Time Course and Recovery of the Movements of Hyoid Bone and Thyroid Cartilage During Swallowing in a Patient With Sarcopenic Dysphagia.

Sarcopenia is known to adversely affect swallowing function. In this report, we describe the treatment progress of an older patient with dysphagia caused by sarcopenia and the analysis results from videofluorographic examination images. An 89-yr-old man who had been hospitalized for lumbar fracture experienced lower back pain and thus had his oral intake reduced. After transfer to a rehabilitation hospital, he developed aspiration pneumonia and then sarcopenia with low nutrition and low activity. At the beginning of intervention, he aspirated food paste, but he recovered sufficiently to be able to ingest a normal meal via a nutritional approach combined with rehabilitation at the time of discharge. During this process, the maximum amounts of displacements and maximum moving velocities of his hyoid bone and thyroid cartilage during swallowing of moderately thick water were improved. Adequate nutrition intake and training for hyoid muscles are considered effective for the patient with sarcopenic dysphagia. It was concluded that measuring the maximum displacements and moving velocities of the hyoid bone and thyroid cartilage during swallowing in patients with sarcopenic dysphagia was an effective way to monitor their improvement.

Accuracy of Thyroid Cartilage Fenestration During Montgomery Medialization Thyroplasty.

INTRODUCTION: Accuracy of thyroid cartilage fenestration during Montgomery thyroplasty (MTIS) is considered a key success factor. The primary aim of the study was to retrospectively evaluate the accuracy of fenestration. Furthermore, recent publications indicate a possible discrepancy in MTIS voice outcomes related to gender. The secondary aim of the study was to investigate whether the fenestration accuracy could explain this discrepancy. MATERIAL AND METHOD: Study was performed by virtually drawing the fenestration on a 3D CT scan as proposed by the MTIS's instructions for use (the "expected window" (EW)), and comparing it to the actually realized fenestration (the "realized window "(RW)). Four position variables, (a) surface overlap (%), (b) the distances between RW and EW centers (mm), (c) the angle between RW and EW (°), and (d) the orientation of RW's center, were studied and compared to MPT (seconds) and VHI-30 scores outcomes. A descriptive statistical analysis and comparison between males and females were performed using a Mann-Whitney U test. Linear regression and multivariate analysis were also performed. RESULTS: The median overlapping surface was 58.8 % [34.6; 75.4]. The median radius was 3.2 mm [1.7; 4.1]. The median angle was 16° [6.8; 21.2]. Results show no significant differences of overlapping surface percentage, distance, or angle by gender. Data show no correlation between voice outcome and percentage overlap, distance, or angle. However, data show better outcomes when fenestration was located in the infero-anterior orientation. All patients of this orientation were males. CONCLUSIONS: Data provided by this study advocate a maximal infero-anterior positioning of the window during MTIS. This position is more difficult to obtain in female patients.

Biomechanical study of the thyroid cartilage: A model of bi-digital strangulation.

The presence of fracture on neck elements is an indication of violence. Both the hyoid bone and the larynx can be damaged by a strangulation mechanism. Thyroid cartilage, more specifically, may present lesions in response to this mechanical stress. These lesions result in fractures at the bases of the horns of the thyroid cartilage. This study focuses on the thyroid cartilage behavior in cases of bi-digital strangulation, using an anthropometric and biomechanical approach. To develop a biomechanical model, we performed an anthropometric study taking into account 14 distances measurements as well as 3 measurements of angles. These measures allowed us to determine a significant sexual dimorphism between individuals. Then, we define 6 morphologies models, composed of 3 females and 3 males individuals. In order to visualize the ossification of the cartilage, each model has been tested with bone properties. Strangulation cases were simulated by applying an imposed velocity of 0.4m/s then 1m/s. We observed different behaviors of the thyroid cartilage according to the sex and the morphology.

How Age and Frequency Impact the Thyroid Cartilages of Professional Singers.

OBJECTIVES/HYPOTHESIS: Young professional singers can easily reach very high pitches. In contrast, older singers often complain that they have to exert substantially more laryngopharyngeal force to reach the same high pitch compared with their earlier years. Various factors such as the property changes of the mucosa and ossification that impact the singing apparatus were suggested as explanations in the literature. The aim of this study was to analyze thyroid deformation-and thereby stiffness indirectly-during singing as a potential reason for this phenomenon. STUDY DESIGN: Prospective study. METHODS/DESIGN: We examined 44 female professional singers. High-resolution computed tomography scans were performed during singing at the fundamental mean speaking frequency and the first and second octaves above it. Digital Imaging and Communications in Medicine scan data were rendered and visualized 3-dimensionally using MIMICS software. By superimposition of the different 3-dimensional images, different positions of the thyroid were visualized. The distance from the posterior border of the thyroid was measured in all the examinations. RESULTS: All laryngeal cartilages could be three-dimensionally visualized. The magnitude of the thyroidal deformation significantly depends on pitch and significantly correlates with age (r2 = 0.7, P < 0.001). CONCLUSIONS: The thyroid cartilage is flexible and its formability is especially important during singing. At higher pitches, the cartilage was more deformed. The larynx in older singers showed less thyroid cartilage deformation.

Relationship between severe obesity and depth to the cricothyroid membrane in third-trimester non-labouring parturients: a prospective observational study.

BACKGROUND: Severely obese parturients have increased 'cannot intubate, cannot oxygenate' risk during Caesarean section under general anaesthesia. Front-of-neck access (FONA) at the cricothyroid membrane (CTM) is definitive management; however, attempted FONA can fail. Point-of-care ultrasonography may provide useful information about CTM depth to aid FONA in obesity. This study determined the difference in CTM depth between severely obese and non-obese parturients, utilising ultrasonography. METHODS: In this prospective observational study, two anaesthetists performed airway ultrasonography on 15 severely obese (BMI >45 kg m-2) and 15 normal-weight (BMI ≤25 kg m-2) parturients in the third trimester, using the transverse and longitudinal planes, sniffing and extended head positions, and nil and firm transducer pressures. The primary outcome was CTM depth (millimetres) measured in the transverse plane with the head extended and nil transducer pressure. Secondary outcomes included CTM depth measurements using other factor configurations. Intra-class correlation coefficients assessed the inter-observer reliability. RESULTS: CTM depth measured in the transverse plane with head extended and nil transducer pressure was significantly greater in severely obese parturients, mean 18.0 mm (95% confidence interval 16.3-19.8), vs 10.6 mm (8.81-12.4) in non-obese (P<0.001); mean difference 7.4 mm (4.9-9.9; P<0.001). CTM depths were increased in the severely obese group regardless of scanning plane, head and neck position, or transducer pressure (all P<0.001). There was excellent inter-observer reliability. CONCLUSIONS: Cricothyroid membrane depth is significantly increased in severely obese vs normal-weight parturients independently of scanning plane, head and neck position, or transducer pressure.

Buckled Thyroid Cartilage: An Anatomic Variant.

OBJECTIVE: Anatomic abnormalities in the larynx can cause significant and bothersome symptoms. Identified here is an anatomical variant of the thyroid cartilage. STUDY DESIGN: This study is a retrospective case series of 11 subjects diagnosed with an anatomic variant of the thyroid cartilage. METHODS: Patients with an anatomic inward buckling of the thyroid cartilage, termed here as buckled thyroid cartilage, were identified through a 20-year retrospective chart review of a tertiary care laryngology practice. RESULTS: We describe 11 patients with fullness or asymmetry in the area of the false vocal fold and an associated inward buckling of the thyroid cartilage on computed tomography scan. All patients presented with a bothersome voice-related complaint. The most common presenting complaints were hoarseness (54%), globus sensation (45%), or vocal fatigue (27%). One patient was found to have a history of known laryngeal trauma. Surgical correction through an external approach on one patient was successfully performed with subsequent resolution of symptoms. CONCLUSION: We postulate that deformity and protrusion of the false vocal fold can result in a dampening effect on the vibratory capacity of the vocal fold that can lead to symptomatic hoarseness and vocal fatigue. Buckled thyroid cartilage is, therefore, an important anatomical variant to be aware of and be able to recognize.

Operative Procedure of Anterior Commissure for Type II Thyroplasty.

OBJECTIVE: We reviewed the clinical anatomy of the anterior commissure and examined the effectiveness of a specialized spreader developed for optimal, efficient spreading of the thyroid cartilage in type II thyroplasty. STUDY DESIGN AND METHODS: The present study was a multicenter retrospective study of patients with spasmodic dysphonia who underwent a primary operation either before or after the introduction of a specialized spreader (in 2008 or 2014, respectively). In these patients, we examined the size of the titanium bridge used, the presence of perforation of the mucosa directly superior to the anterior commissure, and postoperative glottic findings. RESULTS: The sample comprised 39 and 40 patients who underwent surgery in 2008 and 2014, respectively. The mean size of the titanium bridge used during surgery was significantly smaller in 2014 (2.9 mm) than in 2008 (3.81 mm). Perforation of the laryngeal mucosa occurred in 13 patients in 2008 but occurred in only one patient in 2014. Based on glottic findings, spreading the thyroid cartilage using the specialized spreader was deemed to yield an effective glottic gap. CONCLUSIONS: In type II thyroplasty, the handling of the anterior commissure is the most important point. It is necessary to split the tendon and to spread the glottis while the tendon is joined with the cartilage. For this purpose, a specialized spreader was made. The use of a specialized spreader renders separation around the anterior commissure unnecessary, enabling minimally invasive spreading of the thyroid cartilage and thereby improving phonation.

Hemilaryngeal Microsomia: An Anatomic Variant.

OBJECTIVES: This study aims to describe a congenital laryngeal structural variant, hemilaryngeal microsomia (HLM), and to correlate identification on physical examination with computerized tomography scan (CT) and laryngoscopy findings. METHODS: The study was conducted at a tertiary care center. Six patients presenting with hoarseness were admitted to a tertiary care otolaryngology office. These patients had asymmetrical thyroid cartilage prominence on palpation during physical examination. A diagnosis of HLM was made. All patients underwent laryngostroboscopy and CT scan. Four control patients with normal thyroid cartilage anatomy on physical examination, CT, and stroboscopy results were included for comparison. RESULTS: Disparities in thyroid cartilage angles correlated with documented physical examination findings for six out of six HLM patients. On CT scan, the average difference in left and right thyroid laminar angles was 30.2° ± 18.3° in HLM patients vs 4.00° ± 1.63° in control patients (P = 0.023). Strobosocopic findings also correlated with HLM. The arytenoid cartilage was anteriorly or medially displaced on the microsomic side in all six HLM patients. Three patients had anterior placement of the vocal process resulting in shortening of the vocal fold on the microsomic side of the larynx. CONCLUSIONS: HLM is a congenital structural anomaly of the larynx that may be palpated on physical examination. HLM found on physical examination can be correlated with asymmetries found on CT scan and endoscopy. There is no evidence that the structural features of HLM were causally related to voice symptoms, but the findings on HLM may lead to misdiagnosis. A larger study is indicated to confirm laryngeal structural differences between patients with HLM on physical examination and the general population. Whether or not HLM affects clinical or surgical outcomes remains to be studied.

Shape of Thyroid Cartilage Influences Outcome of Montgomery Medialization Thyroplasty: A Gender Issue.

OBJECTIVE: This study aimed to determine whether the shape of the thyroid cartilage and gender influence voice outcomes after a Montgomery thyroplasty implant system (MTIS). METHODS: A retrospective cohort study was performed on 20 consecutive patients who underwent MTIS. Voice outcome variables were the relative decrease in Voice Handicap Index (%) and the absolute increase in maximum phonation time (MPT) (in seconds). Material variables were the angle between the thyroid cartilage laminae (α-angle), the size of the prosthesis, and a combination of both (the α-ratio). Continuous variables were analyzed using medians and were compared between groups using the Mann-Whitney U test. Factors associated with the outcome variables were assessed by multivariable linear regression. A Pearson coefficient was calculated between material variables. RESULTS: The absolute increase in MPT between the pre- and postoperative period was significantly different between men and women, with a median absolute increase of 11.0 seconds for men and of 1.3 seconds for women (P < 0.001). A strong inverse correlation between the α-ratio and the absolute increase in MPT is observed in all patients, with a Pearson correlation coefficient R = -0.769 (P < 0.001). No factors were significantly associated with the relative Voice Handicap Index decrease in univariable or multivariable analyses. A better Pearson coefficient between the α-angle and the prosthesis size was found for females (0.8 vs 0.71). CONCLUSION: The MTIS is a good thyroplasty modality for male patients, but inadequate design of MTIS female implants leads to poor MPT outcomes. This represents a gender issue that needs to be further studied and eventually tackled.

Evaluation of type II thyroplasty on phonatory physiology in an excised canine larynx model.

OBJECTIVES/HYPOTHESIS: Type II thyroplasty is an alternative treatment for spasmodic dysphonia, addressing hyperadduction by incising and lateralizing the thyroid cartilage. We quantified the effect of lateralization width on phonatory physiology using excised canine larynges. METHODS: Normal closure, hyperadduction, and type II thyroplasty (lateralized up to 5 mm at 1-mm increments with hyperadducted arytenoids) were simulated in excised larynges (N = 7). Aerodynamic, acoustic, and videokymographic data were recorded at three subglottal pressures relative to phonation threshold pressure (PTP). One-way repeated measures analysis of variance assessed effect of condition on aerodynamic parameters. Random intercepts linear mixed effects models assessed effects of condition and subglottal pressure on acoustic and videokymographic parameters. RESULTS: PTP differed across conditions (P < .001). Condition affected percent shimmer (P < .005) but not percent jitter. Both pressure (P < .03) and condition (P < .001) affected fundamental frequency. Pressure affected vibratory amplitude (P < .05) and intrafold phase difference (P < .05). Condition affected phase difference between the vocal folds (P < .001). CONCLUSIONS: Hyperadduction increased PTP and worsened perturbation compared to normal, with near normal physiology restored with 1-mm lateralization. Further lateralization deteriorated voice quality and increased PTP. Acoustic and videokymographic results indicate that normal physiologic relationships between subglottal pressure and vibration are preserved at optimal lateralization width, but then degrade with further lateralization. The 1-mm optimal width observed here is due to the small canine larynx size. Future human trials would likely demonstrate a greater optimal width, with patient-specific value potentially determined based on larynx size and symptom severity. LEVEL OF EVIDENCE: NA Laryngoscope, 2016 127:396-404, 2017.

Aerodynamic and nonlinear dynamic acoustic analysis of tension asymmetry in excised canine larynges.

PURPOSE: To model tension asymmetry caused by superior laryngeal nerve paralysis (SLNP) in excised larynges and apply perturbation, nonlinear dynamic, and aerodynamic analyses. METHOD: SLNP was modeled in 8 excised larynges using sutures and weights to mimic cricothyroid (CT) muscle function. Weights were removed from one side to create tension asymmetry, mimicking unilateral SLNP. Two sets of weights were used, 1 light and 1 heavy. Five conditions were evaluated: (a) no tension, (b) symmetrical light tension, (c) asymmetrical light tension, (d) symmetrical heavy tension, and (e) asymmetrical heavy tension. RESULTS: Perturbation parameters were not significantly different across conditions: percent jitter, χ(2)(4) = 3.70, p = .451; percent shimmer, F(4) = 0.95, p = .321. In addition, many measurements were invalid (error values >10). Second-order entropy was significantly different across conditions, F(4) = 5.432, p = .002, whereas correlation dimension was not, F(4) = 0.99, p = .428. Validity of these nonlinear dynamic parameters was demonstrated by low standard deviations. Phonation threshold pressure, χ (2)(4) = 22.50, p < .001, and power, χ (2)(4) = 9.50, p = .05, differed significantly across conditions, whereas phonation threshold flow did not, χ (2)(4) = 4.08, p = .396. CONCLUSIONS: Nonlinear dynamic analysis differentiated between symmetrical and asymmetrical tension conditions, whereas traditional perturbation analysis was less useful in characterizing type 2 or 3 vocal signals. Supplementing acoustic with aerodynamic parameters may help distinguish among laryngeal disorders of neuromuscular origin.

How does the absence or presence of subglottal medialization affect glottal airflow?

OBJECTIVES: Our previous work has shown that the symmetric, smooth, convergent shape of the subglottis reduces turbulent airflow at the glottal entrance. Medialization thyroplasty may alter the glottal shape and is very likely to introduce some degree of glottal asymmetry, which could result in increased turbulence and a reduction in voice quality. This study reports the effects of medializing and not medializing the subglottis in silicone models of human cadaveric larynges. METHODS: In experiment 1, silicone models of 4 human cadaveric larynges were created. The subglottis was then completely medialized in all 4 models. Hot-wire anemometry was used to measure velocity and turbulence profiles at the entrance and exit of the subglottis. In experiment 2, 1 model was created to accommodate incremental medialization of the glottis without any medialization of the subglottis. Airflow characteristics were likewise measured. RESULTS: In experiment 1, the average maximum turbulence intensity (TI) at the exit of the larynx was less than the TI of incoming tracheal airflow for all 4 larynges. In experiment 2, incremental medialization of the glottis did not affect the TI for medialization up to 35%. However, the TI significantly increased for medialization of 53%. CONCLUSIONS: Medialization of the subglottis does not significantly affect the turbulence reduction properties of the subglottis, even though subglottal asymmetry is introduced. On the other hand, large amounts of medialization of the glottis only (with no subglottal medialization) can introduce significant amounts of turbulence.

[Repair of thyroid cartilage defects with chondrocyte-allogenous acellular cartilaginous matrix composite in rabbits].

OBJECTIVE: To investigate the feasibility of repairing thyroid cartilage defects by implantation of chondrocyte-allogenous acellular cartilaginous matrix (chondrocyte-ACM) composite in rabbits. METHODS: The thyroid chondrocytes were isolated and co-cultured in vitro with allogenous acellular cartilaginous matrix (ACM) to form the chondrocyte-ACM composite. The composite was analyzed histologically and was used to repair defects of thyroid cartilage. Eighteen New Zealand adult rabbits were made the defect models of thyroid cartilage at the two sides and divided into three groups. The defects were repaired with chondrocyte-ACM composite in the experimental group (n= 6), with simple ACM in the ACM group (n=6) and without any material in the control group (n=6). The animals were sacrificed at 8 weeks after operation. The specimens were evaluated histologically. RESULTS: In vitro, the growth of chondrocytes was observed on the surface of allogenous acellular cartilaginous matrix and no chondrocytes grew inside the matrix. The defect filled with muscle and connective tissues in control group; the lymphocyte infiltration was observed in the matrix and no new cartilage formation occurred at 8 weeks after operation in simple ACM group and experimental group. So the defect repair of rabbits thyroid cartilage failed. CONCLUSION: The allogenous acellular cartilaginous matrix failed to serve as a scaffold for chondrocytes both in vitro and in vivo. The allogenous acellular cartilaginous matrix should be improved.

Revision thyroplasty.

To document surgical techniques for performing a revision thyroplasty operation and to describe the subjective and objective results of these operations. I undertook a retrospective review of all patients who have undergone thyroplasty in my practice. I identified patients who required revision of a previous thyroplasty and evaluated preoperative and postoperative video and audio analyses of the voice. I identified the surgical steps necessary for successful completion of a revision operation and noted any special findings made at surgery. Charts were reviewed and tabulated for reasons for failure of the first operation, efficacy of the second surgical approach, specific anatomic findings made at revision surgery, and types of surgery available for revision. Of 625 total thyroplasties in 331 patients, revision operations accounted for 61 operations in 48 patients. All thyroplasty operations were found to be revisable or reversible. Objective voice analysis for 35 operations in 32 patients revealed a statistically significant improvement in shimmer in women, and in harmonics-to-noise ratio in all patients. Subjective voice improvement occurred in 80% of patients after revision surgery. I conclude that revision thyroplasty is possible with all thyroplasty types, giving significant improvement in both shimmer (women) and harmonics-to-noise ratio (all patients). Although most voices are still abnormal on postoperative objective voice analysis, 80% of patients are subjectively improved.

Role of laryngeal movement and effect of aging on swallowing pressure in the pharynx and upper esophageal sphincter.

OBJECTIVES: Describe contribution of laryngeal movement to pressure changes at the upper esophageal sphincter (UES) and the effect of aging on the swallowing function. STUDY DESIGN: Manofluorography on 56 nondysphagic adults divided into three age groups: the 21- to 31-year-old group (n = 32), the 61- to 74-year-old group (n = 12) and the 75- to 89-year-old group (n = 12). Analyses of the bolus transit time, the amplitudes and durations of pharyngeal pressures, the timing of a pressure fall at the UES and the laryngeal movements. METHODS: Intraluminal strain-gauge sensors recorded pressure changes in the oropharynx, hypopharynx and the UES. Motion pictures of the videotapes were fed into a personal computer, and movements of the hyoid bone were measured in both the horizontal and vertical directions as an indication of laryngeal movement. RESULTS: In 26- and 70-year-old men with calcification of the thyroid cartilage, it was determined that the larynx and hyoid bone moved in consonance until the end of the rapid hyoid movements in both the superior and anterior directions. In the 21- to 31-year-old group, the magnitude of the pressure fall at the UES was maximal before or almost at the same time as the bolus arrival, in preparation for smooth passage of the bolus from the pharynx to the esophagus. The rapid superior movements of the hyoid bone started significantly early as compared with its anterior movements (P = .0001). The rapid anterior movements of the hyoid bone started simultaneously with the pressure fall at the UES. In the elderly, all segmental transit times were significantly increased. The timing of the pressure fall at the UES was significantly delayed and the UES pressure reached its minimum value after arrival of the bolus at the UES. The minimum pressure at the UES increased to a significantly positive value. The rapid anterior movements of the hyoid were significantly delayed, suggesting that this delay causes the delay in the pressure fall at the UES. CONCLUSIONS: The rapid superior and anterior movements of the hyoid bone are considered to start at the same time as those of the larynx. In the young group, it is suggested that superior laryngeal movement protects the lower airway prior to the anterior laryngeal movement, causing the pressure fall at the UES to enable the passage of a bolus into the UES. In the elderly, smooth passage of the bolus from the pharynx to the esophagus is hindered and the system that prevents aspiration is rendered inefficient by changes in the swallowing pressures and laryngeal movements with aging.

Two-dimensional analysis of vocal fold vibration in unilaterally atrophied larynges.

OBJECTIVE: Considerable inconsistencies regarding the vibratory pattern of the vocal fold among patients with unilateral vocal fold paralysis (UVFP) have been reported. These differences are derived from differences in the position, stiffness, and atrophy of the paralyzed vocal fold and other factors among patients. The purpose of this study was to assess the effects of unilateral atrophy of the vocal fold on vocal fold vibration. METHODS: Seven excised canine larynges were studied. The unilateral recurrent laryngeal nerve was severed to cause vocal fold atrophy in four of the seven. The lateral and vertical displacements were monitored simultaneously with photoglottography and a laser Doppler vibrometer, respectively. Videostroboscopy of each larynx was also performed before and after the experiment to translate photoglottographic output into absolute lengths. Atrophy of the unilateral vocal fold was confirmed histologically. RESULTS: The lateral amplitude was significantly greater than the vertical amplitude in all larynges. The Lissajous trajectories in the normal larynges were shaped like a reverse crescent. Vibration in the unilaterally atrophied larynges was periodical and symmetrical in phase when the thyroid ala on the atrophied side was pressed medially. The lateral and vertical amplitudes on the atrophied side were significantly greater than those on the normal side. The Lissajous trajectories differed from those of the normal larynges. CONCLUSIONS: In the absence of a prephonatory glottal gap, periodical vibration occurs in unilaterally atrophied larynges and the amplitude of vibrations of the atrophied vocal fold is greater in the lateral and vertical directions than that of the normal fold. This implies that phonosurgical procedures aiming at closure of the prephonatory glottal gap may have a beneficial effect on hoarseness in UVFP patients, although displacements of the vocal folds during vibration are not symmetrical.

Quantitative criteria for predicting thyroplasty type I outcome.

The purpose of this study was to ascertain the relation between preoperative glottal gap and postoperative vocal function in thyroplasty type I. Twenty-two of 64 patients who underwent thyroplasty type I between 1987 and 1994 were studied. In preoperative digitized laryngostroboscopic images, the glottal-gap, width (GGW), shape, and area were examined at the maximum closure of vibration and normalized by membranous vocal-fold length (MVFL). Postoperative vocal function analysis was performed with aerodynamic and acoustic measurements and compared with preoperative videostroboscopic images. In patients with preoperative posterior GGW of less than 10% of MVFL, postoperative vocal function was significantly better than in other patients. Although thyroplasty type I is an excellent medialization technique, it may need to be combined with a posterior closure procedure in patients with large posterior gaps.

The fate of medialized cartilage in thyroplasty type I.

Thyroplasty type I is rapidly emerging as the preferred means of medializing a paralyzed vocal fold. We discuss our experience with the fate of a medialized cartilage window 9 months after an otherwise successful operation. Cartilage resorption over time resulted in degeneration of voice and in progressive aspiration. We recommend removing the cartilage window rather than medializing it, in the interest of stabilizing the degree of long-term vocal fold medialization.

[Structures of the anterior commissure of the larynx. Biomechanical and clinical aspects]. / Die Strukturen der vorderen Kommissur des Larynx. Biomechanische und klinische Gesichtspunkte.

The vocal ligaments and vocalis muscles insert at the anterior commissure of the thyroid cartilage. The biomechanical function of the connective tissue of the insertion is to equalise the different elastic modules of tendons and cartilage or bone. Structures of the insertion of plica vocalis at the anterior commissure are clinically important considering the spread of carcinoma that can grow along the vocal ligament in a ventral direction. The lack of perichondrium or periosteum in the area of insertion, ossification of the thyroid cartilage and the associated vascularisation of the skeleton allow the invasion of tumours in the thyroidal skeleton.

Phonatory effects of thyroid cartilage fractures.

Blunt trauma can cause a wide range of injuries to the cartilaginous framework of the larynx. The severity of injury that is required to cause a permanent disorder of vocal function if left untreated has not been defined. A study using excised canine and human larynges was undertaken to identify the effects of minimal displacement or malalignment in simulated thyroid cartilage fractures on selected voice production measurements. These fractures were found to cause changes in glottal configuration sufficient to affect glottal resistance as well as amplitude and noise content of the voice signal produced by each larynx. Therefore, relatively minor injuries of the thyroid cartilage may cause potentially serious disorders of phonation.