[Microanatomical Investigation of the Subtemporal Transtentorial Approach]. / é¢žä¸‹ç»å°è„‘å¹•å ¥è·¯çš„æ˜¾å¾®è§£å‰–å­¦ç ”ç©¶.

Objective: To study the microanatomic structure of the subtemporal transtentorial approach to the lateral side of the brainstem, and to provide anatomical information that will assist clinicians to perform surgeries on the lateral, circumferential, and petroclival regions of the brainstem. Methods: Anatomical investigations were conducted on 8 cadaveric head specimens (16 sides) using the infratemporal transtentorial approach. The heads were tilted to one side, with the zygomatic arch at its highest point. Then, a horseshoe incision was made above the auricle. The incision extended from the midpoint of the zygomatic arch to one third of the mesolateral length of the transverse sinus, with the flap turned towards the temporal part. After removing the bone, the arachnoid and the soft meninges were carefully stripped under the microscope. The exposure range of the surgical approach was observed and the positional relationships of relevant nerves and blood vessels in the approach were clarified. Important structures were photographed and the relevant parameters were measured. Results: The upper edge of the zygomatic arch root could be used to accurately locate the base of the middle cranial fossa. The average distances of the star point to the apex of mastoid, the star point to the superior ridge of external auditory canal, the anterior angle of parietomastoid suture to the superior ridge of external auditory canal, and the anterior angle of parietomastoid suture to the star point of the 10 adult skull specimens were 47.23 mm, 45.27 mm, 26.16 mm, and 23.08 mm, respectively. The subtemporal approach could fully expose the area from as high as the posterior clinoid process to as low as the petrous ridge and the arcuate protuberance after cutting through the cerebellar tentorium. The approach makes it possible to handle lesions on the ventral or lateral sides of the middle clivus, the cistern ambiens, the midbrain, midbrain, and pons. In addition, the approach can significantly expand the exposure area of the upper part of the tentorium cerebelli through cheekbone excision and expand the exposure range of the lower part of the tentorium cerebelli through rock bone grinding technology. The total length of the trochlear nerve, distance of the trochlear nerve to the tentorial edge of cerebellum, length of its shape in the tentorial mezzanine, and its lower part of entering into the tentorium cerebelli to the petrosal ridge were (16.95±4.74) mm, (1.27±0.73) mm, (5.72±1.37) mm, and (4.51±0.39) mm, respectively. The cerebellar tentorium could be safely opened through the posterior clinoid process or arcuate protrusion for localization. The oculomotor nerve could serve as an anatomical landmark to locate the posterior cerebral artery and superior cerebellar artery. Conclusion: Through microanatomic investigation, the exposure range and intraoperative difficulties of the infratemporal transtentorial approach can be clarified, which facilitates clinicians to accurately and safely plan surgical methods and reduce surgical complications.

The M-Point A Novel Landmark in Middle Fossa Surgery: A Cadaveric Morphometric Study.

BACKGROUND: The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE. OBJECTIVE: To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the "M-point." METHODS: A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed to measure the distance between M-point and IAC. Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured. RESULTS: The mean distance between the M-point and the center of the IAC was 14.9 mm (SD ± 2.09), offering a safe drilling area during an MCF approach. CONCLUSIONS: This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC.

Investigating temporal bone variation of colonial populations from St-Lawrence Valley, Quebec: A 3D geometric morphometric approach.

OBJECTIVES: In Quebec, genetic and genealogical research are used to document migratory events and family structures since colonial times, because bioarchaeological analysis is limited by poor skeletal preservation. This article aims to fill this gap by exploring past population structure in the St-Lawrence Valley from the French (1683-1760) and British (1760-1867) regimes using morphological variation of well-preserved temporal bones. MATERIALS AND METHODS: 3D geometric morphometrics shape data from seven populations (five Catholics of French descent and two Protestants of British descent; n = 214) were collected from temporal bones. Using Procrustes distances and both MANOVA and Discriminant Function Analysis, morphological differences were measured to calculate affinities patterns among populations. Shape variations were explored with between-group analysis, Mahalanobis distances and quantified by means of Fst estimates using Relethford-Blangero analysis. RESULTS: Despite strong affinities between all Catholic cemeteries, all show divergent morphological regional diversity -especially Montreal and the fortified villages dedicated to its defense. Montreal exhibits low increase in morphological variance over three centuries. As our results show no morphological differences between the Catholic and the Protestant cemeteries in Montreal, this fact may highlight the potential presence of Irish or admixed individuals in Montreal cemeteries after the British takeover. DISCUSSION: Patterns of morphological diversity highlighted that French colonists did not equally contribute to the descendant populations as reflected by significant interregional variation. Although historical records show that French and English-speaking populations did not tend to admix, morphological affinities between Protestants and Catholics in the beginning of the industrial era in Montreal could reflect the genetic contribution of Catholic Irish migrants. RESEARCH HIGHLIGHTS: All Catholic cemeteries display distinct morphologies, highlighting differential contributions from French colonists and founder effects, which have increased regional differences. Montreal Catholic (French descent) and Protestant (English colonists) cemeteries show significant morphological affinities at the beginning of the industrial era. The Irish migration following the British conquest may explain morphological similarities observed between Catholic and Protestant cemeteries.

OBJECTIFS: Au Québec, les phases de peuplement suivant l'arrivée des premiers colons européens ont presque été exclusivement documentées par des recherches génétiques et généalogiques. Les analyses bioarchéologiques sont limitées par l'important état de fragmentation des collections. L'étude de la variation morphologique de l'os temporal, particulièrement bien conservé, permettrait d'explorer l'histoire des populations de la vallée du Saint-Laurent, du régime français (1683-1760) au régime britannique (1760-1878). MATÉRIELS ET MÉTHODES: Un total de 214 os temporaux issus de sept cimetières catholiques (ascendance française) et protestants (ascendance britannique) a été modélisé en 3D et analysé par morphométrie géométrique. Des analyses de/par distance Procruste couplées avec une analyse discriminante et une MANOVA ont été utilisées pour évaluer les différences et affinités morphologiques entre les cimetières. Les fluctuations morphologiques ont été étudiées à l'aide d'une analyse de distances de Mahalanobis et quantifiées au moyen d'estimations Fst en utilisant l'analyse de Relethford-Blangero. RÉSULTATS: Malgré une forte affinité entre tous les cimetières catholiques, ces derniers présentent également une diversité morphologique régionale divergente - en particulier Montréal et ses villages satellites fortifiés. Montréal présente une faible augmentation de la variance morphologique sur trois siècles. Nos résultats ne montrent pas de différences morphologiques entre les populations francophones et anglophones, ce qui pourrait refléter la présence d'Irlandais après la conquête britannique. DISCUSSION: Les modèles de diversité morphologique interrégionale démontrent que les colons français n'ont pas contribué de manière égale aux populations descendantes comme le démontre les différences morphologiques observés. Les affinités entre protestants et catholiques au début de l'ère industrielle à Montréal pourraient refléter les importantes vagues de migrations irlandaises et le potentiel métissage malgré des différences socio-culturelle importantes.

Evaluation of the Radiological Anatomy of the Temporal Bone Air Spaces and Morphometric Analysis in Turkish Healthy Adults / Evaluación de la Anatomía Radiológica de los Espacios Aéreos del Hueso Temporal y Análisis Morfométrico en Adultos Turcos Sanos

SUMMARY: The temporal bone is a complicate structure which located on the lateral skull. The objective of the present study was to determine the temporal bone air spaces' morphometry, morphology, and pneumatization in Turkish healthy adult people. This retrospective observational study was carried out from 82 subjects (47 males, 35 females) aged 18-69 years. The external auditory canal and related structures' diameters and the volume of these areas were evaluated. The means and standard deviations of the Meatus acusticus externus length (MAEL), meatus acusticus externus pars cartilaginea length (MAEcL), meatus acusticus externus pars ossea length (MAEoL), meatus acusticus externus pars cartilaginea surface (MAEcS), meatus acusticus externus pars ossea surface (MAEoS), meatus acusticus externus volume (MAEV), meatus acusticus externus pars cartilaginea volume (MAEcV), meatus acusticus externus pars ossea volume (MAEoV), processus mastoideus air cells volume (PMACV), cavum tympani volume (CTV), and temporale pneumatic spaces volume (OTPSV) were found as 23.21±3.70 mm, 12.69±3.72 mm, 7.80±3.70 mm, 669.89±107.7 mm2, 267.50±30.51 mm2, 743.50±119.6 mm3, 971.97±156.69 mm3, 419.51±48.67 mm3, 5915.93±650.34 mm3, 673.48±91.93 mm3, 7813.34±717.49 mm3 have found in 82 subjects, respectively. In this paper, the morphometric and volume properties of the temporal bone cavities measurements were significantly higher in males than females. These results may both provide reference values of Turkish healthy population, and lead to decrease potential surgical complications about temporal and mastoid regions.

El hueso temporal es una compleja estructura ubicada en el parte lateral del cráneo. El objetivo del presente estudio fue determinar la morfometría, morfología y neumatización de los espacios aéreos del hueso temporal en individuos adultos turcos sanos. Este estudio observacional retrospectivo que se llevó a cabo en 82 sujetos (47 hombres, 35 mujeres) de entre 18 y 69 años. Se evaluaron los diámetros del meato acústico externo y las estructuras relacionadas y el volumen de estas áreas. Las medias y las desviaciones estándar de la longitud del meato acústico externo (MAEL), la longitud de la parte cartilaginosa del meato acústico externo (MAEcL), la longitud de la parte ósea del meato acústico externo (MAEoL), la superficie de la parte cartilaginosa del meato acústico externo (MAEcS), la superficie de la parte ósea del meato acústico externo (MAEoS), volumen del meato acústico externo (MAEV), volumen de la parte cartilaginosa del meato acústico externo (MAEcV), volumen de la parte ósea del meato acústico externo (MAEoV), volumen de las células aéreas del proceso mastoideo (PMACV), volumen del cavum tympani (CTV) y el volumen de los espacios neumáticos temporales (OTPSV) se encontró como 23,21 ± 3,70 mm, 12,69 ± 3,72 mm, 7,80 ± 3,70 mm, 669,89 ± 107,7 mm2, 267,50 ± 30,51 mm2, 743,50 ± 119,6 mm3, 971,97 ± 156,69 mm3, 419,5. 1±48,67 mm3, 5915,93 ± 650,34 mm3, 673,48 ± 91,93 mm3, 7813,34 ± 717,49 mm3, respectivamente. En este artículo, las propiedades morfométricas y de volumen de las mediciones de las cavidades del hueso temporal fueron significativamente mayores en hombres que en mujeres. Estos resultados pueden proporcionar valores de referencia de la población sana turca y conducir a una disminución de las posibles complicaciones quirúrgicas en las regiones temporal y mastoidea.

Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation.

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Morphometric Analysis and Linear Measurements of the Scala Tympani and Implications in Cochlear Implant Electrodes.

HYPOTHESIS: The objective of this study was to perform detailed height and cross-sectional area measurements of the scala tympani in histologic sections of nondiseased human temporal bones and correlate them with cochlear implant electrode dimensions. BACKGROUND: Previous investigations in scala tympani dimensions have used microcomputed tomography or casting modalities, which cannot be correlated directly with microanatomy visible on histologic specimens. METHODS: Three-dimensional reconstructions of 10 archival human temporal bone specimens with no history of middle or inner ear disease were generated using hematoxylin and eosin histopathologic slides. At 90-degree intervals, the heights of the scala tympani at lateral wall, midscala, and perimodiolar locations were measured, along with cross-sectional area. RESULTS: The vertical height of the scala tympani at its lateral wall significantly decreased from 1.28 to 0.88 mm from 0 to 180 degrees, and the perimodiolar height decreased from 1.20 to 0.85 mm. The cross-sectional area decreased from 2.29 (standard deviation, 0.60) mm 2 to 1.38 (standard deviation, 0.13) mm 2 from 0 to 180 degrees ( p = 0.001). After 360 degrees, the scala tympani shape transitioned from an ovoid to triangular shape, corresponding with a significantly decreased lateral height relative to perimodiolar height. Wide variability was observed among the cochlear implant electrode sizes relative to scala tympani measurements. CONCLUSION: The present study is the first to conduct detailed measurements of heights and cross-sectional area of the scala tympani and the first to statistically characterize the change in its shape after the basal turn. These measurements have important implications in understanding locations of intracochlear trauma during insertion and electrode design.

A cadaveric temporal bone study of the anatomical landmarks for middle turn cochleostomy.

OBJECTIVE: This study aimed to determine anatomical landmarks for accurate and safe middle turn cochleostomy on cadaveric temporal bones. METHODS: In 17 cadaveric wet adult temporal bones, cortical mastoidectomy was performed, followed by extended posterior tympanotomy through which a middle turn opening was created anterior to the stapes footplate. Micro-measurements of various lengths were taken from the cochleostomy to normal middle-ear anatomical landmarks using a digital microscope. RESULTS: The mean length from the middle turn cochleostomy to the processus cochleariformis was 1.8 ± 0.3 mm and to the tympanic segment of the facial nerve was 2.2 ± 0.3 mm. The mean shortest length from the oval window to the osseous spiral lamina was 2.4 ± 0.3 mm and to the internal carotid artery was 5.0 ± 0.6 mm. The mean shortest length from the round window to the internal carotid artery was 4.3 ± 0.6 mm. CONCLUSION: A middle turn cochleostomy can be safely drilled by using the measured lengths in difficult cases.

The feasibility of cochlear implantation in early infancy.

OBJECTIVES: To determine the key image anatomical parameters that are relevant to cochlear implantation (CI) using temporal bone high-resolution computed tomography (HRCT) scans and to identify age group differences in order to provide image anatomical support for early CI. METHODS: The data of 346 temporal bone HRCTs of 173 children from 5 months to 18 years of age were retrospectively selected and reviewed. Parameters of the human temporal bone that are relevant to CI key surgical steps include mastoid thickness (MT), the facial recess width (FRW), and an angle representing the round window visibility. All measurements are performed on axial images. RESULTS: There was no significant difference in the above morphological values by gender (p > 0,05). Two-sided FRW was not significantly different (p > 0,05), but MT and angle A were significantly different (p < 0,001). FRW and angle were independent of age (p > 0,05). However, MT had been found to exhibit postnatal development. The linear function of MT were calculated as y = 2463 × group(s) + 20,574 (p < 0,001). CONCLUSIONS: Based on preoperative imaging analysis at different ages, middle ear development was stable at 5 months of age, allowing early CI in infancy with severe to severe hearing loss at this age. These data must be considered exploratory and more extensive clinical studies are needed.

Development of a navigable 3D virtual model of temporal bone anatomy.

BACKGROUND: Computed Tomography (CT) scanning offers an accurate structural definition of bones, blood vessels, and soft tissues; however, mental integration of cross-sectional 2D CT images for a 3D understanding of complex anatomical structures becomes difficult when the field of view is confined to the temporal bone. This project tried to provide a feasible solution to this problem by creating a navigable 3D virtual model which may aid in better comprehension of the temporal bone anatomy. METHODS: A helical-CT scan was used to obtain high-resolution cross-sectional slices of a cadaveric human temporal bone. Using the volume-rendering capabilities of 3D Slicer®, which involves volume data management, cropping of the data set, and threshold painting, detailed anatomical structures were segmented based on the intensity captured from different regions. This volumetric data was converted to an interactive virtual model using Blender®. RESULTS: The final product is a web page that allows interaction and navigation with a 3D annotated model of the temporal bone, which can be accessed from any device with a web browser. CONCLUSION: This model can function as a training tool for students, teachers, and practitioners to understand and review the complex anatomy of the temporal bone.

Location of the Tympanic Nerve Relative to the Round and Oval Windows.

BACKGROUND: The aim of the study was to measure the distance of the tympanic nerve to the oval window and round window niche in adult cadavers for evaluating its usability as an anatomical landmark during middle ear-related surgeries, including stapedotomy and cochleostomy, and for preventing its iatrogenic damage during surgical practices such as otosclerosis surgery and cochlear implantation. METHODS: The middle ears of 10 adult cadavers aged 74.70 ± 14.56 years were bilaterally dissected with the help of an endoscope and microscope to measure the distance of tympanic nerve to round window niche and oval window. RESULTS: Tympanic nerve was found as 1.60 ± 0.86 mm (range, 0-3.11 mm) and 1.55 ± 0.38 mm (range, 1.04-2.20 mm) away from round window niche and oval window, respectively. In relation to the quantitative values of these 2 distances, neither right-left nor male-female significant differences were determined (P > .05). Tympanic nerve was observed in all temporal bones. In terms of the shape and twigs of tympanic nerve, extreme variations among cadaveric temporal bones were determined. Tympanic nerve-round window niche distance between 0-1 mm was defined as type 1 (20%), between 1 and 2 mm as type 2 (45%), between 2 and 3 mm as type 3 (30%), and between 3 and 4 mm as type 4 (5%). CONCLUSION: Tympanic nerve may be vulnerable at round window niche- or oval window-related surgeries (e.g., cochleostomy).

The Sensory Auricular Branch of the Facial Nerve and its Relationship to Landmarks of the Facial Recess.

OBJECTIVE: Delineate the anatomic relationship of the sensory auricular branch (SAB) of the facial nerve to other structures of the facial recess. METHODS: Ten adult cadaveric temporal bones were randomly selected and dissected under operative microscopy. Linear and angular measurements were obtained for the following parameters: (1) the distance from the tip of the short process of the incus to the point of convergence of the SAB and the main trunk of the facial nerve; (2) the distance from the point of convergence of the SAB and the main trunk of the facial nerve to the chorda tympani (CT) division from the main trunk; (3) the distance from the bifurcation of the CT and facial nerve to the crossover point of the SAB/CT; (4) the angle at which the SAB merges with the main trunk (Y°), and (5) the angle at which the CT divides off the main trunk (X°). RESULTS: The mean distance from the tip of the short process of the incus to the SAB takeoff was 8.7 ± 1.83 mm (range 6-13 mm). The mean distance from the SAB to the CT division from the main trunk was 5.9 ± 2.41 mm (range 3-10 mm). The mean angle at which the SAB merged with the main trunk of the facial nerve was 38.5 ± 12.63° (range 25°-68°). The mean CT-main trunk angle was 16 ± 4.24° (range 8°-21°). The branching point of the SAB from the facial nerve approximately bisected the facial recess. CONCLUSION: Recognizing the SAB and knowing its relationships to surrounding anatomy provides a useful adjunctive landmark for the identification of the main trunk of the facial nerve's mastoid segment. LEVEL OF EVIDENCE: 4.

Morphology and variability of the facial nerve trunk depending on the branching pattern, gender, anthropometric type and side of the head in Moldovan population.

BACKGROUND: Knowledge concerning variability of the facial nerve trunk (FNT) direction after its exit through the stylomastoid foramen is of a great clinical significance for maxillofacial surgeons, otorhinolaryngologists, oncologists, specialists in plastic and aesthetic surgery. The aim of our study was to establish the variation of the FNT direction and its peculiarities depending on the branching pattern, gender, anthropometric type and side of the head. MATERIALS AND METHODS: The direction of the FNT and its branching pattern were studied on 75 dissected hemifaces of adult formalised cadavers (59 male/ /16 female), and the morphometry of the FNT length, width and bifurcation angle was carried out. RESULTS: Seven branching patterns of the facial nerve were established: type I - 18.7%, type II - 14.7%, type III - 20%, type IV - 14.6%, type V - 5.3%, type VI - 18.7%, and type NI - 8% (bizarre types). The FNT had a descending direction in 73.3% of cases; ascending FNT - 9.3% (including 5.3% of very short diffuse branching trunks and 1.3% of arch-shaped FNT); horizontal FNT - 10.7%; number variants - 6.7%. The male/female ratio of the descending FNT was 69.5%/87.4%; ascending - 10.2%/6.3%; horizontal - 11.9%/6.3%; number variants - 8.4% (only in male). The right/left ratio of the descending FNT was 62.9%/82.5%; ascending - 11.4%/7.5%; horizontal - 11.4%/10%; number variants - 14.3% (only on the right side). The ratio of the descending FNT in mesocephalic type (MCT)/brachycephalic type (BCT)/dolichocephalic type (DCT) was respectively 70.6%/100%/66.7%; ascending - 12.1%/0%/0%; horizontal - 12.1/0%/11.1%. Numerical variants in MCT - 5.2%, in DCT - 22.2%. The mean number of FNT in MCT/BCT/DCT was respectively 1.07/1.0/1.22. CONCLUSIONS: Three main directions are characteristic of the FNT: the descending, ascending and horizontal ones, which vary depending on the branching pattern, gender, shape and side of the head.

Sinus tympani revisited for planning retrofacial approach-radiologic study in pneumatized temporal bones and its surgical implications.

BACKGROUND AND PURPOSE: Retrofacial approach (RFA) is an access route to sinus tympani (ST) and it is used in cholesteatoma surgery, especially when type C ST is encountered. It may also be used to gain an access to stapedius muscle to assess the evoked stapedius reflex threshold. The primary object of this study was to evaluate the morphology of sinus tympani and its relationship to facial nerve (FN) and posterior semicircular canal (PSC) in context of planning retrofacial approach in pneumatized temporal bones. METHODS: CBCT of 130 adults were reviewed. The type of sinus tympani was assessed according to Marchioni's classification. Width of entrance to sinus tympani (STW), depth of ST (STD), distance between the posterior semicircular canal and facial nerve (F-PSC), distance between the latter plane to the floor of ST at the right angle (P-ST) were measured at level of round window (RW) and pyramidal ridge (PR). RESULTS: All of the bones were well-aerated and classified in Dexian Tan pneumatization group 3 or 4. Type B of ST is dominant (70.8%) in adult population with no history of inflammatory otologic diseases, followed by type C (22.7%) and then type A (6.5%). The depth of ST (STD) presented significant deviations (ANOVA, p < 0.05) among all three types. STW reaches greater values on the level of PR. F-PSC does not correlate with type of ST. In over 75% of examined type C sinus tympani the distance P-ST was less than 1 mm. CONCLUSIONS: The qualitative classification of the sinus tympani into types A, B and C, introduced by Marchioni is justified by statistically significant differences of depth between individual types of tympanic sinuses. The STW distance reaches greater values inferiorly-it may suggest that RFA should be performed in infero-superior manner rather than opposite direction. Preoperative assessment of temporal bones CT scans gives very important information about size of sinus tympani and distance between FN and PSC.

Air spaces of the temporal bone: a morphometric analysis with clinical implications.

BACKGROUND: The main objective of the present study was to analyse the morphological variations of the air spaces of the temporal bone, that is, the pneumatized and air-filled spaces of the temporal bone cavities. MATERIALS AND METHODS: A total of 99 sides were analysed. Temporal bone pneumatic spaces (TBPS) were defined as the free spaces inside the cavities of the temporal bone filled with air, excluding the volume of the structures present in the investigated region. Total volumes of TBPS were calculated as the sum of total volumes of mastoid air cells (MAC), tympanic cavity (TC), and external auditory canal (EAC). Analyses were performed considering the general population and the female and male subgroups. RESULTS: The overall results obtained on Polish population were set as follows: the median total volume of TBPS was demonstrated at 7882.58 mm3 (lower quartile [LQ]: 6200.56 mm3; higher quartile [HQ]: 10393.16 mm3). The median volume of MAC was set at 5813.05 mm3 (LQ: 4224.94 mm3; HQ: 8181.81 mm3). The median of the total volume of the EAC was demonstrated at 1294.36 mm3 (LQ: 1099.68 mm3; HQ: 1627.84 mm3). CONCLUSIONS: In the present study, the morphometric properties of the temporal bone cavities were analysed. The results showed that the total volume of the MAC was, on average, lower in women than in men. This should be taken into account when performing procedures on the mastoid, such as mastoidectomies. It is hoped that the results of this study can help reduce potential surgical complications associated with otological procedures.

Morphological relationships between external auditory canal and vital structures of tympanic cavity.

PURPOSE: We aimed to evaluate the morphology of the external auditory canal (EAC) using a three-dimensional (3D) reconstruction of computed tomography (CT) scans of the temporal bone to corroborate and predict important anatomical structures involved in middle ear surgery based on the EAC morphology. METHODS: Temporal bone CT from 62 patients (120 ears) was used to perform 3D reconstruction (maximum intensity projection), of which 32 patients (60 ears) had chronic otitis media and 30 patients (60 ears) had normal temporal bones. The anatomical morphology of the EAC, tympanic sinus, vertical portion of the facial nerve, and jugular bulb were measured, and the anatomical relationship between the EAC morphology and important structures of the middle ear was analyzed. RESULTS: In ears with chronic otitis media, the overhang of the inferior wall of the EAC was significantly more than that in normal ears, and the antero-posterior length of the bony tympanic ring was short. Furthermore, the tympanic sinus was shallow, and vertical portion of the facial nerve tended to run outward. The EAC morphology correlated with the tympanic sinus depth and outward orientation of the vertical portion of the facial nerve. CONCLUSION: A severe overhang of the inferior wall of the EAC and short antero-posterior length of the bony tympanic ring indicates a higher possibility of a shallow tympanic sinus and an outward orientation of the vertical portion of the facial nerve. These findings aid in predicting the difficulty of tympanic sinus operation and reducing facial nerve damage risk during EAC excision.

Temporal Bone Anatomy.

Temporal bone anatomy is highly complex, with a complicated configuration of minute anatomic structures housed in a dense osseous structure. Nevertheless, a robust understanding of this anatomy is essential for clinicians, who must accurately diagnose and describe the various pathologies that exist in this region. In this article, we provide a comprehensive overview of temporal bone anatomy, ranging from its large components to its smallest foramina, canals, and clefts.

Statistical Shape Model of the Temporal Bone Using Segmentation Propagation.

HYPOTHESIS: Automated image registration techniques can successfully determine anatomical variation in human temporal bones with statistical shape modeling. BACKGROUND: There is a lack of knowledge about inter-patient anatomical variation in the temporal bone. Statistical shape models (SSMs) provide a powerful method for quantifying variation of anatomical structures in medical images but are time-intensive to manually develop. This study presents SSMs of temporal bone anatomy using automated image-registration techniques. METHODS: Fifty-three cone-beam temporal bone CTs were included for SSM generation. The malleus, incus, stapes, bony labyrinth, and facial nerve were automatically segmented using 3D Slicer and a template-based segmentation propagation technique. Segmentations were then used to construct SSMs using MATLAB. The first three principal components of each SSM were analyzed to describe shape variation. RESULTS: Principal component analysis of middle and inner ear structures revealed novel modes of anatomical variation. The first three principal components for the malleus represented variability in manubrium length (mean: 4.47 mm; ±2-SDs: 4.03-5.03 mm) and rotation about its long axis (±2-SDs: -1.6° to 1.8° posteriorly). The facial nerve exhibits variability in first and second genu angles. The bony labyrinth varies in the angle between the posterior and superior canals (mean: 88.9°; ±2-SDs: 83.7°-95.7°) and cochlear orientation (±2-SDs: -4.0° to 3.0° anterolaterally). CONCLUSIONS: SSMs of temporal bone anatomy can inform surgeons on clinically relevant inter-patient variability. Anatomical variation elucidated by these models can provide novel insight into function and pathophysiology. These models also allow further investigation of anatomical variation based on age, BMI, sex, and geographical location.

Styloid Process Length Variations: An Osteological Study.

OBJECTIVE: The objective of this study was to study the morphometry of the styloid process of the temporal bone and the prevalence of an elongated styloid process in relation to side and gender. MATERIAL AND METHOD: The present study included 200 human skulls which were procured from the rich osteological collections of the Department of Anatomy, Faculty of Medicine, University of Sarajevo. The styloid process was observed macroscopically on both sides of all the skulls and elongations, if any, were noted. The lengths of the styloid processes were measured using digital vernier calipers. The measurements were taken from the point of emergence of the process (base) up to the tip. RESULTS: Out of 200 specimens, only 14 cases (7%) exhibited an elongated styloid process. The mean length of the styloid process was 25.8±4.68 mm and 24.2±4.54 mm for the right and left sides, respectively. The size of the styloid process did not different significantly between the two sides (P=0.724). The mean length of the styloid process was 24.05±3.54 mm in females and 25.95±5.68 mm in males, and the difference was statistically significant (P=0.023). CONCLUSION: The study and knowledge of the anatomical variations of the styloid process in the Bosnian population may help clinicians to diagnose Eagle's syndrome. Knowledge of this disorder can prevent the worsening of the painful symptoms related to an elongated styloid process.

Styloid process elongation and temporomandibular disorders: a pilot study in the Albanian population.

INTRODUCTION: Patients with an elongated styloid process (SP) presented related symptoms as deep neck pain, foreign body sensation in the throat, pain on turning the head, and odynophagia. These symptoms are the source of misdiagnosis of this syndrome since these clinical manifestations are like those of temporomandibular disorders (TMD). This study aimed to investigate a possible correlation between the TMD and elongation of the SP. MATERIALS AND METHODS: The case-control study included 60 participants between 25-60 years of age and was carried out at University Dental Clinic, Department of Maxillo-Facial Surgery, Tirana, Albania during the period November 2020 - March 2021. The study group consisted of 30 patients diagnosed with TMD (21 females and 9 males) and the control group consisted of 30 individuals without TMD (18 females and 12 males). The diagnosis of TMD was performed according to Research Diagnostic Criteria for Temporomandibular Disorders axis I and the SP measurement was performed by a single experienced examiner. The normal range of SP length was considered 20-30 mm. RESULTS: SP >30mm was found in 86.67% of patients with TMD group and 43.33% of individuals of the control group. There was a significant difference between the TMD group and the control group in regards to SP length (p <0.001). CONCLUSIONS: There is a significant association between the elongation of the SP and TMD. Dental clinicians should recognize the morphological changes in the length of SP on the panoramic radiographs, which could be a hint in the proper diagnosis of TMD.

Utility of Temporal Bone Computed Tomography in Pediatric Emergency Medicine.

OBJECTIVE: Temporal bone computed tomography (CT) requires a relatively high radiation dose to produce high-resolution images required to define surgical anatomy. In the acute setting, the need for this detailed evaluation of temporal bone pathology may not be required for nonsurgical management and clinical decision-making. We performed a retrospective review of the clinical characteristics and subsequent management of children who underwent CT of the temporal bone with the goal of optimizing clinical decision-making and mitigating the risks of radiation exposure in children. METHODS: We included pediatric patients (<18 years of age) with International Classification of Diseases (9th or 10th revision) diagnoses consistent with otitis externa, otitis media, mastoiditis, head trauma, temporal bone fracture, and otalgia who were treated in the emergency department and underwent temporal bone CT from January 1, 2012-December 31, 2016. We collected data regarding the patients' presenting symptoms, physical exam findings, indications for imaging, radiographic findings, disposition, and operative intervention within 30 days of imaging. Features of the suspected mastoiditis group were compared between operative and non-operative patients. RESULTS: Over the four-year study period there were 96 temporal bone CTs. Most studies (70%) were associated with a subsequent inpatient admission. Common indications for imaging included evaluation of acute mastoiditis (55%) or trauma (41%). Of the 53 patients with concern for mastoiditis, 27 (51%) required otologic surgery. Two patients in the trauma group required surgical intervention, both for facial nerve decompression. In patients with suspected mastoiditis, mental status changes (P = 0.02), auricular proptosis (P = 0.05), and fluctuance (P = 0.02) were significantly more prevalent in the operative group; however, no other findings were significantly associated with operative intervention. CONCLUSION: Temporal bone CT is beneficial in guiding diagnosis and management of acute mastoiditis. We found that a majority of patients with suspected mastoiditis who underwent temporal bone CT ultimately required surgery or hospital admission. However, the potential for reduction in the use of CT still exists in this population. Fractures of the temporal bone typically do not require urgent operative intervention in the absence of complete facial nerve paralysis; thus, the utility of temporal bone CT in trauma evaluation may be limited.