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.

Unilateral and bilateral agenesis of the upper thyroid horns - A morphometric analysis of the larynx.

The agenesis of one or both upper thyroid horns (UTH) cannot be considered rare with an incidence ranging between 0.8-9.4%. Studies so far have mostly described frequencies, yet surveys on its morphology and traumatology are missing. It is unknown to what extent this anatomical variant impacts the overall symmetry of the larynx. For the trauma reconstruction after cervical trauma this knowledge is required as an asymmetric larynx can show a different fracture pattern. In this investigation, larynxes with unilateral (n=21)/bilateral (n=5) agenesis of the upper thyroid horn(s) and a control group with regular larynxes (n=23) were juxtaposed. Various measurements were taken after µ-CT scanning. In total 10 distances/angles for the thyroid cartilage and 8 for the cricoid cartilage were compared. Using intra-individual and matched pair comparisons the symmetry was assessed. The results of this investigation showed significant differences in the intra-individual and pairwise comparison for the opening angle and the length of the thyroid alae although the lateral inclination of the thyroid alae showed no significant difference. Combining these three parameters into one symmetry score, the comparison was not significant. This research demonstrates that neither unilateral nor bilateral agenesis of the UTH is related to a structural disbalance of the larynx. Thus, different fracture patterns or vulnerabilities are not to be expected.

Symmetrical Apophyses on the Posterior Margins of the Thyroid Cartilage: A Previously Undescribed Anatomical Variation With Potential Forensic Implications.

Differential diagnosis between normal/variant anatomy and pathological/traumatic findings represents one of the main matters of investigation of the so-called forensic clinical anatomy. In the literature, many anatomical variations of the laryngeal thyroid cartilage have been reported, with potential implications in forensic pathology. They include triticeal cartilages, foramen thyroideum, asymmetry, segmentation or agenesis of the superior thyroid horns, bone connections with the hyoid bone, absence of cricothyroid facets, hypertrophy of the inferior thyroid tubercle, and asymmetries in the thyroid notch, isthmus, or length of the inferior horn. In this report, we describe a laryngeal anatomical variation never described before, consisting of 2 apophyses symmetrically arising from the posterior margins of the thyroid laminae. Postmortem computed tomography performed on the laryngeal visceral block excluded previous traumatic injuries or natural pathologies of the laryngeal cartilages, confirming the congenital origin of the finding. An "omega epiglottis" and 3 laryngeal cysts in the piriform sinuses also coexisted, suggesting the possibility of underlying common developmental mechanisms.

Laryngeal anatomical variants and their impact on the diagnosis of mechanical asphyxias by neck pressure.

The aims of this investigation were to determine the characteristics and prevalence of anatomical variants of the larynx apparatus and to evaluate the impact of these variants on the accurate diagnosis of laryngeal fractures. A population-based study was carried out, analyzing a series of 207 consecutive autopsied cases in the Institute of Legal Medicine of Galicia (Northwestern Spain). The prevalence of triticeal cartilage was 52.7% and that of agenesis of thyroid horns 10%. Calcification of the stylo-hyoid ligament accounted for 1.4%. We identified three new anatomical variants: the terminal segmentation of the thyroid horns (11.6%), ectopic superior thyroid horns (8%) and lateral thyrohyoid ossification (5.3%). These three names, based on anatomical criteria, are the author's proposal to solve the lack of uniformity in the designation of these variants. Agenesis of thyroid horns were related to the presence of ectopic superior thyroid horns in 93% of cases, either uni or bilateral. The combination of variants was present in 6.8% of the cases, being the terminal segmentation of the thyroid horns in association with triticeal cartilage the most frequent (3.8%). The probability of misdiagnosis due to the presence of anatomical variations in deaths by pressure on the neck was high in this population (71.5%). The prevalence of triticeal cartilage in more than half of the sample, determined an important rate of potential errors (46.4%), followed by the mistaken diagnoses induced by terminal segmentation of thyroid horns (7.3%) and by ectopic superior thyroid horns (6.3%). The likelihood of a misdiagnosed laryngeal fracture was greater if the thyroid cartilage was affected, with a higher proportion of false positives comparing to the hyoid bone (p<0.001). The higher frequency of thyroid fractures in neck pressure together with the prevalence and location of triticeal cartilage on the lower third of the lateral thyrohyoid ligament are the main reasons for these results. Further studies should be done with larger samples to expand epidemiological data and consolidate these results and their influence on the diagnosis of mechanical asphyxias.

Asymmetry of the greater cornua of the hyoid bone and the superior thyroid cornua: a case report.

The hyoid bone consists of a body and two pairs of processes: the greater cornua (GC) and the lesser cornua. The GC is connected to the superior thyroid cornu (STC) by the lateral thyrohyoid ligament. The GC and the STC share a common embryological origin from the third pharyngeal arch. During anatomical dissection of a male cadaver of 56 years of age, a combined variation of the GC and the STC was found. The left GC was 27.7 mm long, and the right GC was 30 mm long. The left GC axis was in the same plane as the hyoid body, while an angle of 33° was between the right GC axis and the hyoid body plane. The left STC was 17.6 mm long, and the right STC was 25.8 mm long. The angle of left STC medial inclination was 70°, while the right STC was perpendicular to the horizontal plane of the larynx. Anatomical variations of the hyoid bone and the laryngeal cartilages have possible clinical implications, such as Eagle syndrome and the STC syndrome. The case we described may inspire the anatomists to research the occurrence of combined variations of the larynx and the hyoid bone.

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.

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.

Clinically relevant variations of the superior thyroid cornu.

PURPOSE: The superior thyroid cornu (STC) of the thyroid cartilage is a variable structure that maybe associated with different clinical symptoms. This study evaluates the three-dimensional anatomy of the STC. METHODS: Measurements were conducted on 97 CT scans (45 male and 52 female). The protocol models a vector from the base to the tip of the STC and references the cornu to the midline. From these data, the length (C), the rotation angle (γ), the inclination angle (ß), and the deviation of STC base (X 2) and tip (X 3) from the midline were measured. An additional measure of the medial inclination quotient (Q = X 3/X 2) was calculated. RESULTS: The STC has a mean length of 13.9 ± 3.26 mm. The male STC is more bent inwards (rotation angle (γ) 60.95° vs. 12.15°; p < 0.001), and the female STC is more steep (inclination angle (ß) 75.44° vs. 73.44°; p < 0.001). The mean Q in men was significantly lower (0.85 ± 0.15 vs. 0.97 ± 0.15; p < 0.001). An extreme medial deformation was found in 13.4 % of the patients. This variation is associated with Q ≤ 0.7, most of the time unilateral and more common in men (86.7 vs. 13.3 %). Furthermore, we can describe STC variations with close proximity to the common carotid artery or the cervical spine. CONCLUSIONS: The clinically most relevant variation of the STC seems to be the extreme medial deviation, which may lead to symptoms described with the superior thyroid cornu syndrome. The evaluation of Q in axial CT scans is easily done and may propose a helpful tool for clinical diagnostics.

Agenesis of the superior cornua of the thyroid cartilage: a rare variant of medicolegal importance.

It is important that forensic pathologists are familiar with variations in the size and shape of the laryngohyoid complex when interpreting injuries and pathology of the head and neck region. Accurate postmortem examination of the laryngohyoid structures may be difficult if anatomical variation in these structures is present. Agenesis of the upper horns of the thyroid cartilage has medicolegal significance because it may be mistaken for a fracture or other trauma-related conditions. We present 3 cases with different forms of agenesis of the superior cornu of the thyroid cartilage, namely, right unilateral, left unilateral, and bilateral agenesis.

The use of computed tomography in determining developmental changes, anomalies, and trauma of the thyroid cartilage.

Recognition of injury to the hyoid bone and thyroid and cricoid cartilages is intrinsic to post-mortem examination. Due to its increasing brittleness with age the thyroid cartilage is particularly susceptible to injury following neck trauma, although there is inconsistency in the patterns of injury reported. In this study computed tomography scans of the head and neck of 431 deceased persons (235 males and 196 females) between the ages of 1 day and 100 years (mean age 35.93 ± 24.15), and including 25 victims of hangings, were examined to reveal the pattern of age-related change and the types of injury that occurred. Thyroid cartilage anomalies likely to cause confusion and be misinterpreted as trauma-related are documented. Angulation of the thyroid cartilage horns was found to change with age, and it is suggested this may be a significant factor in traumatic neck injury. Unlike in previous reports, the average age of hanging victims with fractures to the thyroid cartilage was 34 years. The base of the superior horn was the most common fracture site and in 50 % of hanging cases was associated with a ligature positioned on the thyrohyoid membrane or thyroid lamina. Although an age-related relationship exists it was not possible to establish narrow age-prediction ranges from calcification of the thyroid cartilage.

Unusual variation of the hyoid bone: bilateral absence of lesser cornua and abnormal bone attachment to the corpus.

The hyoid bone is a horseshoe-shaped and a solitary bone located at the neck just above the thyroid cartilage. It consists of a body, two greater cornua and two lesser cornua. In this report, we demonstrated an extra bone variation which is attached to the hyoid bone and located at the left side of its corpus. In addition to this abnormal bone attachment to the corpus, lesser cornua were absent bilaterally. Abnormal bone attachment was approximately 3.79-cm long and 0.38-0.50-cm wide and heads toward the upper left of the hyoid bone. We believe that clinicians should be aware of such abnormalities of the hyoid bone because of the functional and clinical importance of its variations and abnormal relations within nearby structures. These abnormalities have a great importance for the surgical operations and radiological studies of the neck region and for the forensic medicine because of the susceptibility of the hyoid bone to the fractures in relation to the strangulation cases.

The incidence of the foramen thyroideum in the South African population / Incidencia del foramen tiroideo en la población de sudáfrica

The foramen thyroideum is described as an occasional opening existing in one or both laminae of the thyroid cartilage which may or may not contain a neurovascular component. Foramen thryoideum was first described in the literature by Segond in 1847. Some authors consider its existence a structural variation rather than an anomaly, with classical texts of anatomy providing little detail when describing this foramen. This study was undertaken to investigate the incidence and characteristics of the foramen thyroideum in the South African population. A total of 80 formalin fixed cadaveric laryngeal specimens (obtained from the Department of Clinical Anatomy, University of KwaZulu-Natal, South Africa) were dissected. Larynges were dissected with the aid of a Stemi DV 4 light microscope. The incidence, location, dimensions and contents of the foramen thyroideum were recorded. The horizontal and vertical extent of each foramen was measured with a digital caliper. Six of the 80 (7.5 percent) specimens examined had distinctly identifiable foramina. Five of the six cases (4 male, 1 female) displayed bilateral foramina (6.3 percent), with one case (1 female) of a unilateral foramen (1.3 percent). Of the larynges that had bilateral foramina, a single case presented with two foramina on the same (right) thyroid lamina. A total of twelve foramina were observed. Gender distribution of foramen thyroideum was: male: right 5, left 4; female: right 2, left 1. Preceding investigators of the foramen thyroideum have rightly indicated that awareness of its presence is of paramount importance in order to preserve the structures that traverse it and also to comprehensively treat or contain laryngeal cancer.

El foramen tiroideo se describe como una apertura ocasional existente en una o ambas láminas del cartílago tiroides, la cual puede o no contener un componente neurovascular. El foramen tiroideo fue descrito por primera vez en la literatura por Segond en 1847. Algunos autores consideran su existencia como una variación estructural y no una anomalía, los textos clásicos de anatomía proporcionan pocos detalles al describir este foramen. Este estudio se realizó para investigar la incidencia y características del foramen tiroideo en la población Sudafricana. Fueron disecados 80 especímenes cadavéricos de larínge fijados con formalina (obtenidos del Departamento de Anatomía Clínica de la Universidad de KwaZulu-Natal, Sudáfrica). Las laringes fueron disecadas con la ayuda de un microscopio de luz Stemi DV 4. La incidencia, localización, dimensiones y contenido del foramen tiroideo fueron registradas. La extensión horizontal y vertical de cada foramen se midieron con un caliper digital. Seis de los 80 (7,5 por ciento) especímenes examinados tenían foramen tiroideos claramente identificables. Cinco de los seis casos (cuatro hombres y una mujer) mostraron forámenes bilaterales (6,3 por ciento), y un caso (una mujer) foramen unilateral (1,3 por ciento). De las laringes que presentaron forámenes bilaterales, un solo caso presentó dos forámenes en la misma lámina del cartílago tiroides (derecha). La distribución por sexo del foramen tiroídeo en hombres fue 5 derechos y 4 izquierdos, mientras que en mujeres 2 derechos y 1 izquierdo. Los resultados indican que el conocimiento de la presencia del foramen tiroideo es de vital importancia para preservar las estructuras que lo atraviesan y también para el tratamiento de integral o contención del cáncer de laringe.

Low lying larynx.

We report a rare case of laryngotracheal anomaly and its possible etiology and mode of presentation. A teenager presented with voice change and a neck lump. Investigations revealed a laryngeal anomaly in which the larynx was hyperdescended. It was accompanied by low lying thyroid gland and hyoid bone together with an absence of a cervical segment of the esophagus and trachea. The anomaly only became noticeable secondary to pubertal changes in the thyroid cartilage of the teenager. An embryological defect during the formation of the laryngotracheal tube and esophagus is a possible explanation of this anomaly. The present case probably represents the third reported of its kind.

The thyroid foramen: a case report and literature review of a largely unrecognized laryngeal anomaly.

A thyroid foramen is a congenital linear opening located in the lamina of the posterosuperior portion of the thyroid cartilage. Although its overall incidence is reported to be as high as 39%, few practitioners are aware of its existence. We report the case of a 19-year-old man who was involved in a motor vehicle accident. He experienced transient left true vocal fold paresis and what were initially thought to be "bilateral thyroid cartilage fractures" based on computed tomography of the neck performed as part of his trauma evaluation. On further scrutiny, however, the "fractures" were determined to be bilateral thyroid foramina. The presence of the paresis in the setting of these thyroid foramina prompted us to review the literature to examine the significance of thyroid foramina and the vessels and nerves that course through them. The average diameter of a thyroid foramen is approximately 2.5 mm. These openings appear in an oblique orientation, and they occur both unilaterally and bilaterally. In 70% of cases, an anastomotic branch connects the external and internal branches of the superior laryngeal nerve. Embryologically, thyroid foramina are believed to arise from a combined branchial and neurovascular origin. A detailed understanding of laryngeal anatomy, including its variations and their physiologic implications, is important to head and neck surgeons.

Tracheal atresia as part of an exceptional combination of malformations.

A case of a premature infant with tracheal atresia together with an exceptional combination of congenital abnormalities that partially corresponds to the TACRD and VACTERL associations is presented. Tracheal atresia was not detectable in the prenatal ultrasound due to lacking of the typical diaphragmatic and pulmonary findings because of the esophago-tracheal fistula, and therefore the resuscitation team was not prepared for this severe airway complication. After prolonged resuscitation efforts were terminated and the newborn expired after birth. Even without typical warning signs physicians have to be aware of tracheal atresia and airway obstruction if VACTERL or TACRD associations are diagnosed.

[Pseudohypertrophy of the ventricular bands due to deformation of the thyroid cartilage]. / Pseudohipertrofia de bandas ventriculares por deformación del cartílago tiroides.

Hoarseness due to phonation by the false cords (dysphonia plicae ventricularis) is a common cause of functional dysphonia, in relation to excessive muscular tension in the larynx area. Nevertheless, a mechanic cause can be observed in some cases with dysphonia plicae ventricularis, which is usually due to deformation of the thyroid cartilage. We report a case with hypertrophy of the ventricular bands which was treated by vocal rehabilitation followed by suspension laryngoscopy with partial removal of the ventricular bands, without further improvement. This failure was related to a pseudohypertrophy of the ventricular bands, due to deformation of the thyroid cartilage, which was confirmed by computed tomography.