Comparison of electrode position between round window and cochleostomy inserting approaches among young children: a cone-beam computed tomography study

Background: As the two most commonly used approaches for cochlear implants (CIs), the round-window insertion (RWI) and cochleostomy are still controversial about which approach is optimal. The lack of visual observation methods makes it difficult to compare the electrode position between them.

Objectives: To evaluate and compare the electrode position between RWI and cochleostomy approaches for CI among young children.

Materials and methods: Twenty-four patients (16 male, 8 female) accepting CI and temporal cone-beam computed tomography (CBCT) scan post-operation in our hospital from January 2016 to July 2017 were analyzed retrospectively. Operative notes and images were used to identify the surgical technique. Mainly depending on the round-window exposure, 15 cochleae were performed with RWI and 11 performed with cochleostomy.

Results: Mean age, 2.4 (range 0.8–7) years. The CBCT images showed that all the electrode arrays were located in scala tympani. There were no significantly statistical differences in the distance between electrode contacts and modiolus (EMI), intracochlear insertion length and the angle of electrode arrays at the insertion site of the cochlea.

Conclusions and significance: Both approaches could insert electrodes into scala tympani satisfactorily. As electrodes and cochlear structures could be clearly visualized, CBCT can be applied to assess the electrode position reliably.     

Cone beam computed tomography and histological evaluations of a straight electrode array positioning in temporal bones

Conclusion: CBCT allows a precise evaluation of the dimensions and of the shape of the cochlear duct that is of primary importance for the choice of the length and the design of the electrode array. This radio-histological study confirms that CBCT is a reliable tool to be used in clinical studies to evaluate the position of straight electrode arrays within the cochlear scala.

Objective: To validate the reliability of cone beam computed tomography (CBCT) in the evaluation of cochlear anatomy and positioning of a straight electrode array, by comparing radiological images to histological analysis of cochlear implanted temporal bones.

Methods: Eight temporal bones for four subjects were analysed before and after cochlear implantation with a straight electrode array. The size of the cochlea, the dimensions, and shape of the cochlear duct at 180° and 360° were evaluated on CBCT performed before implantation. Temporal bones then underwent histological analysis to determine the position of the electrode array. Scalar localization of the electrode array was assessed on CBCT performed after implantation, and compared with histological study.

Results: CBCT is a reliable radiological technique to differentiate variability not only of cochlear dimensions, but also of size and shape of the cochlea. Histological analysis confirmed the scalar position of the electrode array assessed by the CBCT in 7/8 temporal bones, but soft tissue trauma such as dissection of the spiral ligament was not identified by the CBCT.     

REZ-1人工耳蜗电极植入方法的改进研究

目的 探讨使REZ-1人工耳蜗电极靠近蜗轴的植入方法.方法 22例尸头标本CT扫描测量耳蜗直径后,植入REZ-1人工耳蜗电极,完成植入后回撤1～2个电极环,耳蜗位摄片,测量蜗轴与电极环之间距离是否有所改变.测量60例CT扫描显示一侧中耳、内耳结构正常病例的耳蜗直径.结果 22例标本中3例植入27个电极环,19例植入28个电极环.回撤电极后,与回撤前相比17例标本中第12至第19个电极环与蜗轴的距离减小(配对t检验,P<0.01),该17例标本的耳蜗直径均小于9.50 mm;而耳蜗直径大于9.60 mm的5例标本均没有出现电极环靠近蜗轴的改变.17例电极回撤后靠近蜗轴的标本耳蜗直径为9.11(0.57)mm[中位数(四分位数间距),下同],另外5例标本耳蜗卣径为9.78(0.28)mm,二者差异具有统计学意义(Mann-Whitney秩和检验,P<0.001).60例正常耳蜗直径(x±s)为(9.04±0.45)mm,90%小于9.50 mm.结论 REZ-1人工耳蜗电极植入后回撤电极的植入方法可以使耳蜗直径小于9.50 mm的患者底回内部分电极环靠近蜗轴.术前CT扫描测量耳蜗直径可以为REZ-1人工耳蜗电极选择植入方法提供帮助.     

Cochlear implants: Insertion assessment by computed tomography

Background and objectives

Imaging exams play a key role in cochlear implants with regard to both planning implantation before surgery and quality control after surgery. The ability to visualize the three-dimensional location of implanted electrodes is useful in clinical routines for assessing patient outcome. The aim of this study was to evaluate linear and angular insertion depth measurements of cochlear implants based on conventional computed tomography.

Paediatric cochlear implantation: how reliable is computed tomography in assessing cochlear patency?

This study investigates the accuracy of pre-operavive high resolution computed tomographic (CT) scans in predicting the patency of the cochlea in children undergoing cochlear implantation. The first 26 children on the Nottingham Paediatric Cochlear Implant programme were reviewed. CT scans were performed utilizing 1 mm contiguous sections and these were then assessed by a neuroradiologist. In patients who had normal inner ears on CT a high degree of accuracy in predicting a patent cochlear was achieved (87%). However, in 15% of cases the degree of ossification was significantly under-estimated causing major difficulties at the time of surgery. Although high resolution CT offers great clarity and fine detail, it has its limitations. Further information may be provided by magnetic resonance imaging.     

维吾尔族成人下颌神经管在CBCT中的影像分析

摘要：目的利用CBCT初步探讨维吾尔族成年人下颌神经管分支的发生率及分型。方法收集2014~2016年就诊于新疆医科大学第一附属医院口腔科维吾尔族患者214例,利用CBCT评估其下颌管及有无分支,并进行统计学分析。结果214例（428侧）维吾尔族患者,51例（23.8%）观察到下颌管分支,其中女31例（14.48%）,男20例（9.34%）。发现下颌管双分支1例,最为常见的下颌管分支为前行管（第Ⅲ类）,发生率为8.88%;其次是磨牙管（第Ⅰ类）,发生率为8.41%;牙管（第Ⅱ类）,发生率为4.67%;最后是颊舌管（第Ⅳ类）,发生率为1.87%。结论利用 CBCT能够很好地观察下颌管有无分支这一解剖结构。     

Imaging cochlear implantation with round window insertion in human temporal bones and cochlear morphological variation using high-resolution cone beam CT

Conclusions: The present experimental set-up of high spatial resolution cone-beam computed tomography (CBCT) showed advantages of demonstrating the critical landmarks of the cochlea in identifying the position of intracochlear electrode contacts and has the potential for clinical application in cochlear implant (CI) surgery. Objective: To evaluate a newly developed CBCT system in defining CI electrode array in human temporal bone and cochlear morphological variation. Methods: Standard electrode, flexible tip electrode (Flex28), and an experimental electrode array with 36 contacts from MED-EL were implanted into the cochleae of six human temporal bones through an atraumatic round window membrane insertion. The cochleae were imaged with 900 frames using an experimental set-up based on a CBCT scanner installed with Superior SXR 130-15-0.5 X-ray tube in combination with filtration of copper and aluminum. Results: In all temporal bones, the landmarks of the cochlea, modiolus, osseous spiral lamina, round window niche, and stapes were demonstrated at an average level of 3.4–4.5. The contacts of electrode arrays were clearly shown to locate in the scala tympani. There was a linear correlation between the ‘A’ value and cochlea height, and between the A value and actual electrode insertion length for the first 360° insertion depth.     

The role of computed tomography for localization of parathyroid adenomas

Objective/Hypothesis: The purpose of this study was to evaluate the use of computed tomography (CT) for localization of parathyroid adenomas (PA) when first‐line imaging is indeterminate. Study Design: Retrospective case series. Methods: A search of operating room and radiology records identified 223 surgical explorations for primary hyperparathyroidism. Adenoma locations on CT, ultrasound, and nuclear scintigraphy were correlated with an independent review of operative records. Results: The presence of adenoma in the correct side and quadrant of the neck was predicted by CT in 89% and 77% of studies, respectively. When first‐line studies were indeterminate, the positive predictive value of CT for localization of PA to the correct side and quadrant of the neck was 87% and 69%, respectively. Conclusions: When first‐line localization studies are indeterminate in patients with primary hyperparathyroidism, CT is a valuable, rapid, and widely available imaging modality that can be used to localize PA.     

Assessing the efficacy of a modified crushing technique for the management of concha bullosa: a cone beam computer tomography study

IntroductionAlthough many surgical techniques exist to manage obstructive concha bullosa, there continues to be a drive to find the least invasive technique with the fewest complications and best results.ObjectivesThe purpose of this study is to describe and assess the short- and long-term efficacy of a modified crushing technique for concha bullosa management.MethodsPatients who met inclusion criteria underwent a detailed nasal examination and cone beam computed tomography imaging prior to and after septoplasty with crushing surgery for obstructive concha bullosa. Patients were divided into short- and long-term groups based on their followup period such that the short-term group had a mean followup of 15.14 months (range 6–22 months) and the long-term group had a mean followup of 56.66 (range 29–80) months.ResultsTwenty-four cases of obstructive concha bullosa were included in this study with 13 short-term and 11 long-term follow-ups. All patients showed a significantly decreased postoperative CB size (p < 0.001). There was no correlation between age and postoperative CB change in area (p = 0.39) and no significant difference in the amount of postoperative CB area reduction between the short-term and long-term groups (p = 0.35). No patients experienced bleeding, synechia, conchal destruction, or olfactory dysfunction on followup evaluations.ConclusionsOur modified crushing technique is a simple, effective, and lasting treatment option for concha bullosa. From our experience, there have been no complications and no instances of concha bullosa reformation during the follow-up period.     

Mirror-image reversal of coronal computed tomography scans

OBJECTIVES/HYPOTHESIS: Mirror-image reversal of coronal computed tomography (CT) scans can be a significant problem in patient care, potentially leading to wrong-sided surgery and malpractice suits. There is no literature describing the problem of mirror-image reversal of coronal CT scans. Generally, medical errors are not widely published: however, with the emphasis on reduction of errors in medicine, this topic should be openly discussed. STUDY DESIGN: Retrospective review of patient care and an assessment of current methods. METHODS: Two cases of mirror-image reversal of coronal CT scans were reviewed, and the authors found that each case represented a different type of error. In the first case, the error was recognized in the operating room. The second case resulted in wrong-sided surgery, and a lawsuit was filed. These two separate occurrences led to a review of the methods for determining right versus left side for orienting and labeling of CT scans. Orientation of coronal scans depends on whether the patient is prone or supine. Thus, technician input is required. If a labeling mistake is made, radiologists may not readily catch the mistake because of the symmetry of the head and neck anatomy. RESULTS: A review of the markings on each scan should provide the otolaryngologist with enough information to determine whether the scan is mislabeled. CONCLUSION: The incidence of mislabeled coronal CT scans is unknown. This error can result in inappropriate patient care and lawsuits for wrong-sided surgery. Awareness of the potential problem and open discussion of interpretation and prevention are necessary.     

Reliability of cone beam computed tomography in scalar localization of the electrode array: a radio histological study

Postoperative imaging plays a growing role in clinical studies concerning prognostic factors in cochlear implantation. Indeed, intracochlear position of the cochlear implant has recently been identified as a contributor in functional outcomes and radiological tools must be accurate enough to determine the final placement of the electrode array. The aim of our study was to validate cone beam computed tomography as a reliable technique for scalar localization of the electrode array. We performed therefore a temporal bone study on ten specimens that were implanted with a perimodiolar implant prototype. Cone beam reconstructions were performed and images were analyzed by two physicians both experienced in cochlear implant imaging, who determined the scalar localization of the implant. Temporal bones then underwent histological control to document this scalar localization and hypothetical intracochlear lesions. In four cases, a dislocation from scala tympani to scala vestibuli was suspected on cone beam reconstructions of the ascending part of the basal turn. In three of these four specimens, dislocation in pars ascendens was confirmed histologically. In the remaining temporal bone, histological analysis revealed an elevation with rupture of the basilar membrane. Histological assessment revealed spiral ligament tearing in another bone. We conclude that cone beam is a reliable tool to assess scalar localization of the selectrode array and may be used in future clinical studies.     

The role of positron emission tomography/computed tomography in the management of recurrent papillary thyroid carcinoma

OBJECTIVES/HYPOTHESIS: The aim of the study was to evaluate the role of combined positron emission tomography/computed tomography (PET/CT) fusion imaging in the detection and management of recurrent papillary thyroid cancer. STUDY DESIGN: A retrospective analysis of 33 patients with suspected recurrent papillary thyroid carcinoma who had undergone PET/CT was performed. PET/CT was compared with standard imaging techniques in each patient to determine whether PET/CT contributed to the therapeutic management plan. Histopathological findings were correlated to PET/CT in patients who underwent surgery. METHODS: The senior author reviewed the charts of 33 patients with recurrent papillary thyroid carcinoma to determine the impact PET/CT had on management. PET/CT was compared with conventional imaging results. In surgical patients, PET/CT was compared with histopathological findings to determine its sensitivity, specificity, accuracy, positive predictive value, and negative predictive value. RESULTS: In 67% of the cases (22 of 33), PET/CT supplied additional information that altered or confirmed the management plan. Twenty of 33 patients underwent surgery with 36 sites assessed by histopathological analysis. PET/CT correlated with histopathological findings in 25 of 36 distinct anatomical sites, with an accuracy of 70%. The sensitivity of PET/CT in identifying recurrence was found to be 66%, with a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 27%. CONCLUSION: Combined PET/CT fusion scanning was most useful in the detection and management of recurrent papillary thyroid cancer in patients who had average thyroglobulin levels greater than 10 ng/mL and when the tumor no longer concentrated radioactive iodine. In 100% of the cases in which PET/CT localized a region suspicious for malignancy, histopathological analysis confirmed the results. When PET/CT is positive, it is a powerful tool for predicting exact locations of recurrent papillary thyroid cancer, thus making it a reliable guide for surgical planning. PET/CT is a supplement to conventional imaging and fine-needle aspiration in the workup of recurrent papillary thyroid cancer. A negative finding on PET/CT is not sufficiently reliable to preclude further investigation and treatment.     

Combining acoustic and electric stimulation in the service of speech recognition

Abstract

The majority of recently implanted, cochlear implant patients can potentially benefit from a hearing aid in the ear contralateral to the implant. When patients combine electric and acoustic stimulation, word recognition in quiet and sentence recognition in noise increase significantly. Several studies suggest that the acoustic information that leads to the increased level of performance resides mostly in the frequency region of the voice fundamental, e.g. 125 Hz for a male voice. Recent studies suggest that this information aids speech recognition in noise by improving the recognition of lexical boundaries or word onsets. In some noise environments, patients with bilateral implants can achieve similar levels of performance as patients who combine electric and acoustic stimulation. Patients who have undergone hearing preservation surgery, and who have electric stimulation from a cochlear implant and who have low-frequency hearing in both the implanted and not-implanted ears, achieve the best performance in a high noise environment.

Sumario

La mayoría de los usuarios recientes de implante coclear, pueden potencialmente beneficiarse de un auxiliar auditivo en el oído contralateral al implantado. Cuando los pacientes combinan la estimulación eléctrica y acústica, el reconocimiento de palabras en silencio y el reconocimiento de oraciones aumenta significativamente. Algunos estudios sugieren que la información acústica que permite el mayor nivel de rendimiento, reside sobre todo en la región frecuencial de la fundamental de la voz, p.ej., 125 Hz en la voz masculina. Estudios recientes sugieren que esta información ayuda para reconocer el lenguaje en ruido, mejorando el reconocimiento de las transiciones lexicales que ocurren en el inicio de las palabras. En algunos ambientes, los pacientes con implante bilateral pueden alcanzar niveles similares de rendimiento a los de quienes combinan la estimulación eléctrica con la acústica. Los pacientes que han sido sujetos de cirugía para preservar la audición, y que tienen estimulación eléctrica de un implante coclear y audición en las frecuencias graves tanto en el oído implantado como en el no implantado, alcanzan los mejores rendimientos en ambientes con ruido intenso.     

Implantation of the ossified cochlea: management with the split electrode array

OBJECTIVES/HYPOTHESIS: To describe indications for, the surgical technique required, and the expected functional results of split electrode array cochlear implants. STUDY DESIGN: Retrospective chart review. METHODS: Data collected included etiology of deafness, radiographic findings, pre- and postoperative aided pure tone thresholds, and speech perception testing. Adult speech perception outcomes were measured using the Consonant Nucleus Consonant (CNC) monosyllable words and Hearing in Noise Test (HINT) in quiet/noise (+10 dB). The children were assessed using the Infants and Toddlers Meaningful Auditory Integration Scale. RESULTS: Five patients were implanted with a split electrode array. This included two adults and three children. Both adults had preoperative binaural aided pure tone averages worse than 50 dB and scores of 0% on both HINT quiet and CNC words. The children had undetectable preoperative aided thresholds and scored an average 4/40 on the IT-MAIS. Postimplant, the average threshold gain was 38.5 dB in the adults and 81.5 dB in the children. One adult improved to score 51%/22% on HINT quiet/noise at 6 months and 72%/30% at 12 months. The other adult continued to score 0% on HINT at 12 months but claimed substantial subjective auditory improvement after the first year of device use. The children averaged 28/40 on the IT MAIS at 6 months after implantation. Forty-two of 48 implanted electrodes were functional. CONCLUSIONS: The split electrode array is a useful alternative to traditional cochlear implants in treating deafened patients with cochlear ossification. Patients implanted with the split array show marked improvement in sound and speech perception.