Temporal Bone Research Articles

Cochlear Implantation of Slim Precurved Arrays Using Automatic Preoperative Insertion Plans.

Preoperative cochlear implant (CI) electrode array (EL) insertion plans created by automated image analysis methods can improve positioning of slim precurved EL. This study represents the first evaluation of a system for patient-customized EL insertion planning for a slim precurved EL. Twenty-one temporal bone specimens were divided into experimental and control groups and underwent cochlear implantation. For the control group, the surgeon performed a traditional insertion without an insertion plan. For the experimental group, customized insertion plans guided entry site, trajectory, curl direction, and base insertion depth. An additional 35 clinical insertions from the same surgeon were analyzed, 7 of which were conducted using the insertion plans. EL positioning was analyzed using postoperative imaging auto-segmentation techniques, allowing measurement of angular insertion depth (AID), mean modiolar distance (MMD), and scalar position. In the cadaveric temporal bones, three scalar translocations, including two foldovers, occurred in 14 control group insertions. In the clinical insertions, translocations occurred in 2 of 28 control cases. No translocations or folds occurred in the seven experimental temporal bone and the seven experimental clinical insertions. Among the nontranslocated cases, overall AID and MMD were 401 ± 41 degrees and 0.34 ± 0.13 mm for the control insertions. AID and MMD for the experimental insertions were 424 ± 43 degrees and 0.34 ± 0.09 mm overall and were 432 ± 19 degrees and 0.30 ± 0.07 mm for cases where the planned insertion depth was achieved. Trends toward improved EL positioning within scala tympani were observed when EL insertion plans are used. Variability in MMD was significantly reduced (0.07 versus 0.13 mm, p = 0.039) when the planned depth was achieved.

Temporal-Parotid Resection for Malignant Parotid Tumors: A Systematic Review.

Surgery involving the skull base has recently gained significant prominence in treatment of head and neck cancer. "En bloc temporal-parotid resection," as applied in primary malignancies of the external ear, should be considered as a shift in the surgical landscape of "extended total parotidectomies" to achieve negative surgical margins and decrease the risk of tumor spillage during the procedure. The purpose of this systematic review is to evaluate survival outcomes and margin status in patients with parotid malignancies involving the temporal bone and treated with temporal-parotid resection (TPR). PubMed, Scopus, and Embase databases were systematically searched until 11 February 2025. The protocol of this investigation was registered on PROSPERO in February 2024 and the systematic review was performed according to the PRISMA method. The study included 336 patients from 13 articles published between 1993 and 2019. Negative surgical margins were achieved in 74.5% of cases. After a median follow-up of 32 months, 64.0% of patients achieved local disease control. Most patients (51.4%) experienced distant metastases during follow-up. Three-year overall survival (OS) and disease-specific survival (DSS) ranged between 72.4%-57.1% and 79.0%-66.7%, respectively. TPR represents a viable strategy to achieve safe oncological margins and adequate local disease control in patients with parotid gland malignancies infiltrating or abutting the temporal bone. Our findings support the growing interest in TPR, highlighting the need for further studies to refine patient selection criteria, surgical techniques, and postoperative management strategies. PROSPERO: CRD42024512013 LEVEL OF EVIDENCE: NA.

Development of the occipitopetrosal junctions: A histological study using human fetuses.

The temporal bone petrosa is connected to the occipital bone at two sites: one junction with the basilar part (medial junction) and another with the lateral part (lateral junction). Using histological specimens from 45 human fetuses (approximately 7-39 weeks of gestational age or GA), we aimed to describe possible changes in histology and topographical anatomy during processes toward the ossified union. In the early term, the junctions were characterized by dense mesh-like fibers that likely corresponded to the thickened basal laminae of the composite cartilage cells. Notably, the mesh-like structure disappeared until 12 weeks of GA and, irrespective of whether a remnant fibrous tissue was present or absent, cartilage tissues became continuous between the occipital and petrosal sides. Until 25 weeks of GA, the inferolateral marginal part of the spheno-occipital junction cartilage extended to the medial junction and attached to the ossified petrosa. The medial junction sometimes contained an irregularly shaped cartilage mass or a woven bone with bone trabeculae, but it was usually attached directly to the bony petrosa without any interruption by calcified cells. In contrast, at the late-term lateral junction, a cartilage mass was sandwiched by bipolar ossification centers on the temporal and occipital bone sides. As the endochondral ossification advances, bones at and around the lateral junction seemed to grow and cover the expanding mastoid air cells. However, the fetal medial junction might grow, in accordance with midline growth at the spheno-occipital junction cartilage. Alternatively, the bony union of these two junctions might establish postnatally.

Otopathologic Patterns of Cellular Degeneration in the Peripheral Vestibular Organ Secondary to Head Trauma.

This study examined patterns of cellular and neural degeneration in the peripheral vestibular system following head trauma, comparing cases with and without skull/temporal bone fractures. We analyzed 26 temporal bones (17 cases) with head trauma with fractures (six cases, nine ears) and ones without fractures (11 cases, 17 ears). Appropriate age-matched control groups comprising temporal bones without temporal bone pathology were included for comparative purposes. Histopathological analyses included counts of Scarpa's ganglion cells (ScGCs) in the superior and inferior vestibular nerves (SVN and IVN), and counts of vestibular hair cells (HCs) in the utricle, saccule, lateral semicircular canal (LSCC), and posterior semicircular canal (PSCC). Mann-Whitney U tests were used for statistical analyses. The group without fractures showed a significant reduction in total ScGCs (SVN + IVN) compared to controls (p = 0.040), with a pronounced decrease in the SVN (p = 0.014). Significant reductions in type I and type II HCs were observed in the utricle (p = 0.008 and p = 0.035) and in type I HCs in the LSCC (p = 0.037). In the group with fractures, only type I HCs in the utricle were significantly reduced (p = 0.038). Head trauma without fractures is associated with more severe vestibular cell degeneration and greater loss of ganglion cells in the SVN in our specimens. These findings suggest that head trauma without fractures may pose a higher risk for vestibular cell damage compared with trauma with fractures. NA.

MRI Features of Cholesterol Granuloma of the Petrous Apex: A Diagnostic Review with a Rare Presentation

Cholesterol granuloma of the petrous apex is an uncommon benign lesion characterized by a foreign body reaction to cholesterol crystals within an air cell tract of the temporal bone. It is often mistaken for other petrous apex lesions such as cholesteatoma or petrous apex effusion. We present the MRI findings in a 16-year-old female with a history of left-sided cholesteatoma surgery at age 7, presenting 9 years later with suspected recurrence on CT. MRI revealed a non-enhancing, T1 and T2 hyperintense lesion with restricted diffusion at the left epitympanum and mastoid, consistent with a cholesterol granuloma associated with recurrent cholesteatoma. This article highlights the imaging hallmarks, diagnostic challenges, differential diagnoses, and current literature on petrous apex cholesterol granulomas, with a focus on MRI.

Influence of CT Radiation Dose and Field-of-View on Automatic Morphometry for Cochlear Implant Planning.

In cochlear implantation (CI), precise preoperative cochlear duct length (CDL) and angular insertion depth (AID) measurements are pivotal for individualized electrode carrier selection, since recipients benefit from sufficient cochlear coverage of the electrode carrier, enabling electric stimulation of all crucial frequency bands. Since the quality of temporal bone CT largely depends on acquisition and reconstruction settings and is limited by the technical capabilities of the CT scanner, this study aims to assess how radiation dose and reconstruction field-of-view (FOV) affect automatic cochlear morphometry and electrode contact determination in conventional multislice CT. Twenty fresh-frozen human petrous bone specimens were examined at three radiation dose levels (40, 20, and 10 mGy) using a multislice CT scanner. Each dataset was reconstructed with three different FOV settings (250, 125, and 50 mm). Preoperative CDL and AID measurements were performed with dedicated otological planning software. Maxed-out dose images (250 mGy) served as standard of reference for comparing the morphometric results. Regardless of the selected combination of dose level and FOV, significant CDL or AID measurement differences were neither ascertained among the individual groups, nor in comparison to the reference scans (all p ≥ 0.05). Likewise, the simulation of all stimulable frequency bandwidths showed no dependency on radiation dose or FOV settings (all p ≥ 0.05). The assessment of cochlear morphometry with conventional multislice CT imaging before CI surgery allowed a radiation dose reduction up to 75% without compromising the accuracy of software-based cochlear analysis. Notably, automatic CDL and AID measurements for surgical planning did not benefit from a smaller reconstruction FOV.

Neuro applications of photon-counting CT.

Photon-counting detector CT, a recent advance in CT technology, has several advantages over conventional energy-integrating detector CT. These include increased spatial resolution, reduced image noise, increased soft-tissue and iodine contrast, lower radiation dose, and inherent spectral imaging. This article comments on recent literatures in neuroradiology covering the vessels, pituitary adenoma, temporal bone, and myelography while addressing certain issues and outlining future directions.

Micro‐CT Examination Reveals a Possible Case of Otosclerosis in an Early Bronze Age Individual From Poland

ABSTRACTContemporary imaging techniques, particularly micro–computed tomography, enable detailed visualization and analysis of pathological changes in skeletal remains. This study examines the right temporal bone of a male individual from the Early Bronze Age Mierzanowice culture (2200–2000 bc), discovered in southeastern Poland. Macroscopic analysis revealed significant unilateral enlargement of the right petrous part and mastoid process. The aim of our study was to identify the underlying condition using high‐resolution micro–computed tomography imaging. Scanning with a Nanotom 180 N device (30‐μm‐slice thickness) revealed substantial structural destruction of the otic capsule, consistent with a diagnosis of otosclerosis. The mastoid process was notably widened, with a clearly visible Koerner's septum. Comparative analysis with a nonpathological reference bone and the absence of systemic skeletal changes helped to rule out differential diagnoses such as osteogenesis imperfecta, otosyphilis, and Paget's disease. Micro–computed tomography provided exceptional insight into the internal architecture of the temporal bone, revealing detailed features associated with otosclerosis, including a hypodense focus in the region of the fissula ante fenestram and the “double ring sign” of the cochlea. These findings underscore the diagnostic power of micro–computed tomography in paleopathology and its potential to uncover subtle yet significant ancient diseases.

Primary Non-Hodgkin Lymphoma of the Temporal Bone: Case Report

Lymphomas account for approximately 2.5% of head and neck malignancies, with primary temporal bone involvement being exceedingly rare. The diagnosis of lymphoma, as with other temporal bone malignancies, is often delayed, which adversely impacts both treatment outcomes and overall prognosis. We report a case of a 55-year-old male who presented to our hospital with left-sided facial palsy, unilateral hearing loss, and auricular pain. Biopsies taken during surgical intervention revealed diffuse large B-cell lymphoma infiltrating the mastoid process, external auditory canal, and tympanic cavity. This case underscores the diagnostic challenges posed by temporal bone lymphoma, particularly in presenting symptoms that mimic benign conditions. It emphasizes the importance of considering malignancy in patients with persistent otological symptoms and facial nerve palsy, warranting thorough investigation. Maintaining a heightened level of suspicion for neoplastic disease is crucial until a definitive diagnosis is confirmed. Early detection through comprehensive imaging and biopsy is essential for effective management and improved outcomes.

Computed tomography of the equine temporohyoid joint: Association between imaging changes and potential risk factors.

Temporohyoid osteoarthropathy (THO) is characterised by bone proliferation and cartilage ossification caused by infectious and degenerative conditions, amongst others. To describe the variable appearance of the temporohyoid joint (THJ) on computed tomography (CT) and investigate associations between CT changes and potential risk factors. Cross-sectional study. Head CT examinations were assessed. A grading system was developed for osseous proliferation (grade 0 [normal] to 3 [severe]) and tympanohyoid cartilage change (grade 0 [normal] to 3 [complete ossification]). Grades were also summed to create an overall sum grade. Ordinal logistic regression was performed to produce a multivariable model that assessed the association between THJ grade and signalment, presenting signs, CT features, and final diagnosis. The horses included (n = 424) most commonly presented for dental and sinus disorders (37.7%). The most frequently observed (mode) bone grade, cartilage grade and overall grade were 2 (41.9%), 0 (52.6%) and 2 (27.0%), respectively. Bone proliferation was most common medially and caudally. Soft tissue swelling (OR 1.9, 95% CI 1.2-3.1, p < 0.05) and temporal bone fragmentation (OR 26.6, 95% CI 5.1-141.4, p < 0.05) were associated with increased bone grade. There was no correlation between increased grade and any presenting sign. Increased sum grade was significantly associated with increased age (OR per year 1.1, 95% CI 1.0-1.1, p < 0.05), Arabians (OR 4.2, 95% CI 1.3-14.0, p < 0.05) and Thoroughbreds (OR 2.9, 95% CI 1.5-5.4, p < 0.05) relative to Warmbloods. Following training, a single observer evaluated images. Moderate caudomedial osseous proliferation of the THJ is common in horses presented for unrelated disease. Cartilage mineralisation, soft tissue swelling, and temporal bone fragmentation may serve as markers of disease. Thoroughbreds and Arabians are at increased risk of greater THJ remodelling. Increased THJ change was associated with age but not otitis, suggesting THO is predominantly degenerative.

Traumatic Temporal Fracture With Parapharyngeal Emphysema: Case Series and Literature Review.

Traumatic temporal bone fractures with parapharyngeal emphysema represent a rare clinical entity with potential serious complications. This retrospective case series has taken 3 cases of traumatic temporal bone fractures with parapharyngeal emphysema and has examined their clinical presentation, management, and outcomes. Recognizing warning signs and managing them accordingly is vital to prevent the occurrence of problems such as airway compromise and deep-neck space infections. A multidisciplinary team consisting of otolaryngologists and oral and maxillofacial surgeons should be considered as a vital element in the process of improving the outcome of patients.

Utility of Computed Tomography Angiography in Characterizing Vascular Injury From Sphenoid Fractures.

Sphenoid fractures are associated with significant neurovascular risks, including blunt cerebrovascular injuries (BCVI). While computed tomography angiography (CTA) is commonly used to detect vascular injuries, its routine use in sphenoid fractures remains a debate. This study aimed to evaluate sphenoid fracture patterns associated with positive CTA findings to optimize imaging protocols. This retrospective cohort study included 131 patients with sphenoid fractures from 2011 to 2023 at a tertiary care center. Of these, 88 patients underwent CTA. Fracture patterns were categorized based on anatomical involvement, and vascular injuries were graded using the Biffl scale. Statistical analyses were performed to evaluate associations between fracture types and CTA findings. Among the 88 patients who underwent CTA, 10 (11.4%) had vascular injuries. Fractures involving the carotid canal were significantly associated with positive CTA findings, while fractures confined to the greater wing or temporal bone were more often associated with negative findings. No significant associations were observed between vascular injuries and demographic or clinical variables. Fractures involving the carotid canal should prompt evaluation with CTA, whereas low-risk fractures involving the temporal bone or greater wings of sphenoid may not require routine imaging. These findings emphasize the importance of fracture location in guiding a more selective approach to CTA use.

State of the densitometry in the diagnostic evaluation of temporal bone osteomyelitis: A case–control study

BackgroundTemporal bone osteomyelitis in necrotizing otitis externa is a threatening condition, especially in immune-deficient people, with a relatively high morbidity and mortality rate. The bone densitometry by computerized tomography scan is one of the best methods in the diagnosis of temporal bone osteomyelitis.MethodsIn this case–control study, 103 patients who suffered from unilateral temporal bone osteomyelitis were referred to two specialist referral hospitals in Tehran. The bone densities of different parts of the temporal bone and adjacent structures were compared with the contralateral healthy ear. The correlation between bone densitometry and the temporal osteomyelitis diagnosis was assessed.ResultsSeventy-five patients were male (72.8%), the mean age was 68 ± 10.2 years, and the right ear was affected in 53 patients (51.5%). Twenty-seven patients (26.2%) had facial palsy. There was a significant difference in bone densities of four parts (mastoid cortex, external ear canal, mandibular condyle, and root of zygoma (paired t-test, p-value < 0.05)) of eight regions in the temporal bone in the infected ear compared with the contralateral healthy ear. There was a significant correlation between mastoid cortex density decreasing and facial palsy. The linear regression test predicted a model for mastoid involvement based on the mastoid cortex density and facial palsy.ConclusionBone density changes in temporal bone tomography can be an important predictive factor of disease and facial nerve involvement following temporal bone osteomyelitis.

Mini-invasive Anterior Petrosal Intertentorial Approach for Trigeminal Neuralgia: Rationale and Limits of the Technique

AbstractThe retrosigmoid approach (RSA) is considered the standard surgical choice to address a neurovascular conflict involving the trigeminal nerve. The subtemporal transtentorial approach (STA) represents the main alternative. We describe here the mini-invasive anterior petrosal intertentorial approach with a view to reduce complications associated with the standard STA.Mini-invasive anterior petrosal intertentorial approach (M-APIA) was described for a case of refractory trigeminal neuralgia. This approach includes a very limited amount of drilling of the petrous ridge to expose the posterior fossa dura and the superior petrosal sinus to facilitate the subsequent tentorial peeling. Tentorial peeling enables to develop an intertentorial plane between the temporal tentorial leaf (TTL) and the posterior fossa tentorial leaf (PFTL). A linear incision over the posterior fossa dura and the PFTL offers a wide exposure of the neurovascular conflict.M-APIA enables to expose the root entry zone (REZ) of the trigeminal nerve without exposing the temporal lobe or the cerebellum.M-APIA can be considered as a safe alternative to the RSA or STA for trigeminal microvascular decompression (MVD), especially for select cases. Additional studies are needed for a better understanding of its advantages and disadvantages.

Cranial Sutures Alter Computational Models of Transcranial Electrical Stimulation.

ROAST (Realistic vOlumetric-Approach-based Simulator for Transcranial electric stimulation) has been increasingly utilized to inform studies of transcranial electrical stimulation (tES). The precision of ROAST is dependent on anatomical accuracy. The aims of the study were to compare using only T1 magnetic resonance images in ROAST (T1 model), with a combination of T1 and T2 magnetic resonance images (T1 and T2 model) and to model the electrical fields generated by tES with commonly used ECT montages: bitemporal, bifrontal, and right unilateral and varying the skull conductivities (based on the electrode position) and including cranial sutures. The "T1 model" was selected for computational modeling. The skull conductivity was varied from the "default setting in ROAST" (0.01S/m) to that of temporal bone (0.0038S/m) and frontal bone (0.0126S/m). "Disc" electrodes (5 cm in diameter) were applied with 1 mA of current. "Pad" electrodes, 0.1 mm high and 40 mm wide, were positioned over the squamous suture, coronal suture and sagittal suture and the skull conductivity changed to approximate suture conductivity (0.32S/m). The "T1 model" differed from the "T1 and T2 model," which resulted in variable electric fields reaching individual tissue layers. Changing skull conductivity and simulating the cranial sutures resulted in changes to the electric current reaching the cortical and subcortical structures with the later having a greater impact. This study demonstrates the importance of anatomically accurate head models in ROAST computational modeling of tES. Varying the skull conductivity based on studies in vivo and including cranial sutures is imperative for more realistic predictions of electric field and reproducibility.

Application of Topographical Anatomy of the Trochlear Nerve in Transtentorial Approaches: An Anatomic Study.

Transection of the free edge of tentorium (FET) might be necessary when approaching cavernous sinus lesions, clip placement in certain posterior communicating artery aneurysms, or during transpetrosal and retrosigmoid transtentorial approaches. No anatomic study has investigated the relationship of the trochlear and oculomotor nerve and FET in an attempt to identify a safe zone for such maneuver. Ten embalmed specimens (20 sides) were studied and the following morphometric measurements were taken using digital microcalipers: trochlear (TP) to oculomotor porus (OP), length of the intratentorial segment of cranial nerve (CN) IV, nerve free FET, and distance along the oculomotor (CN III) from its OP to CN III/trochlear (CN IV) crossing and angle between the long-axis petrous ridge and TP (petrotrochlear angle). The CN IV pierced the deep layer of the FET in all cases at a mean distance 8.11 mm (4.43-11.33) posterior to the OP, measured along the FET. CN IV continued within the tentorial edge for a mean of 6.17 mm (3.18-11.33) before entering the cavernous sinus at a mean distance of 1.9 mm (0-5.46 mm) from the posterior-most aspect of the OP. A nerve-free portion of FET was 1.93 mm (mean) (0-5.46). No nerve-free FET segment (<1 mm) was observed in 4 sides (20%), and a nerve-free FET segment <2.00 mm was seen in 55% of cases. The mean distance from OP to the CN III/IV crossing was 10.17 mm (1.00-15.57). The mean petrotrochlear angle was 164.49° (140.01-183.85), and >175° in 4 specimens (20%). Our data confirm presence of the intratentorial segment of CN IV. Transection of the FET carries the lowest risk of CN IV injury if performed < 2 mm or >10 mm posterior to the OP, or posterior to intersection of the FET and a virtual extension of a petrous ridge.

The intricate interrelationship of cochlear aperture and internal auditory canal diameter in pediatric normal petrous structures.

The intricate interrelationship of cochlear aperture and internal auditory canal diameter in pediatric normal petrous structures.

Utilizing temporal imaging to enhance early diagnosis of eosinophilic otitis media in clinical practice.

The diagnosis of eosinophilic otitis media (EOM) remains a major challenge. Current diagnostic methods rely primarily on accurate samples of middle ear tissue or secretions, which can be complex. In this study, we sought to explore the diagnostic value of mastoid pneumatization combined with other temporal radiological features for EOM. This study included 28 patients with EOM and 32 patients with ordinary OM. All participants underwent the temporal bone HRCT, and middle ear status was assessed using four sections: mesotympanum, attic, antrum, and mastoid air cells. Quantification of negative temporal bone pressure using three-dimensional analysis of mastoid volume images. The volumes of eosinophilic/non-eosinophilic mastoid air cells were approximately the same but were asymmetric. In contrast, in the normal OM group, there was a significant difference in the volume of mastoid air cells between the inflammatory and non-inflammatory sides. Statistically, the degree of opacification to the mesotympanum, attic, and mastoid air cells was more severe in patients with EOM than in patients with ordinary OM on the affected side. Furthermore, on the normal side, the opacification of the all four sites in the eosinophil group was basically worse than that in the control group. Eosinophilic individuals have been found to be specific to the mastoid air cell system and middle ear status and are important factors to consider. Therefore, the potential imaging information of HRCT can help otologists diagnose EOM earlier and provide timely and effective treatment.

NF2-related schwannomatosis: A view from within the inner ear.

NF2-related schwannomatosis (NF2-SWN, formerly known as neurofibromatosis type 2) is an autosomal dominant disorder associated with the growth of bilateral schwannomas on the cochleo-vestibular nerves and meningiomas. NF2-SWN is caused by pathogenic variations in the NF2, moesin-ezrin-radixin-like (MERLIN) tumour suppressor gene. The mostly benign tumours can cause progressive sensorineural hearing loss, tinnitus and balance dysfunction. Outside the inner ear, tumours grow on other intra-cranial nerves, leading to further neurological issues and shortened life-expectancy. Here we re-evaluate some historic cases from our human temporal bone collection, and we review similar instances from the literature to highlight the structural and functional effects of such tumours on the cochlea and vestibular organs. Tumour growth is associated with the remodelling of sensory and ion-transporting epithelia, the loss of afferent neurons and hair cells, and signs of fluid dysregulation. These cases demonstrate the aggressive nature of this disease and the difficulties of surgically excising the bilateral tumours. They also emphasise the need for novel therapies that can slow or prevent tumour growth to preserve sensory function in people living with NF2-SWN.

Measurement of Temporal Bone Structures for the Placement of an Active Bone Conduction Device

Measurement of Temporal Bone Structures for the Placement of an Active Bone Conduction Device