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.

Abnormal hyoid conformation in French Bulldogs: case report and computed tomographic anatomical comparison.

BACKGROUND: Brachycephalic obstructive airway syndrome (BOAS) is common in brachycephalic breeds and comprises multiple anatomic characteristics. Computed tomography (CT) is increasingly used in the preoperative assessment of dogs presenting with BOAS. We describe the case of a French Bulldog with a presumed congenital hyoid malformation and anatomic comparison of hyoid morphology between French Bulldogs and mesaticephalic dogs using CT. METHODS: Skull CT studies of French Bulldogs and mesaticephalic dogs presenting to two referral hospitals between 2013 and 2020 were collected. The degree of curvature of the basihyoid bone and the relative ventrodorsal thickness (RVD) were determined using a novel measurement technique. A circle of best fit was applied to the inside arc of the basihyoid bone, and the radius and sector angle within the basihyoid bone were recorded. The RVD was defined by the ventrodorsal thickness divided by the width in the frontal plane. RESULTS: The basihyoid bone of French Bulldogs had a greater mean ± SD RVD of 0.23 ± 0.04 compared to 0.16 ± 0.03 in mesaticephalic dogs (P < 0.01). The sector angle was also greater in French Bulldogs, measuring 144.08 ± 20.88° compared to 103.94 ± 16.49° in mesaticephalic dogs (P < 0.01). CONCLUSION: This case of hyoid malformation in a French Bulldog reports a rarely documented condition that complicated the management of BOAS. Comparative assessment of hyoid conformation revealed more acute curvature and greater RVD in French Bulldogs than in mesaticephalic dogs. This may represent an additional distorted anatomic component of brachycephalic skull morphology.

Sternocleidohyoid muscle: an unreported variant of cleidohyoid muscle.

Sternohyoid, sternothyroid, omohyoid, and thyrohyoid muscles are collectively known as infrahyoid muscles. These muscles frequently show variations in their attachments. Here, an extremely rare variant muscle belonging to this group has been presented. During cadaveric dissection for undergraduate medical students, an additional muscle was found between sternohyoid and superior belly of omohyoid muscles bilaterally in a male cadaver aged approximately 70 years. This muscle took its origin from posterior surface of the manubrium sterni, capsule of the sternoclavicular joint and the posterior surface of the medial part of the clavicle. It was inserted to the hyoid bone between the attachments of sternohyoid and superior belly of omohyoid muscles and was supplied by a branch of ansa cervicalis profunda. There is no report on such a muscle in the literature and it could be named as "sternocleidohyoid muscle". Knowledge of this muscle could be useful in neck surgeries.

Variants of the hyoid-larynx complex, with implications for forensic science and consequence for the diagnosis of Eagle's syndrome.

Thorough anatomic knowledge of the hyoid-larynx complex is necessary for forensic radiologists and ear-nose-throat surgeons, given the many anatomic variations that originate in embryology. In forensics the anomalies must be distinguished from fractures because the latter are indicative of violence on the neck. In this manuscript we describe the anatomical variations that can be found in the hyoid-larynx complex and explain their etiology. 284 radiological scans of excised hyoid-larynx complexes were examined with X-ray and CT. Some rare cases from literature and historical collections were added. Two third of the examined hyoid-larynx complexes deviated from the anatomical standard and showed uni- or bilateral ankylosis in the hyoid bone and/or so-called triticeal cartilages. In one fifth of the cases we found striking anatomical variants, mostly derived from the cartilage of the second pharyngeal arch. Anatomical variations of the hyoid-larynx complex can be explained by embryological development. The aberrant hyoid apparatus and the elongated styloid processes (Eagle syndrome) should be considered as one clinical entity with two different expressions as both anomalies are derived from the cartilage of the second pharyngeal arch. Several variants can mimic fractures in this region, so our study is important for radiologists and forensic experts assessing cases of possible violence on the neck.

Cerebral embolism and carotid-hyoid impingement syndrome.

Embolic stroke of undetermined source (ESUS) is not uncommon in young patients. Here, we describe two cases of stroke from an unusual aetiology; cerebral embolization from carotid artery injury presumed secondary to hyoid bone impingement. Both patients demonstrated angiographic evidence of hyoid bone impingement. Following resection of the greater cornu of the hyoid bone, neither patient had further strokes.

Carotid Artery Entrapment by the Hyoid Bone-A Rare Cause of Recurrent Strokes in a Young Patient.

The search for etiology of stroke in a young patient may present a diagnostic challenge. In rare cases, chronic trauma to the carotid artery may be the cause of cerebral thromboembolic events. The hyoid bone lies in close proximity to the carotid artery bifurcation, and anatomic variants have been implicated in carotid compression, stenosis, dissection, and pseudoaneurysm. We report a case of recurrent strokes in a 32-year-old woman due to an elongated hyoid bone causing thrombus formation in her right internal carotid artery (ICA), resulting in recurrent embolic strokes confirmed on diffusion-weighted magnetic resonance imaging. Computed tomography angiography of the neck and head demonstrated the right hyoid bone was located between the ICA and external carotid artery (ECA), just above the carotid bifurcation, with residual nonocclusive thrombus in the right ICA. Carotid duplex ultrasonography confirmed that with the neck in neutral position, the hyoid was located between the ICA and ECA; however, with neck rotation, the hyoid slipped across the ICA and out of the bifurcation. There was no evidence of carotid stenosis. After an initial course of anticoagulation and antiplatelet therapy, resection of the greater cornu of the hyoid bone with release of the right ICA was performed. One year postoperatively, the patient had complete return of neurologic function and had no further neurologic events. Hyoid bone entrapment of the carotid artery is a rare etiology of thromboembolic stroke caused by repetitive local trauma. The diagnosis can be confirmed by carotid duplex with provocative maneuvers. Partial hyoid resection is a safe and effective treatment to relieve recurrent symptoms. Hyoid bone entrapment may be an important and under-recognized cause of stroke in young adults.

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.

IMAGING DIAGNOSIS-IDIOPATHIC HYOID MALFORMATION IN AN 8-YEAR-OLD WELSH SECTION D HORSE.

An 8-year-old gelding was evaluated for intermittent dorsal displacement of the soft palate (DDSP) at exercise. Standing laterolateral radiographs demonstrated an abnormal crossed appearance of the stylohyoid bones. Computed tomography (CT) confirmed abnormal positioning of the left stylohyoid bone and articulations with both the left thyrohyoid and ceratohyoid bones. Surgical treatment consisted of combined left ceratohyoidectomy and thyrohyoidectomy. Postoperatively the patient's presenting complaint resolved completely, with the horse returning to full work. Standing laterolateral radiographs should be obtained prior to laryngeal or hyoid surgery to rule out hyoid anomalies, which could result in surgical failure or subsequent hyoid fracture.

Upper airway changes following single-step or stepwise advancement using the Functional Mandibular Advancer.

OBJECTIVES: Purpose of the present study was to determine and compare possible changes in the dimensions of the pharyngeal airway, morphology of the soft palate, and position of the tongue and hyoid bone after single-step or stepwise mandibular advancement using the Functional Mandibular Advancer (FMA). PATIENTS AND METHODS: The sample included 51 peak-pubertal Class II subjects. In all, 34 patients were allocated to two groups using matched randomization: a single-step mandibular advancement group (SSG) and a stepwise mandibular advancement group (SWG). Both groups were treated with FMA followed by fixed appliance therapy; the remaining 17 subjects who underwent only fixed appliance therapy constituted the control group (CG). The study was conducted using pre- and posttreatment lateral cephalometric radiographs. Data were analyzed by paired t test, one-way analysis of variance, and Pearson's correlation coefficient. RESULT: In the SWG and SSG, although increases in nasopharyngeal airway dimensions were not significant compared with those in the CG, enlargements in the oropharyngeal airway dimensions at the level of the soft palate tip and behind the tongue, and decreases in soft palate angulation, were significant. Tongue height increased significantly only in the SWG. Compared with the CG, while forward movement of the hyoid was more prominent in SSG and SWG, the change in the vertical movement of the hyoid was not significant. No significant difference between SWG and SSG was observed in pharyngeal airway, soft palate, tongue or hyoid measurements. CONCLUSIONS: The mode of mandibular advancement in FMA treatment did not significantly affect changes in the pharyngeal airway, soft palate, tongue, and hyoid bone.

The Origin of the Variations of the Hyoid Apparatus in Human.

Currently, theories based on acquired calcification of the stylohyoid ligament are believed to be a pathogenesis of syndromes associated with the hyoid apparatus (HA) and its variations. We studied the development of the HA from Reichert´s cartilage using serial sections of 25 human embryos and 45 fetuses. We ensured a fact that, at the initial stage, the HA appeared as two independent cartilage segments, that is, the cranial or styloid segment and the caudal or hyoid segment of Reichert's cartilage, those are connected by a mesenchymal structure. However, between 8 and 10 weeks of development, the mesenchymal connection was lost. We hypothesize that this disconnection is likely to be one of the major factors to make a descent of the hyoid bone in evolution. The stylohyoid ligament was not observed. The variations of the HA, should be considered variations of the development of Reicherts cartilage. If these variations are maintained in the adult, are likely to explain a major symptom associated with Eagle's syndrome.

Síndrome de Eagle: caso clínico / Eagle syndrome: a clinical case

Se presenta una descripción de las estructuras involucradas en el Síndrome de Eagle o síndrome la apófisis estiloides y sus manifestacionesclínico-radiográficas en referencia a un caso clínico, su diagnóstico diferencial y tratamiento. El objetivo de esta presentación es identificar al Síndrome de Eagle o Síndrome de la apófisis estiloides, mostrando sus características anatómicas, fisiológicas, su diagnóstico por imágenes y su tratamiento...

Internal jugular vein cannulation complications and elimination of the muscular triangle of the neck due to aberrant infrahyoid muscles.

We report on a rare case of anatomical variations of the infrahyoid muscles with prominent clinical significance. The aberrant anatomy was on the right side of the neck and involved the omohyoid and sternohyoid muscles. The superior belly of the omohyoid was duplicated in width due to an aberrant belly anteriorly and merged with fibers of the inferior belly inferiorly and the sternohyoid muscle medially. An additional aberrant muscle slip extended between the inferior third of the sternohyoid muscle and united with the inferior belly of the omohyoid. The intermediate tendon between the two bellies of the omohyoid was absent, whereas the so-called muscular triangle of the neck was diminished. Due to the arrangement and fusion of myofibers the muscle could be termed as omo-sternohyoid muscle. A profound hematoma was noted in the aberrant muscle at the area overlying the internal jugular vein indicating difficulty in obtaining jugular venous access for catheter placement. Clinicians and surgeons should be aware of muscular anatomic variations when intervening in the lateral neck area as the classical anatomical landmarks might be misinterpreted and confuse.

Facial features and hyoid bone position in preschool children with obstructive sleep apnea syndrome.

The aim of the study was to evaluate facial features and hyoid bone position in children with obstructive sleep apnea syndrome (OSAS) by cephalometric radiography. A prospective cross-sectional study was conducted in a tertiary referral hospital. Twenty-nine children in the 3-6 year age bracket were evaluated: 14 children with OSAS and 15 nasal-breathing children. All children underwent otorhinolaryngologic examination, and those with OSAS also underwent in-laboratory polysomnography for diagnostic confirmation. The children were then submitted to orthodontic evaluation and cephalometry. Lateral cephalometric radiographs from children with OSAS were compared to those of nasal-breathing children. We found no differences between the two groups regarding the linear and angular measurements of the face. However, the children with OSAS presented, already at the preschool age, with an inferiorly positioned hyoid bone, thus increasing the pharyngeal area. In children with OSAS, the hyoid bone appears to be in a significantly inferior position at an early age. Our findings provide evidence that there is a relationship between the position of the hyoid bone and OSAS in children, which could contribute to the persistence of OSAS into adulthood.

Distinct functional and temporal requirements for zebrafish Hdac1 during neural crest-derived craniofacial and peripheral neuron development.

The regulation of gene expression is accomplished by both genetic and epigenetic means and is required for the precise control of the development of the neural crest. In hdac1(b382) mutants, craniofacial cartilage development is defective in two distinct ways. First, fewer hoxb3a, dlx2 and dlx3-expressing posterior branchial arch precursors are specified and many of those that are consequently undergo apoptosis. Second, in contrast, normal numbers of progenitors are present in the anterior mandibular and hyoid arches, but chondrocyte precursors fail to terminally differentiate. In the peripheral nervous system, there is a disruption of enteric, DRG and sympathetic neuron differentiation in hdac1(b382) mutants compared to wildtype embryos. Specifically, enteric and DRG-precursors differentiate into neurons in the anterior gut and trunk respectively, while enteric and DRG neurons are rarely present in the posterior gut and tail. Sympathetic neuron precursors are specified in hdac1(b382) mutants and they undergo generic neuronal differentiation but fail to undergo noradrenergic differentiation. Using the HDAC inhibitor TSA, we isolated enzyme activity and temporal requirements for HDAC function that reproduce hdac1(b382) defects in craniofacial and sympathetic neuron development. Our study reveals distinct functional and temporal requirements for zebrafish hdac1 during neural crest-derived craniofacial and peripheral neuron development.

Carotid artery compression by the hyoid bone.

An 83-year-old male presented with bilateral carotid stenosis. Stenosis on the left side was reported to be greater than 70%. A left carotid endarterectomy was undertaken to increase the lumen size and remove the atherosclerotic plaque. During surgery, the hyoid bone was observed to have a 2-cm calcified horn capable of compressing the carotid artery. This unusual compression was confirmed by radiographic images. In cases where the carotid artery is compressed by the hyoid bone, a carotid endarterectomy rather than a stent may be the procedure of choice.

Recurrent syncope caused by compression of internal carotid artery by an anomalous hyoid bone.

In rare cases a syncope can be caused by compression or irritation of the carotid artery and the carotid sinus due to congenital anatomical anomalies of cervical structures like the hyoid bone. We present the case a of 36 year old man with recurrent syncopes when turning his head. Clinical investigations revealed a hyoid bone anomaly with elongated lesser cornua, especially on the right symptomatic side. Surgical resection of the right lesser cornu led to complete resolution of symptoms over a two year follow-up. Syncope especially in younger subjects may be caused by congenital anomalies of the musculoskeletal system in the cervical region and should be considered in the differential diagnosis of syncope, transient cerebral ischemia and stroke.