Petrous Bone Research Articles

Finds of skulls of juvenile <I>Kurdalagonus maicopicus</I> (Сetacea, Cetotheriidae) in the upper Miocene of the Republic of Adygea

Fragments of two skulls of young cetotherium baleen whales have been described from the Fortep’yanka 2 locality (Russia, Republic of Adygea, Maikop district, Fortep’yanka river valley, Upper Miocene, Upper Sarmatian, Blinovskaya Formation). Based on the morphology of the posterior (mastoid) process of the petrous bone, the structure of the posterior edge of the temporal fenestra, and the S-shaped shape of the superoccipital ridges, the finds were attributed to Kurdalagonus maicopicus (Spasskii, 1951). The proportions of the skull and the degree of closure of the sutures of the skull made it possible to determine the individual age of these whales within a year. New findings significantly complement the data on the structure of the sutures of the lateral wall of the skull and age-related variability of cranial morphology in representatives of the genus Kurdalagonus.

Patellae as a source of DNA in forensic and archaeological analysis.

Analysing genetic material from skeletonised human remains has become valuable in forensic and archaeological contexts. While the petrous bone is often preferred for DNA extraction, its availability is not guaranteed, and because of destructive sampling, it is not frequently used in forensic cases. This study explores the potential of patellae as an alternative source of bone material for genetic investigations. Forty-five patellae were sampled from a post-World War II mass grave and an archaeological Christian cemetery dated from the 13th to 19th centuries. A full demineralisation extraction method was used to obtain the DNA, and real-time PCR quantification was used to determine the quantity and quality of DNA. To evaluate the suitability of patellae for forensic and archaeological analyses, short tandem repeat (STR) typing was performed using the ESI17 Fast PCR amplification kit (Promega). To explore the difference in DNA yield, DNA degradation and STR typing success between the post-World War II and archaeological patellae, statistical analysis was performed. The results revealed significantly higher DNA yield and STR typing success in WWII patellae and higher degradation of DNA in archaeological patellae, highlighting the impact of environmental exposure time on genetic material preservation. Almost all WWII patellae achieved a high success rate in STR typing with full profiles generated. More than half of the archaeological patellae showed high STR typing performance and highly informative partial profiles were obtained, indicating the suitability of patellae not only for forensic purposes but also for archaeological genetic analyses.

Radioanatomy of the Petrous Bone

The high-resolution computed tomography (HRCT) scan used in the 1980s offers a distinct advantage in interpreting images of the temporal bone. To obtain a right image reconstruction and to provide meaningful information, a certain degree of tilt is required so that radiologists and clinicians can get more real imaging information on structural abnormalities in the temporal bone and its soft tissue constituents. The technique or protocol in HRCT of the temporal bone becomes an essential primary aspect in presenting the analyzed structure, the assessment of the small form of the auditory bones, the soft tissue of the inner ear and the cranial nerves that pass through the temporal bone structure is much easier to analyze, of course with the help of reconstruction according to the HRCT protocol for temporal bone, however, soft tissue evaluation is preferable to MRI. In the end, the standard structure, congenital abnormalities and pathological problems in the temporal bone structure can be identified and informed to the clinician as a step to determine further treatment action.

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.

Minor's Syndrome or Dehiscence of the Superior Semicircular Canal: A Case Report

Semicircular canal dehiscence is a congenital syndrome that mainly affects the superior and, less commonly, the posterior semicircular canal in the temporal bone. This syndrome was first reported by Minor et al. in 1998. The prevalence is about 0.5% in the general population. The most characteristic symptom is the Tullio phenomenon, predominantly vertigo and nystagmus. Hearing loss (in particular conductive loss) often completes overall clinical picture. The dehiscence may be completely asymptomatic, in which case it is seen as an incidental finding on radiological investigations. Audiological evaluation includes audiometry and vestibular evoked myogenic potentials (VEMPs). Clinical symptoms are based on the pathophysiological concept of a third mobile window within the inner ear. Diagnosis is confirmed by high resolution petrous temporal bone CT with multiplanar reconstructions (MPRs) in the plane of the canal (Pöschls’ plane for the superior semicircular canal) and 3-D surface reconstructions. MR findings are less sensitive for this entity. The most common differential diagnosis is otosclerosis. Clinical–radiological correlations have therapeutic applications even though the indication for surgery depends on the severity of the vestibular symptoms.

Petrous Bone Cholesteatoma- A Comprehensive Management Algorithm and Outcomes

Petrous Bone Cholesteatoma- A Comprehensive Management Algorithm and Outcomes

Systematic contribution of the auditory region to the knowledge of the oldest European Bovidae (Mammalia, Ruminantia).

The ear region has a strong potential for evolutionary studies. While the petrosal bone suffers from ontogeny and allometry, the bony labyrinth provides crucial information for phylogeny. The study of the bony labyrinth itself allowed for argumentation of the early bovid species Eotragus artenensis and Eotragus clavatus being closely related, while a newly described species and genus of early Bovidae from Montréal-du-Gers (France), formerly attributed to Eotragus, clearly belong to another lineage. The morphology of the bony labyrinth of these oldest bovids confirms that Eotragus is a stem Bovidae, while the new Bovidae is more derived. Since the bony labyrinth is a structure that is little affected by ontogeny, allometry, and sexual dimorphism, we propose this structure and its surrounding petrosal bone as the holotype for this new species. This study shows the importance of the ear region in the context of micro- and macro-evolution.

Modified infra-promontorium trans-channel approach to the petrous apex. Case report

This article describes the approach to the petrous pyramid developed at National Medical Research Center of Otorhinolaryngology, namely an endoscopy – microscopy-guided modified trans-channel infra-promontorium approach with internal carotid artery retraction maneuver in patients with lesions of the petrous pyramid but with preserved hearing. A clinical report describing the apical cholesteatoma of the petrous pyramid and the use of this approach are presented. Anatomical and functional features after the surgery are also described. The purpose of this paper is advancing of the surgical approach to the petrous pyramid with the possibility of hearing preservation. The results of surgical treatment in lesions of the petrous pyramid were evaluated in the immediate and distant periods. The functions of facial mimic muscles were evaluated immediately after the surgery, in 6 months, and in one year. The functions of facial mimic muscles remained at the baseline level during the whole follow-up period. The pure tone audiogram demonstrated the preserved hearing function in the postoperative period. Complete elimination of the pathological process was achieved in all cases (n=15); according to the MRI of the temporal bones, no relapses occurred in a year. The surgical approach proposed for patients with the lesions of the petrous pyramid enables complete removal of the pathological process from the petrous pyramid with the preservation of hearing and facial functions, based on the subjective examinations (audiometry, facial function diagnosis) and radiology (CT and MRI of temporal bones) at the preoperative stage.

Petrous bones versus tooth cementum for genetic analysis of aged skeletal remains.

A proper sampling strategy is important to obtain sufficient DNA for successful identification of aged skeletal remains. The petrous bone is the highest DNA-yielding bone in the human body. Because DNA extraction from the petrous bone is very destructive, the demand for other DNA sources is significant. When investigating aged skeletal remains, teeth are usually preserved, and recent studies have shown that DNA in teeth can be best preserved in the dental cementum that surrounds the surface of the tooth root. To extract DNA from the surface of the tooth root, a nondestructive method without grinding was used. Petrous bones and teeth from 60 archaeological adult skeletons were analyzed. The DNA yield, degree of DNA degradation, and STR typing success were compared, and the results showed higher DNA yield and higher amplification success in petrous bones, despite higher degradation of petrous bones' DNA. The greater success of petrous bones is associated with poorly preserved DNA in a quarter of the teeth analyzed. When teeth with badly preserved DNA were excluded from the statistical analysis, no differences in the success of STR loci amplification were observed even if DNA yield was higher in petrous bones, which can be explained by greater degradation of petrous bones' DNA. When teeth are well preserved, they can be used for genetically analyzing aged skeletal remains instead of petrous bones, and a rapid nondestructive extraction method can be applied to shorten the identification process and to physically preserve the biological specimen.

8358 A Diagnostic Challenge: Occult Paraganglioma Misdiagnosed as Pheochromocytoma Leading to Unnecessary Adrenalectomy

Abstract Disclosure: A.R. Kasireddy: None. S. Alshami: None. S. Gummalla: None. C. Balasubramaniapandian: None. J.A. Henske: None. A. Albashaireh: None. Background: Pheochromocytomas and paragangliomas are rare neuroendocrine tumors. Catecholamine-secreting paragangliomas, like pheochromocytomas, can present with hypertension, sweating and episodic headaches. Thoughtful consideration must be given to distinguish between the two and potentially avoid a critical misdiagnosis. Case: A 61-year-old woman with hypertension and diabetes presented for evaluation of glomus jugulare discovered on CT of the head during evaluation of worsening hearing loss and tinnitus. She reported a longstanding history of episodic headaches, palpitations, anxiety spells and excessive sweating with more recent onset of ear fullness. When symptoms first presented, she had a left adrenalectomy 3 years prior. CT abdomen at that time showed 1.8 x 2.2 cm left adrenal nodule with a density of 12.2 HU and early contrast washout. Plasma metanephrines were normal but normetanephrines were elevated at 5.1 nmol/L (nl: less than 0.9 nmol/L). 24-hour urine metanephrines were normal but normetanephrines were elevated to 892mcg/24h (nl: 122-676 mcg/24h). MIBG scan was done and showed increased activity in the left adrenal nodule. Decision was made to proceed with left adrenalectomy. Surgical pathology was benign. Present evaluation after discovery of the glomus tumour with worsening symptoms showed normal plasma metanephrines, elevated plasma normetanephrines at 1529.9 pg/ml (0- 285.2 pg/ml), elevated plasma norepinephrine at 3280 pg/ml (0-874 pg/ml), with normal dopamine and epinephrine levels. CT head showed a 3 x 2.7 x 2.1 cm lytic destructive mass within the petrous temporal bone at the left skull base containing multiple internal calcifications. Given the lab and imaging findings, paraganglioma was diagnosed. Genetic testing revealed SDHB mutation. Neurosurgery consultants determined that the tumour was not amenable to resection. She was treated with radiation therapy, alpha blockade, and close blood pressure monitoring. Discussion: This case highlights the importance of reviewing the degree of hormonal elevations as well as the pattern of elevation to obtain a correct diagnosis. Paragangliomas commonly secrete normetanephrines rather than metanephrines and are often not immediately localized. Understanding the most likely genetic mutations when a paraganglioma is suspected can direct appropriate choice of radionuclide scanning agents. In this case, an earlier diagnostic scan may have prevented unnecessary adrenalectomy and facilitated earlier discovery of the paraganglioma. Presentation: 6/2/2024

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.

Surgical Outcomes in Patients with Endolymphatic Sac Tumors: A Single-Center Experience of 29 Patients.

To analyze the clinical features and surgical outcomes of patients with endolymphatic sac tumors (ELSTs). Single institution retrospective cohort study. The clinical data of 29 patients with 30 ELSTs who underwent surgery were retrospectively reviewed. Information on patient demographics, tumor size and grade, intraoperative blood loss volume, hearing and facial nerve outcomes, and follow-up data was collected and analyzed. The main symptoms were hearing loss in 26 ELSTs (86.7%) and tinnitus in 17 (56.7%). Twenty-four (80%) ELSTs were in advanced stages (Grade III). The median tumor volume was 6.35 cm3. The median intraoperative blood loss volume was 300 mL. Facial nerve function was well preserved in 21 patients. Among all patients with Grade III tumors, 12 patients underwent tension-free anterior facial nerve rerouting, and 11 patients (91.7%) maintained good facial nerve function postoperatively (HB I and HB II). Only one patient exhibited permanent vocal cord paralysis, and no patients experienced cerebrospinal fluid (CSF) leakage postoperatively. Gross total resection was achieved in 22 patients (73.3%), 5 patients (16.7%) experienced tumor recurrence, and 3 (10%) had residual tumors. Most ELSTs tend to be diagnosed in the advanced stage. Tension-free anterior facial nerve rerouting could maximally preserve facial nerve function. The intraoperative blood loss volume was associated with tumor size and stage. Tumor recurrence tends to occur at the posterior edge of the petrosal bone, internal auditory canal, and surface of the posterior fossa. Given the relatively high recurrence rate of ELSTs, long-term follow-up is recommended. 4 Laryngoscope, 2024.

Over the river and into the hills: locals and non-locals at Inzersdorf, a late Bronze Age cemetery in the Traisen Valley (Austria)

The Late Bronze Age is characterized by the increasing homogenization of material culture and the prevalence of urn burials. The cemetery of Inzersdorf, located in the Lower Traisen Valley, Austria, is used to investigate whether changes in burial practices during the Late Bronze Age were locally driven or influenced by external factors. This study interprets strontium isotope data from 215 calcined human bone samples in the context of a local baseline established from 163 modern plant samples (55 locations) within a 10 km radius of Inzersdorf. Complementary Correspondence Analysis and 14C dates were used to identify chronological changes. The high-density sampling carried out in the Traisen Valley for bioavailable strontium (BASr) enabled the differentiation of people who mainly sourced their food from the valley or the hills. A diachronic shift in land use was identified, with the main food resource obtained from the hills for the earlier and the valley providing most of the foods for the later phase of the cemetery, which is more distinct in men than in women. Five individuals with isotopic values that differed from the main population were identified, one of which has an 87Sr/86Sr of 0.7061 falling below the BASr baseline created with the modern plant data. While the latter may indicate metal-related travel, the other four individuals may be interpreted as inhabitants of single farmsteads. Additionally, an individual with a significant shift in isotopic values between the petrous bone and long bone was identified, indicating changing local food sources over the individual’s life.

The using of endoscopic technology in children with petrous bone cholesteatoma

The using of endoscopic technology in children with petrous bone cholesteatoma

Efficacy of Mastoid Morphometry in Sex Determination Using Cone-beam Computed Tomography: A Retrospective Analysis in Dakshina Kannada Population.

To evaluate the morphology of the mastoid process and its role in sex determination with the help of cone-beam computed tomography (CBCT). A retrospective study was conducted on 200 adults who were subjected to full FOV CBCT scans (100 males and 100 females). Eight parameters of the mastoid process were assessed for sex determination. The study measured eight parameters of the mastoid process, including mastoid length (ML), mastoid width, mastoid height (MH), intermastoidale distance (IMD), intermastoidale lateral surface distance (IMLSD), mastoid medial convergence angle, mastoid size (MS), and mastoid surface area (MSA). Data were recorded and statistically analyzed. Statistics revealed a significant value for MH (p < 0.001), IMD (p < 0.001), IMLSD (p < 0.001), MSA (p < 0.001), MS (p < 0.001), and ML (p = 0.032). A highly significant value was noted for MH (p < 0.001), IMD (p < 0.001), IMLSD (p < 0.001), MSA (p < 0.001), MS (p < 0.001), followed by ML, all of which were found to be greater in males. Out of the eight parameters, IMD was found to be the best sex determinant among all the eight parameters, with an accuracy of 70%. The study showed a significant difference between the mastoid process morphometric measurements for males and females. It can be concluded from the present study that IMD can be used as a good index for sex determination. The combined parameters that were found to be the most accurate were right MH, left ML, and IMLSD, with an accuracy of 75%. The three-dimensional imaging techniques can contribute significantly towards disaster victim identification and sex determination in the fields of forensic odontology and anthropology. For the recognition of victims, sex determination becomes one of the most difficult parameters to assess. In such events, the mastoid process can become an important anatomical landmark for the estimation of sex. This is due to the condensed nature of the petrous bone and its protected position in the skull. How to cite this article: Ahmed J, Saha A, Muralidharan A, et al. Efficacy of Mastoid Morphometry in Sex Determination Using Cone-beam Computed Tomography: A Retrospective Analysis in Dakshina Kannada Population. J Contemp Dent Pract 2024;25(5):453-458.

Searching for alternative high DNA-yielding bone types for DNA analysis of aged skeletal remains

The petrous bone contains significantly higher amounts of DNA than any other human bone. Because of highly destructive sampling and because it is not always part of the recovered remains, the need for alternative sources of DNA is important. To identify additional optimal bone types, petrous bones were compared to femurs, tali, and calcanei sampled from 66 adult skeletons from two distinct modern-era Christian cemeteries. An extraction method employing full demineralization was used to obtain DNA, real-time PCR quantification to ascertain DNA quantity and degradation, and a commercial forensic short tandem repeats (STR) PCR amplification kit to determine genetic profiles. Statistical analysis was performed to explore the differences in DNA yield, DNA degradation, and success of STR amplification. A systematic studies exploring intra-skeletal variability in DNA preservation including various excavation sites differing by time period and geographical position are rare, and the second part of the investigation was based on a comparison of both archaeological sites, which allowed us to compare the effect of different post-mortem intervals and environmental conditions on DNA preservation. The older burial site in Črnomelj was active between the 13th and 18th century, whereas the more recent Polje burial was in use from the 16th to 19th century, creating different temporal and geographical environments. Results for the Črnomelj burial site revealed that the petrous bone outperformed all other bone types studied, except the calcaneus. At the Polje archeological site calcanei, tali, and femurs yielded the same STR typing success as petrous bones. The results obtained highlight the importance of careful bone sample selection for DNA analysis of aged skeletal remains. In addition to petrous bones, calcanei were found to be an alternative source of DNA when older burial sites are investigated. When more recent burial sites are processed, calcanei, tali, and femurs should be sampled besides petrous bones, not only because they exhibited good performance, but also because of easier sampling and easier grinding in the case of trabecular bones. This study contributes valuable insights into the potential use of various skeletal types as a source of DNA for investigation of aged skeletal remains, and it offers practical implications for forensic and archaeological investigations.

Dose assessment in petrous bone CT: Effect of tube current modulation and scan length

The aim of this study is to compare the dosimetric performance of two CT acquisition protocols for the petrous bone: a standard fixed mAs protocol and a protocol using tube current modulation (TCM). By analyzing the scan length, dose-length product (DLP) and effective dose (ED) obtained with each protocol, we investigate whether TCM offers an advantage in terms of dose reduction while maintaining comparable image quality. To this end, 249 patients (women: 52%; men: 48%) were included in this study. The first center used TCM (120 kVp, 150 mA reference) for image acquisition, while the other centers opted for fixed mAs values. Acceptability of image quality was assessed using a standardized phantom (model 610 AAPM) by measuring noise uniformity and accuracy, contrast-to-noise ratio (CNR) and spatial resolution. The CTDIvol was not significantly different between center A and the other centers (p > 0.05), while DLP and ED were significantly different (p < 0.001), being reduced by a factor of 2 and 2.23 for scan length. We concluded that a scan with a 14.28% decrease in tube voltage from 140 kVp (136–170–210) mAs fixed to 120 kVp with TCM to 150 mA reference in helical scan mode can be recommended as an optimized protocol during CT examination of petrous bone while reducing DLP and ED to 50% without loss of diagnostic accuracy.

Elevated modiolus density on high-resolution computed tomography as an indicator of cochlear neurodysplasia: a retrospective case-control study.

Cochlear neurodysplasia (CND) is recognized as a contributing factor to sensorineural hearing loss in children. This study aimed to investigate the relationship between modiolus density on high-resolution computed tomography (HRCT) and CND, and to evaluate its performance in diagnosing CND. This retrospective study collected HRCT images of 34 patients diagnosed with unilateral neurological hearing loss in the Children's Hospital of Chongqing Medical University from March 2018 to December 2023, who were also diagnosed with unilateral CND by computed tomography (CT) and magnetic resonance imaging (MRI) hydroimaging. CT values of the modiolus and petrous bone were measured on the affected and healthy sides, in addition to determining the width of cochlear nerve foramina and the width of internal auditory tract. The receiver operator characteristic (ROC) curve was used to evaluate the diagnostic performance of these features. Simultaneously, comparisons were conducted with parameters obtained from normal children. A total of 29 patients without CND were randomly selected as a control group. The unilateral sensorineural hearing loss group had 34 patients, comprising 18 males and 16 females, with a median age of 4.5 years, ranging from 0.7 to 11 years. The normal children group consisted of 20 males and 9 females, with a median age of 5.9 years, ranging from 0.5 to 12.0 years. Statistically significant differences were observed in the CT values of the modiolus, modiolus/petrous bone CT value ratio, width of cochlear nerve foramina, and width of internal auditory tract between the affected and healthy sides in patients with unilateral sensorineural hearing loss (P<0.05). The area under the ROC curve (AUC) of the modiolus CT value and the width of cochlear nerve foramina for the diagnosis of unilateral sensorineural hearing loss was 0.98 [95% confidence interval (CI): 0.95-1.00] and 0.99 (95% CI: 0.98-1.00), respectively. the modiolus density was significantly elevated in the affected sides in patients with unilateral CND. The optimal cut-off value of modiolus CT values was 983 Hounsfield unit (HU). The elevated density of the modiolus on HRCT holds significant value in diagnosing CND.

FIB-SEM Study of Archaeological Human Petrous Bones: 3D Structures and Diagenesis

The petrous bone generally preserves ancient DNA better than other fossil bones. One reason for this is that the inner layer of the petrous bone of pigs and humans contains about three times as many osteocytes as other bones, and hence more DNA. A FIB-SEM study of modern pig petrous bones showed that the 3D structure of the thin inner layer is typical of woven bone that forms in the fetus, whereas the thicker outer layer has a lamellar structure. The lamellar structure is common in mammalian bones. Here we study human petrous bones that are about 2500 years old, obtained from three Phoenician sites in Sicily, Italy. A detailed FIB-SEM study of two of these bones, one well preserved and the other poorly preserved, shows that the 3D bone type structure of the human petrous inner layer is woven bone, and the outer layer is lamellar bone. These are the same bone type structures found in pig petrous bones. Furthermore, by comparing nine differently preserved petrous bones from the same archaeological region and age, we show that their collagen contents vary widely, implying that organic material can be significantly altered during diagenesis. The mineral crystals are better preserved and hence less crystalline in the inner layers compared to the outer layers. We therefore infer that the best-preserved DNA in fossil petrous bones should be found in the thin inner layers immediately adjacent to the otic cavity where much more DNA is initially present and the mineral phase tends to be better preserved.

Comparative Anatomy of the Contralateral Transmaxillary Approach Alone and With Ipsilateral Transpterygoid Extension: Quantitative Insights on Surgical Exposure and Maneuverability in the Petroclival Region.

Beyond qualitative evidence legitimizing endoscopic corridors through contralateral transmaxillary (CTM) and endonasal ipsilateral transpterygoid (ITP) corridors to the petrous apex and petroclival region, surgical feasibility by direct quantitative comparative anatomy is sparse. Our cadaveric study addresses this by performing the CTM approach followed by ITP extension to quantify the extent of petrous apex resection, instrument maneuverability, and working distance to petrous apex. Anatomic dissections were performed bilaterally on 5 latex-injected human cadaveric heads (10 petrous bones). After CTM dissections were quantified, the ITP approach was added enlarging initial exposure. Differences were measured with statistical significance when P values are < .05. The mean petrosectomy volume was 0.958 cm3 with CTM and 1.987 cm3 with CTM + ITP, corresponding to 14.53% and 30.52% petrous apex resection, respectively. Craniocaudal instrument mobility was more limited in the lateral extent of dissection compared with the midline for both CTM (8.062° vs 14.416°) and CTM + ITP (5.4° vs 14.4°). The CTM approach achieved the lateral-most dissection at the body of the petrous apex (15.936 mm), with lateralization more limited in the superior petroclival region (9.628 mm) and the inferior petroclival region (8.508 mm). Angle of surgical maneuverability increased superiorly vs inferiorly in the CTM approach (mean 12.596° vs 8.336°, respectively). The CTM approach offered the shortest mean working distance (88.624 mm) to the petroclival region compared with the bi-nares approach (100.5 mm). CTM + ITP achieved greater lateralization in the superior (21.237 mm) and inferior (22.087 mm) aspects of the petroclival region compared with the CTM approach. Operative considerations are discussed in accessing target neurovascular structures through the uniquely shaped corridors formed by the CTM or combined CTM + ITP. Allowing mobilization of the internal carotid artery laterally and eustachian tube inferiorly, addition of the ITP allowed for larger petrosectomy than CTM alone, especially in the inferior and lateral aspects of the petrous bone.