Morphometry of the thyroid cartilage, epiglottis and piriform sinus: An anatomical study.

Background: The goal was to measure the piriform sinus, epiglottis, and thyroid cartilage in our sample population. Methods: This study included 22 adult embalmed cadavers available in the Department of Anatomy. Dimensions were measured using a digital Vernier caliper. Results: The mean height of the thyroid laminae was 27 ± 1.4 mm at the right side and 25.5 ± 1.4 mm at the left side. Mean width of the thyroid lamina was 27.1 ± 1.3 mm at the right side and 27.4 ± 0.9 mm at the left side. The mean thickness of thyroid cartilage was found to be 4.4 ± 0.4 mm and 3.9 ± 0.5 mm over the right and left sides. The mean length, width and thickness of the epiglottis were 29.1 ± 0.5 mm, 22.2 ± 0.6 mm and 2.6 ± 0.3 mm correspondingly. The height, width and thickness of the right piriform sinus were 25 ± 0.5 mm, 14.2 ± 0.5 mm and 12.6 ± 0.5 mm, the same parameters were 25.3 ± 1.3 mm, 15.1 ± 0.7 mm and 13.3 ± 0.4 mm for the left side. Conclusions: The height and thickness of the thyroid cartilage were greater on the right side than on the left side (p<0.05). It was statistically observed that the width and thickness were greater on the left side than on the right side (p < 0.05). The data about the height, width and thickness of the thyroid cartilage, epiglottis and piriform sinus are essential during the laryngeal and other neck surgeries. They guide in the preoperative positioning, predicting the difficulty of intraoperative exposure and retractor pulling.

The vertical topography of the carotid bifurcation - original study and review.

PURPOSE: The vertical level of carotid bifurcation (CB) is commonly indicated at the superior margin of the thyroid cartilage. Few studies observed the CB vertical topography. It was aimed at studying the vertical location of the CB as referred to vertebral and anterior cervical landmarks. METHODS: An archived lot of 147 computed tomography angiograms was documented for the vertical level of CB referred to vertebral and anterior cervical landmarks. The topography of the CB in relation to anterior landmarks was classified into seven types: (1) at the superior margin of the thyroid cartilage; (2) between the hyoid and the thyroid cartilage; (3) at the hyoid level; (4) between the hyoid and mandible; (5) subgonial or supragonial CB; (6) lower cervical level; (7) intrathoracic. RESULTS: The most common locations of CB were at C3 (27.21%), C3/C4 (26.19%) and C4 (25.51%). Bilateral symmetry of CB was found in 51.7%, except for C2 and C5/C6. Type 7 was not found, type 3 occurred in 39.12%, type 2 in 24.49%, type 1 in 13.95%, type 4 in 13.61%, type 5 in 6.12%, and type 6 in 2.72% (294 CBs). Bilateral symmetry of anterior types was found in 59.86%. Statistically significant correlations were found between sex and both left and right types and vertebral levels of CB. CONCLUSIONS: The vertical topography of the CB is highly variable and has sex-related specificity. This detail should be included in the teaching of anatomy. Surgeons and interventionists should better document the carotid anatomy on a case-by-case basis.

The previously undescribed variant of the thyrohyoid muscle and its potential impact on surgical procedures.

The thyrohyoid muscle belongs to the infrahyoid group located in the carotid triangle. It normally originates from thyroid cartilage and inserts into hyoid bone. Quite often, it is continuous with the sternohyoid muscle. Furthermore, there are variants that have their origin in the cricoid cartilage only, however, this occurs very rarely. During anatomical dissection, a two-headed variant of this muscle was found. One head had its origin in the cricoid cartilage and the other in the thyroid cartilage. This variant of thyrohyoid had not been previously described in the available literature. Therefore, we believe that it may be referred to as the cricothyrohyoid muscle. As the thyrohyoideus is often used as a landmark during surgical procedures in the prelaryngeal area and as a muscle graft, a thorough knowledge of its anatomy and variation is extremely important. We speculate that the two-headed version of this muscle may be problematic during surgical procedures in this region, however, it may also provide more options as a muscular graft.

Long-Term Outcomes of Cricothyroidotomy Versus Endotracheal Intubation in Military Personnel: A Retrospective Comparative Analysis Cohort Study.

INTRODUCTION: Emergency airway management is critical in trauma care. Cricothyroidotomy (CRIC) is a salvage procedure commonly used in failed endotracheal intubation (ETI) or difficult airway cases. However, more data is needed regarding the short and long-term complications associated with CRIC. This study aimed to evaluate the Israel Defense Forces experience with CRIC over the past 2 decades and compare the short-term and long-term sequelae of prehospital CRIC and ETI. METHODS: Data on patients undergoing either CRIC or ETI in the prehospital setting between 1997 and 2021 were extracted from the Israel Defense Forces trauma registry. Patient data was then cross-referenced with the Israel national trauma registry, documenting in-hospital care, and the Israel Ministry of Defense rehabilitation department registry, containing long-term disability files of military personnel. RESULTS: Of the 122 patients with short-term follow-up through initial hospitalization, 81% underwent prehospital ETI, while 19% underwent CRIC. There was a higher prevalence of military-related and explosion injuries among the CRIC patients (96% versus 65%, P = 0.02). Patients who underwent CRIC more frequently exhibited oxygen saturations below 90% (52% versus 29%, P = 0.002). Injury Severity Score was comparable between groups.No significant difference was found in intensive care unit length of stay and need for tracheostomy. Regarding long-term complications, with a median follow-up time of 15 y, CRIC patients had more upper airway impairment, with most suffering from hoarseness alone. One patient in the CRIC group suffered from esophageal stricture. CONCLUSIONS: This retrospective comparative analysis did not reveal significant short or long-term sequelae among military personnel who underwent prehospital CRIC. The long-term follow-up did not indicate severe aerodigestive impairments, thus suggesting that this technique is safe. Along with the high success rates attributed to this procedure, we recommend that CRIC remains in the armamentarium of trauma care providers. The findings of this study could provide valuable insights into managing difficult airway in trauma care and inform clinical decision-making in emergency settings.

Investigation of triticeal cartilage anatomy in forensic autopsy cases.

PURPOSE: This study aims to determine the presence and morphology of triticeal cartilage (TrC) through autopsy cases and to examine its relationship with age, gender, and height, thus contributing to clinical practices and forensic perspective. MATERIALS AND METHODS:  Our study was conducted on a total of 84 autopsy cases between the ages of 20-90 years who came to Tokat Forensic Medicine Institute. The laryngeal region was palpated to determine whether TrC was present. The dimensions of the TrC and the length of the upper horn of thyroid cartilage (UHThC) were measured with precise digital calipers, and its weight was measured with an accurate digital scale. RESULTS: The presence of TrC was identified in 56% of the autopsy cases examined. The prevalence of TrC was higher in males (61.9%) than in females (23.1%). It was determined to be bilateral in 45% of the cases and unilateral in 11%. TrCs had a cylindrical shape in 68.2%, an oval shape in 25.8%, and a pyramidal shape in 5.8%. The average weight of TrC was 67.93 ± 33.91 mg on the right side and 72.67 ± 32.23 mg on the left. As the individual's height increased, the weight of TrC increased (p < 0.001). Additionally, there was a strong positive correlation between the lengths of TrC and UHThC and the individual's height (p < 0.001). CONCLUSION: TrC may be confused with UHThC fractures. Therefore, we believe that knowledge of the presence and morphology of TrC will contribute to clinical approaches and forensic cases, especially in relation to the neck region.

[Thyroid cartilage fracture following sneezing as a cause of spontaneous pneumomediastinum]. / Perelom shchitovidnogo khryashcha vsledstvie chikhan'ya kak prichina spontannogo pnevmomediastinuma.

OBJECTIVE: To evaluate the possible etiological factors of spontaneous pneumomediastinum and to describe a case that was unusual in its etiology: a thyroid cartilage fracture as a result of sneezing. MATERIAL AND METHODS: Six patients (four male, two female, aged 16-82 years) were hospitalized with spontaneous pneumomediastinum diagnosed with a chest X-ray in five patients and 100% with computed tomography. Treatment was symptomatic. RESULTS: The commonest symptoms (cough, shortness of breath, hoarseness) were in four patients. Spontaneous pneumomediastinum developed in three cases as a result of bronchospasm during an attack of bronchial asthma, in one patient after exercise, in one after fibrogastroscopy, in one after sneezing. We report a 30-year-old man who presenting subcutaneous emphysema on the neck, hoarseness, pain when swallowing, hemoptysis developed after sneezing. His computed tomography revealed a pneumomediastinum due to fistula of the fracture of the thyroid cartilage following sneezing while simultaneously obstructing both nostrils. At laryngoscopy, there was a linear hematoma in the resolution stage on the anterior wall of the larynx. He was treated conservatively and recovered rapidly. There are no previous published reports of spontaneous pneumomediastinum following fracture of the thyroid cartilage. CONCLUSION: Fracture of the thyroid cartilage as a result of a sharp rapid increase in airway pressure during a sneeze with blocked nasal passages can be one of the rare causes of spontaneous pneumomediastinum. Avoid closing both nostrils at the same time when sneezing.

Comparison of diffusion ranges at different local anesthetic volumes during superior laryngeal nerve block.

OBJECTIVES: Ultrasound-guided superior laryngeal nerve (SLN) block is a practical and painless approach to avoid the hemodynamic stress response during endotracheal intubation and relieve sore throat after laryngeal surgery. The main purpose of this study was to establish an optimal dosage of local anesthetic when performing SLN block to help anesthetists balance analgesia and side effects. METHODS: Twenty fresh larynx specimens were obtained immediately after resection and then injected with 2-, 3-, 4-, or 5- mL of a lidocaine-blue dye mixture at bilateral SLN puncture sites. Superficial areas of deposited blue dye were measured. Dye leakage and surrounding dyed tissue were recorded. Another 40 patients were included in the ultrasound investigation. Distances between the internal branch of the SLN (iSLN) and adjacent structures were calculated. RESULTS: The dye spread area was greater with the administration of larger doses, especially to the visceral space. A 2- or 3-mL injection of local anesthetic was sufficient to infiltrate the SLN gap. A higher incidence of dye leaking out of the thyrohyoid membrane and anterior epiglottis space was observed; furthermore, there was substantially more dyed hyoid/thyroid cartilage with 4 and 5 mL of injected dye mixture than 2 mL. There was no significant difference between the specimen and ultrasound measurements of for length of iSLN-adjacent structures. CONCLUSIONS: In the Chinese population, 2- or 3- mL of local anesthetic is a safe dose during SLN block. A larger volume could overflow from the cavity to cause complications. The thyrohyoid membrane combined with the superior laryngeal artery is a reliable target for positioning the iSLN during ultrasound-guided regional anesthesia.

The Effect of Thyroid Surgery on the Accuracy of Palpation-Based Cricothyroid Membrane Identification in Female Patients: A Prospective Observational Cohort Study.

Background and Objectives: This study examined how a history of thyroid surgery impacts the precision of cricothyroid membrane (CTM) identification through palpation (validated by ultrasound) in female patients visiting the operating room for surgeries unrelated to neck procedures. Materials and Methods: This prospective observational cohort study enrolled adult female patients undergoing elective non-neck surgery, dividing them into control (no thyroid surgery history; n = 40) and experimental (with thyroid surgery history; n = 40) groups. CTM identification was performed by palpation and confirmed via ultrasound. Results: There were no significant differences between two groups in the demographic characteristics of the patients. The success rate and accuracy of CTM identification through palpation were significantly higher in the control group compared to the experimental group (90% vs. 42.5%, respectively; p < 0.001). For female patients with a history of thyroid surgery, the sensitivity of successful CTM palpation was 42.5%, and the specificity was 10%. These figures are based on the calculated true positives (17), false positives (36), true negatives (4), and false negatives (23). Conclusions: Thyroid surgery history in female patients may hinder the accurate palpation-based identification of the CTM, suggesting a need for enhanced clinical practices and considerations during airway management training.

Lowered hyoid bone overlapping the thyroid cartilage in CT angiograms.

BACKGROUND: The ventral enclosure of the thyroid cartilage by a collapsed hyoid bone (CHB) is poorly encountered in previous research. It was aimed to observe whether or not these malformations could be found and detailed anatomically in a consistent lot of computed tomography (CT) files. METHODS: Two hundred archived CT angiograms were explicitly observed for the CHB anatomical variant. RESULTS: Different possibilities of CHB were found in 6/200 cases, five males and one female. The symmetrical overlap of the thyroid cartilage by the hyoid body was found in one male case. In three cases, two males and one female, there was asymmetrical overlapping due to tilted hyoid bones. In one male case with such asymmetrical CHD, an ossified anterior longitudinal ligament was noted: the tips of the superior horns of the thyroid cartilage reached lateral to it, thus being retropharyngeal. A different male case had a lowered hyoid with a greater horn fused to the superior horn of the thyroid cartilage, with an interposed ossified triticeal cartilage. In the last male case, the right greater horn collapsed laterally to an ossified triticeal cartilage fused with the thyroid cartilage's superior horn. CONCLUSIONS: The CHB is an undeniable anatomical possibility of an atavism that alters conventional anatomical and surgical landmarks. Different anatomical components of the hyoid bone can descend uni- or bilaterally.

Postnatal changes in thyroid cartilage shape and cartilage matrix composition are not synchronized in Mus musculus.

The study was conducted to quantify laryngeal cartilage matrix composition and to investigate its relationship with cartilage shape in a mouse model. A sample of 30 mice (CD-1 mouse, Mus musculus) from five age groups (postnatal Days 2, 21, 90, 365, and 720) were used. Three-dimensional mouse laryngeal thyroid cartilage reconstructions were generated from contrast-enhanced micro-computed tomography (CT) image stacks. Cartilage matrix composition was estimated as Hounsfield units (HU). HU were determined by overlaying 3D reconstructions as masks on micro-CT image stacks and then measuring the attenuation. Cartilage shape was quantified with landmarks placed on the surface of the thyroid cartilage. Shape differences between the five age groups were analyzed using geometric morphometrics and multiparametric analysis of landmarks. The relationship between HU and shape was investigated with correlational analyses. Among five age groups, HU became higher in older animals. The shape of the thyroid cartilage changes with age throughout the entire life of a mouse. The changes in shape were not synchronized with changes in cartilage matrix composition. The thyroid cartilage of young and old M. musculus larynx showed a homogenous mineralization pattern. High-resolution contrast-enhanced micro-CT imaging makes the mouse larynx accessible for analysis of genetic and environmental factors affecting shape and matrix composition.

External laryngotracheal trauma: a case series and an algorithmic management strategy.

OBJECTIVES: External laryngotracheal trauma (ELT), blunt or penetrating, is a rare but potentially life-threatening injury. Immediate care in the emergency department can be challenging because it requires managing a potentially unstable airway and may have associated vascular injuries with massive bleeding. Here, we look at the details of injury, treatment measures, and outcomes in patients following ELT. METHODS: We retrospectively analyzed 22 patients treated at our center for ELT from January 2005 up to December 2021 with varying grades of injury. We looked at their status at presentation, management strategy and functional status. RESULTS: In our report, we include 18 men and 4 women having varying Schaefer injury grades. Eight patients had tracheostomy at presentation and eight had vocal fold immobility. Two patients were treated endoscopically, 12 had open surgery and 8 received no treatment. Of the patients undergoing open surgery, thyroid cartilage fracture was seen in 9 patients, thyroid plus cricoid fracture and cricotracheal separation were seen in 3 patients each. All patients were safely decannulated and spontaneous recovery of vocal cord palsy was seen in some patients. CONCLUSION: The success of managing ELT relies on fast decision-making, correct patient evaluation, securing the airway and maintaining the hemodynamic stability. Early surgical intervention must be aimed at optimally treating the larygotracheal injuries to prevent long-term disastrous consequences.

Thyroid cartilage infiltration in advanced laryngeal cancer: prognostic implications and predictive modelling.

Objective: Detection of laryngeal cartilage invasion is of great importance in staging of laryngeal squamous cell carcinoma (LSCC). The role of prognosticators in locally advanced laryngeal cancer are still widely debated. This study aimed to assess the impact of volume of thyroid cartilage infiltration, as well as other histopathologic variables, on patient survival. Materials and methods: We retrospectively analysed 74 patients affected by pT4 LSCC and treated with total laryngectomy between 2005 and 2021 at the Department of Otorhinolaryngology - Head and Neck Surgery of the University of Brescia, Italy. We considered as potential prognosticators histological grade, perineural (PNI) and lympho-vascular invasion (LVI), thyroid cartilage infiltration, and pTN staging. Pre-operative CT or MRI were analysed to quantify the volume of cartilage infiltration using 3D Slicer software. Results: The 1-, 3-, and 5-year disease free survivals (DFS) were 76%, 66%, and 64%, respectively. Using machine learning models, we found that the volume of thyroid cartilage infiltration had high correlation with DFS. Patients with a higher volume (>670 mm3) of infiltration had a worse prognosis compared to those with a lower volume. Conclusions: Our study confirms the essential role of LVI as prognosticator in advanced LSCC and, more innovatively, highlights the volume of thyroid cartilage infiltration as another promising prognostic factor.

Palpation Versus Ultrasonography for Identifying the Cricothyroid Membrane in Case of a Laterally Deviated Larynx: A Randomized Trial.

BACKGROUND: Large neck circumference and displacement of the trachea due to pathology increase the risk of failed identification of the cricothyroid membrane and cricothyroidotomy. We investigated whether ultrasound aids in the successful identification of the cricothyroid membrane in a model of an obese neck with midline deviation of the trachea. METHODS: We developed silicone neck models that were suitable for both palpation and ultrasonography and where the trachea deviated laterally from the midline to either side. After reading a book chapter and participating in a 25-minute lecture and a 15- to 23-minute hands-on demonstration and rehearsal of ultrasonography for identification of the cricothyroid membrane, anesthesiologists and anesthesiology residents randomly performed identification with either ultrasound or palpation on 1 of 2 neck models. RESULTS: We included 57 participants, of whom 29 and 28 were randomized to palpation and ultrasound, respectively. Correct identification of the cricothyroid membrane was achieved by 21 (75.0%) vs 1 (3.5%) of participants in the ultrasound versus palpation groups (risk ratio [RR], 21.8 [95% confidence interval {CI}, 3.1-151.0]). The tracheal midline position in the sagittal plane was identified correctly by 24 (85.7%) vs 16 (55.2%) of participants in the ultrasound versus palpation groups (RR, 1.6 [95% CI, 1.1-2.2]). CONCLUSIONS: Identification of the cricothyroid membrane in a model of an obese neck with midline deviation of the trachea was more often successful with ultrasound compared to palpation. Our study supports the potential use of ultrasound before induction of anesthesia and airway management in this group of patients, and it may even be applied in emergency situations when ultrasound is readily available. Further studies in human subjects should be conducted.

Determination of the Cricothyroid Membrane Height by Age and Sex and Optimal Tracheal Tube Size.

OBJECTIVES: The primary aim of this study was to determine the average cricothyroid membrane (CTM) height in healthy volunteers, and the secondary aim was to determine the hypothetical success rate for emergency cricothyrotomy with a tracheal tube with an 8.0 mm outer diameter. METHODS: This study included healthy volunteers aged 18 years and older. The participants' clinical characteristics were recorded, and their CTM height was measured using ultrasound, with their necks placed sequentially in the neutral and extension positions. The relationship between the CTM height and sex, age, height, weight, body mass index, and sternomental distance was evaluated using linear regression analysis. An equation that could estimate the height of the CTM was obtained with the parameters found significant in this analysis. RESULTS: Of the 340 participants, 208 (61.2%) were male. The mean (SD) height of the CTM in the extension position was 9.60 (1.54) mm, and it was significantly shorter in the women than in the men (8.72 [1.19] mm vs. 10.16 [1.48] mm, p < 0.001). Among the participants of short stature, the CTM was significantly shorter, regardless of sex. The hypothetical success rate for emergency cricothyrotomy was 93.3% for the males and 73.5% for the females. The equation for estimating the height of the CTM in the extension position was determined as -4.36 + 5.27 × height (m) + 0.32 × sternomental distance (cm). CONCLUSIONS: Since the CTM height may differ according to age, sex, and height, cricothyrotomy sets should be available in various outer diameters. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1825-1830, 2024.

Systematic review of laryngohyoid fractures in fatal falls: A potential mimicker of strangulation.

Fractures of the laryngohyoid complex are classically associated with deaths due to strangulation. Recent studies, however, indicate the possible presence of such fractures in fatal falls. The primary focus of this systematic review is to analyze the characteristics of laryngohyoid fractures in the context of falls to aid in a more accurate interpretation of autopsy findings. Search for relevant literature occurred on PubMed on the 26th of October 2022, and Embase and Web of Science on the 5th of November 2022. Inclusion criteria included being a primary study, published in English, involving fatal falls and injuries to the laryngohyoid complex, and presenting sufficient details about the relevant cases. Four case reports and six descriptive retrospective studies were included in the final analysis yielding a sum of 38 cases. The risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools. Potential limitations of this study include the inclusion of case reports and studies published in English only. The cumulative male-to-female ratio was 23:15 with a mean age of 48 years old. The fall height ranged from standing height to 60 m. Forty-three fractures to the laryngohyoid complex were identified with the thyroid cartilage most commonly affected, followed by fracture of the hyoid bone, and finally the cricoid cartilage. While cases of falls did indeed display hallmark laryngohyoid findings classically displayed in strangulation, they also featured unique presentations such as fractures of the clavicle and a reduced prevalence of conjunctival petechiae.

Analysis of female strangulation homicides in King County, Washington, from 1978 to 2022.

Asphyxia due to strangulation is an uncommon but important modality of homicide that tends to disproportionately involve female victims. The present study was designed to investigate the circumstances, motivations, and injuries associated with strangulation homicides of females and to measure trends in incidence over time. Electronic records of the King County Medical Examiner's Office in Seattle, Washington, were used to compile a data set of all homicides in King County from 1995 through 2022. A second data set of female homicides due to strangulation was constructed with additional records prior to 1995, supplemented with data abstracted from autopsy reports, and linked to the Washington Attorney General's Office Homicide Investigation Tracking System database. This comprehensive data set was used to analyze demographics, circumstances, motives, and injuries of female strangulation homicides from 1978 through 2016. The results found that, from 1995 through 2022, females accounted for 22.8% of 2394 homicides but 80.3% of strangulation homicides. The average annual rate of all strangulation homicides decreased until 2020. Mean ages of female decedents were 27.7 years in homicides associated with sexual assault, 36.8 years with domestic violence, and 63.9 years with robbery. Lethal assaults most often occurred in private homes, and perpetrators were usually well known to the victim. Injuries included petechiae in 83%; ligature marks in 20%; fingernail marks in 1.4%; hyoid fractures in 23%; and thyroid cartilage fractures in 31%. Fractures were more common in manual strangulation and in decedents of ages over 40 years.

Hanging: Commonly Encountered by Forensic Experts at Autopsy.

Though human lives have become easier and faster due to rapid twist in urbanization, industrialization and digitalization suicidal tendency among common people are often seen. Hanging is the commonly chosen method to do so. The study was designed to find out the pattern of hanging cases and to discover the immensity of hanging as a method of committing suicide. This retrospective study was done for three years by retrospectively collected data at the department of Forensic Medicine and Toxicology of Chattogram Medical College. A total of 193 cases (6.73%) of hanging were observed among 2850 autopsies done from January 2015 to December 2017. The age group of 31-40 years was mostly affected i.e. in 54(27.97%) followed by 21-30 years 48(24.87%). Males 112(58.03%) out numbered the females 81(41.96%). Clothes 88(45.59%) were mostly used as ligature material followed by jute rope (33.67%) and nylon rope (20.72%). Maximum cases were atypical hanging 160(82.90%), while we observed 33 typical (17.09%) hangings. In 166 cases (86.01%) we observed no injuries to the neck while contusion of the neck in 27 cases (13.99%). This study revealed fracture of the thyroid cartilage in 5 cases (2.59%) and hyoid in 2 cases (1.03%). One hundred & eighty five (185) cases (95.85%) were of suicidal and only 8 cases (4.14%) were of accidental. As per observation of this study, hanging has been found to be a common means of committing suicide in Bangladesh.