Normal Temporal Bone Anatomy Research Articles

Impact of superior semicircular canal dehiscence on cochlear implant audiologic outcomes

PurposeDetermine whether adult cochlear implant users with radiographic superior semicircular canal dehiscence experience clinically significant differences in audiological outcomes when compared to cochlear implant users with normal temporal bone anatomy. Materials and methodsRetrospective, single institution review. Adult, post-lingual deaf patients implanted between 2010 and 2020. Inclusion criteria included age 18 years or older, available preoperative computed tomography imaging, and preoperative and postoperative AzBio audiological data for at least 6 months of cochlear implant use. Preoperative and postoperative AzBio Sentence Test scores were compared between patients with normal temporal bone anatomy and those with radiographic superior semicircular canal dehiscence or near dehiscence. Results110 patients met inclusion criteria. Mean AzBio score for normal temporal bone anatomy group improved from 35.2 % (SD 28.2) preoperatively to 70.3 % (SD 25.7) postoperatively, an improvement of 35.1 % (SD 28.6). Mean AzBio score for near dehiscent temporal bone anatomy group improved from 26.6 % (SD 28.9) preoperatively to 64.5 % (SD 30.6) postoperatively, an improvement of 37.9 % (SD 27.9). Mean AzBio score for dehiscent temporal bone anatomy group improved from 26.3 % (SD 20.4) preoperatively to 65.1 % (SD 27.6) postoperatively, an improvement of 38.7 % (SD 26.9). Utilizing the one-way analysis of variance test, there was no significant difference in audiologic outcomes between the three groups. ConclusionsPatients with complete or near complete radiographic superior canal dehiscence at the time of cochlear implantation achieve similar improvements in speech perception scores compared to normal anatomy adult cochlear implant users.

The effects of cochlear implantation on middle ear function: A prospective study.

Although sound conduction mechanisms may influence by cochlear implantation (CI), it is not very clear whether, how, and to what extent these mechanisms may be influenced the pediatric population. Wideband tympanometry (WBT) is a sensitive tool to evaluate alternations in the middle ear mechanics in a wide frequency range. The current study aimed to explore CI's impacts on sound conduction across the middle ear cavity using WBT in pediatrics. In a prospective design, 35 unilaterally implanted children (<24 months of age) with normal temporal bone anatomy were included in this study. Traditional tympanometry (226-Hz) and WBT measures were compared for each child in the implanted and non-implanted ears preoperatively and three months postoperatively. No significant changes in the "static acoustic admittance" and "peak pressure" parameters were observed between the pre-CI and post-CI conditions in the implanted and non-implanted ears in the 226-Hz tympanometry test. Wideband absorbance recordings before CI surgery exhibited a double-peaked pattern over a frequency range of 250 to 8000Hz. The pre- and postoperative acoustic energy absorbance comparisons indicated a significantly reduced mid-frequency (1260 to 3175Hz) and high-frequency (5040 to 8000Hz) absorbance in the implanted ears. However, our results indicated no significant differences in sound absorbance between the pre- and postoperative conditions in non-implanted ears. Our findings suggested that WBT is a more sensitive method than traditional tympanometry for monitoring the mechanical status of the middle ear after cochlear implantation in pediatrics. Cochlear implantation in young children can significantly reduce mid- and high-frequency acoustic absorbance measured by WBT.

Cochlear Implantation in Chronic Otitis Media with and without Cholesteatoma: Surgical Considerations and Auditory Outcomes

Introduction: Cochlear implant (CI) surgery is a safe and standardized procedure in the presence of normal temporal bone anatomy. However, in the surgery of patients with chronic otitis media (COM), the surgeon may encounter several problems. The aim of this study was to evaluate the impact of COM with and without cholesteatoma on surgical and auditory outcomes of CIs. Methods: The study group consisted of 39 patients with COM who received CIs. Age- and gender-matched 38 standard CI patients served as controls. The surgical techniques and complications, pure tone audiometry (PTA) scores, speech discrimination scores (SDS), and the International Outcome Inventory for Hearing Aids (IOI-HA) questionnaire results of the groups were compared. Results: The presence of COM was associated with a higher rate of complication than controls. Staging the surgeries, presence or absence of cholesteatoma, and type of surgical technique were not associated with surgical outcomes and complications (p > 0.05). There was no significant difference between the groups in terms of postoperative PTA scores, SDS, and IOI-HA scores (p > 0.05). Conclusion: Postoperative complications like device failure and skin breakdown are increased in cases of COM compared to standard CI surgeries. However, that increase is not associated with staging the surgeries, presence or absence of cholesteatoma, and type of ear surgery performed. It is advocated to close the external ear canal and eustachian tube without mastoid obliteration in the presence of a radical mastoidectomy cavity, which will decrease the postoperative complication rates and allow for radiological follow-up with computed tomography for the possibility of cholesteatoma recurrence. The auditory benefits of CI in patients with and without COM are comparable.

Assessment of the preoperative classification for computed tomography predictability of round window niche visibility through posterior tympanotomy during cochlear implant surgery

Background Transmastoid facial recess is the classical approach for cochlear implant. Many methods have been reported in the literature to detect round window niche (RWN) visibility through posterior tympanotomy during that approach. Many had unclear methodology or complex software needed for their application.Objective The aim of the present study was to assess the preoperative predictability of multislice computed tomography for RWN visibility posterior tympanotomy.Patients and methods Computed tomography scans of 32 pediatric cochlear implant patients with otherwise normal temporal bone anatomy were studied for RWN visibility through posterior tympanotomy, using two methods. The first was a modification of a method by Kashio and colleagues and another by Mandour and colleagues. The visibility of the RWN was assessed intraoperatively after performing the posterior tympanotomy. Statistical analysis was then performed.Results The method of Kashio and colleagues was of statistical significance (P=0.002), whereas the method of Mandour and colleagues was statistically insignificant (P=0.465).Conclusion Kashio and colleagues is an easy and accurate method to preoperatively predict the visibility of the RWN through posterior tympanometry.

Assessment of the preoperative computed tomographic predictability for round window membrane visibility and accessibility during cochlear implant surgery

ObjectivesThe aim of the present study was to assess the preoperative predictability of multi-slice computed tomography for round window membrane (RWM) visibility and accessibility through round window niche (RWN) intraoperatively. Patients and methodsComputed tomographic scans of 61 adult cochlear implant patients with otherwise normal temporal bone anatomy were studied for RWN extent using two methods. The first was a modification of a method by Park and colleagues and another simple method proposed by our group. The visibility of the RWN through RWN was assessed intraoperatively after performing the posterior tympanotomy and good exposure of the RWN. Statistical analysis was then performed.ResultsModified Park and colleagues method was statistically significant in predicting RWM visibility (P=0.018) and a cutoff point was detected at more than or equal to 0.7 with a specificity of 69.23% for low or no visibility of RWM. Our proposed method was also statistically significant (P=0.001) with a cutoff point of more than or equal to 1.43mm with a specificity of 96.15%.DiscussionRWN depth has been studied repeatedly in the literature with only rarely correlation to intraoperative findings. These methods were also frequently either cadaveric or radiological with complex reconstruction, thus were with doubtful clinical value. In the present study, two methods were used and were found to be significant to predict the degree of visibility of RWN visibility through RWM.ConclusionThe modified Park’s and our proposed methods can statistically significantly predict RWM visibility through RWN. However, our proposed method had higher specificity and smaller P value.

Anatomy and Surgical Approach of the Ear and Temporal Bone.

The temporal bone is one of the more complex structures at the skull base that houses the hearing and vestibular organs, numerous nerves, and vessels. A host of inflammatory and neoplastic processes can occur within the temporal bone that often necessitate permanent and frozen section pathologic examination. A number of simple to complex surgical procedures are used to manage temporal bone pathology. This chapter will provide a brief overview of normal temporal bone anatomy, common surgical approaches, normal histology, and indications for pathologic examination.

Temporal bone anatomy characteristics in superior semicircular canal dehiscence

IntroductionSuperior semicircular canal dehiscence (SCD) remains difficult to diagnose despite advances in high-resolution computed tomography (HRCT) imaging. We hypothesize possible associations between gross temporal bone anatomy and sub-millimeter pathology of the semicircular canals, which may supplement imaging and clinical suspicion. This pilot study investigates differences in gross temporal bone anatomic parameters between temporal bones with and without SCD. MethodsRecords were reviewed for 18 patients referred to an otology clinic complaining of dizziness with normal caloric stimulation results indicative of non-vestibular findings. Eleven patients had normal temporal bone anatomy while seven had SCD. Three-dimensional reconstruction of every patient's temporal bone anatomy was created from patient-specific computational tomography images. Surface area (SA), volume (V), and SA to V ratios (SA:V) were computed across temporal bone anatomical parameters. ResultsSCD temporal bones have significantly smaller V, and larger temporal bone SA. Mean (±SD) V was 21,484 ± 3,921 mm3 in temporal bones without SCD and 16,343 ± 34,471 mm3 for those with SCD. Their respective SA were 13,733 ± 1,603 mm2 and 18,073 ± 3,002 mm2. Temporal bone airspaces and lateral semicircular canals did not demonstrate significant differences where SCD was and was not present. Plots of MVwarm response against computed SCD temporal bone anatomic parameters (SA, V and SA:V) showed moderate to strong correlations: temporal bone SA:V (r = 0.64), temporal bone airspace V (r = 0.60), temporal bone airspace SA (r = 0.55), LSCC SA (r = 0.51), and LSCC-to-TM Distance (r = 0.65). ConclusionsThis analysis demonstrated that SCD is associated with decreased temporal bone volume and density. The defect in SCD does not appear to influence caloric responses.

The cases of complications after cochlear implantation

The objective of study: To improve the methods of surgical stage of cochlear implantation by means of analysis of clinical findings during incorrect insertion of the active electrode into the spiral canal of the cochlea and the decision on such patients management. Materials and methods: At the period of 2014 through 2016, 920 patients aged 8 months to 24 years, were examined and operated on in the Federal State Budgetary Institution Clinical Research Centre of Otorhinolaryngology of the Russian Federation and the Hospital of the Ministry of Internal Affairs named after A. Hejdarov of the Republic of Azerbaijan in the framework of cochlear implantation program. Results: The authors revealed 4 cases of incorrect insertion of the active electrode into the cochlea. Of them, 3 cases have been observed in children aged 3–6 years with the abnormalities of the inner ear development and 1 case in an adult patient with the normal temporal bone anatomy. Each of the 4 cases required repeated surgery. Conclusion: Improper positioning of the electrode grid should be included in the differential diagnosis in cases that even in several years after the implantation the patients have no hearing improvement. Extracochlear displacement of active electrode is a rare complication, the published incidence is in average 0.37% [16]. However, this range is probably underestimated, and the true incidence may remain unknown until universal centralized database for recording of such cases is created. In majority of such cases described in the literature and in this study the management approach is explantation and reimplantation.

Cochlear implant outcomes in patients with superior canal dehiscence

ObjectiveTo determine whether adult cochlear implant (CI) users with superior canal dehiscence syndrome (SCDS) or asymptomatic superior semicircular canal dehiscence (SCD) have different surgical, vestibular, and audiologic outcomes when compared to CI users with normal temporal bone anatomy.MethodsA retrospective single institution review of CI users with either superior semicircular canal dehiscence syndrome or asymptomatic superior semicircular canal dehiscence identified eight post-lingually deafened adults with unilateral or bilateral cochlear implantation between 2006 and 2010. Preoperative and postoperative speech perception scores as well as medical and epidemiological data were recorded and analyzed.ResultsOne patient with superior canal dehiscence syndrome and seven patients with asymptomatic superior semicircular canal dehiscence were identified, representing 7% or 8/113 of CI patients that fulfilled selection criteria. Average dehiscence length was 3.3 mm ± 0.79 SEM. Three patients received bilateral implants and five patients received a unilateral implant. Among asymptomatic superior semicircular canal dehiscence patients, subjective rates of post-operative dizziness were similar to those seen in patients with normal temporal bone anatomy (12.5 % vs. 15.9%, respectively). Speech perception abilities after surgery were poorer in SCD patients compared to the non-SCD cohort (Consonant Nucleus Consonant 33.7 ± 7.78 SEM vs. 56.7 ± 2.15 SEM P = 0.011), although both groups improved substantially relative to pre-operative performance. We also completed detailed analyses of auditory and vestibular outcomes in one patient with SCDS who underwent CI surgery in the symptomatic ear, which demonstrated preservation of vestibular function post-operatively, improved quality-of-life measures, and reduced dizziness symptomatology.ConclusionsOur data suggest that patients with asymptomatic superior canal dehiscence at the time of CI surgery have similar albeit decreased speech perception scores compared to non-SCD adult CI users. Subjective rate of dizziness or vertigo following CI surgery was similar in both asymptomatic SCD and non-SCD cohorts, with detailed analyses of a single symptomatic SCD patient revealing improved vestibular function and reduced SCD symptoms following CI.

Interactive Web-based Learning Module on CT of the Temporal Bone: Anatomy and Pathology

An interactive Web-based learning module on the temporal bone has been developed. It shows normal temporal bone anatomy in four imaging planes: axial, coronal, and parallel and perpendicular to the long axis of the petrous bone. After reviewing the normal anatomy, users should be able to identify key imaging features of pathologic conditions of the temporal bone. Children with congenital abnormalities of the temporal bone may present with conductive or sensorineural hearing loss or both and may have a genetic syndrome. Acute otitis media is the most common infection of the temporal bone and is most prevalent among children. Although imaging is unnecessary in uncomplicated otitis media, it is important for evaluation of infectious complications. Classically, temporal bone fractures were described as longitudinal or transverse with respect to the long axis of the petrous bone. However, it is increasingly recognized that many fractures have both longitudinal and transverse components. Patients with temporal bone fractures may have conductive or sensorineural hearing loss in addition to other complications. The most common tumor of the temporal bone at the cerebellopontine angle is the vestibular schwannoma. Paraganglioma is the second most common tumor of the temporal bone and the most common tumor of the middle ear. Supplemental material available at http://uwmsk.org/temporalbone/atlas.html.

Multichannel cochlear implantation in radical mastoidectomy cavities.

We report on our experience in cochlear implantation in patients with radical mastoidectomy cavities. Study Design, Setting, and Methods: Retrospectively, records of patients from the Department of Otolaryngology, University of Parma between December 1991 and March 2000 were reviewed, and 6 postlingually deafened adults who received a cochlear implant in a radical cavity were identified. Speech performances were evaluated in terms of bisyllabic word and sentence recognition and common phrase comprehension. To date, with a follow-up of 1 to 9 years, no patient has experienced extrusion of electrodes or other local or intracranial complications. Mean bisyllabic word and sentence recognition scores were 74% and 80%, respectively. Mean comprehension score for common phrases was 86%. By obliterating and isolating the radical mastoidectomy cavity from the outer environment, patients who previously had undergone radical surgery of the middle ear can be safely implanted with satisfactory hearing results.

Segmental anatomy of the temporal bone

More of us suffer from hearing loss than from visual impairment, coronary artery disease, and cancer combined. Auditory dysfunction is detected in less than one third of newborns afflicted and is underdiagnosed in the elderly. Despite biomedical and technological advances, our understanding of vestibular dysfunction has grown little. Forming part of the lateral and inferior surfaces of the skull, the temporal bone contains the organs of hearing and balance. Diagnosis of diseases in these important regions requires adequate clinical information and a thorough knowledge of normal temporal bone anatomy to recognize abnormal findings when present. This article dissects the temporal bone into segments, describes the relevant radiologic anatomy of each, and discusses the imaging appropriate to specific concerns.

Magnetic resonance imaging of the normal temporal bone.

Recent advances in magnetic resonance imaging (MRI) technology has allowed the development of imaging sequences tailored to the assessment of exquisite anatomic detail of the temporal bone structures. This article describes MRI of the normal temporal bone anatomy, with emphasis on common anatomic variants and clinically relevant structures.

The facial nerve in congenital ear malformations.

The facial nerve is the nerve of the second branchial arch and is intimately related to the temporal bone. Knowledge of facial nerve anatomy is critical to the success of any otologic or neurotologic surgical procedure. While this is true of normal temporal bone anatomy, it is of even greater significance for congenital ear malformations.

The facial nerve in revision mastoid surgery: Avoiding complications

Revision mastoid surgery carries increased risk of facial nerve injury as compared with primary surgery because of distortion of normal temporal bone anatomy caused by progressive disease and/or previous surgical manipulation. When confronted with a revision procedure, the otologist must combine knowledge of facial nerve anatomy and surgical skills to obtain a successful surgical outcome. The facial nerve must be identified at a distance from the disease, and then disease must be exenterated with constant visualization of the facial nerve in the involved region of the temporal bone. This can only be accomplished if the otologist understands the course of the facial nerve in the temporal bone and its related anatomy. This article will review the salient features of the surgical anatomy of the facial nerve and describe approaches to the facial nerve used in canal wall up and canal wall down revision surgery.

Otologic features of bacterial meningitis of childhood

Sixteen temporal bones from eight children who had died of meningitis were histopathologically evaluated. Concurrent acute otitis media was demonstrated in 14 bones. In no case could a pathway of infection from the tympanomastoid compartment to the intracranial cavity be located. Further, inner ear infection appeared to be the result of retrograde bacterial invasion from the meninges rather than from an inoculation via the middle ear or mastoid. Should surgical drainage be required, the histopathologic findings indicate that mastoidectomy would have little advantage over myringotomy. We infer that a child with normal temporal bone anatomy is probably not at enhanced risk for development of bacterial meningitis from acute otitis media via a route of direct extension.