Conus Elasticus Research Articles

A comparison between succinylcholine and rocuronium on the recovery profile of the laryngeal muscles during intraoperative neuromonitoring of the recurrent laryngeal nerve: A prospective porcine model

The use of succinylcholine and rocuronium are reportedly feasible during intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) in thyroid surgery. This study aimed to investigate and compare the recovery profiles of succinylcholine and rocuronium on the laryngeal muscle during IONM of the RLN in a porcine model. Nine male Duroc-Landrace piglets were anesthetized with thiamylal and underwent tracheal intubation without neuromuscular blocking agents (NMBAs). Needle electrodes were inserted into the vocalis muscles through the cricothyroid ligament. The RLN was exposed and stimulated. Electromyographic (EMG) signals were obtained before and after the intravenous administration of a NMBA. The EMG amplitudes were measured before and after (at 1-minute intervals) the administration of the study drug until complete recovery. The study NMBA regimen included succinylcholine (1 mg/kg), low-dose rocuronium (0.3 mg/kg), and standard dose rocuronium (0.6 mg/kg). The maximal neuromuscular blockade and 80% recovery (i.e., duration) of the control responses were recorded and analyzed. The 80% recovery of the control response for succinylcholine (1 mg/kg) was 19.7 ± 1.5 minutes; low-dose rocuronium (0.3 mg/kg), 16.3 ± 2.5 minutes; and standard dose rocuronium (0.6 mg/kg), 29.3 ± 5.7 minutes. Succinylcholine (1 mg/kg) and low-dose rocuronium (0.3 mg/kg) had significantly shorter durations than standard dose rocuronium (0.6 mg/kg). The EMG signal recovery returned to baseline within 30 minutes in the succinylcholine and low-dose rocuronium groups, but it did not return to baseline until 1 hour after surgery in the rocuronium (0.6 mg/kg) group. In this study, succinylcholine (1 mg/kg) and low-dose rocuronium (0.3 mg/kg) had favorable recovery profiles on the laryngeal muscle. It is recommended that low-dose rocuronium may replace succinylcholine for the induction of general anesthesia during IONM of the RLN in thyroid surgery.

Assessment of the influence of osteopathic myofascial techniques on normalization of the vocal tract functions in patients with occupational dysphonia

Occupational voice disorders are accompanied by increased tension of the external laryngeal muscle which changes the position of the larynx and consequently disturbs the conditions of functioning of the vocal tract. The aim of the study is to assess the use of osteopathic procedures in the diagnosis and treatment of occupational dysphonia. Study subjects included 40 teachers with chronic diseases of the voice organ (38 women and 2 men) aged from 39 to 59 (mean age: 48.25). Before and after the voice therapy the osteopathic examination according to Libermann's protocol was performed as well as phoniatric examination including laryngovideostroboscopy (LVSS), assessment of the maximum phonation time (MPT) and the Voice Handicap Index (VHI) score. The voice therapy, scheduled and supervised by a laryngologist-phoniatrician and conducted by a speech-language pathologist, was supplemented with osteopathic myofascial rehabilitation of the larynx. The chi-square McNemar test and non-parametric Wilcoxon matched pairs test were applied in the statistical assessment. The applied interdisciplinary treatment including osteopathic and vocal therapy resulted in a statistically significant decrease in tenderness of muscles raising the larynx (cricothyroid ligament, sternocleidomastoid muscles, and pharyngeal constrictor muscles) and in lowering the tonus (geniohyoid muscles, pharyngeal constrictor muscles and sternocleidomastoid muscles). A significant improvement was also observed in the case of dysfunction of the cricothyroid joint examined during glissando and yawning, as well as in asymmetry of the thyrohyoid apparatus. Moreover, the therapy resulted in significantly better normalization of the head position and better control of the centre of gravity of the body. Statistically significant post-therapy improvement was observed in the phoniatric examination, including VHI scores, MPT results and parameters of videostroboscopic examination. The use of osteopathic therapy helps significantly improve the functions of the vocal tract in patients with occupational dysphonia.

Patterns of extralaryngeal spread of laryngeal cancer

Laryngeal preservation programs for patients with advanced laryngeal squamous cell carcinomas (SCC) have generally excluded patients with T4 disease. The accuracy of preoperative imaging in evaluating thyroid cartilage penetration and extralaryngeal spread (ELS) has previously been questioned. Clinically, SCC spread into noncartilaginous structures may have less of a functional impact when compared with thyroid cartilage penetration. The current study was designed to characterize and quantify the routes and frequency of ELS. A total of 103 laryngectomy specimens with preoperative contrast-enhanced neck computed tomography scans were coded according to the observed extent of disease by pathological and radiological data. Previously irradiated tumors or those of pyriform sinus origin were omitted. Routes of spread were categorized as anterior (thyroid cartilage penetration), posterior (arytenoid cartilage destruction and thyroarytenoid space widening), inferior (conus elasticus penetration), and superior (base of tongue, thyrohyoid membrane or thyroid notch penetration involvement). Sixty-three cases of ELS were identified. Anterior spread by thyroid cartilage penetration occurred in 44% of all instances of ELS, followed by both inferior and posterior spread each representing 33% of ELS cases. Superior spread occurred with a frequency of 24%. Although thyroid cartilage penetration is a common route of ELS of glottic and supraglottic SCC, ELS into surrounding structures with thyroid cartilage penetration was found to occur in only 44% of the cases of ELS in the current study. As illustrated, advanced SCC spreads in a variety of pathways. Once these patterns are better understood and identified at the time of initial evaluation, subgroups of patients with ELS who may still be candidates for laryngeal preservation may be identified.

Clinically Correlated Anatomical Basis of Cricothyrotomy and Tracheostomy

Cricothyrotomy and tracheostomy are performed by physicians in various disciplines. It is important to know the comprehensive anatomy of the laryngotracheal region. Hemorrhage, esophageal injury, recurrent laryngeal nerve injury, pneumothorax, hemothorax, false passage of the tube and tracheal stenosis after decannulation are well known complications of the cricothyrotomy and tracheostomy. Cricothyrotomy and tracheostomy should be performed without complications and as quickly as possible with regards the patients' clinical condition. A total of 40 cadaver necks were dissected in this study. The trachea and larynx and the relationship between the trachea and larynx and the surrounding structures was investigated. The tracheal cartilages and annular ligaments were counted and the relationship between tracheal cartilages and the thyroid gland and vascular structures was investigated. We performed cricothyrotomy and tracheostomy in eleven cadavers while simulating intensive care unit conditions to determine the duration of those procedures. There were 11 tracheal cartilages and 10 annular ligaments between the cricoid cartilage and sternal notch. The average length of trachea between the cricoid cartilage and the suprasternal notch was 6.9 to 8.2 cm. The cricothyroid muscle and cricothyroid ligament were observed and dissected and no vital anatomic structure detected. The average length and width of the cricothyroid ligament was 8 to 12 mm and 8 to 10 mm, respectively. There was a statistically significant difference between the surgical time required for cricothyrotomy and tracheostomy (p < 0.0001). Tracheostomy and cricothyrotomy have a low complication rate if the person performing the procedure has thorough knowledge of the neck anatomy. The choice of tracheostomy or cricothyrotomy to establish an airway depends on the patients' clinical condition, for instance; cricothyrotomy should be preferred in patients with cervicothoracal injury or dislocation who suffer from respiratory dysfunction. Furthermore; if a patient is under risk of hypoxia or anoxia due to a difficult airway, cricothyrotomy should be preferred rather than tracheostomy.

P075: Prognostic Indicator of Unilateral Vocal Fold Paralysis

Objectives: To determine what factor would be helpful in determining prognosis of unilateral vocal fold paralysis (UVFP) and to reconfirm the feasibility of published laryngeal electromyography (LEMG) decision rules in assessing prognosis of UVFP Methods: A cohort study with retrospective data analysis was conducted at voice clinic of a tertiary medical center from Nov. 2004 to Jun. 2006. Independent variables including patient gender, age, laterality of UVFP, etiology, symptom duration, or LEMG findings for 30 patients diagnosed as idiopathic or iatrogenic UVFP were collected. The LEMG was performed between 3 weeks and 6 months from the onset of symptoms and patients were followed for a minimum of 6 months after symptom onset and 3 months after LEMG to check the motion of the diseased vocal fold. Univariate analysis, logistic regression and Receive Operating Characteristic curve were used to decide the significant prognostic indicators. Results: According to the LEMG decision ruling proposed by Dr. Munin normal or nearly normal motor unit recruitment and absence of spontaneous activities gave a good prognosis. The predictive values for negative test and positive test, sensitivity, specificity and accuracy of LEMG were 75%, 80.8%, 95.5%, 37.5%, and 80% respectively. Univariate analysis and logistic regression showed that symptom duration and overall LEMG result significantly correlated with outcome of UVFP (p the prognostic role of electromyography in laryngeal paralysis. Otolaryngol Head Neck Surg.1994;111:770-775. 9 Munin MC, Rosen CA, Zullo T. Utility of laryngeal electromyography in predicting recovery after vocal fold paralysis. Arch Phys Med Rehabil. 2003; 84:1150-1153. Bibliography From Nov. 2004 to Jun. 2006, medical records of 30 patients diagnosed as idiopathic or iatrogenic UVFP who received LEMG between 3 weeks and 6 months from the onset of symptoms were retrospectively reviewed after institutional review board approval was obtained. The office-based LEMG (Fig. 1) was all performed by the first author; a laryngologist familiar with the anatomy of intrinsic laryngeal muscles. The LEMG findings were all interpreted by the second author; a neurologist with 15 years experience in electrodiagnostic medicine. All LEMG examinations were performed by a machine (Cadwell Sierra 6200A, Cadwell Laboratories, Inc., 909 North Kellogg Street, Kennewick, Washington, 99336) with a computer-based electrodiagnostic system. The cricothyroid (CT) muscle and thyroarytenoid (TA) muscle were both approached transcutaneously without local anesthesia, while only the signals representing recurrent laryngeal nerve function obtained from TA muscle were used to predict prognosis of UVFP. TA muscle was approached by inserting a needle through the cricothyroid ligament approximately 0.5 cm from the midline. The needle was then angled superiorly 30° to 45° to an approximate depth of 1-2 cm. The position of the needle was validated by asking the patient to say a sustained vowel /i/ with the absence of activation during respiration and neck flexion. The outcome measurement of vocal fold motion (Fig. 2) was done with flexible laryngoscope or video-stoboscope at least 3 months after LEMG and at least 6 months after onset of symptoms. These criteria gave patients at least 3 months (ranging from 3 to 5 months) follow up duration to observe the predictive ability of LEMG in this time window. Methods and Materials Table 2 Table 3

Anatomical Definition of the Subglottic Region

Background: Due to laryngeal neoplasia, as well as infectious and autoimmune diseases, the subglottic region is of great clinical relevance. However, descriptions of the subglottic structures are inconsistent. The aim of our study was to present a precise analysis of the subglottic region and derive functional and clinical conclusions. Methods: Histological, histochemical and immunohistochemical investigations as well as scanning electron microscopy were performed and combined with injection techniques applied to the subglottic region of the larynges of 33 body donors. Results: The three-dimensional extensions of the subglottic region were newly defined: the inferior arcuate line of the vocal cord was defined as the cranial border. The lower margin of the cricoid is the caudal border. Craniolaterally, the elastic cone and, further caudally, the cricoid form the border. Therefore, the definition presented comprises heretofore unnamed ventral and dorsal parts of the lower larynx. The subglottic region can be described as cylindrical, becoming smaller in the cranial direction, following the elastic cone. The ventral boundary is formed by the median part of the cricothyroid ligament (ligamentum conicum), the dorsal part by the cricoid cartilage. The walls of the subglottis are divided into three or four layers composed of collagenous and elastic fibres in which seromucous glands are embedded. Subglottic blood vessels including a tight subepithelial capillary plexus were delineated. Conclusion: The new definition of the subglottic extensions presented is helpful and essential for precise laryngeal tumour classification. The results indicate that the boundaries are unlikely to counteract tumour progression in the subglottis. Furthermore, the findings suggest that these structures contribute to temperature regulation of breath, protection against inflammation as well as breath frequency and depth-dependent mucus secretion.

A new device for cricothyroidotomy

A new instrument for coniotomy was developed and tested with cadaver experiments. The instrument should be simple, easy to handle, and should not have the various drawbacks of the existing devices. The new instrument was tested by 17 medical students and medical doctors on fresh human cadavers. We measured the time necessary for performing a successful experiment. It lasted 5-28 sec (mean value 22 sec) depending on the experience of the people carrying out the tests. This time is much shorter than with other existing instruments tested under experimental conditions. The instrument consists of a tube and a trocar with a small knife on the tip. The knife is used to incise the skin over the cricothyroid ligament and to perforate this ligament in sagittal position. The tube is provided with a plastic stripe, which limits the depth of the entrance of the instrument into the larynx and can also be used to attach the tube to the neck of the patient. After entering the larynx, the tube can be connected to an inflating bag. The correct seat of the tube was tested by inflation, with a calibrated probe or with laryngoscopy. The results of our tests encourage the development of this new instrument for industrial production.

Applied anatomy for cricothyrotomy and tracheostomy

If upper respiratory obstruction cannot be cleared by other means, puncture of the cricothyroid ligament offers rapid access to the airway via the gap between the cricoid and thyroid cartilages; both of which can be readily palpated in the midline of the fully extended neck. The opening can be made with a knife, a wide bore needle or trocar, or by means of a special intubation kit. It is important to be able to identify the midline structures of the fully extended neck: the hyoid bone, at the level of the third cevical vertebra; the laryngeal notch and the laryngeal prominence, at the fourth cervical vertebra; below which lies the isthmus of the thyroid cartilage; with the depression of the cricothyroid membrane below this. This depression lies above the easily felt cricoid cartilage (the only complete ring of cartilage in the respiratory tree) at the level of the sixth vertebra. Below this can be felt the rings of the trachea. The isthmus of the thyroid gland usually crosses the second to fourth rings but cannot normally be felt unless enlarged. Formal tracheostomy is a relatively major surgical operation and is seldom indicated as an emergency. However, a mini-tracheostomy kit is now available for a percutaneous emergency procedure.

Risk factors of paralysis and functional outcome after recurrent laryngeal nerve monitoring in thyroid surgery

Recurrent laryngeal nerve monitoring (RLNM) has been suspected to reduce postoperative RLN paralysis (RLNP). However, functional outcome of RLNM in comparison with no nerve identification and visual nerve identification only has not been analyzed. Analysis of 16,448 consecutive multi-institutional operations resulted in 29,998 nerves at risk. Three groups of different RLN treatment were compared: group 1, no RLN identification; group 2, visual RLN identification; and group 3, visual RLN identification and electromyographic monitoring. RLNM was performed with a bipolar needle electrode that was placed through the cricothyroid ligament into the vocal muscle. Risk factors for permanent RLNP were recurrent benign and malignant goiter (odds ratios, [ORs]), 4.7, and 6.7, respectively), primary surgery in thyroid malignancy (OR, 2.0), lobectomy (OR, 1.8), no nerve identification (OR, 1.4), low or medium volume hospital (OR, 1.3), and low volume surgeons (OR, 1.2). Based on these data, visual nerve identification was identified to be the gold standard of RLN treatment in thyroid surgery. RLNM is a promising tool for nerve identification and protection in extended thyroid resection procedures. However, because of the overall low frequency of RLNP, no statistical difference compared with visual nerve identification only was reached in the setting of this study.

Intrinsic and extrinsic forces determine the distortion of the split cricoid ring

An anterior cricoid split (ACS) causes an immediate distortion of the cricoid cartilage resulting in an anterior gap due to retraction of the cut ends. The objective of this animal study is to investigate: (1) to what extent the distortion after ACS is influenced by non-cartilaginous structures like tunica elastica, membranes, ligaments and muscles, which are connected to the cricoid; (2) how distortion is changing with further development; (3) in what way the distortion is affected by scoring of the internal surface of the cricoid; and (4) whether an immediate or late injury-induced distortion is related to age. Surgical interventions were performed in 20 young (8 weeks of age, 1300-1600 g) and 5 adult (28 weeks of age, 3500-4000 g) New Zealand White rabbits. The immediate effects were measured, and then the animals were followed for 20 weeks to study the long-term effects of the various procedures. (1) The gap, immediately following an ACS, increased after additional transection of the cricothyroid ligament and the cricotracheal membrane, and even more when the cricovocal membrane was elevated from the inner surface of the cricoid arch. (2) The degree of distortion after various interventions in young animals appeared to increase substantially during further growth. (3) When the above-mentioned successive surgical steps were combined with scoring of the internal surface of the cricoid arch, a marked malformation of the split cricoid did develop with warping of the cut ends in lateral direction and a latero-cephalic rotation, the latter due to the action of the cricothyroid muscles. (4) The immediate distortion appeared to be similar in young and adult animals. During a follow-up of 20 weeks, a progressive distortion of the split cricoid ring was observed in the young growing rabbits. In adult animals, no significant progression of the distortion was found. The immediate and long-term distortion of the split cricoid is determined by the release of intrinsic forces of the cartilage, and extrinsic forces from non-cartilaginous structures like ligaments, muscles, membranes and tunica elastica.

Rupture of the larynx in a newborn

BACKGROUND: Lesions of the laryngotrachea due to repeated intubation trauma after birth are reported. CASE: A macrosomic neonate was born at term after uneventful pregnancy. On the basis of diminished uterine contractions and arrest of descent, the head was delivered by using obstetric forceps. No intubation was attempted after birth. Ten hours later, the infant developed acute life-threatening respiratory distress and subcutaneous emphysema. Intubation was impossible. Open surgical exploration of the neck revealed a rupture of the cricothyroid ligament within the larynx. The defect was closed immediately, and after artificial ventilation for 7 days, the infant was extubated. One year later, the child is developing satisfactorily, without stridor or hoarseness. CONCLUSION: In macrosomic neonates after traumatic delivery, a laryngotracheal lesion should be considered when respiratory distress syndrome combined with subcutaneous emphysema occurs.

Cricoid Area of the Larynx: Its Physiological and Pathological Significance

The three-dimensional distribution of the cricoid area was investigated using computer graphics and its histological structure and pathology were studied using whole-organ serial sections. A total of 26 adult human larynges were examined. The findings were as follows: 1. Cricoid areas were located along the superior portion of the cricoid arch on both sides. 2. The cricoid area was surrounded by the perichondrium of the cricoid cartilage, the conus elasticus and the fibrous layer of the subglottic mucosa. 3. The cricoid area was a loose areolar area, mainly composed of adipose tissue and loose elastic and collagenous fibers. 4. Many vessels were present in the cricoid area and a superficial branch of the cricothyroid artery ran through it. 5. Vessels in the cricoid area penetrated the anteroinferior portion of the conus elasticus and extended into the prelaryngeal region. 6. In larynges with laryngeal carcinoma, cancer invasion into the cricoid area and intravascular tumor invasion facilitated metastasis to the prelaryngeal, pretracheal and/or paratracheal regions and stomal recurrence. Cricoid areas were related to the growth pattern of laryngeal cancer.

声門癌声門下進展例の治療方針-T2症例を中心に-

Over a 16-year period, from 1980 though 1995, 41 patients with T2 glottic squamous cell carcinoma (SCC) with subglottic extension were treated at the National Cancer Center Hospital. The treatment modalities included radiotherapy, partial laryngectomy (P.L), and total laryngectomy (TL). The treatment results were analyzed to determine a strategy for management of T2 glottic SCC with subglottic extension.The indication of radiotherapy in these patients was limited in cases with superficial and small subglottic extension. TL was required in a majority of the patients with recurrent carcinoma after radiotherapy. TL should be initially required for patients with invasion of cricothyroid ligament and with subglottic extension over 1cm in diameter at the posterior part of the vocal cord. PL was the first choice of the treatment in a majority of the patients without superficial and small subglottic extension nor invasion of cricothyroid ligament. The local control rates and the laryngeal preservation rates were 70% and 70% with PL, versus 40% and 50% with radiotherapy. The correct diagnosis of subglottic extension via long laryngo-bronchofiberscope was very important to determine the modality of treatment.

Characterization of the medial surface of the vocal folds.

A method is developed for the quantification of the medial surface of the vocal folds in excised larynges. Lead molds were constructed from the glottal airway of a canine larynx for 3 distinct glottal configurations corresponding to "pressed" folds, just barely adducted folds, and 1-mm-abducted folds as measured between the vocal processes. With a high-resolution laser striping system, the 3-dimensional molds were digitally scanned. Low-order polynomials were fitted to the data, and goodness-of-fit statistics were reported. For all glottal configurations, a linear variation (flat surface) approximated the data with a coefficient of determination of 90%. This coefficient increased to roughly 95% when a quadratic variation (curvature) was included along the vertical dimension. If more than the top 5 mm or so of the folds was included (the portion usually corresponding to vibration), a cubic variation along the vertical dimension was necessary to explain a change in concavity at the conus elasticus. These findings suggest the utility of a model based on a convergence coefficient and a bulging coefficient. For all glottal configurations, the convergence coefficients and bulging coefficients can be computed. Because pre-phonatory conditions have a profound influence on vocal fold vibration and on the quality of phonation, such shaping parameters are highly significant. With the viability of this method substantiated, it is envisioned that future studies will characterize greater quantities of glottal shapes, including those of human vocal folds.

Cancer spread in the larynx: A pathologic basis for conservation surgery

Background Previous pathologic studies of the spread of laryngeal carcinoma have drawn inferences about the site of origin of tumors, their mechanisms of growth, or the role of structures as potential barriers to tumor spread. Most of the information is based on the study of advanced or recurrent tumors and is difficult to apply to conservation surgical technique. We carried out a systematic analysis of a wide range of laryngeal tumors with the aim of providing a basis for conservation surgery. Methods We analyzed tumor invasion of the laryngeal spaces and the laryngeal framework in relation to the mucosal tumor extent by axial sectioning of 80 sequential partial and total laryngectomy specimens. Results Invasion of a particular laryngeal space could be accurately predicted by mucosal tumor extent and vocal cord mobility. Invasion of the laryngeal framework was associated with tumor extension to the ventricle, subglottis, or pyriform fossa. The thyroid cartilage and the cricothyroid space and ligament were the most frequent sites of invasion. Conclusions The mucosal distribution of a tumor and observation of vocal cord mobility can be used to determine accurately the extent of tumor invasion of the laryngeal spaces and framework and therefore the extent of resection necessary. © 2000 John Wiley & Sons, Inc. Head Neck 22: 265–274, 2000.

Cancer spread in the larynx: a pathologic basis for conservation surgery.

Previous pathologic studies of the spread of laryngeal carcinoma have drawn inferences about the site of origin of tumors, their mechanisms of growth, or the role of structures as potential barriers to tumor spread. Most of the information is based on the study of advanced or recurrent tumors and is difficult to apply to conservation surgical technique. We carried out a systematic analysis of a wide range of laryngeal tumors with the aim of providing a basis for conservation surgery. We analyzed tumor invasion of the laryngeal spaces and the laryngeal framework in relation to the mucosal tumor extent by axial sectioning of 80 sequential partial and total laryngectomy specimens. Invasion of a particular laryngeal space could be accurately predicted by mucosal tumor extent and vocal cord mobility. Invasion of the laryngeal framework was associated with tumor extension to the ventricle, subglottis, or pyriform fossa. The thyroid cartilage and the cricothyroid space and ligament were the most frequent sites of invasion. The mucosal distribution of a tumor and observation of vocal cord mobility can be used to determine accurately the extent of tumor invasion of the laryngeal spaces and framework and therefore the extent of resection necessary.

Anatomical bases of glottic widening surgery related to arytenoidectomy.

Derived from arytenoidectomy, different surgical techniques have been developed for widening the glottis in cases of bilateral vocal cord paralysis. Their anatomical bases were reinvestigated in plastinated serial sections of 25 adult human larynges. At the anterolateral surface of the arytenoid cartilage, blood vessels crossing the crista arcuata may cause bleeding complications. The arytenoid cartilage is related to three major histologic complexes which must be taken into account during surgery. The dense connective tissue complex consists of the cricoarytenoid ligament and the conus elasticus, which are connected ventrocaudally. The cricoarytenoid ligament and the vocal cord are separated by the cartilaginous inscription of the vocal process. The muscular complex consists of the transverse arytenoid muscle, which is the posterior wall of the glottis, and the thyroarytenoid muscle, which is intimately fixed to the conus elasticus near the arytenoid cartilage. The loose connective tissue complex is represented by the vestibular fold, containing adipose tissue, mucous glands, few collagenous fiber septa, and at its posterior end, a small cranial extension of the vocal cord. For glottic widening surgery, the arytenoid cartilage must be regarded as an integrated component of an extended fibro-cartilaginous framework supporting the laryngeal airway. Shrinking processes of the dense connective tissue elements may complicate surgical interventions. Iatrogenic lesions of the posterior glottis should be avoided to prevent the development of synechia or insufficient closure of the larynx during swallowing.

頚部・縦隔気腫の増悪にて緊急挿管された喉頭外傷例

A 35-year-old man was involved in an automobile collision and was brought to the emergency room of our hospital by ambulance. He had cuts on his forehead and left knee, and complained of dyspnea and hoarseness. Since swelling and crepitation were palpable on his anterior neck without any other external injury, he was suspected of having sustained a laryngeal trauma caused by the seatbelt pressing on his neck. A CT scan indicated a slight disruption of the lower part of the laryngeal framework, which appeared to cause emphysema extending from the neck to the mediastinum. Examination with a flexible endoscope was tried, resulting in an unexpected exacerbation of the emphysema into a respiratory crisis possibly due to increased subglottic pressure. An immediate oral intubation relieved this crisis.After his general condition was observed for two days in the ICU, we studied his larynx and hypopharynx using endoscopes under general anesthesia by tracheostomal intubation and found a mucosal disruption in the subglottic area. Under sequential open reduction, we also found fractures of the antero-lateral cricoid arch and the lower thyroid cartilage with disruptions of the sternohyoid muscle and the crico-thyroid muscle and ligament. The injuries healed well under repairs by suturing and wiring. We observed no sign of subglottic stenosis without a stent for a period of 5 weeks, and then repaired the tracheostome. Presently, the patient's vocal cords are mobile, and the vibratory patterns observed with a stroboscope appear normal. However, he has continued to demonstrate limitations in high-pitched phonation for 2 months.We discuss in detail the effects of the laryngeal injuries in this case regarding postoperative phonatory function using 3D images reconstructed with a helical CT. In addition, we also discuss the usefulness of so-called endoscopic 3D-CT images in cases of laryngeal trauma with mucosal disruption as a non-invasive examination in place of endoscopy.

Three-dimensional analysis of cricoarytenoid joint motion.

The normal motion of the cricoarytenoid joint was characterized and analyzed in this study using seven fresh cadaver larynges mounted rigidly in an external fixator apparatus after radiopaque markers were attached to laryngeal landmarks. Fluoroscopic imaging and recording was performed of top, front, and side views while the arytenoid cartilages of each larynx were manipulated through the full range of motion from adduction to abduction. Computer video capture was performed of the recordings and editing of still frames accomplished to generate three-dimensional plots of cricoarytenoid joint motion, which are shown in the manuscript. Selective and varying sequential disconnection of muscular and ligamentous structures to the arytenoid cartilage was achieved to determine their contributions to cricoarytenoid joint motion limitations and stability. The vocalis ligament, cricoarytenoid ligament, and conus elasticus are most important in controlling abduction, whereas the posterior cricoarytenoid muscle and conus elasticus are crucial in limiting adduction. The vocalis ligament prevents posterior displacement of the vocal process, while the cricoarytenoid ligament and a newly described ligament, the posterior capsular ligament, restricts anterior vocal process migration. Another ligament, the anterior capsular ligament, is described, which limits backward arytenoid cartilage tilting and lateral movement of the arytenoid cartilage on the cricoid cartilage facet. Section of the vocalis ligament with underlying conus elasticus produced reducible lateral arytenoid cartilage subluxation. Confirmation of cricoarytenoid joint facet relationships in full adduction and abduction was accomplished by fixation of the cricoarytenoid joints of one larynx in the two positions with adhesive, and subsequent exposure of the joint surfaces. Review of literature detailing human laryngeal embryological development shows that the glottis and arytenoid cartilages are formed in adduction, which explains how cricoarytenoid joint ligaments collaborate to achieve accurate vocal process approximation in adduction despite side-to-side asymmetries of the cricoarytenoid joint structures in the same larynges.

Subglottic region: normal topography and possible clinical implications.

A precise definition of clinically important laryngeal regions and compartments is still a matter of controversy. The often neglected subglottic area was reinvestigated in plastinated serial sections of 21 human adult specimens. The superior border of the subglottic region is defined by the transition of squamous stratified epithelium covering the vocal cords into the respiratory epithelium of the caudal airways. It is found at the inferior margin of the vocal fold at variable distance from the free edge of the vocal cord and bears a high risk of carcinogenesis. The anterior border of the subglottic region is the cricothyroid space between the thyroid cartilage and cricoid arch. Medially, it is bridged by the median cricothyroid ligament. Laterally, the gap between thyroid and cricoid cartilage is filled by adipose tissue in most cases. This provides a broad connection of intra- and extralaryngeal connective tissue. There, cancer may escape the larynx. The conus elasticus is often regarded as a firm fibroelastic membrane within the subglottic region, but its structure may be disturbed by piercing blood vessels or age-related changes, facilitating cancerous spread. The cricoid lamina representing the dorsal border of the subglottic space ossifies preferentially in its superior part, which is often attacked by tumor invasion. The inferior border of the subglottic region is defined at the inferior rim of the cricoid cartilage. At this level, the endocricoid submucosal tissue contains loosely arranged collagenous fibers, which probably do not act as an anatomic barrier.