Intermitochondrial signaling regulates the uniform distribution of stationary mitochondria in axons.

In the central nervous system (CNS), many neurons develop axonal arbors that are crucial for information processing. Previous studies have demonstrated that premature axons contain motile and stationary mitochondria, and their balance is important for axonal arborization. However, the mechanisms by which neurons determine the positions of stationary mitochondria as well as their turnover remain to be elucidated. We observed that the distribution of stationary mitochondrial spots along the unmyelinated and nonsynaptic axons is not random but rather relatively uniform both in primary cultured neurons and in tissues. Intriguingly, whereas the positions of each mitochondrial spot changed over time, the overall distribution remained uniform. In addition, local inactivation of mitochondria by KillerRed mediated chromophore-assisted light inactivation (CALI) inhibited the translocation of mitochondrial spots in adjacent axonal regions, suggesting that functional mitochondria enhance the motility of other mitochondria in the vicinity. Signals of ATP:ADP sensor, PercevalHR indicated that the ATP:ADP ratio was relatively high around mitochondria, and treating axons with phosphocreatine (PCr), which supplies ATP, reduced the immobile mitochondria induced by the local mitochondrial inactivation. In a mathematical model, we found that the ATP gradient generated by mitochondria, and ATP dependent regulation of mitochondrial motility could establish uniform mitochondrial distribution. These observations suggest that axons in the CNS possess the system that distributes mitochondria uniformly, and intermitochondrial signaling contribute to the regulation. In addition, our results suggest the possibility that ATP might be one of the molecules mediating the signaling.

Genetic landscape of external auditory canal squamous cell carcinoma.

External auditory canal squamous cell carcinoma (EACSCC) is an extremely rare and aggressive malignancy. Due to its rarity, the molecular and genetic characteristics of EACSCC have not yet been elucidated. To reveal the genetic alterations of EACSCC, we performed whole exome sequencing (WES) on 11 primary tumors, 1 relapsed tumor and 10 noncancerous tissues from 10 patients with EACSCC, including 1 with a rare case of synchronous bilateral EACSCC of both ears. WES of the primary tumor samples showed that the most frequently mutated gene is TP53 (63.6%). In addition, recurrent mutations in CDKN2A, NOTCH1, NOTCH2, FAT1 and FAT3 were detected in multiple samples. The mutational signature analysis of primary tumors indicated that the mutational processes associated with the activation of apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) deaminases are the most common in EACSCC, suggesting its similarity to SCC from other primary sites. Analysis of arm-level copy number alterations detected notable amplification of chromosomes 3q, 5p and 8q as well as deletion of 3p across multiple samples. Focal chromosomal aberrations included amplifications of 5p15.33 (ZDHHC11B) and 7p14.1 (TARP) as well as deletion of 9p21.3 (CDKN2A/B). The protein expression levels of ZDHHC11B and TARP in EACSCC tissues were validated by immunohistochemistry. Moreover, WES of the primary and relapsed tumors from a case of synchronous bilateral EACSCC showed the intrapatient genetic heterogeneity of EACSCC. In summary, this study provides the first evidence for genetic alterations of EACSCC. Our findings suggest that EACSCC mostly resembles other SCC.

Use of negative pressure wound therapy to treat a cochlear implant infection around the auricle: a case report.

Although negative pressure wound therapy (NPWT) is widely used, its application to the head and neck region remains challenging due to anatomical complexities. This report presents the case of a female patient presenting with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes, uncontrolled diabetes and severe bilateral sensorineural hearing loss. The patient had undergone cochlear implant surgery and five months later the wound was infected with methicillin-resistant Staphylococcus aureus (MRSA). NPWT was started shortly after removing the internal receiver and was stopped 11 days later. NPWT helped in controlling infection and led to a successful wound closure. In this case, NPWT was effective in treating infectious wounds around the auricle after cochlear implant surgery. Declaration of interest: The authors have no financial support for this article and no conflict of interest directly relevant to the content of this article.

Ultrahigh-resolution CT scan of the temporal bone.

OBJECTIVE: Ultrahigh-resolution CT (U-HRCT) provides better spatial resolution than conventional multi-detector row CT (ConvCT) and could be expected to identify microstructures with its 0.25-mm collimation, 1792 channels and 160 detector rows, 0.4 × 0.5 mm focus size, and a 1024 matrix. The aim of the study was to evaluate key anatomic structures in temporal bone using U-HRCT comparing it to ConvCT. MATERIALS AND METHODS: A total of 30 patients (14 males and 16 females; age range, 8-82 years; median 49 years) underwent both U-HRCT and ConvCT. All CT images were obtained with 0.5 mm section thickness and a 512 × 512 matrix, and field of view of 80 mm. Transverse scans were acquired in a plane parallel to the orbitomeatal plane in the helical mode with 120 kV. Images of the 30 temporal bones of unaffected side were reviewed by two independent neuroradiologists who rated the visibility of key anatomic structures for both U-HRCT and ConvCT. The ratings between U-HRCT and ConvCT were compared using Wilcoxon matched-pairs signed rank test. The interobserver agreement on the rating of stapedius tendon was evaluated using weighted κ statistics. RESULTS: Excellent interobserver agreement was shown for U-HRCT (κ = 0.920), whereas good agreement was obtained for ConvCT (κ = 0.733). According to both observers, stapedius tendon was more clearly visualized using U-HRCT than ConvCT (p < 0.0001). All other anatomic structures were well visualized using both CT scanners. CONCLUSION: The anatomy of temporal bone is more conspicuous on U-HRCT than on ConvCT because of its ultra-high-resolution detector. U-HRCT may provide beneficial information for determining surgical indication or procedures.

High-resolution three-dimensional diffusion-weighted MRI/CT image data fusion for cholesteatoma surgical planning: a feasibility study.

The aim of the study was to assess the feasibility of high-resolution three-dimensional diffusion-weighted images (HR3D-DWIs)/multi-detector row CT (MDCT) images' data fusion for surgical planning for cholesteatoma. A total of 12 patients (7 male and 5 female; age range 11-72 years; mean 38.1 years) with cholesteatoma underwent preoperative MRI using a 3.0-T clinical unit and an 8-channel array-head coil. For each subject, HR3D-DWIs were obtained using a turbo field-echo with diffusion-sensitized driven-equilibrium preparation with 1.5 mm iso-voxel dimension. These patients also underwent MDCT with a slice thickness of 0.5 mm. Fusion of the HR3D-DWIs and MDCT images was performed using an automated rigid registration and subsequent manual fine-tuning by a board-certified neuroradiologist on a workstation. Fused images were compared to CT and findings confirmed based on operation reports. On the fused images, the extent of the cholesteatoma, which was depicted as a conspicuous high-intensity lesion could be easily evaluated with background bony structures. In all patients, the location and extent of the cholesteatoma on the fused images corresponded well with the intraoperative findings. Image fusion between HR3D-DWIs and MDCT images is feasible, and provides valuable preoperative information for surgical planning to otorhinolaryngologists.

Template-guided implantation of the Bonebridge: clinical experience.

The surgical procedure for Bonebridge implantation cannot be done in some cases without exposing the dura mater or sigmoid sinus. Surgical simulation technology can help to identify such difficulties prior to surgery and be used to clarify the optimal location and orientation of the device to be implanted. However, there has not been a simple strategy to drill the temporal bone at exactly the same location as that simulated on the computer. Based on our previous development of the surface template-assisted marker positioning (STAMP) method for performing image-guided otologic surgery, we recently developed a noninvasive guiding method, the BB-STAMP method, for performing image-guided Bonebridge implantation. Three patients underwent Bonebridge implantation at our surgical center during the years of 2013-2014. The authors in the simulation center supported the surgery using the BB-STAMP method. The time and effort required to prepare for the surgery were evaluated. In addition, a postoperative analysis was performed to assess the accuracy of placing the device in the planned location. The BB-STAMP method enabled the surgeon to precisely replicate the computer simulation in the real patient with submillimetric accuracy without complexity. Thus, the use of experienced and elaborative simulation coupled with the creation of a tailor-made three-dimensional template (BB-STAMP) enables surgeons to perform quick, precise and safe surgical procedures at distant institutions.

High-risk HPV-related squamous cell carcinoma in the temporal bone: a rare but noteworthy subtype.

High-risk human papillomavirus (HPV) is a risk factor for the development of several head and neck squamous cell carcinomas (SCCs). However, there have been few reports of high-risk HPV infection in temporal bone squamous cell carcinomas (TBSCCs), and thus the prevalence and clinicopathologic significance of high-risk HPV in TBSCCs are still unclear. We retrospectively collected 131 TBSCCs and analyzed them for transcriptionally active high-risk HPV infection using messenger RNA in situ hybridization; we also assessed the utility of p16-immunohistochemistry (IHC) and Rb-IHC to predict HPV infection. Eighteen (13.7%) of the 131 TBSCCs were positive for p16-IHC, and five of them were positive for high-risk HPV infection (the estimated high-risk HPV positivity rate was 3.8% [5/131]). Interestingly, all five HPV-positive patients were male and had TBSCC on the right side. In the p16-IHC+/HPV+ cases (n = 5), the Rb-IHC showed a partial loss pattern (n = 4) or complete loss pattern (n = 1). In contrast, all p16-IHC-negative cases (n = 113) showed an Rb-IHC preserved pattern. The positive predictive value (PPV) of p16-IHC positivity for high-risk HPV infection was low at 27.8%, while the combination of p16-IHC+/Rb-IHC partial loss pattern showed excellent reliability with a PPV of 100%. The prognostic significance of high-risk HPV infection remained unclear. High-risk HPV-related TBSCC is an extremely rare but noteworthy subtype.

Acute necrotic disorder of the small intestine post-coronavirus disease-2019 vaccination.

The Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccine is extensively used worldwide, and its safety has been proven. Herein, we report a case of an acute necrotic disorder in the small intestine post-COVID-19 vaccination. The patient developed severe abdominal pain the day after the first vaccination. Contrast-enhanced computed tomography showed extensive ileum wall thickening and ascites. Colonoscopy revealed a ring-shaped ulcer and stricture in the terminal ileum. Ileocecal resection was performed, and the patient did not have further episodes of a necrotic disorder in the small intestine. Although it is unknown if this event is associated with vaccination, and this occurrence also does not outweigh the efficacy and safety of the Pfizer-BioNTech COVID-19 vaccine, gastroenterologists need to be aware of this rare case, given its noteworthy timing.

No evidence for an association between persistent measles virus infection and otosclerosis among patients with otosclerosis in Japan.

Otosclerosis, which is characterized by disordered bone remodeling, occurs exclusively in the human temporal bone. The etiology of the disease is unknown, but a popular hypothesis is that it is caused by persistent measles virus (MV) infection. Paramyxovirus-like filamentous structures were found in otosclerotic lesions of stapes footplates from patients with otosclerosis. Although MV RNAs have been detected in otosclerotic samples by using reverse transcription-PCR, no complete MV mRNA sequence has been reported, nor has infectious virus been isolated from clinical samples. Furthermore, one study failed to obtain evidence of MV infection in otosclerotic bone samples. In this study, we tested, by three different protocols, for the presence of MV in clinical samples from patients with otosclerosis in Japan. We used a highly sensitive reverse transcription-quantitative PCR method which is able to detect viral mRNA in cells infected with MV at around one infectious unit per well. We obtained no evidence of MV infection in bone samples, primary cell cultures derived from stapes bones, or MV-susceptible cell lines (Vero/hSLAM and II-18 cells) cocultured with bone samples or primary cell cultures derived from them. Thus, our results do not support the hypothesis that persistent MV infection is involved in the pathoetiology of otosclerosis.

Mice lacking ganglioside GM3 synthase exhibit complete hearing loss due to selective degeneration of the organ of Corti.

The ganglioside GM3 synthase (SAT-I), encoded by a single-copy gene, is a primary glycosyltransferase for the synthesis of complex gangliosides. In SAT-I null mice, hearing ability, assessed by brainstem auditory-evoked potentials (BAEP), was impaired at the onset of hearing and had been completely lost by 17 days after birth (P17), showing a deformity in hair cells in the organ of Corti. By 2 months of age, the organ of Corti had selectively and completely disappeared without effect on balance or motor function or in the histology of vestibule. Interestingly, spatiotemporal changes in localization of individual gangliosides, including GM3 and GT1b, were observed during the postnatal development and maturation of the normal inner ear. GM3 expressed in almost all regions of cochlea at P3, but at the onset of hearing it distinctly localized in stria vascularis, spiral ganglion, and the organ of Corti. In addition, SAT-I null mice maintain the function of stria vascularis, because normal potassium concentration and endocochlear potential of endolymph were observed even when they lost the BAEP completely. Thus, the defect of hearing ability of SAT-I null mice could be attributed to the functional disorganization of the organ of Corti, and the expression of gangliosides, especially GM3, during the early part of the functional maturation of the cochlea could be essential for the acquisition and maintenance of hearing function.

Evaluation of volitional and reflexive swallowing in elderly patients with a history of pneumonia.

OBJECTIVES: Precise assessment of the risk of aspiration is critical in older patients with a history of pneumonia. However, the currently popular videofluoroscopic and videoendoscopic examinations of swallowing only evaluate volitional swallowing. A method for quantitative analysis of reflexive swallowing is not yet available. METHODS: We evaluated volitional swallowing in the sitting position by videoendoscopic examination and then measured the volume of injected water that triggered reflexive swallowing in the supine position in 54 patients with a history of pneumonia and 24 control patients of a similar age who had no history of pneumonia. RESULTS: The volume of injected water that triggered reflexive swallowing was larger in the pneumonia group than in the control group (mean, 1.64 +/- 0.61 mL versus 0.71 +/- 0.28 mL; p < 0.001). Both impaired volitional swallowing and impaired reflexive swallowing independently correlated with a history of pneumonia. CONCLUSIONS: The endoscopic supine swallow-evoking test ("ESSET") may detect previously omitted risk factors for aspiration in patients who can volitionally swallow.

Orientation of the Cochlea From a Surgeon's Perspective.

Background: One of the mechanisms that cause tip fold-over is a misalignment between the electrode array's coiling direction and the cochlea's curving direction. Objectives: We reviewed surgical videos and computed tomography (CT) datasets of the patients who underwent cochlear implantation procedures from January 2010 to December 2021, paying particular attention to the cochlea's orientation in the surgeon's microscopic view. Methods: CT dataset and video recordings were analyzed to measure the "slope angle," which is the angle between the cochlea's coiling plane and the horizontal plane. Results: There were 220 cases that met the criteria and completed the analysis. The mean slope angle was 12.1° ± 9.5°, with a minimum of -9.4° and maximum of 44.6°. However, each surgeon had a favored slope angle range. Conclusion: Understanding the slope angle and making an effort to reduce the chance of misalignment during electrode insertion may help prevent tip fold-over of slim perimodiolar electrode arrays.

Factors Influencing the Purchase Rate of Cartilage Conduction Hearing Aids.

BACKGROUND: Innovated hearing aids (HAs), termed cartilage conduction hearing aids (CC-HAs), show good performance in patients with closed ears and continuous otorrhea. However, factors other than the ear condition that influence the purchase rate of CC-HAs remain unclear. PURPOSE: To identify the factors that influence the purchase rate of CC-HAs. RESEARCH DESIGN: A correlational study. STUDY SAMPLE: A total of 249 patients were enrolled. DATA COLLECTION AND ANALYSIS: The patients' demographics, clinical characteristics, outcomes, and CC-HA transducer types were compared. The data were analyzed for six groups classified based on the ear condition. RESULTS: In the unilateral closed-ear group, the purchase cases were significantly younger than the nonpurchase cases (p < 0.05). Regarding the outcomes in the bilateral closed-ear group, the purchase cases showed significantly better-aided thresholds at 0.25 and 0.5 kHz than the nonpurchase cases. No significant differences in the functional gains and speech recognition scores were found between purchase and nonpurchase cases in all six groups. Regarding the transducer type, the continued-use rate of the simple transducer type was significantly lower in the bilateral chronic continuous otorrhea, bilateral open, and unilateral open groups. CONCLUSION: In the closed ears, no remarkable negative factors were found. Transducer type had a significant influence on the continued-use rate in the nonclosed ears including the ears with chronic continuous otorrhea, although the purchase rate of CC-HAs in the bilateral chronic continuous otorrhea group was comparable to the closed ears.

Corpus callosotomy for drug-resistant epilepsy in a pediatric patient with Waardenburg syndrome Type I.

BACKGROUND: Waardenburg syndrome (WS) is caused by autosomal dominant mutations. Since the coexistence of epilepsy and WS type I is rare, the detailed clinical features and treatment of epilepsy, including surgery, have not been fully reported for these patients. We report the first case of an individual with WS type I, who underwent corpus callosotomy (CC) for drug-resistant epilepsy and obtained good seizure outcomes. CASE DESCRIPTION: A boy was diagnosed as having WS type I and developmental delay based on characteristic symptoms and a family history of hearing loss. He underwent cochlear implantation at 18 months of age. At 4 years of age, he developed epileptic seizures with a semiology of drop attack. Electroencephalography (EEG) showed bilateral synchronous high-amplitude spikes and wave bursts, dominant in the right hemisphere. Based on the multimodality examinations, we considered that ictal discharges propagated from the entire right hemisphere to the left, resulting in synchronous discharge and a clinical drop attack; therefore, CC was indicated. At 9 years of age, he underwent a front 2/3rd CC. At 1 year, the patient became seizure free, and interictal EEG showed less frequent and lower amplitude spike and wave bursts than before. CONCLUSION: When patients with WS Type I and cognitive impairment show drug-resistant epilepsy, clinicians should consider a presurgical evaluation.

Cartilage Conduction Hearing Aid Fitting in Clinical Practice.

BACKGROUND: Cartilage conduction hearing aids (CCHAs) were newly devised and spread fast in Japan since their launch in 2017. However, little knowledge is available for this new device. PURPOSE: The aim of this study was to establish the knowledge of CCHAs and suggest their indication. RESEARCH DESIGN: Correlational study. STUDY SAMPLE: A total 256 patients were registered. DATA COLLECTION AND ANALYSIS: The fitting of CCHAs was surveyed in nine institutions. The outcomes were assessed by audiometric tests. The patients were classified into seven groups, depending on the ear conditions. The clinical characteristics, assessment results, and purchase rates were compared among the groups. The assessment results of CCHAs were also compared with those of previously used hearing aids. RESULTS: Most patients who used CCHAs were classified into the bilateral closed (aural atresia or severe stenosis) ear (n = 65) or unilateral closed ear (n = 124) groups. The patients in these groups achieved good benefits that resulted in a high purchase rate. The bilateral continuous otorrhea group also supported a high purchase rate, although the benefits of CCHAs were not always excellent. In contrast, the purchase rate was poor in the patients who could use air conduction hearing aids (ACHAs) without absolute problems. As for using a CCHA as a contralateral routing of signals hearing aid, the benefits depended on the patients. CONCLUSIONS: CCHAs are considered as a great option not only to the patients with closed ears but also to those who had difficulties in ACHAs usage.

Primary Advanced Squamous Cell Carcinoma of the Temporal Bone: A Single-Center Clinical Study.

OBJECTIVES/HYPOTHESIS: The extreme rarity of temporal bone squamous cell carcinoma (TB-SCC) has delayed the accumulation of high-quality clinical evidence. For the purposes of retrospective meta-analysis in the future, a large dataset with information from various institutions would be ideal. Our objective here was to retrospectively review cases of TB-SCC encountered at a single tertiary referral center and explore survival outcomes and prognostic factors. STUDY DESIGN: Retrospective chart review. METHODS: The medical records of all TB-SCC cases were retrospectively reviewed. The resulting dataset contained 71 cases of primary cancer eligible for initial definitive (curative) treatment. RESULTS: T4 status was associated with lower disease-specific 5-year survival than T1 to T3 staging (T1: 100%, T2: 92%, T3: 86%, T4: 51%). Survival was significantly higher in operable than in inoperable cases, even when restricted to advanced (T3/T4) cancers. The tumor extension to the middle ear cavity was observed in 13/17 of T3 cases, but it was not associated with poor survival. In addition, among operable cases, negative surgical margins were associated with significantly higher survival than positive margins. CONCLUSIONS: Definitive treatments can offer disease-specific 5-year survival of over 85% in T1 to T3 cases of TB-SCC. The tumor extension to the middle ear cavity is not associated with poor survival. T4 status, inoperability, nodal invasion, and positive surgical margin are identified as a predictor of poor prognosis. Still, the matter of how to deal with unresectable tumors remains an outstanding issue in the treatment of TB-SCC. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E583-E589, 2021.

Management of Residual Hearing with Cartilage Conduction Hearing Aid after Lateral Temporal Bone Resection: Our Institutional Experience.

BACKGROUND: There is no guideline for hearing compensation after temporal bone resection. This study aimed to retrospectively analyze surgical cases with reconstruction for hearing preservation after temporal bone malignancy resection and propose a new alternative to compensate for hearing loss. METHODS: We retrospectively reviewed the medical records of 30 patients who underwent lateral temporal bone surgery for temporal bone malignancy at our institution and examined their hearing abilities after surgery. RESULT: The hearing outcomes of patients with an external auditory meatus reconstruction varied widely. The mean postoperative air-bone gap at 0.5, 1, 2, and 4 kHz ranged from 22.5 dB to 71.25 dB. On the other hand, the average difference between the aided sound field thresholds with cartilage conduction hearing aid and bone conduction thresholds at 0.5, 1, 2, and 4 kHz ranged from -3.75 to 41.25. More closely located auricular cartilage and temporal bone resulted in smaller differences between the aided sound field and bone conduction thresholds. CONCLUSIONS: There is still room for improvement of surgical techniques for reconstruction of the auditory meatus to preserve hearing after temporal bone resection. The cartilage conduction hearing aid may provide non-invasive postoperative hearing compensation after lateral temporal bone resection.

A Multi-Institutional Study of Older Hearing Aids Beginners-A Prospective Single-Arm Observation on Executive Function and Social Interaction.

OBJECTIVES: To obtain new insights into research questions on how executive function and social interaction would be observed to change after the introduction of hearing aids (HAs) in older people with hearing impairment. DESIGN: Multi-institutional prospective single-arm observational study. SETTING AND PARTICIPANTS: Outpatients with complaints of hearing difficulty who visited HA clinics between October 18, 2017, and June 30, 2019, in 7 different university hospitals in Japan. METHODS: The inclusion criteria of the study named Hearing-Aid Introduction for Hearing-Impaired Seniors to Realize a Productive Aging Society-A Study Focusing on Executive Function and Social Activities Study (HA-ProA study) were age ≥60 years and no history of HA use. A series of multi-institution common evaluations including audiometric measurements, the digit symbol substitution test to assess executive functions, convoy model as an index of social relations, and hearing handicap inventory for the elderly (HHIE) were performed before (pre-HA) and after 6 months of the HA introduction (post-HA). RESULTS: Out of 127 enrollments, 94 participants completed a 6-month follow-up, with a mean age of 76.9 years. The digit symbol substitution test score improved significantly from 44.7 at baseline to 46.1 at 6 months (P = .0106). In the convoy model, the social network size indicated by the number of persons in each and whole circles were not significantly different between pre- and post-HA; however, the total count for kin was significantly increased (P = .0344). In the analyses of HHIE, the items regarding the family and relatives showed significant improvement. CONCLUSIONS AND IMPLICATIONS: HA use could benefit older individuals beginning to use HAs in executive function and social interaction, though the results should be interpreted cautiously given methodological limitations such as a single-arm short 6 months observation. Reduction in daily hearing impairment would have a favorable effect on relationships with the family.

Pivotal role of actin depolymerization in the regulation of cochlear outer hair cell motility.

Cochlear outer hair cells undergo reversible changes in shape when externally stimulated. This response, known as OHC motility, is a central component of the cochlear amplifier, the mechanism responsible for the high sensitivity of mammalian hearing. We report that actin depolymerization, as regulated by activation/inhibition of LIMK/cofilin-mediated pathways, has a pivotal role in OHC motility. LIMK-mediated cofilin phosphorylation, which inhibits the actin depolymerizing activity of this protein, increases both electromotile amplitude and total length of guinea pig OHCs. In contrast, a decrease in cofilin phosphorylation reduces both OHC electromotile amplitude and OHC length. Experiments with acetylcholine and lysophosphatidic acid indicate that the effects of these agents on OHC motility are associated with regulation of cofilin phosphorylation via different signaling cascades. On the other hand, nonlinear capacitance measurements confirmed that all observed changes in OHC motile response were independent of the performance of the motor protein prestin. Altogether, these results strongly support the hypothesis that the cytoskeleton has a major role in the regulation of OHC motility, and identify actin depolymerization as a key process for modulating cochlear amplification.

Asymmetrical surface scanning registration for image-guided otologic surgery: A phantom study.

OBJECTIVE: To develop a registration procedure to achieve a higher degree of registration accuracy in image-guided otological surgery, paying particular attention to the registration centroid. METHODS: A head phantom was used to measure the target registration error (TRE) at measurement points at various depth from the surface of the head. The surface-matching registration was performed using a commercially available surgical navigation system. We registered the phantom using only one ear of either side (right 100% - left 0%, or right 0% - left 100%) or using both ears with variable ratios (right 75% - left 25%, right 50% - left 50%, or right 25% - left 75%). RESULTS: The overall TRE was the smallest when registration was performed equally on both sides. However, the TRE at 20-50 mm from the surface was the smallest when the fiducial points for the registration were collected asymmetrically at a ratio of 75:25 and weighed heavier on the operating side, and this difference was statistically significant. CONCLUSION: The accuracy of image-guided surgery can be improved by carefully planning the registration procedure without changing the procedure itself. Accurate image-guided surgery at the middle and inner ear was achieved using 75% of the point cloud for the operating side and 25% of that for the opposite side for the registration.