Educational simulator for mastoidectomy considering mechanical properties using 3D printing and its usability evaluation.

Complex temporal bone anatomy complicates operations; thus, surgeons must engage in practice to mitigate risks, improving patient safety and outcomes. However, existing training methods often involve prohibitive costs and ethical problems. Therefore, we developed an educational mastoidectomy simulator, considering mechanical properties using 3D printing. The mastoidectomy simulator was modeled on computed tomography images of a patient undergoing a mastoidectomy. Infill was modeled for each anatomical part to provide a realistic drilling sensation. Bone and other anatomies appear in assorted colors to enhance the simulator's educational utility. The mechanical properties of the simulator were evaluated by measuring the screw insertion torque for infill specimens and cadaveric temporal bones and investigating its usability with a five-point Likert-scale questionnaire completed by five otolaryngologists. The maximum insertion torque values of the sigmoid sinus, tegmen, and semicircular canal were 1.08 ± 0.62, 0.44 ± 0.42, and 1.54 ± 0.43 N mm, displaying similar-strength infill specimens of 40%, 30%, and 50%. Otolaryngologists evaluated the quality and usability at 4.25 ± 0.81 and 4.53 ± 0.62. The mastoidectomy simulator could provide realistic bone drilling feedback for educational mastoidectomy training while reinforcing skills and comprehension of anatomical structures.

Diagnostic and Imaging Findings in Inflammatory Opacifications of the Middle Ear: A Review of the Literature.

Opacification in the middle ear and mastoid region can stem from a wide range of factors. In terms of diagnostic imaging, CT is the primary tool due to its exceptional spatial resolution, particularly for examining the temporal bone and ossicles. MRI complements this by offering detailed soft tissue lesion characterization and assessing involvement in the inner ear and cranial nerves. This study focuses on inflammatory causes of opacification in the middle ear and mastoid, with an emphasis on the utility of CT and MRI. This comprehensive review aimed to provide a practical framework for considering potential differential diagnoses.

Diagnosis and treatment of Eagle's syndrome and possible complications.

BACKGROUND: Eagle's syndrome (ES) is a term describing a group of symptoms associated with the elongation of the styloid process (SP) of the temporal bone or with ossification of the stylohyoid ligament. Clinically, it manifests through pain in the orofacial and pharyngeal regions, similar to that experienced by patients with temporomandibular joint disease. The presented paper aims to assess the evaluation of the success of surgical treatment and the complications associated with such treatment. METHODS: Our retrospective study includes nine patients with ES treated in our Department Oral and Maxillofacial Surgery in years 2019-2023 (median age of 47 years) - all patients affected with this disease out of 2,716 patients examined at our department due to a temporomandibular joint disease. Eight of these patients underwent a surgical resection of the SP. The success and complications in these patients are evaluated in this study. RESULTS: In seven patients, the problems disappeared or at least diminished, which is consistent with data from the literature. Postoperative complications such as deficit of the marginal branch of the facial nerve (n. VII), limited sticking the tongue out (n. XII), and velopharyngeal insufficiency (n. IX) occurred in three patients. CONCLUSION: The wide spectrum of clinical manifestations makes ES a condition that should be considered in the differential diagnosis of temporomandibular joint disorders, post-traumatic conditions, or complicated eruption of wisdom teeth or their extraction. ES can be treated conservatively or (mostly) surgically. Surgical treatment can be relatively successful and effective, but it is necessary to respect the anatomical placement of the SP, which can be associated with the development of complications, especially in cases with extremely long SP.

Localization of the Vertical Part of the Facial Nerve in the High-Resolution Computed Tomography During Pediatric Cochlear Implantation.

BACKGROUND: This study proposed a classification of the vertical portion of the facial nerve (VPFN) location, incorporating the previous classifications regarding the posterior-to-anterior and medial-to-lateral dimensions. We also evaluated the implication of this proposed classification on the round window visibility during pediatric cochlear implantation (CI). METHODS: It was a retrospective multicenter observational cohort study. This study included 334 cases that underwent CI between 2015 and 2022 at multiple referral institutes. Two physicians evaluated the preoperative computed tomography images of 334 patients and determined the radiological type of the VPFN. These types were matched with intraoperative round window accessibility. RESULTS: The Spearman's correlation coefficient showed a strong correlation between the proposed VPFN type and the intraoperative round window visibility, as the P-value was <.001. CONCLUSION: This classification could provide the surgeon preoperatively with the precise location of the VPFN in the lateral-to-medial and posterior-to-anterior dimensions. Furthermore, this location classification of the VPFN was significantly correlated with intraoperative round window accessibility, with an accuracy of 90.42%. Therefore, types C and D were expected to have difficult accessibility into the round window, and more surgical interventions were needed to modify the posterior tympanotomy or use other approaches.

Transmastoid Approach to Repair Iatrogenic Cerebrospinal Fluid Otorhinorrhea After Cerebellopontine Angle Tumor Resection.

BACKGROUND: The precise treatment of iatrogenic cerebrospinal fluid (CSF) otorhinorrhea has been poorly studied. The purpose of the study was to investigate the clinical manifestation, surgical results, and management of CSF leak. METHODS: Electronic medical record database of iatrogenic CSF leaks after erebellopontine angle(CPA) surgery from 2019 to 2022 was retrospectively analyzed. Three patients returned to the hospital with the complication of CSF leak. After failed attempts of conservative strategies or reverse surgical repair, adipose tissue was applied to the mastoid cracks repair. RESULTS: With the techniques described above, the CSF leaks were successfully settled. The identified patients were observed for at least 10 months. and there was no recurrence or other complications. CONCLUSION: Conservative treatment and initial surgical methods for occult postoperative CSF leaks are prone to delay effective results, particularly in patients with well-evaporated temporal bone. This complication can be minimized with transmastoid closure utilizing autologous fat.

[Clinical case of tuberculous otitis media in early childhood]. / Klinicheskii sluchai tuberkuleznogo srednego otita v rannem detskom vozraste.

Nowadays, the incidence of tuberculosis remains high all over the world, despite the vaccination, medical support, social policy. The main reasons for this are the high level of migration, the prevalence of bad habits, the prevalence of immunodeficiency conditions, the formation of resistance to antimicrobial drugs, the tendency to refuse vaccination. At the same time, great difficulties arise in the diagnosis of extrapulmonary forms of infection. The purpose of this publication is to remind about the peculiarities of the course and diagnosis of tuberculous otitis media. According to the literature, the main characteristic features of tuberculous of the middle ear are prolonged suppuration without pronounced pain syndrome, inefficiency of standard antibacterial therapy, the anamnestic data about contacts or violation of the vaccination schedule, multiple perforations and a pronounced granulation process during otoscopy, a pronounced destructive process in the temporal bone during X-ray examination. The article presents a clinical case of the development of tuberculous otitis media in a young child with delayed diagnostics and the development of mastoiditis with required emergency surgical treatment. Verification of the etiology of the disease and the specific treatment carried out made it possible to achieve complete relief of ear symptoms, restoration of the tympanic membrane and ventilation of the middle ear.

Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model.

OBJECTIVES: The aim of this study is to improve our understanding of the mechanics involved in the insertion of lateral wall cochlear implant electrode arrays. DESIGN: A series of 30 insertion experiments were conducted by three experienced surgeons. The experiments were carried out in a previously validated artificial temporal bone model according to established soft surgery guidelines. The use of an in vitro setup enabled us to comprehensively evaluate relevant parameters, such as insertion force, intracochlear pressure, and exact electrode array position in a controlled and repeatable environment. RESULTS: Our findings reveal that strong intracochlear pressure transients are more frequently caused during the second half of the insertion, and that regrasping the electrode array is a significant factor in this phenomenon. For choosing an optimal insertion speed, we show that it is crucial to balance slow movement to limit intracochlear stress with short duration to limit tremor-induced pressure spikes, challenging the common assumption that a slower insertion is inherently better. Furthermore, we found that intracochlear stress is affected by the order of execution of postinsertion steps, namely sealing the round window and posterior tympanotomy with autologous tissue and routing of the excess cable into the mastoid cavity. Finally, surgeons' subjective estimates of physical parameters such as speed, smoothness, and resistance did not correlate with objectively assessed measures, highlighting that a thorough understanding of intracochlear mechanics is essential for an atraumatic implantation. CONCLUSION: The results presented in this article allow us to formulate evidence-based surgical recommendations that may ultimately help to improve surgical outcome and hearing preservation in cochlear implant patients.

Intraoperative hybrid technique for excision of temporal bone paraganglioma: A case report.

BACKGROUND: Temporal bone paragangliomas are vascularized neoplasms. Although preoperative angioembolization serves as a valuable approach to reduce intraoperative blood loss, it comes with an elevated risk of cranial neuropathies, offers no assurance of complete hemostasis, and precludes real-time adjustments during surgery. METHODS: A 74-year-old patient presented with recurrent episodes of ear bleeding. On examination, a vascular lesion obstructed her external auditory canal. It had the clinical and radiological characteristics of a paraganglioma. Angiography revealed that it had three feeding vessels. RESULTS: The patient was successfully scheduled for hybrid, intraoperative angiography and temporary balloon occlusion of the feeding vessels supplying the lesion instead of preoperative angioembolization. CONCLUSIONS: Utilizing hybrid intraoperative angiography with temporary balloon occlusion during the surgical removal of temporal bone paragangliomas represents an innovative technique that reduces the risk of permanent cranial neuropathies while providing the capacity for real-time adjustments and improved hemostasis.

The Association Between Obesity and Spontaneous Temporal Bone CSF Leak Outcomes: A Systematic Review and Meta-Analysis.

OBJECTIVE: We undertook a systematic review of the literature with meta-analysis to identify the role of obesity (BMI ≥30) in the patient characteristics presenting with spontaneous cerebrospinal fluid (sCSF) leaks of the lateral skull base and the outcomes of their repair. DATA SOURCES: A Systematic Review of English Articles using MEDLINE, EMBASE, and Cochrane Library. REVIEW METHODS: The research algorithm included the following keywords: "spontaneous CSF leak," "lateral skull base," "temporal bone," "meningocele," "encephalocele," and "otorrhea." We also manually searched the references of included studies, to identify possible studies missed during our literature search. RESULTS: More than two-thirds of the patients were female (69.2%) and often were obese (mean BMI 36.5 kg/m2) with a mean age of 57. Most common presenting symptoms were otorrhea and hearing loss. Most authors did not report a routine use of a post-operative lumbar drain. Most patients had a single skull base defect and encephaloceles prolapsing through, across obese and non-obese groups. Median length of stay in hospital was 3.2 days, and the majority of patients did not have any recurrence during their follow-up (89.6%), which was not affected by obesity. CONCLUSION: Obesity does not affect length of hospital stay or recurrence rate following surgical repair of lateral skull base sCSF leaks. Surgical repair is a safe and viable approach in the management of obese patients with sCSF leaks in the temporal bone. LEVEL OF EVIDENCE: NA Laryngoscope, 134:2012-2018, 2024.

Exploratory Study of Growth of Circumference of Mandibular Fossa Adjacent to Petrous Portion of Temporal Bone Using Dried Skulls.

The morphogenetic process of development of the circumference of the mandibular fossa during tooth eruption, which involves the replacement of deciduous teeth with permanent teeth, is strongly affected by occlusion. To the best of our knowledge, no studies have investigated the effect of occlusion on this process. This study investigated the morphogenetic process of development during tooth eruption using dried skulls harvested from Indian donors. The average distance between the ala-major-squamosa suture and the foramen ovale according to age group was as follows: 3.24 mm in the 8-month-old group and 8.92 mm in the adult group. The average distance between the ala-major-squamosa suture and the apex of the articular tubercle according to age groups was as follows: 10.38 mm in the 8-month-old group and 19.34 mm in the adult group. The average distance between the point of intersection of the petrosquamous fissure and petrotympanic fissure located on the perpendicular line drawn posteriorly from the shortest distance of the medio-lateral axis between the ala-major-squamosa suture and the apex of the articular tubercle according to age group was as follows: 9.68 mm in the 8-month-old group and 14.3 mm in the adult group. These results suggest that the mandibular fossa is strongly affected by load due to occlusion, unlike the growth of the neurocranium. This indicates that the effect of occlusion is a secondary element in the morphogenetic process of development of the circumference of the mandibular fossa.

[The imaging presentations of the fallopian canal cerebrospinal fluid leaking].

Objective: To summarize the imaging presentations of the fallopian canal cerebrospinal fluid leaking (FCCFL). Methods: The high resolution CT (HRCT)and MRI materials of 4 patients (4 ears) with FCCFL confirmed by surgery between August 2016 to November 2023 were retrospectively analyzed. Among these, there were 2 males and 2 females, their ages ranged from 6 to 69 years. Results: All of the FCCFL were unilateral, including 2 on the left and 2 on the right.Clinically, the patients with FCCFL suffered from clear nasal fluid flow, ear tightness, and hearing loss. On CT, all of the affected ears were depicted markedly dilatation of the proximal portion of fallopian canal(FC), the labyrinthine segment and geniculate fossa were involved in 4 cases, and involvement of tympanic segment in 1 case at the same time. The geniculate fossa in the affected side were significantly enlarged, protruding upwards into the tympanic cavity, with one case simultaneously involving the cochlea. On MRI, the hyposignal on T1WI and hypersignal on T2WI or water sequence like cerebrospinal fluid (CSF) were shown in the enlargement FC, without diffusion restriction, and non-enhancing with administration Gadolinium contrast.CSF-like signal effusion was shown in all of the affected tympanum, of which, the CSF-like signal effusion was demonstrated in the area along the superficial petrosal nerve, the right pterygopalatine fossa and the parapharyngeal space. The adjacent intracranial meninges were presented thickening in 3 cases. Conclusion: The imaging appearances of FCCFL present some characteristics:on HRCT, the proximal portions of the affected FC depicts markedly enlargement,especially the geniculate fossa.While they present CSF-like signal, no diffusion restriction, and no enhancement administration, Gadolinium contrast on MRI, accompanying the CSF-like signal effusion in the affected tympanum.

Variability in Manual Segmentation of Temporal Bone Structures in Cone Beam CT Images.

PURPOSE: Manual segmentation of anatomical structures is the accepted "gold standard" for labeling structures in clinical images. However, the variability in manual segmentation of temporal bone structures in CBCT images of the temporal bone has not been systematically evaluated using multiple reviewers. Therefore, we evaluated the intravariability and intervariability of manual segmentation of inner ear structures in CBCT images of the temporal bone. METHODS: Preoperative CBCTs scans of the inner ear were obtained from 10 patients who had undergone cochlear implant surgery. The cochlea, facial nerve, chorda tympani, mid-modiolar (MM) axis, and round window (RW) were manually segmented by five reviewers in two separate sessions that were at least 1 month apart. Interreviewer and intrareviewer variabilities were assessed using the Dice coefficient (DICE), volume similarity, mean Hausdorff Distance metrics, and visual review. RESULTS: Manual segmentation of the cochlea was the most consistent within and across reviewers with a mean DICE of 0.91 (SD = 0.02) and 0.89 (SD = 0.01) respectively, followed by the facial nerve with a mean DICE of 0.83 (SD = 0.02) and 0.80 (SD = 0.03), respectively. The chorda tympani had the greatest amount of reviewer variability due to its thin size, and the location of the centroid of the RW and the MM axis were also quite variable between and within reviewers. CONCLUSIONS: We observed significant variability in manual segmentation of some of the temporal bone structures across reviewers. This variability needs to be considered when interpreting the results in studies using one manual reviewer.

Parameterisation and Prediction of Intra-canal Cochlear Structures.

Accurate 3D models of the cochlea are useful tools for research in the relationship between the electrode array and nerve fibres. The internal geometry of the cochlear canal plays an important role in understanding and quantifying that relationship. Predicting the location and shapes of the geometry is done by measuring histologic sections and fitting equations that can be used to predict parameters that fully define the geometry. A parameter sensitivity analysis is employed to prove that the size and location of the spiral lamina are the characteristics that most influence current distribution along target nerve fibres. The proposed landmark prediction method more accurately predicts the location of the points defining the spiral lamina in the apical region of the cochlea than methods used in previous modelling attempts. Thus, this technique can be used to generate 2D geometries that can be expanded to 3D models when high-resolution imaging is not available.

Complications After Pediatric Temporal Bone Fractures by Classification System: A Systematic Review and Meta-analysis.

OBJECTIVE: To analyze the rates of complications after pediatric temporal bone fractures (TBF) and the utility of the longitudinal, transverse, and mixed versus the otic capsule sparing (OCS) and otic capsule violating (OCV) classification systems in predicting these complications. DATA SOURCES: PubMed, Scopus, and CINAHL. REVIEW METHODS: Per PRISMA guidelines, studies of children with TBFs were included. Meta-analyses of proportions were performed. RESULTS: A total of 22 studies with 1376 TBFs were included. Children with TBF had higher rates of conductive hearing loss (CHL) than sensorineural hearing loss (SNHL) (31.3% [95% confidence interval [CI] 23.2-40.1] vs 12.9% [95% CI 8.9-17.5]). No differences in both CHL and SNHL were seen between longitudinal and transverse TBFs; however, OCV TBFs had higher rates of SNHL than OCS TBFs (59.3% [95% CI 27.8-87.0] vs 4.9% [95% CI 1.5-10.1]). Of all patients, 9.9% [95% CI 7.2-13.1] experienced facial nerve (FN) paresis/paralysis, and 13.4% [95% CI 5.9-23.2] experienced cerebrospinal fluid otorrhea. Transverse TBFs had higher rates of FN paresis/paralysis than longitudinal (27.7% [95% CI 17.4-40.0] vs 8.6% [95% CI 5.2-12.8]), but rates were similar between OCS and OCV TBFs. CONCLUSION: CHL was the most common complication after TBF in children; however, neither classification system was superior in identifying CHL. The traditional system was more effective at identifying FN injuries, and the new system was more robust at identifying SNHL. While these results suggest that both classification systems might have utility in evaluating pediatric TBFs, these analyses were limited by sample size. Future research on outcomes of pediatric TBFs stratified by type of fracture, mainly focusing on long-term outcomes, is needed.

Transoral robotic styloidectomy for Eagle syndrome: A systematic review.

OBJECTIVES: The aim of the study is to conduct a systematic review of the existing literature on styloidectomy performed through transoral robotic surgery (TORS) in Eagle syndrome (ES). DESIGN AND SETTING: Two independent reviewers (RC and AC) conducted a systematic review of PubMed and Embase databases, seeking articles on TORS performed for ES treatment. The search was conducted in July 2023. The review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PARTICIPANTS: The review included a total of 17 adult patients, comprising 12 females and 5 males, with an average age of 52.2 years, all diagnosed with ES. MAIN OUTCOME MEASURES: For each patient, we assessed the overall length of the styloid process, the affected side, total intervention duration, hospitalization duration, pre and postoperative Visual Analogue Scale (VAS) scores, and the presence of minor and major complications. RESULTS: We identified 4 articles describing 17 instances of TORS as a surgical treatment for ES in the literature, totaling 18 styloidectomies. The mean age of the patients was 52.2 years, with 12 females and 5 males. The average operation time, inclusive of the docking phase, was 68.8 minutes. Sixteen patients (94.1% of the total) experienced complete symptom disappearance or near-complete resolution after surgery. One patient (5.9%) showed improvement categorized as 'non-meaningful.' Only one case of minor complication was reported among the 17 procedures (5.9%).

Eagle jugular syndrome accompanied by de novo brainstem cavernous malformation: a case-based systematic review.

BACKGROUND: Eagle jugular syndrome (EJS), recently identified as a cause of cerebrovascular disease (CVD) due to venous obstruction by an elongated styloid process (SP), is reported here alongside a case of concurrent de novo cerebral cavernous malformation (CCM). This study aims to explore the potential causal relationship between EJS and de novo CCM through a comprehensive literature review. METHOD: Systematic literature reviews, spanning from 1995 to 2023, focused on EJS cases with definitive signs and symptoms and de novo CCM cases with detailed clinical characteristics. Data on the pathophysiology and clinical manifestations of EJS, as well as potential risk factors preceding de novo CCM, were collected to assess the relationship between the two conditions. RESULT: Among 14 patients from 11 articles on EJS, the most common presentation was increased intracranial hypertension (IIH), observed in 10 patients (71.4%), followed by dural sinus thrombosis in four patients (28.6%). In contrast, 30 patients from 28 articles were identified with de novo CCM, involving 37 lesions. In these cases, 13 patients developed CCM subsequent to developmental venous anomalies (43%), seven following dural arteriovenous fistula (dAVF) (23%), and two after sinus thrombosis (6%). In a specific case of de novo brainstem CCM, the development of an enlarged condylar emissary vein, indicative of venous congestion due to IJV compression by the elongated SP, was noted before the emergence of CCM. CONCLUSION: This study underscores that venous congestion, a primary result of symptomatic EJS, might lead to the development of de novo CCM. Thus, EJS could potentially be an indicator of CCM development. Further epidemiological and pathophysiological investigations focusing on venous circulation are necessary to clarify the causal relationship between EJS and CCM.

Experiences of Percutaneous Endoscopic Approach for the Mastoid Lesions: A Novel Minimally Invasive Ear Surgery.

OBJECTIVES: We developed a novel keyhole surgery, named "percutaneous endoscopic ear surgery" (PEES), with the aim of further reducing the invasiveness of otologic surgery. We reported the cases we encountered and retrospectively analyzed the invasiveness of PEES. METHODS: We analyzed the ears of eight patients who underwent PEES for mastoid lesions that could not be manipulated with transcanal endoscopic ear surgery (TEES) at our hospital between July 2021 and November 2022. We performed PEES alone in three patients, including one case of type A (preauricular incision) and two cases of type B (retroauricular incision). The last five patients underwent combined endoscopic ear surgery, which is simultaneous PEES and TEES. In these cases, one patient underwent type A PEES, and four patients underwent type B PEES. RESULTS: PEES was performed in all patients without converting to conventional microscopic mastoidectomy. The mean length of skin incisions was 19.1 ± 4.5 mm, which was smaller than that in conventional mastoidectomy. In all cases, the average length of the major axis of the keyhole was <10 mm, indicating that sufficient minimally invasive surgery was achieved. The average depth from the keyhole to the deepest site was 21.6 ± 8.9 mm. There was no change in the mean hearing level before and after the surgery. CONCLUSION: PEES is a minimally invasive procedure for manipulating lesions in the mastoid. In addition, the combination of PEES and TEES is an ideal, minimally invasive procedure that can be used to treat all regions of the temporal bone.

Traumatic Eagle's Syndrome: A Rare Cause of Neck Pain and Headache in Trauma Patients.

BACKGROUND Eagle syndrome can be a rare cause of neck pain and headache. The elongated styloid process typically irritates and compresses adjacent neurovascular structures in the neck, leading to insidious signs and symptoms classic of Eagle syndrome. However, neck pain after traumatic events can be the only sign of elongated styloid processes. Therefore, knowledge of this syndrome is necessary to prevent misdiagnosis and futile attempts at treatment, especially in the setting of trauma. CASE REPORT In this article, we report the case of a 20-year-old man who presented with throbbing neck pain and headache immediately after a motor vehicle accident. The patient's symptoms did not improve with analgesics and muscle relaxants. He was then admitted for overnight monitoring while awaiting computed tomography imaging of the head and neck, which revealed elongated styloid processes on both sides. CONCLUSIONS One of the most challenging aspects of diagnosing Eagle syndrome is the need for high clinical suspicion combined with adequate understanding of the neck anatomy and its structures. Owing to the proximity of the elongated styloid process to important neurovascular structures, such as the carotid arteries and vagus nerve, early diagnosis of Eagle syndrome is necessary to guide the clinical decision-making and provide optimal care for patients.

Intracochlear Trauma and Local Ossification Patterns Differ Between Straight and Precurved Cochlear Implant Electrodes.

HYPOTHESIS: Trauma to the osseous spiral lamina (OSL) or spiral ligament (SL) during cochlear implant (CI) insertion segregates with electrode type and induces localized intracochlear ossification and fibrosis. BACKGROUND: The goal of atraumatic CI insertion is to preserve intracochlear structures, limit reactive intracochlear tissue formation, and preserve residual hearing. Previous qualitative studies hypothesized a localized effect of trauma on intracochlear tissue formation; however, quantitative studies failed to confirm this. METHODS: Insertional trauma beyond the immediate insertion site was histologically assessed in 21 human temporal bones with a CI. Three-dimensional reconstructions were generated and virtually resectioned perpendicular to the cochlear spiral at high resolution. The cochlear volume occupied by ossification or fibrosis was determined at the midpoint of the trauma and compared with regions proximal and distal to this point. RESULTS: Seven cases, all implanted with precurved electrodes, showed an OSL fracture beyond the immediate insertion site. Significantly more intracochlear ossification was observed at the midpoint of the OSL fracture, compared with the -26 to -18 degrees proximal and 28 to 56 degrees distal to the center. No such pattern was observed for fibrosis. In the 12 cases with a perforation of the SL (9 straight and 3 precurved electrodes), no localized pattern of ossification or fibrosis was observed around these perforations. CONCLUSION: OSL fractures were observed exclusively with precurved electrodes in this study and may serve as a nidus for localized intracochlear ossification. Perforation of the SL, in contrast, predominantly occurred with straight electrodes and was not associated with localized ossification.