Transpetrosal approach: an anatomical study of temporal bone (original) (raw)
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Okajimas Folia Anatomica Japonica, 1998
Transtemporal approaches exposing the petroclival region require extensive drilling of the petrous bone. This is only possible with an understanding of the three dimensional anatomy of the temporal bone and the cranial base. The purpose of this study is to review the topographic anatomy of the petrous bone and peripetrous region, with emphasis on the relationships critical to the lateral approaches for posterior and lateral skull base. To understand the surgical anatomy and the cranial base approaches to this area, 8 cadaveric heads and 76 dry skulls were studied. Cadaveric dissections were performed, and morphometric data from measurements of the relationships of the surface landmarks in the petroclival region were provided. The results and the observations could be useful to understand the anatomy better, and to estimate the degree and direction of a safe bony removal for the most radical transpetrosal surgery.
Indian Journal of Otolaryngology and Head & Neck Surgery, 2010
Suboccipital retrosigmoid craniotomy with removal of posterior wall of internal auditory canal is preferred by many surgeons operating on acoustic neuromas, as it is a simple and safe approach. To study the topographic landmarks of the posterior surface of the temporal bone. We studied the surgical anatomy of 224 dry adult human temporal bones, measured the various distances on posterior wall of petrous bone relevant for suboccipital surgical approach to internal auditory canal. The internal auditory canal (IAC) lies within 32-44 mm from posterior wall of sigmoid sulcus and within 3-8 mm from the superior border of petrous bone. The point corresponding to highest point of jugular bulb was found between 4 and 9 mm away from the inferior border of IAC. The maximum distance found between bony orifice of vestibular aqueduct and IAC was 14 mm and the minimum distance was 6 mm.The vertical diameter of IAC ranged between 3 and 7 mm. These parameters may help the surgeons for better exposure of internal auditory canal and for avoiding damage to vital surrounding structures.
Correlations of External Landmarks With Internal Structures of the Temporal Bone
Otology & Neurotology, 2015
Hypothesis: The internal anatomy of a temporal bone could be inferred from external landmarks. Background: Mastoid surgery is an important skill that ENT surgeons need to acquire. Surgeons commonly use CT scans as a guide to understanding anatomical variations before surgery. Conversely, in cases where CT scans are not available, or in the temporal bone laboratory where residents are usually not provided with CT scans, it would be beneficial if the internal anatomy of a temporal bone could be inferred from external landmarks. Methods: We explored correlations between internal anatomical variations and metrics established to quantify the position of external landmarks that are commonly exposed in the operating room, or the temporal bone laboratory, before commencement of drilling. Mathematical models were developed to predict internal anatomy based on external structures. Results: From an operating room view, the distances between the following external landmarks were observed to have statistically significant correlations with the internal anatomy of a temporal bone: temporal line, external auditory canal, mastoid tip, occipitomastoid suture, and Henle's spine. These structures can be used to infer a low lying dura mater (p = 0.002), an anteriorly located sigmoid sinus (p = 0.006), and a more lateral course of the facial nerve (p G 0.001). In the temporal bone laboratory view, the mastoid tegmen and sigmoid sinus were also regarded as external landmarks. The distances between these two landmarks and the operating view external structures were able to further infer the laterality of the facial nerve (p G 0.001) and a sclerotic mastoid (p G 0.001). Two nonlinear models were developed that predicted the distances between the following internal structures with a high level of accuracy: the distance from the sigmoid sinus to the posterior external auditory canal (p G 0.001) and the diameter of the round window niche (p G 0.001). Conclusion: The prospect of encountering some of the more technically challenging anatomical variants encountered in temporal bone dissection can be inferred from the distance between external landmarks found on the temporal bone. These relationships could be used as a guideline to predict challenges during drilling and choosing appropriate temporal bones for dissection.
A Study of Middle Cranial Fossa Anatomy and Anatomic Variations
Ear, Nose & Throat Journal, 2007
We conducted a study to establish standardized measurements of the common anatomic landmarks used during surgery via the middle cranial fossa approach. Results were based on high-resolution computed tomography (CT) images of 98 temporal bones in 54 consecutively presenting patients. Measurements were obtained with the assistance of the standard PACS (picture archiving and communication system) software. We found that the superior semicircular canal (SSC) dome was not the highest point on the temporal bone (i.e., the arcuate eminence) in 78 of the temporal bone images (79.6%). Pneumatization above the SSC and above the internal auditory canal (IAC) was found in 27 (27.6%) and 39 (39.8%) temporal bone images, respectively. The anterior wall of the external auditory canal was always anterior to the anterior wall of the IAC. The mean angles between the SSC and the posterior and anterior walls of the IAC were 42.3° and 60.8°, respectively. We also measured other distances, and we compare...
Radiographic Anatomy of the Infracochlear Approach to the Petrous Apex for Computer-Assisted Surgery
Otology & Neurotology, 2010
Objective-1) To define the surgical anatomy and dimensions of the infracochlear approach to the petrous apex through use of high resolution computed tomography (HRCT) 2) use of digitized images of cadaveric temporal bones for computer simulation of infracochlear access using the OSC/OSU temporal bone simulator Background-The petrous apex is a surgically challenging area to access. Many routes have been described and used successfully in clinical practice. However, these routes have not been defined with the aim of application in computer-assisted surgery. The infracochlear approach, due to its access via a transcanal route, affords the opportunity for its potential application in minimally invasive computer-assisted surgery. Methods-High resolution CT (HRCT) scans were performed on 102 cadaveric skulls (total of 204 temporal bones). Standard measurements were taken using an open source Picture Archiving and Communication System (PACS) software of the maximum height, width, and depth of the infracochlear approach. In addition, the maximum diameter of a circular fenestration that could be created in the infracochlear space without breaching the basal turn of the cochlea, internal carotid artery, or the jugular bulb was used to simulate a drill path. In addition, five temporal bone specimens (3 left, 2 right) underwent HRCT with the digitized images being used to create simulated temporal bones for infracochlear surgical access; the transcanal infracochlear approach was then performed by the same surgeon on the cadaveric bone. Results-The mean height, width and depth of the infracochlear space in temporal bones with non-pneumatized petrous apices were 7.2 +/− 0.4mm, 9.4 +/− 0.8mm and 17.5 +/− 1.0mm respectively. Corresponding dimensions in pneumatized petrous apices were 7.6 +/− 0.4mm, 10.1+/− 1.1 and 18.6 +/−0.8mm. The mean diameter of the circular fenestra in the nonpneumatized petrous apices was 5.1 +/− 0.4mm compared to 5.7 +/− 0.6mm in pneumatized petrous pieces. This was statistically significant (Unpaired t-Test, p value = 0.04). The time to perform a simulated infracochlear approach to the petrous apex ranged from 3.1-12.6 minutes
2022
Introduction The endoscopic anatomy of the middle ear (ME) and of the external acoustic meatus (EAM) has been described in cadavers, in fresh temporal bones, or in vivo using conventional video recording, but not in dry bones or using an alternative inspection and recording technique. Objective To study the anatomy of the ME and of the EAM in dry temporal bones using a smartphone-endoscope system. Methods The EAM and the ME were studied in dry temporal bones using an endoscopic transcanal approach with a telescope connected to a smartphone (Mscope mobile endoscope app and adaptador, GBEF Telefonia, São Paulo, SP, Brazil). Results Out of 50 specimens, 2 had exostosis of the EAM and 3 contained remains of the tympanic membrane. The anterior wall of the EAM was prominent in 10/48 specimens (20.8%). Ossicles were seen in 13/45 (28.8%), stapes at the oval window were seen in 12/45 (26.6%), and the incus was seen in 1/45 (2.2%) specimens. The facial canal was open and protruding in 15/45 (33.3%) and in 7/45 (15.5%) specimens, respectively. Of the 45 MEs evaluated, type A was predominant for finiculus (93.3%), subiculum (100%), and ponticulus (95.6%). The rest were type B. None was classified as type C. According to its position in relation to the round window, the fustis was classified into type A (68.9%) or B (31.1%). The pyramidal eminence, the bony portion of the Eustachian tube, the semicanal of the tensor tympani muscle, and the cochleariform process were visualized completely or partially in all cases. Conclusion The use of a smartphone-based endoscopic transcanal procedure in dry temporal bones allowed the evaluation of anatomical variations in the EAM and in the ME.
Links Between Surgical Landmarks of the Temporal Bone and Cochlear Implant Approaches
Acta Medica Marisiensis, 2015
We aimed to underline the surgical importance of the distances between the landmarks of the temporal bone, important for quantifying the benefits and disadvantages of two different cochlear implant techniques. Methods: We have gathered all data from the Radiology Department in Emergency County Hospital in Tîrgu Mureș, namely computed tomography imagistic studies in order to perform the required measurements, according to pre-defined inclusion/exclusion criteria. The time interval was 5 months. Results: The comparison between the sets of data shows a good match for the risk/benefit ratio for the two types of technique for cochlear implantation. Conclusions: The middle cerebral fossa approach for the electrode insertion into the cochlea is a viable and needed surgical technique as the classic approach has reached its boundaries and new challenges appear. As surgical decisions are largely based on radiology data, our work underlines the importance of solving the borderline pathology, the extreme cases and the role of surgery in improving the quality of life for every patient with cochlear implant indication.
INTERNATIONAL JOURNAL OF ANATOMY RADIOLOGY AND SURGERY, 2021
Introduction: Knowledge regarding projections on cerebral aspect of petrous temporal bone especially in relation to dural venous sinuses or at the site of dural attachments is required for evaluating and differentiating normal from abnormal. Aim: This study was aimed to observe the incidence and localisation of various bony projections relating to sulcus for Dural venous sinus on the postero-superior surface of petrous temporal bone. Materials and Methods: The study was conducted on 260 skulls (out of which 20 were obtained from cadavers during dissection and 240 were dry skull) in the Department of Anatomy, ANIIMS from April 2016 to December 2019. The cerebral aspect of petrous temporal bone was observed for presence and localisation of projections. They were classified according to their size (small- <1 mm, medium- 1-3 mm, large->3 mm), location, laterality and its relation to sulcus for dural venous sinus. Images were taken and the data was tabulated with percentage inciden...