A Peculiar Case of Isolated Bilateral Tympanic Plate Fractures.

Tympanic plate fractures are uncommon injuries and carry the risk of external auditory canal stenosis. These injuries are often associated with fractures of adjacent bones like the mandible, maxilla, and temporal bone. Isolated bilateral tympanic bone fractures have rarely been reported. The most frequently advocated treatment for these injuries is surgical to prevent canal stenosis in the future. The effectiveness of non-operative management has been seldom reported. In the current case report, we present an uncommon injury with isolated bilateral tympanic plate fractures secondary to trauma to the mandible with no associated mandible or condylar fractures that were treated non-operatively. The functional outcomes were favorable at one year of follow-up.

The diagnostic conundrum in necrotizing otitis externa.

Necrotizing otitis externa (NOE) is an aggressive and fast-evolving infection of the external auditory canal. Late diagnoses and untreated cases can lead to severe, even fatal consequences and so early diagnosis and treatment are paramount. NOE is a notoriously challenging diagnosis to make. It is therefore important to understand what diagnostic modalities are available and how otolaryngologists can use them to accurately treat such an aggressive disease. This review aims to evaluate the different diagnostic options available in NOE and discuss their advantages and limitations, thus, providing an up-to-date picture of the multimodal approach required in the diagnosis of this disease.

The Petrosquamosal Sinus: A Rare Vascular Variant Encountered During Cochlear Implantation Surgery.

The petrosquamosal sinus is a rare and almost unknown emissary vein of the temporal bone. It traverses the middle cranial fossa along the petrosquamosal fissure and connects dural sinuses with extracranial venous networks. It is known to undergo normal involution during fetal and early postnatal life, and therefore is rarely found in humans. When encountered during surgery, it can be a significant source of bleeding hindering proper visualization of important surgical landmarks. Here we report the case of a PSS, encountered in a child during cochlear implantation surgery. We discuss its clinical significance and impact on the surgical approach. Laryngoscope, 2024.

Skull Base Osteomyelitis- Marauders of the Skull.

Skull base osteomyelitis is a vicious infection of temporal bone associated with very high morbidity and mortality. But few studies have been undertaken recently for eliciting its increasing incidence. Hence this study aims to describe the clinical profile of skull base osteomyelitis and changes noted in the post-covid period, and encourage a uniform treatment policy globally. This descriptive study was conducted among 140 patients diagnosed with skull base osteomyelitis. Data was collected using semi-structured proforma, HRCT temporal bone findings, microbiological reports, histopathology of granulation tissue, ESR and House-Brackmann grading. Male patients in 61-70 age group were most commonly affected and all patients had uncontrolled diabetes mellitus, usually presenting with nocturnal otalgia, ear canal granulation and cranial nerve palsy. Pseudomonas aeruginosa was the most common isolate followed by Staphylococcus aureus. Among fungal pathogens, candida albicans were the most common. 29.3% patients had extensive disease according to Thakar et al. staging and on follow up, 43.75% patients showed a satisfactory response. Coronary artery disease and cerebrovascular accidents were the leading cause of death. More atypical organisms, extensive disease and changes in antibiotic sensitivity were noted in the post-covid period. Prolonged treatment with culture sensitive antibiotic is the main stay of treatment. A uniform treatment guideline is needed for proper management of such patients. Level of Evidence 4.

Temporal bone squamous cell carcinoma: Aggressive behavior coursing with cerebellar invasion and hydrocephalus.

Background: Temporal bone squamous cell carcinoma (TBSCC) is a very rare condition. The prognosis is dismal for advanced tumors. Due to its rarity, information in the literature is scarce. Here, we report a unique case of TBSCC with cerebellar invasion and hydrocephalus. Case Description: A 46-year-old reported right-sided hearing loss and a painful right retroauricular mass for 4 months. Magnetic resonance imaging revealed a 8.7 × 7.6 × 6.4 cm mass invading the right temporal and occipital bones. After a biopsy and 3 surgical procedures over 6 months, the diagnosis of TBSCC was obtained. Due to invasion of the cerebellar tissue and obstructive hydrocephalus, a ventriculoperitoneal shunt was performed. The patient was referred for adjuvant radiotherapy. However, palliative care was initiated due to tumor progression. Conclusion: We report a case of advanced TBSCC with poor prognosis despite surgical treatment and radiotherapy. More data are necessary to provide new and better treatment to these patients.

Ultra-high-resolution CT of the temporal bone: The end of stapes prosthesis dimensional error and correlation with patient symptoms.

PURPOSE: To describe the reliability of ultra-high-resolution computed tomography (UHR-CT) in the measurement of titanium stapes prostheses using manufacturer data as a reference. MATERIALS AND METHODS: This retrospective study included patients treated by stapedectomy with titanium prostheses who underwent UHR-CT between January 2020 and October 2023. Images were acquired using an ultra-high-resolution mode (slice thickness: 0.25 mm; matrix, 1024 × 1024). Two radiologists independently evaluated the length, diameter, and intra-vestibular protrusion of the prosthesis. Post-operative air-bone gaps (ABGs) were recorded. RESULTS: Fourteen patients were enrolled (mean age, 44.3 ± 13.8 [SD] years, 9 females), resulting in 16 temporal bone UHR-CTs. The exact length was obtained in 81.3 % (n = 13/16) and underestimated by 0.1 to 0.3 mm in the remaining 18.7 % (n = 3/16) CT scans for both readers (mean misestimation: -0.02 ± 0.06 [SD] mm, overall underestimation of 0.43 %). The exact diameter was reported in 75 % (n = 12/16) and 87.5 % (n = 14/16) of the CT scans for readers 1 and 2, respectively, and was off by 0.1 mm in all discrepancies (mean misestimation: 0.01 ± 0.04 [SD] mm, overall overestimation of 2.43 %). Intravestibular prosthesis protrusion was of 0.5 ± 0.43 [SD] mm (range: 0-1) and 0.49 ± 0.44 [SD] mm (range: 0-1.1) for readers 1 and 2, respectively, and did not correlate with ABGs (r = 0.25 and 0.22; P = 0.39 and 0.47 for readers 1 and 2, respectively). Intra and interobserver agreements were excellent. CONCLUSION: UHR-CT provides 99.6 % and 97.6 % accuracy for prosthesis length and diameter measurements, respectively.

Submental Island Flaps for Lateral Reconstruction: Technical Refinements for Optimal Outcomes and Resource Efficiency.

Objective: To describe our modifications to the submental island flap (SMIF) in a case series that demonstrates improved reproducibility, shortened length of stay (LOS), and reduced utilization of hospital resources. Study Design: This retrospective case series with chart review included adult patients who underwent resection of malignant or benign tumors resulting in lateral facial, parotid, or temporal bone defects, which were reconstructed with SMIF. Setting: A tertiary-care academic referral center. Methods: Retrospective case series included all adult patients who underwent SMIF reconstruction between March 2020 and August 2021. Patient demographic and clinical data were collected. Primary outcomes were measures of hospital utilization including duration of surgery, LOS, and postoperative outcomes. Results: Twenty-eight patients were included with a mean age of 71.7 years. Eighty percent were male. All patients underwent parotidectomy, and the mean operative time was 347 minutes. The median LOS was 2.5 days (range 0-16 days). Seventy-five percent of the flaps drained into the internal jugular vein, and 25% drained into the external jugular vein. No patients required reoperation or readmission. All flaps survived. Conclusion: SMIFs are a safe and effective option for reconstruction of lateral facial, parotid, and temporal bone defects. Compared to free flap reconstruction, SMIFs offer reduced length of surgery, decreased use of health care resources, and lower rate of reoperation. As health care resource allocation is increasingly important, the SMIF offers an excellent alternative to free flap reconstruction of lateral defects.

Hampshire Sheep as a Large-Animal Model for Cochlear Implantation.

BACKGROUND: Sheep have been proposed as a large-animal model for studying cochlear implantation. However, prior sheep studies report that the facial nerve (FN) obscures the round window membrane (RWM), requiring FN sacrifice or a retrofacial opening to access the middle-ear cavity posterior to the FN for cochlear implantation. We investigated surgical access to the RWM in Hampshire sheep compared to Suffolk-Dorset sheep and the feasibility of Hampshire sheep for cochlear implantation via a facial recess approach. METHODS: Sixteen temporal bones from cadaveric sheep heads (ten Hampshire and six Suffolk-Dorset) were dissected to gain surgical access to the RWM via an extended facial recess approach. RWM visibility was graded using St. Thomas' Hospital (STH) classification. Cochlear implant (CI) electrode array insertion was performed in two Hampshire specimens. Micro-CT scans were obtained for each temporal bone, with confirmation of appropriate electrode array placement and segmentation of the inner ear structures. RESULTS: Visibility of the RWM on average was 83% in Hampshire specimens and 59% in Suffolk-Dorset specimens (p = 0.0262). Hampshire RWM visibility was Type I (100% visibility) for three specimens and Type IIa (> 50% visibility) for seven specimens. Suffolk-Dorset RWM visibility was Type IIa for four specimens and Type IIb (< 50% visibility) for two specimens. FN appeared to course more anterolaterally in Suffolk-Dorset specimens. Micro-CT confirmed appropriate CI electrode array placement in the scala tympani without apparent basilar membrane rupture. CONCLUSIONS: Hampshire sheep appear to be a suitable large-animal model for CI electrode insertion via an extended facial recess approach without sacrificing the FN. In this small sample, Hampshire specimens had improved RWM visibility compared to Suffolk-Dorset. Thus, Hampshire sheep may be superior to other breeds for ease of cochlear implantation, with FN and facial recess anatomy more similar to humans.

Automated detection of otosclerosis with interpretable deep learning using temporal bone computed tomography images.

Objective: This study aimed to develop an automated detection schema for otosclerosis with interpretable deep learning using temporal bone computed tomography images. Methods: With approval from the institutional review board, we retrospectively analyzed high-resolution computed tomography scans of the temporal bone of 182 participants with otosclerosis (67 male subjects and 115 female subjects; average age, 36.42 years) and 157 participants without otosclerosis (52 male subjects and 102 female subjects; average age, 30.61 years) using deep learning. Transfer learning with the pretrained VGG19, Mask RCNN, and EfficientNet models was used. In addition, 3 clinical experts compared the system's performance by reading the same computed tomography images for a subset of 35 unseen subjects. An area under the receiver operating characteristic curve and a saliency map were used to further evaluate the diagnostic performance. Results: In prospective unseen test data, the diagnostic performance of the automatically interpretable otosclerosis detection system at the optimal threshold was 0.97 and 0.98 for sensitivity and specificity, respectively. In comparison with the clinical acumen of otolaryngologists at P < 0.05, the proposed system was not significantly different. Moreover, the area under the receiver operating characteristic curve for the proposed system was 0.99, indicating satisfactory diagnostic accuracy. Conclusion: Our research develops and evaluates a deep learning system that detects otosclerosis at a level comparable with clinical otolaryngologists. Our system is an effective schema for the differential diagnosis of otosclerosis in computed tomography examinations.

Integration of 3D-printed middle ear models and middle ear prostheses in otosurgical training.

BACKGROUND: In otosurgical training, cadaveric temporal bones are primarily used to provide a realistic tactile experience. However, using cadaveric temporal bones is challenging due to their limited availability, high cost, and potential for infection. Utilizing current three-dimensional (3D) technologies could overcome the limitations associated with cadaveric bones. This study focused on how a 3D-printed middle ear model can be used in otosurgical training. METHODS: A cadaveric temporal bone was imaged using microcomputed tomography (micro-CT) to generate a 3D model of the middle ear. The final model was printed from transparent photopolymers using a laser-based 3D printer (vat photopolymerization), yielding a 3D-printed phantom of the external ear canal and middle ear. The feasibility of this phantom for otosurgical training was evaluated through an ossiculoplasty simulation involving ten otosurgeons and ten otolaryngology-head and neck surgery (ORL-HNS) residents. The participants were tasked with drilling, scooping, and placing a 3D-printed partial ossicular replacement prosthesis (PORP). Following the simulation, a questionnaire was used to collect the participants' opinions and feedback. RESULTS: A transparent photopolymer was deemed suitable for both the middle ear phantom and PORP. The printing procedure was precise, and the anatomical landmarks were recognizable. Based on the evaluations, the phantom had realistic maneuverability, although the haptic feedback during drilling and scooping received some criticism from ORL-HNS residents. Both otosurgeons and ORL-HNS residents were optimistic about the application of these 3D-printed models as training tools. CONCLUSIONS: The 3D-printed middle ear phantom and PORP used in this study can be used for low-threshold training in the future. The integration of 3D-printed models in conventional otosurgical training holds significant promise.

Solitary Bone Plasmacytoma of the Skull Base With an Unusual Presentation.

Solitary bone plasmacytoma (SBP) is a rare hematological malignancy that usually occurs in the spine and rarely in the skull. It rarely presents in the skull base, but presenting symptoms are associated with cranial nerve involvement depending on the site of the disease. We present the case of a 61-year-old man with an unusual presentation of hoarseness secondary to vocal fold palsy. Imaging showed a large bony lesion in the temporo-occipital region with involvement of the jugular foramen. Further detailed diagnostic procedures confirmed SBP of the skull base. Radiotherapy was given with an uneventful recovery of vocal fold function. Skull base plasmacytoma can be considered as a differential diagnosis of causes of unilateral vocal fold palsy. Early therapeutic management may improve vocal fold function.

Evaluation of surgical skill among otology residents during cadaveric temporal bone dissection using an objective assessment tool.

Background: The acquisition and refinement of technical skills by the surgical residents are central to surgical teaching; hence, there is increasing interest in the objective assessment of surgical competence. In the field of otology, as of now, there are limited studies for the assessment of surgical competence, also, various subjective methods are being used to assess this vital aspect of training. This study aimed to validate and use an objective assessment tool for the valuation of surgical skills in a tertiary care teaching institute in the Indian subcontinent. Methods: Surgical competence of the residents in temporal bone dissection was assessed on a Likert scale by using a grading scale developed by Wan et al., after obtaining necessary permissions. Results: Junior residents in ENT who had completed one year of residency in otolaryngology were asked to perform temporal bone surgery (cortical mastoidectomy) and were marked according to the proforma by two senior experienced otologists. The Cronbach's alpha value was .86 which is an indicator of good technical validity. Conclusions: In our study, we have validated a grading scoring scale used by Wan et al. to objectively assess the ability of an otology resident to perform temporal bone surgery. It is recommended for use in Indian scenario due to its good technical validity. The use of a Likert scale to individually rate each competency makes the evaluation precise and simple.

Development and validation of a surgical planning tool for bone-conduction implants.

Background: The BONEBRIDGE® (Med-El GmbH) is a bone-conduction device comprising an external audio processor and an internal Bone Conduction-Floating Mass Transducer (BC-FMT) surgically anchored to the temporal bone. Due to the implant's size, its placement may be challenging in certain anatomies, necessitating thorough surgical planning. Manual planning methods are laborious, time-intensive, and prone to errors. This study aimed to develop and validate an automated algorithm for determining skull thickness, aiding in the surgical planning of the BONEBRIDGE and other devices requiring similar bone thickness estimations. Materials and methods: Twelve cadaveric temporal bones underwent clinical computed tomography (CT). A custom Python algorithm was developed to automatically segment bone from soft tissue, generate 3D models, and perform ray-tracing to estimate bone thickness. Two thickness colormaps were generated for each sample: the cortical thickness to the first air cell and the total thickness down to the dura. The algorithm was validated against expert manual measurements to achieve consensus interpretation. Results: The algorithm estimated bone-to-air thicknesses (mean = 4.7 mm, 95% Confidence Interval [CI] of 4.3-5.0 mm) that closely matched the expert measurements (mean = 4.7 mm, CI of 4.4-5.0 mm), with a mean absolute difference (MAD) of 0.3 mm. Similarly, the algorithm's estimations to the dura (6.0 mm, CI of 5.4-6.5 mm) were comparable to the expert markings (5.9 mm, CI of 5.4-6.5 mm), with a MAD of 0.3 mm. Conclusions: The first automated algorithm to calculate skull thickness to both the air cells and dura in the temporal bone was developed. Colormaps were optimized to aid with the surgical planning of BONEBRIDGE implantation, however the tool can be generalized to aid in the surgical planning of any bone thickness application. The tool was published as a freely available extension to the open-source 3D Slicer software program (www.slicer.org).

Deep learning reconstruction for high-resolution computed tomography images of the temporal bone: comparison with hybrid iterative reconstruction.

PURPOSE: We investigated whether the quality of high-resolution computed tomography (CT) images of the temporal bone improves with deep learning reconstruction (DLR) compared with hybrid iterative reconstruction (HIR). METHODS: This retrospective study enrolled 36 patients (15 men, 21 women; age, 53.9 ± 19.5 years) who had undergone high-resolution CT of the temporal bone. Axial and coronal images were reconstructed using DLR, HIR, and filtered back projection (FBP). In qualitative image analyses, two radiologists independently compared the DLR and HIR images with FBP in terms of depiction of structures, image noise, and overall quality, using a 5-point scale (5 = better than FBP, 1 = poorer than FBP) to evaluate image quality. The other two radiologists placed regions of interest on the tympanic cavity and measured the standard deviation of CT attenuation (i.e., quantitative image noise). Scores from the qualitative and quantitative analyses of the DLR and HIR images were compared using, respectively, the Wilcoxon signed-rank test and the paired t-test. RESULTS: Qualitative and quantitative image noise was significantly reduced in DLR images compared with HIR images (all comparisons, p ≤ 0.016). Depiction of the otic capsule, auditory ossicles, and tympanic membrane was significantly improved in DLR images compared with HIR images (both readers, p ≤ 0.003). Overall image quality was significantly superior in DLR images compared with HIR images (both readers, p < 0.001). CONCLUSION: Compared with HIR, DLR provided significantly better-quality high-resolution CT images of the temporal bone.

The variations of osseous structure of the internal acoustic canal: an anatomical study.

OBJECTIVES: The internal acoustic meatus is an osseous canal that connects the inner ear to the posterior cranial fossa. It is located in the petrous portion of the temporal bone. A thin cribriform osseous plate known as the fundus is situated at the lateral end of the canal. This study assesses the structural and numerical variations of the fundus formations. METHODS: Fifty-four temporal bones of unknown gender and age were examined with the surgical microscope. RESULTS: The temporal bones analyzed were 46.2% right-sided and 53.7% left-sided. Only one temporal bone had two parallel transverse crests, while three had a single anterior crest that split into two branches posteriorly. The number of foramina at the transverse crest varied, with 29.6% having none, 48.1% having a single foramen, and 22.2% having several foramina. An anterior crest structure was seen in 53.7% of the temporal bones, with 5% having a slightly constricted entry to the facial canal. In cases with a single nerve foramen, 48.1% had one, while 51.8% had more than one, including examples with three or four foramina. A crest was found between the foramina of the single nerve in 7% of patients. Furthermore, a crest between the saccular nerve foramen and the high fiber foramina was seen in 25.9% of cases, and 5% had two saccular nerve foramina. CONCLUSION: We think that revealing the anatomical, structural and numerical variations in the fundus will be useful in explaining the disease-symptom relationship. LEVEL OF EVIDENCE: Level 4.

Moving Beyond the Temporal Bone Lab: Creating a Drilling Station in the Otolaryngology Clinic.

With the advent of operable 3-dimensional (3D)-printed models, case preparation could occur outside of the cadaveric laboratory. The objective of this study was to design a mobile drilling station that can be used for surgical practice in a variety of clean workplaces. Using materials obtained from hardware stores and online retailers, a wheelable drilling station was constructed to mimic laboratory conditions while also being easily maneuverable into clinic rooms. The station houses the otologic drill, suction, and irrigation mechanisms, is height adjustable, and has a shielded workspace. The mobile drilling station was moved into a microscope-containing otolaryngology clinic room where faculty and trainees were asked to drill a pediatric 3D-printed temporal bone followed by completing an evaluation survey. This is the first mobile drilling station described in the literature and can be easily constructed, mobilized, and used in an otolaryngology clinic for dedicated surgical practice using 3D-printed models.

[Online training for hearing implant surgery : A new approach to otological training. German version]. / Online-Training für Hörimplantatchirurgie : Ein neuer Ansatz in der otologischen Ausbildung.

OBJECTIVE: Education in microsurgery of the ear includes staged training to allow for mastering of the complex microsurgical procedures, particularly in the context of middle ear reconstruction and cochlear implantation. Traditional surgical training includes temporal bone preparations by cadaver dissection and supervised operating room practice. As these on-site trainings are limited, there is a need to broaden education facilities in an on-line format. Therefore, a first basic on-line training for otosurgery was developed. MATERIALS AND METHODS: The system consists of an artificial temporal bone model together with a set of basic surgical instruments and implant dummies. As an essential part of the training kit, a high-resolution camera set is included that allows for connection to a video streaming platform and enables remote supervision of the trainees' surgical steps by experienced otological surgeons. In addition, a pre-learning platform covering temporal bone anatomy and instrumentation and pre-recorded lectures and instructional videos has been developed to allow trainees to review and reinforce their understanding before hands-on practice. RESULTS: Over the three courses held to date, 28 participants with varying levels of prior surgical experience took part in this otological surgical training program. The immediate feedback of the participants was evaluated by means of a questionnaire. On this basis, the high value of the program became apparent and specific areas could by identified where further refinements could lead to an even more robust training experience. CONCLUSION: The presented program of an otosurgical online training allows for basal education in practical exercises on a remote system. In this way, trainees who have no direct access to on-site instruction facilities in ear surgery now have the chance to start their otosurgical training in an educational setting adapted to modern technologies.

Middle meningeal artery arising from the petrous internal carotid artery: Outcome of unusual stapedial artery regression.

Background: The internal and external carotid arterial systems are generally separate regarding branching patterns. However, these two systems do form collateral circulations with their terminal parts. On rare occasions, branches that belong to one arterial system may arise from the other. Case Description: We present a rare variant of a middle meningeal artery, generally derived from the external carotid artery, arising from the internal carotid artery and entering the floor of the middle cranial fossa by traveling through a small unnamed foramen. This anatomy and embryology and other variants of the middle meningeal and petrous carotid systems are discussed. Conclusion: Embryologically, this variant anatomy signifies an atypical regression of the distal stapedial artery and its connection to the external carotid artery. Surgeons who operate on the skull base, vascular interventionalists, and radiologists should be aware of this potential anatomical variation of the skull base.

Traumatic arteriovenous fistula of the middle meningeal artery treated with selective coil embolization: A case report.

Background: Dural arteriovenous fistulas (AVFs) are reportedly induced by trauma. We report a rare case of traumatic AVF with a direct shunt from the middle meningeal artery (MMA) to the middle meningeal vein (MMV) and multiple drainage routes after head trauma. The patient was effectively treated with selective coil embolization alone without liquid embolic material. Case Description: A 56-year-old woman was admitted to the emergency department with mild disturbance of consciousness caused by a head contusion after alcohol consumption. She exhibited impaired consciousness with a Glasgow coma scale score of 14 (E4V4M6), complained of headache, and presented with a hemorrhage in the left ear. Computed tomography suggested a skull fracture and cerebral hemorrhage. Magnetic resonance imaging conducted on the 4th day after the injury indicated shunt disease with a feeder in the right MMA. Cerebral angiography on the 7th day suggested a direct shunt from the right MMA to the MMV aligned with the temporal bone fracture line, with multiple drainage route perfusion. Coil embolization was performed on the 14th day to occlude the shunt point selectively. In the final image, the MMA was absent, and the MMV, superior sagittal sinus, or pterygoid plexus was not visible through the shunt. Her symptoms improved, and she was discharged on the 20th day and did not exhibit recurrence at the 1-year follow-up. Conclusion: AVF with a direct shunt from the MMA to MMV after head trauma can be effectively and safely treated with coil embolization alone, despite the need for long-term postoperative follow-up.

Traumatic Events Preceding the Development of Superior Canal Dehiscence Syndrome.

OBJECTIVE: To describe the features of antecedent head trauma in patients with superior canal dehiscence syndrome (SCDS). STUDY DESIGN: Cross-sectional survey. SETTING: Tertiary referral center. METHODS: An online survey was sent to 450 adult patients who underwent surgical repair for SCDS patients asking questions about the nature of internal or external traumatic events preceding symptoms. RESULTS: One-hundred and thirty-six patients (avg. age, 51.9 years, 62.8% female) completed the survey, of which 61 (44.9%) described either preceding external head trauma (n = 35, 26%), preceding internal pressure event (n = 33, 25%), or both (8, 6%). Of those endorsing external trauma, 22 (63%) described a singular event (head hit by object (n = 8); head hit ground (n = 5); motor vehicle accident (n = 4); assault (n = 2); other (n = 3). One-third experienced loss of consciousness because of the trauma. For those describing internal pressure events (n = 33), the most common events were heavy physical exertion (9, 27%); pressure changes while flying (6, 18%); coughing, nose blowing with illness (5, 15%); childbirth (5, 15%); and self contained underwater breathing apparatus diving events (3, 9%). The interval between trauma and onset of symptoms averaged 5.6 years (SD, 10.7 years). One-third (n = 19) described onset of symptoms immediately after the external trauma or internal pressure event. Symptoms began on the side ipsilateral to the trauma in 91%. Sound- and pressure-induced vertigo/oscillopsia developed more commonly after external trauma versus internal pressure events (68% and 61% vs 44% and 32%, respectively). CONCLUSION: Trauma or internal pressure-related events precede SCDS symptoms in nearly half of cases, with roughly half of preceding events being external.