Petrous Part Research Articles

Long-term facial nerve outcome in surgically treated petrous bone cholesteatoma patients.

The term petrous bone cholesteatoma (PBC) represents a slow-growing epidermal lesion arising from the petrous part of the temporal bone. It is a rare incidence accounting for only 4-9% of all petrous bone lesions. PBC represents a real surgical challenge due to its complex relationship with critical neurovascular structures. To demonstrate our experience in using various options of facial nerve (FN) management during surgical treatment of PBC and analyze the long-term facial function outcomes. Retrospective medical record review in a quaternary skull-base center. Medical records of 298 PBC cases operated between the years 1983 and 2024 were thoroughly evaluated. Sanna's classification scheme was used to classify cases into the appropriate class and the House-Brackmann (HB) grading system of the FN was used to assess the facial function pre- and postoperatively. A total of 298 PBC cases were surgically treated at our center. Males constitute 68% (n = 203) of total operated PBC patients while the rest 32% (95) were females, making the male-to-female ratio 2.2:1. The age in this series ranged from 9 to 85. According to updated Sanna's PBC classification, 44% were supralabyrinthine, 33% were massive, 9% were infralabyrinthine-apical, 8% were infralabyrinthine, and 5% were apical. On preoperative FN function examination, 45% (n = 133) of patients had various degrees of paresis and complete paralysis whereas 55% (n = 165) had normal FN function. The commonest degree of paresis observed was HB-III (18.5%) followed by HB-IV (5.7%). A total of 40(13.4%) patients, however, had complete facial paralysis at the initial presentation. The facial function was compromised more frequently in supralabyrinthine and massive PBCs. Among the total patients who had an abnormal facial function at presentation, 52% had paresis/paralysis for less than a year whereas 48% had FN paresis/paralysis for greater than one year. The most commonly used surgical approaches at our center were transotic (TO), modified transcochlear type A (MTCA) with rerouting of the FN, and translabyrinthine (TLAB) with external auditory canal (EAC) closure. Intraoperatively an intact fallopian canal was found only in 33% (n = 99) cases whereas the rest 67% (n = 199) had erosion of the fallopian canal either with intact (n = 24) or infiltrated FN (n = 175). The FN was maintained in the bony fallopian canal in 35% (n = 104) cases. An active form of FN management, however, was required in 65% (n = 194) of cases either intraoperatively or as a second-stage procedure. Factors affecting postoperative FN function include age, preoperative FN function (HB), duration of paralysis, class of PBC, surgical approach, and method of active FN management. PBCs represent diagnostically and surgically challenging lesions of temporal bone which are usually frustrating to the treating surgeon. Preoperative anatomic classification of the lesion enables the physician to choose the appropriate surgical approach. Sanna's classification is the most widely accepted system used to classify PBC. This classification is based on the relation of the lesion to the labyrinthine block. Active FN management, including rerouting, end-to-end anastomosis, cable nerve grafting, and masseteric-to-FN anastomosis routinely come into play in the surgical management of PBCs, and the postoperative FN results after such interventions can be satisfactory in most cases.

Comparison of commercial targeted amplicon sequencing assays for human remains identification casework.

Targeted amplicon sequencing (TAS) facilitates the genotyping of forensically informative single nucleotide polymorphisms (SNPs) using massively parallel sequencing (MPS). For human remains identification, where any extracted DNA is likely to be degraded, TAS may succeed when short tandem repeat (STR) profiling using capillary electrophoresis fails. Further, as well as yielding identity information, SNPs can provide information about ancestry, phenotype, kinship and paternal lineage (Y chromosome haplotypes). Two TAS platforms were compared in this study: Ion AmpliSeq™ panels coupled with Ion Torrent sequencing on an Ion GeneStudio™ S5 Plus System, manufactured by Thermo Fisher Scientific, and the ForenSeq® Kintelligence Kit coupled with Illumina sequencing on the MiSeq FGx® Sequencing System, manufactured by QIAGEN. Four Ion AmpliSeq™ panels (Precision ID Identity, Precision ID Ancestry, DNA Phenotyping and HID Y-SNP) share 177 SNPs with the ForenSeq® Kintelligence Kit and all five were used to profile the DNA extracted from the petrous part of the temporal bone from six skeletonised cadavers. Of the 6 × 177 = 1,062 SNP genotype comparisons, 1,055 (99%) were concordant between the Ion AmpliSeq™ panels and Kintelligence Kit. Of the seven (< 1%) non-concordant SNPs, only three of them (0.3%) would have resulted in erroneous genotypes being reported as a result of allele dropout by either assay, using our optimised relative variant frequency windows for allele calling. We conclude that both the Ion AmpliSeq™ panels and the ForenSeq® Kintelligence Kit were suitable for TAS applied to the human remains in this study.

An evaluation of morphometry and dehiscence of facial canal: a systematic review and meta-analysis of observational studies.

The facial canal (FC) is an extensive bony canal that houses the facial nerve and occupies a central position in the petrous part of temporal bone. It is of utmost significance to otologists due to its dehiscence and relationship to the inner or middle ear components. The main objectives of current investigation are to detect variations in the reported values ​​of FC anatomy that may occur due to different methodology and to elucidate the influence of age and ethnic factors on the morphological features of FC. The methodology is adapted to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled weighted estimation was performed to calculate the mean length, angle, and prevalence of dehiscence. The cross-sectional shape of FC varied from circular to ellipsoid index and is 1.45 [95% CI, 0.86-2.6]. The mean length of the FC is 34.42mm [95% CI, 27.62-40.13mm] and the mean width or diameter is 1.35mm [95% CI, 1.013-1.63mm]. The length of the FC in fetuses and children is 21.79mm [95% CI, 18.44-25.15mm], and 26.92mm [95% CI, 23.3-28.3mm], respectively. In meta-regression, age is observed as a predictor and accounts for 36% of the heterogeneity. The prevalence of FC dehiscence in healthy temporal bones is 29% [95% CI, 20-40%]. The different segments of the FC exhibit significant variability and an unusually high incidence of dehiscence, which could potentially have clinical implications for the etiopathogenesis of facial nerve dysfunction.

Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) combined with conventional MRI for the detection of skull-base invasion in nasopharyngeal carcinoma: comparison with 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT).

The extent of skull base invasion (SBI) in nasopharyngeal carcinoma (NPC) directly impacts tumor staging, treatment strategies, and prognosis assessment for NPC patients, emphasizing the critical need for prompt diagnosis and precise assessment of invasion. Thus, we aimed to integrate the advantages of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and conventional magnetic resonance imaging (cMRI), and assess their combined diagnostic efficacy versus that of 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) for detecting SBI in NPC patients. The study prospectively and randomly recruited 62 patients newly diagnosed with NPC by pathological biopsy at the Cancer Center of Affiliated Hospital of Guangdong Medical University from January 2021 to September 2022. All patients underwent baseline cMRI, IVIM-DWI, and PET/CT scans. The IVIM-DWI analysis included 3 primary parameters: true diffusion coefficient (D), pseudodiffusion coefficient (D*), and pseudodiffusion fraction (f). SBI was defined as the involvement of any substructure confirmed by follow-up MRI and clinical symptoms. Inter-observer agreement was evaluated utilizing the intraclass correlation coefficients (ICC) and kappa coefficients. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of cMRI, IVIM-DWI plus cMRI, and PET/CT. DeLong test was used to compare the areas under the curve (AUC) of the 3 modalities. Excellent inter-observer reliability was observed (range, 0.841-0.946). Among the IVIM-DWI parameters, D* + f demonstrated comparable accuracy to D + D* + f (AUC 0.906 vs. 0.904; sensitivity 88.9% vs. 89.8%; specificity 92.3% vs. 91.0%). IVIM-DWI plus cMRI yielded an overall AUC of 0.947, sensitivity of 92.6%, and specificity of 96.8%, surpassing cMRI alone with an AUC of 0.914 (P=0.025), sensitivity of 91.2%, and specificity of 91.7%, as well as 18F-NaF PET/CT with an AUC of 0.852 (P<0.001), sensitivity of 80.1%, and specificity of 90.4%. In detecting substructures of SBI, IVIM-DWI plus cMRI showed superior performance compared to 18F-NaF PET/CT within the petrous part of the temporal bone (AUC 0.968 vs. 0.871, P=0.011; sensitivity 93.5% vs. 87.1%, specificity 100% vs. 87.1%), pterygopalatine fossa (AUC 0.935 vs. 0.831, P=0.032; sensitivity 93.9% vs. 69.7%, specificity 93.1% vs. 96.6%), and foramen ovale (AUC 0.885 vs. 0.710, P=0.019; sensitivity 76.9% vs. 61.5%, specificity 100% vs. 80.6%). IVIM-DWI plus cMRI can accurately detect SBI and the substructures in NPC, providing a valuable reference for personalized treatment strategies and precise prognosis assessment.

Exposure of the facial nerve within the facial canal: A technical report

BackgroundThe facial canal lies in the petrous part of the temporal bone and contains the facial nerve. The facial canal and nerve are divided into three segments: the labyrinthine, tympanic and mastoid segments, which travel in different planes. These segments are closely related to the structures of the middle- and inner-ear, so pathology of the intracranial facial nerve is often evident in cochlear implant users. The facial canal and nerve are of great concern to otologists during electrode placement for a cochlear implant, as any damage to the nerve may result in untreatable facial paralysis. Few studies have been conducted on a cadaveric population, with most carried out on CT images of the cochlea and facial nerve. Thus, there is no standard or straightforward methodology to visualise the facial canal and nerve directly. We propose a detailed dissection technique to bridge this gap in research. MethodFour cadavers were used, and both the left and right facial canals were dissected. After the exposure of the cranial floor, the internal acoustic meatus and the facial canal were dissected out using drilling tools to remove the surrounding temporal bone and expose the facial nerve within the facial canal. ResultsThis technique allowed for morphometric analyses and observations of the facial canal in relation to the middle- and inner-ear. ConclusionKnowledge of the facial canal may assist otosurgeons in safely dissecting the region without injuring vital structures within this area.

Anatomical and Radiological Analysis of Structures of Petrous Part of the Temporal Bone and Their Impact on Area of Anterior Petrosectomy

Anterior petrosectomy is a commonly recognized approach for accessing tumors located in the petrous apex region. The essence of anterior petrosectomy lies in drilling the petrous part of the temporal bone within the Kawase quadrangle. In our study, we conducted radiological and anatomical analyses of the structures within the petrous portion of the temporal bone, evaluating their impact on the surgical field during anterior petrosectomy. We conducted an analysis of 15 anatomical specimens and 20 3D reconstructions based on computed tomography scans of the middle ear. The analyzed structures included the impression of the trigeminal nerve, the groove of the greater petrosal nerve, the arcuate eminence, and the angle between eminentia arcuata and grove for greater petrosal nerve. The mean surface area measured by radiological methods does not deviate significantly from the mean surface area measured by anatomical methods 276.265mm2 (IQR: 217.603-309.188) vs 233.21mm2 (IQR: 210.923-255.453) p=0.051. We established a threshold 195,99mm2 for radiological determination of the surface area at which another approach should be considered. Additionally, we have developed corrections for specific radiological factors to enable a better assessment of anatomical conditions. Our results indicate that preoperative assessment of anatomical conditions based on 3D reconstructions of computed tomography of the middle ear can be a valuable tool in preoperative planning of surgery on tumors in the petroclival region using the anterior petrosectomy. Further studies involving a larger sample size are necessary to validate the findings of our study.

Fungal carotiditis with aneurysm - a rare complication of mucormycosis: presentation and management

During the COVID-19 pandemic, cases of mucormycosis (ROCM) had increased drastically, especially in the second wave. Most of these cases involved the paranasal sinuses, orbit and occasionally brain. This case report presents a rare case of mucormycosis complicated with a mycotic aneurysm of the petrous part of the internal carotid artery (ICA). A 43-year-old man presented with left-sided facial weakness for which high resolution computed tomography scan of the Temporal bones was done. A scrutiny of the computed tomography temporal bone showed evidence of osteomyelitis extending to the petrous apex around the foramen Lacerum. Computed tomography and magnetic resonance imaging of the paranasal sinus done later confirmed the diagnosis of mucormycosis. The patient underwent endoscopic surgical debridement of the nose and sinuses, with post-operative amphotericin B. After 3 weeks, the patient presented with bouts of profuse nasal bleed. Computed tomography angiogram showed an aneurysm in the petrous segment of the ICA suggestive of mycotic carotiditis complicated from mucormycosis spread along the skull base. It was successfully managed neurosurgically by a bypass shunting procedure. Mucormycosis is a disease that typically has an aggressive and startling fatality rate. ICA aneurysm is an uncommon occurrence in mucormycosis. Subjects with ROCM should be examined for brain and vascular involvement. Computed tomography angiogram should be performed as soon as possible if the skull base is involved in the ICA area. Morbidity and mortality can often be reduced by early diagnosis and interventions by a multidisciplinary team.

Anatomical variations of Koerner's septum: a computed tomography-based, single-centered study.

Koerner's septum (KS) is a bony plate located at the junction of the petrous and squamous parts of the temporal bone. The reported prevalence of KS varied between studies. KS variations are associated with various pathologies and pose difficulties during surgeries. The study aims to determine the KS frequency in Omani patients and analyze its association with sex and side. The present study investigated the KS topography in 344 computed tomography (CT) scans of normal temporal bones of adult Omani patients at Sultan Qaboos University Hospital. The presence of KS and its parts (complete or incomplete), as well as its thickness at three anatomical landmarks were recorded. Additionally, sex and laterality differences in KS parameters were analyzed using a Chi-square test. The overall frequency of KS among Omani subjects was 39.5%. The complete KS was observed only in 14% of cases. The thickness of KS was 0.78 ± 0.21 mm, 0.93 ± 0.28 mm and 0.78 ± 0.21 mm at the head of the malleus (HM), the superior semicircular canal (SSC) and the tympanic sinus (TS), respectively (p<0.01). KS was present most constantly at the level of HM (64.7%), followed by SSC (57.4%), and less constantly at the level of TS (49.3%). KS frequency was similar in both males than females (41.9% vs 37.3%), with statistically insignificant difference (p = 0.38). No side differences were observed concerning KS frequency (p = 0.955). The KS frequency in Omani subjects within the range of previously reported studies. It is incomplete in most of the cases and constantly present at the level of HM. Its thickness is more at the level of SSC.

Aneurysm of Petrous and Cavernous Parts of the Internal Carotid Artery: A Case Report.

İnternal carotid artery (ICA)aneurysmsare rare but they can cause high morbidity and mortality. Although these aneurysms are usually asymptomatic, they can reach huge sizes and compress the surrounding neurovascular structures. Patients typically present with neurologic symptoms due to cranial nerve compression. If they rupture, they can lead to massive epistaxis and autorage. In physical examination, pulsatile mass in the middle ear or nasal cavity can be seen. If there is a clinical suspicion of an ICA aneurysms, diagnostic radiological imaging should be performed before the surgical procedure or biopsy. Cerebral digital subtraction angiography (DSA) should be performed for definitive diagnosis. After diagnosis, appropriate endovascular or open intervention should be performed. In this case report, we present a 48-year-old female patient with severe epistaxis complaint due to an ICA aneurysm. This report aims to present this case and review the current literature.

Validation process of automatic DNA extraction from bone material using a new advanced protocol for the EZ2 Connect instrument

Identification of human remains using genetic methods is an important task of forensic science. DNA markers are proving essential in the identification of unknown human remains. However, environmental factors can lead to poor preservation of DNA, including in bone material. The aim of this study was therefore to compare two methods of DNA isolation from bone material: the traditional organic method and the new protocol using the EZ2 Connect instrument. The study involved three types of bone material, namely molars/premolars, petrous parts of the temporal bone and femurs, all with an estimated PMI of 70–80 years. Importantly, the biological material was obtained from three different environments, categorized as preserving, neutral and degrading, based on basic physico-chemical tests and the potential impact on the bone.The results obtained show that the DNA was best preserved in the petrous bone, followed by the teeth, and the femur. DNA extraction using the EZ2 Connect instrument with a new protocol gave slightly better results for the petrous bone, comparable results for the teeth and worse results for the femur compared to the organic method. Several protocol modifications were tested and optimal conditions for DNA isolation were proposed for the EZ2 protocol. Furthermore, the use of an automated method facilitated the effective accumulation of isolates and increased the chances of successful identification of unknown human remains.

A rare clinical case of a labyrinthine lesion: an endolymphatic sac tumor

Endolymphatic sac tumors are rare neoplasms originating from the endolymphatic epithelium of the intraosseous part of the endolymphatic duct and sac, typically characterized by slow growth and local destructive changes. We present a case of an endolymphatic sac tumor in a 28-year-old man who consulted an otoneurologist with complaints of progressive hearing loss and dizziness attacks and was referred for a CT scan of the temporal bones and MRI of the inner ear with delayed contrast enhancement. The data of otoneurological and radiological examinations before and after surgical treatment and the results of surgical treatment with histological verification of the tumor are presented. The objective of this case presentation is to demonstrate the usefulness of CT and MRI methods in detecting an endolymphatic sac tumor, to compare the results of otoneurological and radiological examinations and intraoperative and histological data followed by surgery. Radiological examination revealed a neoplasm of the right temporal bone with typical imaging characteristics of endolymphatic sac tumor. Surgery was performed, the mass was removed completely, and the endolymphatic sac tumor was histologically verified. Radiologic presentation includes a typically located area of bone destruction in the petrous part of the temporal bone in the area of the vestibular aqueduct, possibly with the spread of the tumor into the cerebellopontine angle, with a heterogeneous structure, with uneven contrast enhancement. Due to the rarity of this pathology, diagnosis in the early stages is often difficult, and for the correct interpretation of radiologic findings in patients with hearing loss and dizziness, knowledge of the normal anatomy of the temporal bone and awareness of rare variants of its lesions are of key importance. Timely examination of patients with suspected temporal bone lesions and correct diagnosis are the key to successful treatment and maintaining the quality of life in this group of patients.

Evaluation of subarcuate canal on CT images in the perspective of clinical basis.

The aim of our study to contribute to the field of morphometrics by including measurements of the SAC and SAF and their distances from surrounding structures, particularly for surgeons involved in retrosigmoid approach for internal acoustic meatus tumor surgery and cerebellopontine angle surgery. Although there is limited information in the literature regarding the role of the subarcuate fossa (SAF) and subarcuate canal (SAC), it has been suggested that the SAC may be a potential pathway for infection from the middle ear to the posterior cranial fossa, and cerebellar abscesses may have this origin. For the images of our study, computerized tomography images of 118 individuals (59 females and 59 males) between the ages of 18-65 who applied to Bayındır Health Group. The width of the cranial opening of the subarcuate canal was determined as 44 ± 0.54mm, width of the labyrinth opening of the subarcuate canal was determined as 60 ± 0.42mm, Length of the subarcuate canal was determined as 8.79 ± 2.31mm, width of the subarcuate canal was determined as 5.54 ± 1.75mm, and depth of subarcuate fossa was determined as 1.67 ± 0.69mm. The distance of the cranial opening of the subarcuate canal to the superior semicircular canal (SSC-SAC/C) was measured as 5.33 ± 1.81mm, The distance of the labyrinth opening of the subarcuate canal to the superior semicircular canal (SSC-SAC/L) was measured as 3.90 ± .98mm, length of the petrous part of the temporal bone medial to the anterior semicircular canal measured from the apex to the SSCD (PLM) was measured as 33.56 ± 0.42mm. No statistically significant differences were found between the right and left sides. The morphometric measurements obtained in this study can provide useful information for neurosurgeons, neurotologist and otolaryngologists involved in retrosigmoid approach for internal acoustic meatus tumor surgery and cerebellopontine angle surgery, and for patients undergoing cochlear implant planning with a retrofacial approach.

Morphometric Dimensions of Male Auditory Ossicles among Nigerian Population

Introduction The auditory ossicles transfer sound vibrations in the tympanic membrane from the middle ear to the inner ear. These ossicles are located in the petrous part of the temporal bone and they form a chain across the tympanic cavity from the tympanic membrane to the oval window. Aim The present study was aimed at providing the morphometric dimensions of the male auditory ossicles among the Nigerian population. Materials and Methods The study was carried out on 94 malleus (R=44, L=50), 70 incus (R=34, L=36), and 27 stapes (R=10, L=17) auditory ossicles collected from 57 unidentified adult male cadavers from the departments of anatomy of various universities in Nigeria. The various parameters were taken with the help of a digital vernier caliper and weighed with Mettler Toledo weighing balance. Results This study revealed no statistically significance difference (p&gt;0.05) between morphometric measurements of the bones of the right and left side except in the malleus. The mean weights (mg) of the malleus, incus and stapes were 22.04, 27.02, and 3.34, respectively. The mean lengths (mm) of the malleus and incus were 8.02 and 6.73, respectively and the mean length of footplates in stapes was 1.94 mm. The mean width of the incus was 4.12 mm and the mean width of the footplate in stapes was 2.88 mm. Conclusion The three auditory ossicles are morphometrically identical in both ears except the malleus. The precise measurements of the ossicles have been reported in this study among the adult male Nigerian population which would be very helpful in forensic study. Variations were observed in the dimensions of the ossicles when compared with previous studies which may be due to racial or regional factors as the values from published authors are from Asian and Caucasian populations.

The Presence of the Human Auditory Ossicles—Detected Postmortem by CT Scan—As a Taphonomic Indicator

Introduction: Three tiny bones compose the human ossicular chain: malleus, incus and stapes. Also known as auditory ossicles, they are united by joints in the middle ear cavity of the petrous part of the temporal bone. Completely developed two years after birth, the ossicular chain is involved in the physiological process of hearing, by which sound waves from the environment are converted into electrochemical impulses. In the last 500 years, most studies have focused on the morphogenesis, morphological variability and clinical pathology of the ossicular chain, whilst only a few studies have added relevant knowledge to anthropology and forensic science. The auditory ossicles and the enclosing petrous bone are some of the hardest in the human skeleton. This is reflected in a relative resistance to fire and in the possibility of preservation and fossilization in millions of years. Materials and Methods: The literature and four present-day forensic cases were included in studying the postmortem loss of the auditory ossicles in skeletal or decomposing remains. Results indicate that it can be ascribed to their destruction or physical displacement, by either macro-micro-faunal action and/or any other natural or artificial disturbance. Discussion: Physical displacement is closely connected to the depositional environment of the skeletal remains, such as burial, entombment (sarcophagus, coffin, vault…), submersion or exposure to natural elements. Auditory ossicles can be recovered in situ, or very close to their anatomical location, when the skeletal material has been involved in an archaeological excavation. In the case of accessible or disturbed remains, scavengers may remove the tiny ossicles and/or they can slip out of the middle ear cavity following skull movements. Entombment offers effective protection against the displacement of the auditory ossicles, whereas aquatic submersion and aquatic movement almost invariably displace them. Conclusion: the preservation of the human auditory ossicles should be critically considered in the comprehensive context of any forensic investigation on human remains since it can assist the reconstruction of their taphonomic history. Taphonomic histories of remains can add crucial information to forensic investigations (e.g., the Post Mortem Interval, PMI). The aim of this study, limited by scarce relevant literature, is to discuss the potential role of the ossicular chain, detected by postmortem imaging techniques, as a taphonomical indicator in decomposing and/or skeletonized bodies.

The venous plexus of Rektorzik - anatomo-clinical issues retrieved from the literature data.

The venous plexus of Rektorzik is a network of small veins, which enlace outside the wall of the internal carotid artery while it traverses the petrous part of the temporal bone. The anatomical and clinical issues related to the communication between the plexus of Rektorzik and other cranial venous structures were discussed in this paper.

A Case of Giant Petrous Apex Cholesteatoma With Pseudomonas Aeruginosa Infection.

Petrous apex cholesteatoma is a relatively rare and chronic aggressive disease that occurs in the petrous part of the temporal bone and can be classified as congenital or acquired. Due to the tendency of petrous cholesteatomas to cause bone destruction and invade important structures such as the facial nerve, cochlea, and semicircular canal, patients present mainly with severe hearing loss, progressive peripheral facial palsy, vertigo, etc. When the lesion invades the intracranial region or is infected, intracranial symptoms such as meningitis, lateral sinus thrombosis, and brain abscess may be present. We report a case of giant petrous cholesteatoma with Pseudomonas aeruginosa infection, with the aim of exploring the corresponding clinical treatment and surgical modalities to provide a reference for the clinical management of this type of disease.

Extracting the Cochlea from a Human Temporal Bone: A Cadaveric Protocol.

The extraction of the cochlea from a cadaver human temporal bone may be required for different studies of the inner ear. For histological evaluations, the inner ear must be extracted from the temporal bone to facilitate histologic processing; likewise, some micro-computed tomography devices are too small to accommodate the complete temporal bones; additionally, the image quality can be enhanced when the cochlea is isolated. The inner ear is located within the petrous part of the temporal bone. The inner ear can be divided into the osseous labyrinth or otic capsule and the membranous labyrinth inside the otic capsule. Furthermore, the inner ear can be divided into the vestibular system (the semicircular canals and the vestibule) and the cochlea. The appreciation of the location and orientation of the cochlea within the temporal bone is difficult, as it is embedded within bony structures and thus cannot be directly visualized. Nevertheless, there are distinct anatomical structures that can help guide the process to allow a reliable drill-out of the cochlea. The landmarks in the posterior parts of the cochlea are the facial nerve, semicircular canals, and the vestibule. In the middle, the inferior borders of the cochlea are identified by the round window and the basal turn of the cochlea. In the anterior border, one encounters the carotid artery; the landmark for the superior border is the genicular ganglion (GG) of the facial nerve. The medial structures are determined by the locations of the internal auditory canal, the superior semicircular canal, and the canal of the internal carotid artery. In this article, we present a method for extracting the cochlea reliably out of the temporal bone by drill-out while following several anatomical landmarks.

Morpho-metric study of the facial nerve in the Andaman and Nicobar islands population: A Cadaveric study

Background: Facial nerve (FN) is the seventh cranial nerve. It is the only cranial nerve which has a long course in a bony canal. From the brain stem, to its terminal branches, it changes its direction 5 times, to innervate, muscles of the second pharyngeal arch. Hence, it is morphometric study and has great clinical importance. Aims and Objectives: This study was conducted to ascertain the variations of the length of facial Never at different parts of the crania so that this study could be helpful for neurosurgeon, radiologist, and clinician, to deal with various diseases of FN. Materials and Methods: Thirty-five (35) male cadaveric temporal bones, were taken out, by removing soft parts attached to it. The FN was exposed. The length of the FN was measured, by digital vernier calliper, in different regions, of the temporal bone. Results: 7.90 (SD±1.24) in petrous part, 3.7 (SD±0.40) in labyrinthine part, 12.13 (SD±0.36) in tympanic, 12.24 (SD±1.86) mastoid part, 15.76 (SD±0.54) length of nerve to stapedius, and 19.06 (SD±0.66) length of branches of chorda-tympani. Conclusion: The present cadaveric study has clinical importance, for the ENT surgeon, neurosurgeon, neurophysician, and the radiologist.

Anatomy and Histology of the Petrous Carotid Membrane: Application to Skull Base Surgery

Published reports regarding the tissue types that surround the internal carotid artery (ICA) as it travels through the carotid canal vary. Reports have variably defined this membrane as periosteum, loose areolar tissue, or dura mater. With such discrepancies and realizing that knowledge of this tissue might be important for skull base surgeons who expose or mobilize the ICA at this location, the present anatomical/histological study was performed. In 8 adult cadavers (16 sides), the contents of the carotid canal were evaluated; specifically, the membrane surrounding the petrous part of the ICA was studied, and its relationship to the deeper lying artery was observed. These specimens were stored in formalin and submitted for histological evaluation. Grossly, the membrane within the carotid canal traversed the entire carotid canal and was loosely adherent to the underlying petrous part of the ICA. Histologically, all membranes surrounding the petrous part of the ICA were consistent with dura mater. The dura mater of the carotid canal had an outer endosteal layer and an inner meningeal layer as well as a clear dural border cell layer in most specimens that approximated and was loosely applied to the adventitial layer of the petrous part of the ICA. The membrane that surrounds the petrous part of the ICA is dura mater. To our knowledge, this is the first histological investigation of this structure and thus serves to establish the true identity of this membrane and correct previous reports in the literature that have erroneously concluded that it is periosteum or loose areolar tissue.

Bilateral Superior Semi-Circular Canal Dehiscence Presenting as Conductive Hearing Loss with Vestibular Symptoms: A Client Centre Case Report

Background: Superior semicircular canal dehiscence (SSCD) is a rare bone defect in the petrous part of the temporal bone. In this syndrome, a third window is created between the middle cranial fossa and the bony labyrinth of the inner ear which can lead to stimulation of the vestibular system by sound. Patients usually have symptoms such as vertigo, imbalance, autophony, pulsatile tinnitus, and aural fullness. The clinical symptoms of this disease vary from person to person. The Case: This study reports a case of a rare bilateral SSCD in a 39-year-old woman with imbalance and autophony problems. The audiological findings showed a bilateral mild conductive hearing loss at low frequencies with symptoms of vertigo and torsional nystagmus. The SSCD was diagnosed by computed tomography. Then, the patient underwent bone repair surgery. Auditory and balance tests were performed again after the surgery to evaluate the extent of recovery. Conclusion: The SSCD can be diagnosed by using the mentioned test battery. By choosing the appropriate treatment methods and following up of the outcomes, most of the problems of patients with SSCD can be solved. Keywords: Superior semicircular canal dehiscence; bilateral; conductive hearing loss