A full-head model to investigate intra and extracochlear electric fields in cochlear implant stimulation.

OBJECTIVE: Despite the widespread use and technical improvement of cochlear implant (CI) devices over past decades, further research into the bioelectric bases of CI stimulation is still needed. Various stimulation modes implemented by different CI manufacturers coexist, but their true clinical benefit remains unclear, probably due to the high inter-subject variability reported, which makes the prediction of CI outcomes and the optimal fitting of stimulation parameters challenging. A highly detailed full head model that includes a cochlea and an electrode array is developed in this study to emulate intracochlear voltages and extracochlear current pathways through the head in CI stimulation. APPROACH: Simulations based on the finite element method were conducted under monopolar, bipolar, tripolar, and partial tripolar modes, as well as for apical, medial, and basal electrodes. Variables simulated included: intracochlear voltages, electric field (EF) decay, electric potentials at the scalp and extracochlear currents through the head. To better understand CI side effects such as facial nerve stimulation, caused by spurious current leakage out from the cochlea, special emphasis is given to the analysis of the EF over the facial nerve. MAIN RESULTS: The model reasonably predicts EF magnitudes and trends previously reported in CI users. New relevant extracochlear current pathways through the head and brain tissues have been identified. Simulated results also show differences in the magnitude and distribution of the EF through different segments of the facial nerve upon different stimulation modes and electrodes, dependent on nerve and bone tissue conductivities. SIGNIFICANCE: Full head models prove useful tools to model intra and extracochlear EFs in CI stimulation. Our findings could prove useful in the design of future experimental studies to contrast FNS mechanisms upon stimulation of different electrodes and CI modes. The full-head model developed is freely available for the CI community for further research and use.

Clinical practice guideline on the management of vestibular schwannoma.

INTRODUCTION: Vestibular schwannoma (VS) is the most common tumour of the cerebellopontine angle. The greater accessibility to radiological tests has increased its diagnosis. Taking into account the characteristics of the tumour, the symptoms and the age of the patient, three therapeutic strategies have been proposed: observation, surgery or radiotherapy. Choosing the most appropriate for each patient is a frequent source of controversy. MATERIAL AND METHODS: This paper includes an exhaustive literature review of issues related to VS that can serve as a clinical guide in the management of patients with these lesions. The presentation has been oriented in the form of questions that the clinician usually asks himself and the answers have been written and/or reviewed by a panel of national and international experts consulted by the Otology Commission of the SEORL-CCC. RESULTS: A list has been compiled containing the 13 most controversial thematic blocks on the management of VS in the form of 50 questions, and answers to all of them have been sought through a systematic literature review (articles published on PubMed and Cochrane Library between 1992 and 2023 related to each thematic area). Thirty-three experts, led by the Otology Committee of SEORL-CCC, have analyzed and discussed all the answers. In Annex 1, 14 additional questions divided into 4 thematic areas can be found. CONCLUSIONS: This clinical practice guideline on the management of VS offers agreed answers to the most common questions that are asked about this tumour. The absence of sufficient prospective studies means that the levels of evidence on the subject are generally medium or low. This fact increases the interest of this type of clinical practice guidelines prepared by experts.

Checklist of the temporal bone and lateral skull base CT-scan.

Computed tomography scan of the temporal bone is a fundamental imaging modality for both the diagnosis and treatment of a wide range of pathologies affecting this complex structure. Temporal bone computed tomography scan provides a more detailed depiction of bone structures, compared with magnetic resonance imaging and, for this reason computed tomography scan is the imaging modality of choice in the planning of otological surgery. The aim of this article is to present a checklist to allow the otolaryngologist to assess systematically and in an organized manner the main anatomical landmarks, anatomical variants, as well as the most common postoperative surgical changes, which can be identified before any safe otological surgery. This revision was promoted by the Spanish Society of Otolaryngology and elaborated in a checklist template divided into the different areas of the temporal bone and the lateral skull base.

Cholesteatoma: Influence of surgical technique and EAONO/JOS stage on audiological results.

INTRODUCTION AND OBJECTIVE: The treatment of cholesteatoma is surgical in most cases. When it is indicated, it is preferable to choose a reconstructive surgical technique with the dual purpose of eradicating the disease and preserving or improving the patient's hearing. In 2017, the European Academy of Otology and Neuro-Otology/Japanese Otological Society (EAONO/JOS) published a new cholesteatoma classification. The aims of this study were to determine the influence of the surgical technique used and this classification on patient's hearing outcomes. METHODS: A retrospective study that included patients who underwent reconstructive surgery of cholesteatoma between 2012 and 2017 was carried out. Based on pre-surgical computed tomography (CT) images, disease was staged according to the EAONO/JOS classification. Hearing outcomes obtained by pre and postoperative pure tone audiometry were analysed according to the surgical technique used and according to the stage of the disease. RESULTS: 143 patients with no statistically significant differences in hearing thresholds before surgery were included. One year after surgery, all the patients' (P = .01 and P = .001) airpure tone average (PTA) and mean differential auditory threshold had improved significantly. Those patients who underwent tympanoplasty with two-stage canal wall up mastoidectomy presented better postsurgical air PTA and postsurgical mean differential auditory threshold outcomes (P = .007 and P = .014) than those patients who underwent tympanoplasty with canal wall down mastoidectomy. Moreover, the patients who underwent tympanoplasty with two-stage canal wall up mastoidectomy had improved air PTA and mean differential auditory threshold one year after the surgery with statistical significance (P = .001, P = .013). The mean differential auditory threshold was also better (P = .008) in the patients who underwent tympanoplasty with canal wall down mastoidectomy one year after the procedure. CONCLUSIONS: Reconstructive surgical techniques improve hearing one year after surgery. In our study, this improvement was significantly greater with tympanoplasty with two-stage canal wall up mastoidectomy.

Checklist for the evaluation of magnetic resonance imaging in otological pathology.

Otolaryngology specialists must be familiar with radiological studies that allow the diagnosis of different otological pathologies. Magnetic resonance imaging is a complement to computed tomography, which allows a better evaluation of soft tissues and contributes to the differential diagnosis of space-occupying lesions located in the temporal bone and lateral skull base. It is also the technique of choice for the evaluation of the inner ear and the anatomical structures located in the cerebellopontine angle. In this article we present a checklist for magnetic resonance imaging of the ear with different sections that will allow a systematic review of all structures of interest in otological practice, as well as the preferred sequences for each situation.

Checklist for the evaluation of magnetic resonance imaging in otological pathology. / Lista de verificación para la evaluación de imágenes de resonancia magnética en patología otológica.

Otolaryngology specialists must be familiar with radiological studies that allow the diagnosis of different otological pathologies. Magnetic resonance imaging is a complement to computed tomography, which allows a better evaluation of soft tissues and contributes to the differential diagnosis of space-occupying lesions located in the temporal bone and lateral skull base. It is also the technique of choice for the evaluation of the inner ear and the anatomical structures located in the cerebellopontine angle. In this article we present a checklist for magnetic resonance imaging of the ear with different sections that will allow a systematic review of all structures of interest in otological practice, as well as the preferred sequences for each situation.

Cholesteatoma: Influence of surgical technique and EAONO/JOS stage on audiological results. / Colesteatoma: influencia de la técnica quirúrgica y el estadio EAONO/JOS en los resultados audiológicos.

INTRODUCTION AND OBJECTIVE: The treatment of cholesteatoma is surgical in most cases. When it is indicated, it is preferable to choose a reconstructive surgical technique with the dual purpose of eradicating the disease and preserving or improving the patient's hearing. In 2017, the European Academy of Otology and Neuro-Otology/Japanese Otological Society (EAONO/JOS) published a new cholesteatoma classification. The aims of this study are to determine the influence of the surgical technique use and this classification on patient's hearing outcomes. METHODS: A retrospective study that include patients who underwent reconstructive surgery of cholesteatoma between 2012 and 2017 is carried out. Based on pre-surgical computed tomography (CT) images, disease is staged according to the EAONO/JOS classification. Hearing outcomes obtained by pre and postoperative pure tone audiometry are analysed according to the surgical technique used and according to the stage of the disease. RESULTS: 143 patients with no statistically significant differences in hearing thresholds before surgery are included. One year after surgery, all the patients' airbone pure tone average (PTA) and mean differential auditory threshold have improved significantly (P = .01 and P = .001). Those patients who undergo tympanoplasty with two-stage canal wall up mastoidectomy presente better postsurgical air PTA and postsurgical mean differential auditory threshold outcomes (P=.007 and P=.014) than those patients who underwent tympanoplasty with canal wall down mastoidectomy. Moreover, the patients who underwent tympanoplasty with two-stage canal wall up mastoidectomy had improved airbone PTA and mean differential auditory threshold one year after the surgery with statistical significance (P=.001 and P=.013). The mean differential auditory threshold is also better (P=.008) in the patients who undergo tympanoplasty with canal wall down mastoidectomy one year after the procedure. CONCLUSIONS: Reconstructive surgical techniques improve hearing one year after surgery. In our study, this improvement is significantly greater with tympanoplasty with two-stage canal wall up mastoidectomy.

Seizure as Early Presentation of a Pneumocephalus after Cochlear Implant: A Case Report.

Pneumocephalus after cochlear implantation is very rare with five reported cases in the literature. The presence of clinical features in the immediate postoperative period has never been reported, because they occur weeks after surgery. These neurological manifestations can compromise the patient's life; thus, it is important to have proper knowledge and management of these manifestations. We present a case report with a review of the literature. A 35-year-old man began having seizures a few hours after a cochlear implantation. Computed tomography (CT) scan revealed a pneumocephalus and bone defect at the level of the electrode's drilling path, not objected during the surgery. The patient was handled conservatively, and in subsequent reviews, CT objected reabsorption of the pneumocephalus. The presence of a pneumocephalus should be taken into account in the neurological features of a patient with cochlear implant, especially if mastoid bone defects are suspected during surgery. The management of the pneumocephalus will, in most cases, be conservative, consisting of clinical observation and imaging tests. Surgical treatment is reserved for situations in which the clinical manifestations are very symptomatic and when they are tension pneumocephalus.

Short-term audiological outcomes of stapedotomy: microdrill at low revolutions versus manual perforator to perform a small footplate fenestra. A prospective observational study.

<b>Introduction:</b> Stapedotomy is currently the surgical technique of choice for treating otosclerosis. Despite this, there is no agreement about the best technique to perform a small fenestra footplate, therefore multiple procedures have been proposed. The aim of this study was to investigate the hearing outcomes of microdrill and manual perforator. <br><b>Material and Methods:</b> An observational prospective study was carried out on patients who underwent stapedotomy. We analyzed the hearing threshold in two groups of patients according to the way the fenestra footplate was realized by microdrill or manual perforator. <br><b>Results:</b> A total of 113 patients were evaluated. Postoperative hearing gain of the microdrill group was 23.29 (18.58) dB HL 95% CI (18.40-28.18), while in the manual perforator group, it was 22.67 (12.91) dB HL 95% CI (19.07-26.26). Both groups were statistically significant. Postoperative bone conductive hearing threshold at the frequencies of 0.5, 1 and 2 KHz and postoperative air conductive hearing threshold at the frequencies of 2 and 4 KHz showed statistically significant differences in the manual perforator group. The closure of air-bone gap was higher in the microdrill group with statistically significant differences. <br><b>Conclusion:</b> Both manual perforator and microdrill have good hearing outcomes at six months after surgery. The manual perforator has better audiological outcomes than microdrill. Hence, the manual perforator is a safe technique and can be used in centers that do not have other methods to make the small fenestra.

Improved planning of endoscopic sinonasal surgery from 3-dimensional images with Osirix® and stereolithography.

INTRODUCTION AND OBJECTIVES: The high variability of sinonasal anatomy requires the best knowledge of its three-dimensional (3D) conformation to perform surgery more safely and efficiently. The aim of the study was to validate the utility of Osirix® and stereolithography in improving endoscopic sinonasal surgery planning. METHODS: Osirix® was used as a viewer and Digital Imaging and Communications in Medicine (DICOM) 3D imaging manager to improve planning for 114 sinonasal endoscopic operations with polyposis (86) and chronic rhinosinusitis (CRS) (28). Stereolithography rapid prototyping was used for 7 frontoethmoidal mucoceles. RESULTS: Using Osirix® and stereolithography, a greater number of anatomical structures were identified and this was done faster, with a statistically-significant clinical-radiological correlation (P<.01) compared with 2D CT plates. With a share of more than 75% of surgery performed by residents, surgical time was reduced by 38±12.3min in CRS and 42±27.9 in sinonasal polyposis. The fourth-year residents reached 100% surgical competence in critical surgical milestones with 16 surgeries (CI 12-19). CONCLUSIONS: The systematic use of Osirix® for visualisation and treatment of 3D sinonasal images from DICOM data files, along with the surgical team's ability to manipulate them as virtual reality, allows surgeons to perform endoscopic sinonasal surgery with greater confidence and in less time than using 2D images. Residents also achieve surgical competence faster, more safely and with fewer complications. This beneficial impact is increased when the surgical team has stereolithography rapid prototyping in more complex cases.