcine larynx covered with artificial skin. An intra-tracheal endoscope recorded the procedure. The video was evaluated for success/failure or posterior wall injury by independent evaluators. Larynxes with a distance from the outer surface to the inner lumen exceeding 13 mm were excluded. The distance in each larynx was measured by dissection after the study. Success and posterior wall injury rates were analyzed using Fisher exact test (P < .05 was statistically significant).Results:Forty-seven residents participated in the study. Data for two residents were excluded. There was no statistically significant difference in success rate between the commercial kit (100%, 45/45) and the shorter needle (91%, 41/45, P = .12). Failure was defined if the needle tip did not reach the lumen in four trials. Cannulated but complicated by posterior wall injury occurred in 33% (15/45) with the commercial kit and 5% (2/43) with the shorter needle (P < .01).Conclusion:During needle cricothyroidotomy, force is needed for the needle to penetrate the cricothyroid ligament. The advancing needle sometimes cannot be stopped after penetrating the cricothyroid ligament. These data suggest that needle length is associated with posterior wall injury.

Recurrent laryngeal nerve monitoring during thyroidectomy and parathyroidectomy in children

ObjectiveInjury of the recurrent laryngeal nerve (RLN) is the most frequent complication of thyroid and parathyroid (TP) surgery. Monitoring of the RLN in children is not widely studied as this is not a common disease in the pediatric population. The aim of our study was to evaluate the reliability, feasibility and benefits of RLN monitoring during TP surgery in children. MethodsWe analyzed all children who underwent TP surgery in our department between January 2009 and March 2018. Patients were classified into three groups: without monitoring (group 1), monitoring with an endotracheal tube (group 2) and monitoring with a double-needle electrode placed through the cricothyroid ligament (group 3). ResultsWe performed 53 surgeries (77 RLNs at risk) on 47 patients aged between 6 months and 18 years. Fourteen RLNs were in group 1, 47 in group 2 and 16 in group 3. We found one transient lesion of the RLN in group 1, three in group 2 and two in group 3. Seven patients in group 3 could not undergo monitoring with the tube because they need an orotracheal tube smaller than the smallest monitoring tube size available. The sensitivity and specificity values of the monitoring methods were 33% and 97% in group 2 and 67% and 100% in group 3, respectively. The positive and negative predictive values were 50% and 95% in group 2 and 100% and 92% in group 3, respectively. No complications arose during insertion of the electrode through the cricothyroid ligament. ConclusionMonitoring of the RLN with a double-needle electrode inserted through the cricothyroid ligament is a reliable method with no associated complication, which is achievable at any age.

Lubricin/proteoglycan 4 detected in vocal folds of humans and five other mammals.

Lubricin/proteoglycan-4 (PRG4) lubricates connective tissues such as joints and tendon sheaths, enabling them to better withstand shearing and frictional forces during motion. We wondered whether PRG4 might play a role in phonation, as normal vocal folds withstand repetitive, high-velocity deformations remarkably well. As a first step, we tested whether PRG4 is expressed in vocal folds. Laboratory study. Anatomical and molecular methods were applied to 47 larynges from humans, macaque (Macaca fascicularis), canines, pigs, calves, and rats. Immunohistochemistry (IHC), Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR) methods were used to test for the presence of PRG4. In all species, the true vocal fold lamina propria (TVF-LP) was positive for PRG4 by IHC, whereas immunoreactivity of the false vocal fold was weak or absent, depending on the species. Human TVF-LP was strongly stained across all layers. Immunoreactivity was seen variably on the vocal fold surface and within the vocal fold epithelium, in the conus elasticus and thyroglottic ligament, and at the tip of vocal process. Western blots of four humans and six pigs demonstrated immunoreactivity at appropriate molecular weight. qRT-PCR of pig tissues confirmed PRG4 mRNA expression, which was highest in the TVF-LP. PRG4 was found in phonatory tissues of six mammals. We suggest it might act as a lubricant within the lamina propria and possibly on the vocal fold surface, limiting phonation-related damage to vocal fold extracellular matrix and epithelium, and enhancing vocal efficiency by reducing internal friction (viscosity) within the vocal fold. NA Laryngoscope, 129:E229-E237, 2019.

Impact of medialization laryngoplasty on dynamic nanomechanical vocal fold structure properties.

Although the primary goal of medialization laryngoplasty is to improve glottic closure, implant placement is also likely to alter the biomechanical properties of the vocal fold (VF). We sought to employ novel, nanoscale technology to quantify these properties following medialization based on the hypothesis that different medialization materials will likely yield differential biomechanical effects. Ex vivo. Nine pig larynges were divided into three groups: control, Silastic (Dow Corning, Midland, Michigan, U.S.A.) block medialization, or Gore-Tex (W.L. Gore & Associates, Newark, Delaware) medialization. Laryngoplasty was performed on excised, intact larynges. The larynges were then bisected in the sagittal plane and each subjected to dynamic nanomechanical analysis (nano-DMA) at nine locations using a 250-μm flat-tip punch and frequency sweep-load profile across the free edge of the VF and inferiorly along the conus elasticus. Silastic block and Gore-Tex implant introduced increased storage and loss moduli. Overall, storage moduli mean (maximum) increased from 38 kilopascals (kPa) (119) to 72 kPa (422) and 129 kPa (978) in control, Gore-Tex, and Silastic implants, respectively. Similarly, loss moduli increased from 13 kPa (43) to 22 kPa (201) and 31 kPa (165), respectively. Moduli values varied widely by location in the Silastic block and Gore-Tex groups. At the free VF edge, mean (maximum) storage moduli were lowest in the Gore-Tex group, 20 kPa (44); compared to control, 34.5 kPa (86); and Silastic, 157.9 kPa (978), with similar loss and complex moduli trends. Medialization laryngoplasty altered VF structure biomechanical properties; Silastic and Gore-Tex implants differentially impact these properties. NA. Laryngoscope, 128:1163-1169, 2018.

Aryepiglottic fold augmentation as treatment for late-onset dysphagia following surgical treatment of recurrent laryngeal neuropathy.

Coughing and dysphagia have been described following prosthetic laryngoplasty (LP) with or without ventriculectomy/ventriculocordectomy (VE/VCE) for the treatment of recurrent laryngeal neuropathy. All previous case descriptions include patients with acute onset of clinical signs after surgery that persisted. The authors observed a late-onset of dysphagia and coughing months to years after LP±VE/VCE. The condition was always associated with an abnormality of the aryepiglottic fold (AEF). Treatment options for those patients are limited. We suggest augmentation of the AEF as treatment for affected horses. The goal of the study was two-fold: Firstly, to describe a new condition of late-onset dysphagia in horses following LP±VE/VCE associated with an abnormal appearance of the AEF, and secondly, to offer a minimally invasive and successful treatment for those patients. Six horses were presented because of dysphagia and coughing with an onset of months to years after LP±VE/VCE. Endoscopically, the AEF always appeared thinner and more flaccid to a varying degree. The food path was traceable along the AEF into the trachea using dyed molasses. An initial injection of hyaluronic acid (HA) into the AEF led to immediate improvement of the dysphagia. The procedure was performed in the standing sedated horse. The needle was placed through the cricothyroid ligament and the injection performed under endoscopic guidance. All horses tolerated the injection well. Injection of HA was successful only in the short term in all cases and repeated injections were needed for permanent resolution using either cross-linked HA, polyacrylamide hydrogel or platelet rich plasma. Horses may develop dysphagia and coughing months to years after LP±VE/VCE as a late-onset complication. The condition seems to be associated with an abnormal appearance and function of the AEF. Successful treatment is possible by augmenting the AEF. However, careful patient selection is mandatory.

Sensitivity of Source-Filter Interaction to Specific Vocal Tract Shapes.

A systematic variation of length and cross-sectional area of specific segments of the vocal tract (trachea to lips) was conducted computationally to quantify the effects of source-filter interaction. A one-dimensional Navier-Stokes (transmission line) solution was used to compute peak glottal airflow, maximum flow declination rate, and formant ripple on glottal flow for Level 1 (aero-acoustic) interactions. For Level 2 (tissue movement) interaction, peak glottal area, phonation threshold pressure, and deviation in fo were quantified. Results show that the ventricle, the false-fold glottis, the conus elasticus entry, and the laryngeal vestibule are the regions to which acoustic variables are most sensitive. Generally, any narrow section of the vocal tract increases the degree of interaction, both in terms of its length and its cross-sectional area. The closer the narrow section is to the vocal folds, the greater the effect.

Dynamic nanomechanical analysis of the vocal fold structure in excised larynges.

Quantification of clinical outcomes after vocal fold (VF) interventions is challenging with current technology. High-speed digital imaging and optical coherence tomography (OCT) of excised larynges assess intact laryngeal function, but do not provide critical biomechanical information. We developed a protocol to quantify tissue properties in intact, excised VFs using dynamic nanomechanical analysis (nano-DMA) to obtain precise biomechanical properties in the micrometer scale. Experimental animal study. Three pig larynges were bisected in the sagittal plane, maintaining an intact anterior commissure, and subjected to nano-DMA at nine locations with a 250-μm flat-tip punch and frequency sweep load profile (10-105 Hz, 1,000 μN peak force) across the free edge of the VF and inferiorly along the conus elasticus. Storage, loss, and complex moduli increased inferiorly from the free edge. Storage moduli increased from a mean of 32.3 kPa (range, 6.5-55.38 kPa) at the free edge to 46.3kPa (range, 7.4-71.6) 5 mm below the free edge, and 71.4 kPa (range, 33.7-112 kPa) 1 cm below the free edge. Comparable values were 11.6 kPa (range, 5.0-20.0 kPa), 16.7 kPa (range, 5.7-26.8 kPa), and 22.6 kPa (range, 9.7-38.0 kPa) for loss modulus, and 35.7 kPa (range, 14.4-56.4 kPa), 50.1 kPa (range, 18.7-72.8 kPa), and 75.4 kPa (range, 42.0-116.0 kPa) for complex modulus. Another larynx repeatedly frozen and thawed during technique development had similarly increased storage, loss, and complex modulus trends across locations. Nano-DMA of the intact hemilarynx provides a platform for quantification of biomechanical responses to a myriad of therapeutic interventions to complement data from high-speed imaging and OCT. NA Laryngoscope, 127:E225-E230, 2017.

Bystander cricothyrotomy with ballpoint pen: a fresh cadaveric feasibility study

ObjectiveIn motion pictures and anecdotal reports, ballpoint pens have been used for life-saving cricothyroidotomies. The objective of this study was to examine the widespread belief that ballpoint pens can perforate...

The role of subglottal acoustics in speech production and perception

In this talk, we present an overview of subglottal acoustics, with emphasis on the significant anatomical structures that define subglottal resonances, and we present results from our experiments incorporating subglottal resonances into automatic speaker normalization and speech recognition technologies. Speech samples used in the modeling and perception studies were obtained from a new speech corpus (the UCLA-WashU subglottal database) of simultaneous microphone and (subglottal) accelerometer recordings of 50 adult speakers of American English (AE). We will discuss new findings about the Young's Modulus of tracheal soft tissue, the viscosity of tracheal cartilage, and the effect of going from a circular cross-section to a rectangular cross-section in the conus elasticus. We also present results from studies demonstrating a small, but significant, role of subglottal resonances in discriminating speaker height and of the interaction between subglottal resonances and formants in height discrimination.

Characterization of the Vocal Fold Vertical Stiffness in a Canine Model

Characterizing the vertical stiffness gradient that exists between the superior and inferior aspects of the medial surface of the vocal fold. Characterization of this stiffness gradient could elucidate the mechanism behind the divergent glottal shape observed during closing. Basic science. Indentation testing of the folds was done in a canine model. Stress-strain curves are generated using a customized load-cell and the differential Young's modulus is calculated as a function of strain. Results from 11 larynges show that stress increases as a function of strain more rapidly in the inferior aspect of the fold. The calculations for local Young's modulus show that at high strain values, a stiffness gradient is formed between the superior and inferior aspects of the fold. For small strain values, which are observed at low subglottal pressures, the stiffness of the tissue is similar in both the superior and inferior aspects of the vocal fold. Consequently, the lateral force that is applied by the glottal flow at both aspects results in almost identical displacements, yielding no divergence angle. Conversely, at higher strain values, which are measured in high subglottal pressure, the inferior aspect of the vocal fold is much stiffer than the superior edge; thus, any lateral force that is applied at both aspects will result in a much greater displacement of the superior edge, yielding a large divergence angle. The increased stiffness observed at the inferior edge could be due to the proximity of the conus elasticus.

Die totalendoskopische Schilddrüsenresektion in der ABBA-Technik: Anmerkungen zur Integrierung des intraoperativen Neuromonitorings in die Operationsmethode

Background: Total endoscopic thyroid resections without any scars on the neck are a special challenge for the surgeon. Clinical results of intraoperative neuromonitoring (IONM) in the axillo-bilateral-breast-approach (ABBA) have not been described so far. Methods: 29 female patients (~ 40 years) were operated for one-sided thyroid pathology using the ABBA technique (20 subtotal resections, 9 hemithyroidectomies). Suspected malignoma, size > 35 mL, known thyroiditis and recurrencies were excluded. For stimulation a 30-cm handprobe and for signal deviation a tube adhesive electrode (ISIS; Fa. Inomed, Emmendingen, Germany) were used. Results: The average operation time was 132 minutes. Intraoperative blood loss necessitated conversion to the open procedure in 1 case. A single tube electrode dislocation occurred. In the alternative a bipolar needle electrode was inserted percutaneously through the cricothyroid ligament. One intraoperative signal loss was confirmed by the laryngoscopic finding of vocal cord paresis, which recovered within 6 months. An additional case of incomplete brachial plexus paralysis was observed with a 2-day recovery time. Conclusion: Direct neuromonitoring of the recurrent laryngeal nerve can be easily applied in the total endoscopic ABBA technique for thyroid resection. Vagal stimulation, which is obligatory in open thyroid surgery, cannot consequently be included in this endoscopic operation method. Unexpected tube electrode dislocation may cause IONM misinterpretation. A risk of double-sided vocal cord palsy is theoretically present.

Eosinophilic Angiocentric Fibrosis of the Subglottis

Objectives: Eosinophlic angiocentric fibrosis (EAF) is a rare disorder that belongs to the spectrum of IgG4-related diseases (IgG4-RD). We review a case of EAF presenting as a subglottic stenosis. Methods: We discuss the pertinent clinical, radiographic, and histological findings, demonstrating the diagnostic challenges associated with EAF. We review the literature on respiratory tract EAF and discuss the associated management dilemmas when this otherwise benign disease affects critical structures. A 44 year-old female presented a twelve-month history of progressive dyspnea and stridor. A pulmonary function test (PFT) showed flattened inspiratory and expiratory flow loops suggestive of subglottic stenosis. Pre-operative computed tomography (CT) revealed a subglottic mass with cricoid erosion. During endoscopy, a submucosal lesion was noted to involve the conus elasticus and cricoid. The airway was temporized with CO2 laser resection of the mass and dilation. Results: Histology showed an inflammatory infiltrate composed of lymphocytes, plasma cells, and eosinophils. Fibrosclerosis was organized around thickened vessels in an onionskin pattern. Immunohistochemical revealed a minor IgG-4 plasma cell component. Staining was negative for beta-catenin and ALK-1. The specimen was found to be consistent with EAF. Serum IgG-4 was mildly elevated at 117 mg/dL. The patient has been managed with oral steroids, and her airway remains stable. Conclusions: EAF is a subtype of inflammatory fibrosclerosis that belongs in the spectrum of IgG4-RD. Most commonly reported in the orbit or sinonasal tract, EAF lesions of the laryngotracheal complex are exceedingly rare. Although benign, EAF pseudotumors can be locally destructive, requiring a multidisciplinary approach to care.