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.

Jugular bulb anatomical variations and pneumatization patterns: a comprehensive CBCT analysis.

PURPOSE: This study aims to assess the anatomical possibilities of the jugular bulb (JB). METHODS: Fifty archived CBCT scans were analyzed. RESULTS: The average distance between the internal acoustic canal (IAC) and the JB was 7.97 mm on both sides (Right: SD = 2.56 mm, range 3.16-13.3 mm; Left: SD = 2.5 mm, range 2.9-13.6 mm). JB walls' pneumatization was classified into eight patterns. Deep petrosal cells (DPCs) prevailed in the lateral wall of the JB. The absence of pneumatization (NP) was commonly found on the left side. The presence of infralabyrinthine and hypotympanic cells varied. Less common types included accessory occipital cells (AOCs), posteromedial tracts (PMTs), and basi-occipital cells (BOCs), which determined a consistent variation of the lateral wall pneumatization patterns. Pneumatization of the medial wall was not observed in 50 right sides and 49 left sides. The inferior wall analysis revealed symmetry in AOC distribution and a predominant occurrence of NP. Cases with hypotympanum (HT) in the lateral wall showed a statistically significant IAC-JB distance increase by an average of 4.67 mm compared to NPs. Specific pneumatizations, particularly HT on the lateral side, have a significant effect on the IAC-JB distance, showing a clear pattern of increasing distance from DPC to NP and then to HT. A significant distance increase in HT pneumatization was noted. There were also recorded instances of JB hypoplasia and hyperplasia, JB diverticula, dehiscent JBs, and high JBs. CONCLUSION: This study establishes a novel classification of JB pneumatizations to aid in the understanding of the temporal bone anatomy.

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.

Fenestration of the anterior and posterior cerebral arteries in coexistence with a contralateral posterior cerebral artery of fetal origin.

PURPOSE: The present case report aims to describe the rare coexistence of three variants of the cerebral arterial system diagnosed by computed tomography angiography (CTA). METHODS: A retrospective study on head and neck CTAs was performed on a Greek adult population from the Department of Radiology, University Hospital of Larissa. An interesting case of an 80-year-old male was further investigated. RESULTS: The cerebral arterial circle presented with a combination of three variations. The left anterior cerebral artery (ACA) was fenestrated 1.4 mm proximally to the anterior communicating artery formation. The left posterior cerebral artery (PCA) was also fenestrated, 5.5 mm distally to its origin from the basilar artery. Lastly, the right PCA originated from the ICA supraclinoid segment. CONCLUSIONS: This case report highlights an unusual coexistence of A1 and P1 segments fenestration with a fetal PCA, resulting in a unique cerebral circle. A1 segment fenestration has been previously reported as rare, while the PCA fenestration as extremely rare variant. Awareness of these rare variations could aid interventionists in their preoperative assessments.

The anterior communicating artery variants: a meta-analysis with a proposed classification system.

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery's hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Anatomical Possibilities of the Alveolar Bone at the Upper Second Premolar Level.

Background and Objectives: The upper posterior teeth are typically regarded as being exclusively inferior to the maxillary sinus (MS). The expansion of the nasal fossa above the maxillary alveolar base (MAB) needs better investigation. The hypothesis was raised that the MAB in the upper premolar region, which is usually addressed by surgeons for the elevation of the antral floor, is not exclusively beneath the MS. Therefore, we aimed to document the possible upper relations of the MAB as antral, nasal, or both. Materials and Methods: A total of 145 CBCT scans were used to study four types of MAB: type 1-antral; type 2-antral with a palatal recess; type 3-antral and nasal; type 4-nasal. In type 2, the orthoradial width of the alveolar bone, the rectilinear width of the antral floor, and the maximum depth of the palatal recess were measured. For type 3, the MAB width and the straight widths of the antral and nasal segments of the MAB were measured. Results: Type 1 was found in 67.24%, type 2 in 13.45%, type 3 in 16.21%, and type 4 in 3.1% of the 290 MSs investigated. Palatal recesses were found in 11.72% of the MSs on the right side and 15.17% of the MSs on the left side. Types 1 and 2 exhibited strongly statistically significant bilateral symmetry (Pearson's Chi2 = 86.42, p < 0.001). Type 3 correlated equally with contralateral types 1 and 3. The bilateral symmetry for types 1-3 was stronger in the males (Pearson's Chi2 = 47.83, p < 0.001) than in the females (Pearson's Chi2 = 56.96, p < 0.001). There were no statistically significant associations between sex and the unilateral anatomical type. Conclusions: The MAB in the upper second premolar area should not be considered to be exclusively antral during surgeries or in anatomical teaching.

Anatomical Variations of the External Jugular Vein: A Pictorial and Critical Review.

(1) Background: The external jugular vein (EJV) descends on the sternocleidomastoid muscle to drain deep into the subclavian vein. Anatomical variations of the EJV are relevant for identification of the greater auricular nerve, flap design and preparation, or EJV cannulation. (2) Methods: Different publications were comprehensively reviewed. Dissections and three-dimensional volume renderings of peculiar cases were used to sample the review. (3) Results: Different anatomical possibilities of the EJV were critically reviewed and documented: fenestrations and double fenestrations, true or false duplications, triplication, absence, aberrant origin or course, or bifurcation. Tributaries of the EJV, such as the facial and posterior external jugular veins, are discussed. The internal jugular vein termination of the EJV is also presented. (4) Conclusions: Care should be taken when different morphological features of the EJV are encountered or reported.

The Vertebral Artery: A Systematic Review and a Meta-Analysis of the Current Literature.

(1) Background. The anatomical variations of the vertebral arteries (VAs) have a significant impact both in neurosurgery and forensic pathology. The purpose of this study was to evaluate the variational anatomy of the vertebral artery. We evaluated anatomical aspects regarding the V1 and V2 segments of the VA: origin, course, tortuosity, hypoplasia, and dominance, and established the prevalence of each variation. (2) Methods. We conducted a systematic search in PubMed and Google Scholar databases, up to December 2022. Sixty-two studies, comprising 32,153 vessels, were included in the current meta-analysis. We used a random-effects model with a DerSimonian-Laird estimator. The confidence intervals were set at 95%. The heterogeneity between studies was assessed using I2. The funnel plot and Egger's regression test for plot asymmetry were used for the evaluation of publication bias. Statistical significance was considered at p < 0.05. (3) Results. The most common site for the origin of both VAs was the subclavian artery. The aortic arch origin of the left VA had a prevalence of 4.81%. Other origins of the right VAs were noted: aortic arch (0.1%), right common carotid artery (0.1%), and brachiocephalic trunk (0.5%). Ninety-two percent of the VAs entered the transverse foramen (TF) of the C6 vertebra, followed by C5, C7, C4, and least frequently, C3 (0.1%). Roughly one out of four (25.9%) VAs presented a sort of tortuosity, the transversal one representing the most common variant. Hypoplasia occurred in 7.94% of the vessels. Left VA dominance (36.1%) is more common, compared to right VA dominance (25.3%). (4) Conclusions. The anatomy of the VA is highly irregular, and eventual intraoperative complications may be life-threatening. The prevalence of VA origin from the subclavian artery is 94.1%, 92.0% of the VAs entered the TF at C6, 26.6% were tortuous, and 7.94% were hypoplastic.