scholarly journals Braincase anatomy of the Paleocene crocodyliform Rhabdognathus revealed through high resolution computed tomography

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11253
Author(s):  
Arthur Erb ◽  
Alan H. Turner
Keyword(s):  
Computed Tomography ◽  
Inner Ear ◽  
Semicircular Canals ◽  
Spherical Shape ◽  
Micro Computed Tomography ◽  
High Resolution Computed Tomography ◽  
System A ◽  
Near Shore ◽  
Increase Surface Area ◽  
Close Relatives

Dyrosaurids were highly specialized, largely marine, relatives of living crocodylians, and one of the few archosaur lineages to survive the K-Pg extinction. Dyrosaurids lived during the Cretaceous to the Eocene and represent a unique combination of morphology and ecology not seen in living crocodylians. Little is known about their endocranial anatomy, leaving many questions about their neurosensory adaptations unaddressed. Recently, µCT (micro-computed tomography) scans were made of a well-preserved skull of Rhabdognathus, a Paleocene dyrosaurid from Mali. This marks the first time the braincase and neurosensory features of a dyrosaurid have been examined using CT. We focus our attention to three specific internal structures: the cranial endocast; the inner ear; and the paratympanic sinuses. The cranial endocast of Rhabdognathus revealed novel features including a unique conformation of its paratympanic system, a prominent dorsal venous system that communicates with the external skull table, extremely enlarged tympanic vestibules that meet at the midline of the endocranium, a prominent spherical cerebrum, and elongate olfactory tracts accounting for half the total endocast length. The bizarre laterally facing lateral Eustachian foramen of dyrosaurids is now understood to be a complex fossa including both a ventrally directed lateral Eustachian foramen and a laterally directed foramen for the basioccipital diverticulum. A novel median pterygopharyngeal canal was discovered connecting the pharynx to the adductor chamber. These revelations require a reinterpretation of the associated external foramina visible on the posterior of the skull in dyrosaurids and potentially their close relatives the pholidosaurids. The olfactory tract terminates in an enlarged olfactory region possessing complex bony projections—a unique morphology perhaps serving to increase surface area for olfaction. The inner ear of Rhabdognathus exhibits characteristics seen in both Pelagosaurus and Gavialis. The vestibule is spherical, as in Gavialis, but is significantly expanded. The semicircular canals are enlarged but pyramidal in shape as in the thalattosuchian Pelagosaurus. The proportion of the cochlear length to total endosseous labyrinth height is roughly 0.5 in Rhabdognathus implying that the hearing capabilities resemble that of thalattosuchians. A suite of expanded sense organs (e.g., bony olfactory lamina; hypertrophied vestibule of the inner ear), and the clear expansion of the cerebrum to a more symmetrical and spherical shape suggest that dyrosaurids possess neuroanatomical modifications facilitating an agile predatory near-shore ecology.

Computed Tomography and Magnetic Resonance Imaging of the Inner Ear

1988 ◽  
Vol 99 (5) ◽  
pp. 494-504 ◽  
Author(s):  
Robert K. Jackler ◽  
William P. Dillon
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
Inner Ear ◽  
Semicircular Canals ◽  
Resonance Imaging ◽  
High Resolution Computed Tomography ◽  
Membranous Labyrinth ◽  
Prosthetic Devices ◽  
Ear Malformations

The majority of temporal bone radiographic studies are obtained either for middle ear and mastoid disease or in the evaluation of retrocochlear pathology. With recent technologic advances, diagnostic imaging of the inner ear has developed an increasing role in the evaluation and management of diseases that affect the cochlea, semicircular canals, and the vestibular and cochlear aqueducts. High-resolution computed tomography (CT) provides excellent detail of the osseous labyrinth, whereas magnetic resonance imaging (MRI) generates images derived from the membranous labyrinth and its associated neural elements. Optimal techniques for obtaining high quality CT and MRI images of the normal and diseased inner ear are presented. CT has proved useful in the evaluation of inner ear malformations, cochlear otosclerosis, labyrinthine fistulization from cholesteatoma, translabyrinthine fractures, otic capsule osteodystrophies, in the assessment of cochlear patency before cochlear implantation, and in the localization of prosthetic devices such as stapes wires and cochlear implants. While MRI produces discernible images of the soft tissue and fluid components of the inner ear, it has yet to demonstrate any unique advantages in the evaluation of inner ear disease. However, MRI produces excellent and highly useful images of the audiovestibular and facial nerves, cerebellopontine angle, and brain.

Role of Computed Tomography and Magnetic Resonance Imaging in detecting the Prevalence of inner ear anomalies among cochlear implant candidates

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Alaa Nasser Hussain Zaher ◽  
Tougan Taha Abd El Aziz ◽  
Ahmed Samy Abdelrahman
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Hearing Loss ◽  
Cochlear Implant ◽  
Inner Ear ◽  
Resonance Imaging ◽  
High Resolution Computed Tomography ◽  
Vestibular Aqueduct ◽  
Incomplete Partition ◽  
Ear Anomalies

Abstract Background Hearing loss management using cochlear implants in patients with inner ear anomalies has long been discussed in the otology community. Magnetic resonances imaging (B,/IRI) and Computed tomography (CT) play important roles in the preoperative assessment of inner ear abnormalities such as cochlear nerve deficiency and variant anatomy as these abnormalities may not only affect the decision of the implantation procedure or the patient's prognosis regarding auditory improvement, but also the risk of complications. Objective To examine the prevalence of inner ear anomalies among cochlear implant recipients in patients with congenital sensorineural hearing loss among the pediatric age group in the Demerdash hospital, Ain Shams university using High resolution computed tomography (HRCT) and MRI imaging. Methods A retrospective descriptive study over the course of 9 months that included all patients that are candidates for cochlear implant referred to the Radiology department, Ain Shams University Hospitals for a preoperative imaging in the form of CT and VIRI scans. Results CT and MRI scans of 33 patients who had congenital hearing loss and were candidates for cochlear implantation with total 66 ears were reviewed. Inner ear anomalies were identified in 8 patients representing a prevalence (24.2%) with 14 ear diseased. Anomalies were seen bilaterally in 6 patients and unilaterally in 2 patients. Among the 14 diseased ear, 9 ears (64.3%) were seen with incomplete partition Il, 7 ears (50%) were seen with enlarged vestibular aqueduct, 4 ears (28.6%) were seen with cochlear hypoplasia, 3 ears (21.4%) were seen with semicircular canal aplasia, 2 ears (14.3%) were seen with incomplete partition type I, 2 ears (14.3%) were seen with cochlear nerve aplasia, 2 ears with cochlear aplasia (14.3%), I ear (7.1%) was seen with common cavity ear (7.1%) with complete labyrinthine aplasia. Conclusion Prevalence of inner ear anomalies among cochlear implant candidates was 24.2%. This result is consistent with results worldwide and the most common anomalies were Incomplete partition Il and large vestibular aqueduct. Abbreviations Computed tomography (CT), Magnetic resonance imaging (MRI), High resolution computed tomography (HRCT), Internal auditory canal (IAC), Cerebellopontine angle (CPA).

scholarly journals Facial nerve anomalies in paediatric cochlear implant candidates: radiological evaluation

2016 ◽  
Vol 131 (1) ◽  
pp. 26-31 ◽  
Author(s):  
F B Palabiyik ◽  
K Hacikurt ◽  
Z Yazici
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Facial Nerve ◽  
Cochlear Implant ◽  
Inner Ear ◽  
Resonance Imaging ◽  
High Resolution Computed Tomography ◽  
Ear Anomalies

AbstractBackground:Pre-operative radiological identification of facial nerve anomalies can help prevent intra-operative facial nerve injury during cochlear implantation. This study aimed to evaluate the incidence and configuration of facial nerve anomalies and their concurrence with inner-ear anomalies in cochlear implant candidates.Methods:Inner-ear and concomitant facial nerve anomalies were evaluated by magnetic resonance imaging and temporal high-resolution computed tomography in 48 children with congenital sensorineural hearing loss who were cochlear implant candidates.Results:Inner-ear anomalies were present in 11 out of 48 patients (23 per cent) and concomitant facial nerve anomalies were present on 7 sides in 4 patients (7 per cent of the total). Facial nerve anomalies were accompanied by cochlear or vestibular malformation.Conclusion:Potential facial nerve abnormalities should always be considered in patients with inner-ear anomalies. Pre-operative facial nerve imaging can increase the surgeon's confidence to plan and perform cochlear implantation. Magnetic resonance imaging should be used to detect inner-ear anomalies; if these are identified, temporal high-resolution computed tomography should be used to evaluate the facial nerve.

Innervation of the cow’s inner ear derived from micro-computed tomography

2017 ◽  
Author(s):  
Anna Khimchenko ◽  
Loic Costeur ◽  
Bastien Mennecart ◽  
Bert Müller ◽  
Georg Schulz
Keyword(s):  
Computed Tomography ◽  
Inner Ear ◽  
Micro Computed Tomography

scholarly journals Experimental Fusion of Contrast Enhanced High-Field Magnetic Resonance Imaging and High-Resolution Micro-Computed Tomography in Imaging the Mouse Inner Ear

2015 ◽  
Vol 9 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Allen Counter S ◽  
Peter Damberg ◽  
Sahar Nikkhou Aski ◽  
Kálmán Nagy ◽  
Cecilia Engmér Berglin ◽  
...  
Keyword(s):  
High Resolution ◽  
Inner Ear ◽  
High Field ◽  
Ex Vivo ◽  
Semicircular Canals ◽  
Vestibular Apparatus ◽  
Resonance Imaging ◽  
Micro Computed Tomography ◽  
Ultra High Field

Objective: Imaging cochlear, vestibular, and 8th cranial nerve abnormalities remains a challenge. In this study, the membranous and osseous labyrinths of the wild type mouse inner ear were examined using volumetric data from ultra high-field magnetic resonance imaging (MRI) with gadolinium contrast at 9.4 Tesla and high-resolution micro-computed tomography (µCT) to visualize the scalae and vestibular apparatus, and to establish imaging protocols and parameters for comparative analysis of the normal and mutant mouse inner ear. Methods: For in vivo MRI acquisition, animals were placed in a Milleped coil situated in the isocenter of a horizontal 9.4 T Varian magnet. For µCT examination, cone beam scans were performed ex vivo following MRI using the µCT component of a nanoScan PET/CT in vivo scanner. Results: The fusion of Gd enhanced high field MRI and high-resolution µCT scans revealed the dynamic membranous labyrinth of the perilymphatic fluid filled scala tympani and scala vestibule of the cochlea, and semicircular canals of the vestibular apparatus, within the µCT visualized contours of the contiguous osseous labyrinth. The ex vivo µCT segmentation revealed the surface contours and structural morphology of each cochlea turn and the semicircular canals in 3 planes. Conclusions: The fusion of ultra high-field MRI and high-resolution µCT imaging techniques were complementary, and provided high-resolution dynamic and static visualization of the complex morphological features of the normal mouse inner ear structures, which may offer a valuable approach for the investigation of cochlear and vestibular abnormalities that are associated with birth defects related to genetic inner ear disorders in humans.

scholarly journals High resolution computed tomography of so-called Mondini type inner ear anomalies.

1986 ◽  
Vol 79 (9) ◽  
pp. 1395-1403
Author(s):  
Toshio SUZUKI ◽  
Katsubumi HOKI ◽  
Noboru YAMANAKA ◽  
Akikatsu KATAURA
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Inner Ear ◽  
High Resolution Computed Tomography ◽  
Ear Anomalies

scholarly journals High morphological variation of vestibular system accompanies slow and infrequent locomotion in three-toed sloths

2012 ◽  
Vol 279 (1744) ◽  
pp. 3932-3939 ◽  
Author(s):  
Guillaume Billet ◽  
Lionel Hautier ◽  
Robert J. Asher ◽  
Cathrin Schwarz ◽  
Nick Crumpton ◽  
...  
Keyword(s):  
Inner Ear ◽  
Morphological Variation ◽  
Relative Size ◽  
Semicircular Canals ◽  
High Resolution Computed Tomography ◽  
Bony Labyrinth ◽  
Wide Range ◽  
Pattern Of Variation ◽  
High Level ◽  
Intraspecific Morphological Variation

The semicircular canals (SCs), part of the vestibular apparatus of the inner ear, are directly involved in the detection of angular motion of the head for maintaining balance, and exhibit adaptive patterns for locomotor behaviour. Consequently, they are generally believed to show low levels of intraspecific morphological variation, but few studies have investigated this assumption. On the basis of high-resolution computed tomography, we present here, to our knowledge, the first comprehensive study of the pattern of variation of the inner ear with a focus on Xenarthra. Our study demonstrates that extant three-toed sloths show a high level of morphological variation of the bony labyrinth of the inner ear. Especially, the variation in shape, relative size and angles of their SCs greatly differ from those of other, faster-moving taxa within Xenarthra and Placentalia in general. The unique pattern of variation in three-toed sloths suggests that a release of selection and/or constraints on their organ of balance is associated with the observed wide range of phenotypes. This release is coincident with their slow and infrequent locomotion and may be related, among other possible factors, to a reduced functional demand for a precise sensitivity to movement.

Adjunctive Steps for Disinfection of the Mandibular Molar Root Canal System: A Correlative Bacteriologic, Micro–Computed Tomography, and Cryopulverization Approach

2016 ◽  
Vol 42 (11) ◽  
pp. 1667-1672 ◽  
Author(s):  
Flávio R.F. Alves ◽  
Carlos V. Andrade-Junior ◽  
Marília F. Marceliano-Alves ◽  
Alejandro R. Pérez ◽  
Isabela N. Rôças ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Root Canal ◽  
Micro Computed Tomography ◽  
Canal System ◽  
System A ◽  
Mandibular Molar ◽  
Root Canal System
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