Temporal Bone CT Research Articles

Electrically evoked ABR during cochlear implantation and postoperative development of speech and hearing abilities in infants with common cavity deformity as a type of inner ear malformation

Background: The electrically evoked auditory brainstem response (eABR) during cochlear implantation in common cavity (CC) deformity has not been clinically well studied.Aim/Objective: To investigate the eABR wave configuration during cochlear implantation, the postoperative development of hearing, and educational settings in infants with CC deformity.Materials and Methods: Nine infants who were congenitally deaf and found to have CC deformity and suspected cochlear nerve deficiency by temporal bone CT and MRI were studied. All of them underwent sequential and unilateral cochlear implantation and their eABRs were recorded during the surgery. The postoperative development was followed up.Results: eABRs of all the nine infants with CC deformity showed that the mean peak of the evoked wave V (eV) was the same as that in controls at latencies but was twofold higher than that in controls at thresholds and their postoperative hearing thresholds improved markedly.Conclusion and Significance: The brainstem auditory pathways of the infants were considered intact on the basis of the eV peak latencies in the eABRs. The postoperative development of their speech and hearing abilities and their educational settings varied, probably because of the twofold higher thresholds of their eABRs and limited number of auditory neural units.

Is CT necessary for imaging paediatric congenital sensorineural hearing loss?

Objectives: To determine if MRI alone is adequate for pre-operative assessment of paediatric congenital sensorineural hearing loss (SNHL). While aberrant intratemporal facial nerve anatomy is usually occult on MRI, we postulate that the majority of cases have no adverse bearing on surgical outcomes.Methods: MRI and CT of the temporal bones were analysed in 240 children who underwent both on the same day for SNHL. Only children under the age of 5 years with no reported clinical syndrome or dysmorphic external ear anatomy were included.Results and discussion: 169 patients satisfied the inclusion criteria. MRI detected 32/54 cases of cochleovestibular dysplasia, with the majority of the additional CT findings comprising subtle incomplete partition type 2 (IP2) anomalies. Of the 22 cases not evident on MRI, 13 patients also had large vestibular aqueduct syndromoe (LVAS), which would have prompted evaluation with CT due to the near universal co-existence of these entities. Only one patient exhibited aberrant intratemporal facial nerve anatomy that may have conferred surgical risk and was occult on MRI.Conclusion: In a defined paediatric SNHL cohort, the addition of routine temporal bone CT to MRI offers limited additional yield but confers a significant radiation burden on a young population.

A Persistent Foramen of Huschke: A Small Road to Misery in Necrotizing External Otitis.

Necrotizing external otitis is a serious complication of external otitis with different spreading patterns. A persistent foramen of Huschke is a dehiscence located antero-inferior in the osseous external ear canal and posterior-medial to the temporomandibular joint. This dehiscence can facilitate extension of infection in an anterior pattern next to classic spread along the fissures of Santorini. The aim of this study was to define the prevalence and size of a persistent foramen of Huschke in patients with necrotizing external otitis. We retrospectively examined 78 CT temporal bone studies (39 patients with necrotizing external otitis, 39 control subjects). The side and presence of the foramen were noted, and its prevalence was calculated. The maximal width of the foramen of Huschke was measured in the axial plane and classified as subtle, mild, moderate, or extensive. A persistent foramen of Huschke was present in 21 patients (26 ears) and 7 control subjects (9 ears). Prevalence was 50% (20/40) and 11.5% (9/78) in affected ears of patients with necrotizing external otitis and control subjects, respectively. Almost all affected ears showed an anterior distribution pattern of necrotizing external otitis. The extensive dehiscence was most common in affected ears. An anterior necrotizing external otitis spreading pattern is associated with the presence and increased size of a persistent foramen of Huschke. These findings facilitate the theory that a persistent foramen of Huschke is an additional risk factor the development of necrotizing external otitis.

Symptom: Postauricular Mass

Symptom: Postauricular Mass

Standardization of Temporal Bone CT Planes across a Multisite Academic Institution.

Variable head positioning in the CT gantry results in variable and inconsistent temporal bone imaging planes. Our aim was to evaluate whether an automated postprocessing algorithm or an educational intervention with postprocessing by a technologist could result in consistent temporal bone image reformations into planes referenced to the lateral semicircular canal. Instructions to reformat small-FOV images in planes referenced to the lateral semicircular canal were posted at 12 CT scanner consoles and e-mailed to 65 CT technologists at a single multisite institution. Automated reformatted images were also produced. The angles between the technologist- and automated-reformatted axial image planes and lateral semicircular canal planes were measured. Group differences were calculated with Mann-Whitney-Wilcoxon tests. Differences in homogeneity of variances were calculated with Fligner-Killeen tests. Two hundred ten temporal bones were imaged in 4 months following the intervention. Reformats by technologists were accurate in 87% of the axial and 81% of the coronal planes, with a trend toward improvement with time. Eighty percent of incorrectly reformatted images occurred at off-site, inpatient, and emergency department scanners. The error angle was significantly lower for technologist-reformatted images (median, 4.9°) than for acquisition plane images (median, 14.6°; P = 3 × 10-14) or automated-reformatted images (median, 13.8°; P = 9 × 10-13). The angle error variance was significantly more homogeneous for technologist-reformatted images (P = 3 × 10-8) and automated-reformatted images (P = 1 × 10-5) than for acquisition plane images. Both technologist and automated reformatting of temporal bone images resulted in significantly less imaging plane variance compared with images reformatted in the acquisition plane, but reformatting by technologists remains necessary at our institution given our preference for standardized planes referencing the lateral semicircular canals.

Symptom: Dizziness with Ear Pressure

Symptom: Dizziness with Ear Pressure

Extended Retro/Infralabyrinthine Approach to Cerebellopontine Angle and Internal Auditory Canal, a Radio-Anatomic Study.

There is a considerable controversy about approaches that preserve hearing in acoustic neuroma surgery. Transtemporal approaches have the advantage of extradural drilling and minimal cerebellar retraction. We aimed to measure the limits and exposure of extended infra/retrolabyrinthine approach using temporal bone dissection and temporal high resolution computed tomography (HRCT). Hundred temporal bone sides (unpaired) underwent HRCT. The images were used to estimate the limits and exposure of infra/retrolabyrinthine approach. Also, 10 temporal bone sides underwent the same imaging protocol then were dissected to measure actual exposure and limits of dissection. These measures were compared with those retrieved by HRCT to find if they are appropriate to be applied in general population. Mean posterior fossa angle of vision (24.5 degrees), retrolabyrinthine (internal auditory canal) IAC (58.6%), and infralabyrinthine IAC exposures (73.2%) were documented based on data retrieved from CT scan. After temporal bone dissection, posterior fossa (p = 0.139) and infralabyrinthine exposures (p = 0.674) were not statistically different comparing with measures retrieved from CT scan; however, retrolabyrinthine exposure was overestimated (p = 0.012). We found that at least 20% more of IAC length can be exposed by extension of retrolabyrinthine to infralabyrinthine dissection. Infralabyrinthine exposure can be estimated preoperatively using temporal bone CT but the same is not true for retrolabyrinthine exposure.

TEMPORAL BONE IMAGING IN UNILATERAL SEVERE TO PROFOUND SNHL.

Background: The effect of unilateral sensor ineural hearing loss (UHL) on the quality of life is well documented. Studies found a direct link between UHL and educational and social delays. Radiological studies aimed to detect the associated anomalies of the earen countered a wide variation in the rates of incidence. Aim of the work: Our study aims to detect and give an estimate about the rate of incidence of different anomalies. Patients and methods: A review of the medical records of Audiology department in Eldemerdash hospital between 2014 to 2017 was done. Only cases with severe to profound USNHL diagnosed before age of 12 years were included. Clinical examination, full audiological assessment, MRI and CT temporal bone were done for all cases and results were reviewed for each patient. Results: 50 cases were included (8 cases with severe USNHL and 42 cases with profound USNHL). The mean age of diagnosis was 7.6 years.Only16 cases (32%) had risk factors known to contribute to SNHL. The most common abnormality found was cochlear nerve (CN)deficiency in 22 cases (44%).Bilateral findings were present in 4 cases (8%). Conclusion: Radiological evaluation is not only for detection of the cause but also allows proper counselling and exploring the possible options of rehabilitation.

Diagnostic value of CT and MRI of Temporal Bone in Cochlear Implantation Candidates

Background Cochlear implantation is an approved treatment which can be used to treat severe to profound hearing loss. Imaging before cochlear implant surgery is very important in decision making and assessing the temporal bone anatomy for surgery. We aimed to assess the diagnostic value of high resolution CT scan (HRCT), and MRI of temporal bone in candidate patient for cochlear implantation and compared with surgical results. Materials and Methods The present cross-sectional study was conducted on 34 patients aged under 5 years with sensorineural hearing loss (SNHL) undergoing cochlear implantation (CI) in Ahvaz cochlear implant center, Ahvaz, Iran. All patients were assessed via temporal bone HRCT and MRI before surgery. In addition, the radiological findings were analyzed and compared with surgical results. Results Obstruction of cochlear patency was found in 7 patients. The mean sensitivity/specificity of CT and MRI assessments were 100/94% and 100/96.3%, respectively. Associated anomalies were found in 4 patients. The mean sensitivity/specificity of CT and MRI assessments were 50/100% and 75/100%, respectively. Conclusion Based on the results, since CT scans are more accessible and cost less for the patient, it is recommended to perform CT scan as a primary method for assessment before surgery, while the MRI is only applied when the initial findings are unclear.

Correlation between pre-operative CT findings and intra-operative features in pediatric cholesteatoma: a retrospective study on 26 patients.

To assess the predictive value of pre-operative CT imaging in pediatric patients affected by cholesteatoma of the middle ear, comparing pre-operative CT findings to intra-operative features. A retrospective study was performed on a population of 26 pediatric patients who underwent tympanoplasty for middle ear cholesteatoma at the Otorhinolaryngology Departments of Verona and Modena University Hospitals between December 2011 and June 2018. Comparison between pre-operative CT images and intra-operative findings (assessed from video recording) was made focusing on the involvement of specific structures: ossicular chain, tegmen tympani, labyrinthine fistula, facial nerve, and temporal bone involvement. CT sensitivity, specificity, positive and negative predictive values were calculated. Overall, 28 surgical procedures were evaluated. No statistically significant differences were encountered between CT images and intra-operatory findings regarding the selected parameters. Based on our study, pre-operative temporal bone CT scan is a valuable tool for the assessment of pediatric patient candidates for cholesteatoma surgery given the absence of statistically significant differences between radiologic and intra-operative findings. The present findings might support the indication to routinely perform temporal bone CT scan in children with cholesteatoma as part of pre-surgical plan. III.

Symptom: Deafness After Stapedectomy

Symptom: Deafness After Stapedectomy

Clinical observation of attic retraction pocket by otoendoscopes

Objective:To explore the clinical effect, key points and techniques of otoendoscopic surgery in patients with attic retraction pocket. Method:Data of 25 patients (25 ears) of chronic suppurative otitis media who treated with transcanal endoscopic ear surgery for attic retraction pocket were retrospectively analyzed. Patients were examined by otoendoscopes at postoperative 1, 3 and 6 month，respectively. Patients were tested by pure tone audiometry，tympanometry test and high resolution CT of temporal bone at postoperative 6 month. Result:The healing rate of perforation was 100% in 25 patients (25 ears) at postoperative 1 month. There was no infection, tinnitus, vertigo, decrease of air-bone conduction hearing and other complications. All patients had good tympanic membrane shape, no perforation, no invagination or adhesion in tympanic membrane at postoperative 6 month.The mean preoperative air conduction threshold was (39.59±8.37)dB HL, while it was (26.21±7.51)dB HL at postoperative 6 month (t=8.265，P<0.01).The mean preoperative air-bone gap was (28.67±6.58)dB HL, while it was (13.63±7.33)dB HL at postoperative 6 month (t=11.862，P<0.01).The mean air conduction threshold and the mean preoperative air-bone gap were significantly improved compared with those preoperative (P<0.01). Tympanometry test was "A" type at postoperative 6 month. Conclusion:The treatment of attic retraction pocket by otoendoscopes through external auditory canal has the advantages of clear image, wide field of vision, simple operation, less trauma, short operation time, accurate effect, and can reduce the residual and recurrence of lesions.

Comparison of Temporal Bone Tomography Findings of Chronic Otitis Media with Intraoperative Findings

Background and Objectives: Chronic otitis media is considered a common disease in our region. There are various methods for evaluation of chronic suppurative otitis media including otoscopy, CT scan, X-ray, and MRI. Nowadays, computed tomography or CT scan is used as the selected method to investigate the temporal bone. This study aims to collect the intraoperative findings and compare them with preoperative reports of temporal bone CT scans. Materials and Methods: The patients’ data with chronic otitis media who were reviewed tomographically, hospitalized and operated between 2012 and 2014 in Tabriz Sina Hospital by only one otolarynologist included in this study collected. Results: The most common lesion based on the highest frequency and percentage is Tympanosclerosis. 21.4 percent of patients whom Tympanosclerosis were not diagnosed preoperatively, found during the surgery. 78.9 And 21.1 percent of bone erosions have been diagnosed by CT scan and by direct vision, respectively. Conclusion: Although preoperative CT of Middle ear lesions is useful for surgery planning but some lesion may not be completely diagnosed by CT scan and intraoperative assessment of surgical field is crucial.

Atlas-based segmentation of temporal bone surface structures.

To develop a time-efficient automated segmentation approach that could identify surface structures on the temporal bone for use in surgical simulation software and preoperative surgical training. An atlas-based segmentation approach was developed to segment the tegmen, sigmoid sulcus, exterior auditory canal, interior auditory canal, and posterior canal wall in normal temporal bone CT images. This approach was tested in images of 20 cadaver bones (10 left, 10 right). The results of the automated segmentation were compared to manual segmentation using quantitative metrics of similarity, Mahalanobis distance, average Hausdorff distance, and volume similarity. The Mahalanobis distance was less than 0.232mm for all structures. The average Hausdorff distance was less than 0.464mm for all structures except the posterior canal wall and external auditory canal for the right bones. Volume similarity was 0.80 or greater for all structures except the sigmoid sulcus that was 0.75 for both left and right bones. Visually, the segmented structures were accurate and similar to that manually traced by an expert observer. An atlas-based approach using a deformable registration of a Gaussian-smoothed temporal bone image and refinements using surface landmarks was successful in segmenting surface structures of temporal bone anatomy for use in pre-surgical planning and training.

Etiology-Specific Mineralization Patterns in Patients with Labyrinthitis Ossificans.

Our aim was to identify whether specific patterns of ossification in labyrinthitis ossificans are associated with the known risk factors. Labyrinthitis ossificans has been described as sequela of prior temporal bone trauma, prior infection, and other disorders including sickle cell disease. Specific patterns of mineralization in the membranous labyrinth associated with these risk factors has not been previously described. This was a retrospective study evaluating temporal bone CT scans at our institution from November 2005 to May 2018 in patients with labyrinthitis ossificans. Membranous labyrinthine structures evaluated for ossification included the following: basal, middle, and apical cochlear turns; lateral, posterior, and superior semicircular canals; and the vestibule for both ears in all patients. These structures were assigned a severity score, 0-4, based on degree of mineralization. Clinical records were reviewed for potential labyrinthitis ossificans risk factors. Basic descriptive statistics and a mixed model were used to correlate the degree and patterns of ossification with clinical history. Forty-four patients (58 ears) with labyrinthitis ossificans were identified and evaluated. The most common risk factors were chronic otomastoiditis (n = 18), temporal bone surgery (n = 9), temporal bone trauma (n = 6), sickle cell disease (n = 5), and meningitis (n = 4). For all etiologies, the semicircular canals were most severely affected, and the vestibule was the least. In patients with prior temporal bone surgery, significantly greater mineralization was seen in the basal turn of the cochlea (P = .027), the vestibule (P = .001), and semicircular canals (P < .001-.008). No significant pattern was identified in patients with meningitis, sickle cell disease, or trauma. Significant patterns of mineralization in labyrinthitis ossificans were observed in patients with prior temporal bone surgery. For all etiologies, the semicircular canals were most severely affected. No significant mineralization pattern was observed in patients with chronic otomastoiditis, meningitis, sickle cell disease, or prior temporal bone trauma.

Development of vestibular ocular reflex and gross motor function in infants with common cavity deformity as a type of inner ear malformation

Background： The function of common cavity deformity demonstrated by temporal bone CT and MRI has been unknown.Aim/Objective: To investigate the developmental changes of vestibular ocular reflex and acquisition of postural control in infants with common cavity deformity.Material and methods: Eight infants who were congenitally deaf complicated by common cavity deformity were studied. The damped rotational chair test was carried out to evaluate vestibular ocular reflex. Acquisition of head control and independent walking in these infants was compared with that in normal infant’s milestones of gross motor development.Results: All of the eight infants with common cavity deformity did not show per-rotatory nystagmus in the damped rotational chair test around the first year of life. However, a normal number of beats and a longer duration of per-rotatory nystagmus for their age were recorded at around three or four years of age.Conclusions and significance: In the eight infants with common cavity deformity, vestibular ocular reflex was not present around the first year of life, but appeared after three or four years probably because of some vestibular sensory cells. Head control and independent walking were delayed but eventually acquired by the central vestibular compensation.

Application of bone-plastic materials for mastoidoplasty

The aim of this study is comparative assessment of of different bone-plastic materials for mastoidoplasty. The study included 30 patients who underwent 'canal wall down' mastoid surgery with mastoidoplasty. The following criteria were used for comparing: 1) simplicity of modeling of the material 2) the wound healing process 3) osteointegration - the process of formation of 'new bone' tissue (CT of temporal bones 6 and 12 months after oreretion). It was confirmed that the main groups of bone-plastic material (bioglass, composite materials and β-tricalcium phosphate) is suitable for mastoidoplasty after 'canal wall down' mastoid surgery.

Isolated Internal Auditory Canal Diverticula: A Normal Anatomic Variant Not Associated with Sensorineural Hearing Loss.

Bony internal auditory canal diverticula are relatively common, occurring in approximately 5% of temporal bone CTs. Internal auditory canal diverticula have historically been considered incidental; however, a recent publication reported that internal auditory canal diverticula are associated with sensorineural hearing loss. The objective of this study was to further characterize this potential association in a large cohort of patients. A total of 1759 patients undergoing high-resolution temporal bone CT were collected during a 6-year interval, and audiometric data were obtained from those with internal auditory canal diverticula. To assess any association of isolated internal auditory canal diverticula with sensorineural hearing loss, we excluded from further analysis patients with concomitant otosclerosis and bilateral diverticula and those without audiometric data, leaving 22 index cases. Audiometric data for the ear with a diverticulum was compared with that in the contralateral ear, to serve as an internal control. Of 1759 patients, 82 (4.7%) had either unilateral (n = 33, 40%) or bilateral (n = 49, 60%) internal auditory canal diverticula. The co-incidence of otosclerosis and internal auditory canal diverticula was 34% (n = 28). There was no correlation between patient age and diverticulum size on either side. Among the index cases with isolated unilateral internal auditory canal diverticula and complete audiometric data, word recognition scores and the prevalence and severity of sensorineural hearing loss were not significantly different comparing the internal auditory canal diverticulum side to its contralateral control. This study did not find a statistically significant association between ears with internal auditory canal diverticula and worsening sensorineural hearing loss or word recognition. Internal auditory canal diverticula most likely represent a normal anatomic variant in ears without otosclerosis.

Pulsatile Tinnitus Due to a Sigmoid Sinus Diverticulum and/or Dehiscence

In 2009, a 52-year-old man presented with a two year history of intermittent right-sided pulse-synchronous tinnitus. He noted that the tinnitus worsened when his blood pressure was elevated. Otologic exam was unremarkable, with no obvious middle ear fluid or mass. There was no neck bruit, and the tinnitus diminished on manual compression of the ipsilateral internal jugular vein. In keeping with the recommendations for clinical imaging at that time, a non-contrast CT of the temporal bone was performed. This was to evaluate for conditions such as : a middle ear glomus, an aberrant internal carotid artery, a jugular bulb variant (e.g. a high-riding jugular bulb), otosclerosis, superior semicircular canal dehiscence syndrome, a persistent stapedial artery, or a hemangioma of the temporal bone.1 No evidence of these conditions was found. An MRI of the brain, with MR angiography and venography of the intracranial vasculature also performed to evaluate for conditions such as: idiopathic intracranial hypertension, a dural arteriovenous fistula, an arteriovenous malformation, vascular loop syndrome, and dural sinus stenosis or thrombosis.2 All of these conditions were excluded. As no definite pathology was identified, no firm treatment reommendations were initiallly made.&#x0D; In 2011, Eisenman reported on a series of 13 patients with pulsatile tinnitus due to a sigmoid sinus diverticulum and/or dehiscence who were successfully treated surgically via an extraluminal transmastoid approach.3 This was the first relatively large series published in the otologic literature. This publication likewise reported on the subtle radiologic signs that signify the presence of a sigmoid sinus diverticulum and/or dehiscence, such as an irregularity of the normal semicircular contour of the bony sinus wall, focal thinning of the calvarial cortex overlying the adjacent sinus wall, absence of the normal thin layer of cortical bone overlying the sinus, and the "air-on-sinus" sign, where mastoid air cells directly contact the sinus wall, without overlying bone.3&#x0D; In light of this new information, the patient's imaging studies were re-evaluated, and evidence of a right-sided sigmoid sinus diverticulum and/or dehiscence was identified. The images below show the findings on an axial slice of the patient's temporal bone CT study.&#x0D; How significant is this condition ? Sigmoid sinus diverticulum and/or dehiscence is being increasingly recognized as a common cause of pulsatile tinnitus. In fact, a recent study by Schoeff et al. found its prevalence to be 23% in patients with pulsatile tinnitus.4 As such, the identification of this condition is highly relevant, particularly because effective surgical management is available for its alleviation.

The Unwound Cochlea: A Specific Imaging Marker of Branchio-Oto-Renal Syndrome

Branchio-oto-renal syndrome is an important syndromic cause of hearing loss. Our aim was to determine the test characteristics of the unwound cochlea on temporal bone CT for the diagnosis of branchio-oto-renal syndrome in a cohort of children with hearing loss. Patients were identified retrospectively with a clinical diagnosis of branchio-oto-renal syndrome and CT imaging of the temporal bones. Age-matched controls were also identified with sensorineural hearing loss not related to a diagnosis of branchio-oto-renal syndrome and CT imaging of the temporal bones. All examinations were reviewed by 2 neuroradiologists blinded to the diagnosis of branchio-oto-renal syndrome versus controls for the absence/presence of an unwound cochlea defined as anteromedial rotation and displacement of the middle and apical turns away from the basal turn. The final study group comprised 9 patients with branchio-oto-renal syndrome (age range, 1-14 years; mean age, 8.0 ± 4.3 years) and 50 control patients (age range, 1-16 years; mean age, 7.9 ± 4.1 years). The cochlea was subjectively abnormal in all 9 patients. In 8 patients (89%), imaging demonstrated a typical unwound cochlear morphology. By contrast, none of the control subjects demonstrated an unwound cochlea on either side. Statistically, the unwound cochlea was significantly more frequent in the branchio-oto-renal group compared with controls (P < .001). The unwound cochlea was 89% sensitive and 100% specific for the diagnosis of branchio-oto-renal syndrome. The unwound cochlea is a specific imaging marker of branchio-oto-renal syndrome. These findings further support the diagnostic accuracy and therefore the utility of temporal bone imaging in the diagnosis of this disorder.