Fundus Of Internal Auditory Canal Research Articles

Peritumoral Signal on Postcontrast FLAIR Images: Description and Proposed Biomechanism in Vestibular Schwannomas.

Anecdotally, postcontrast FLAIR images of vestibular schwannomas can show peritumoral hyperintense signal, hypothesized to represent gadolinium extravasation. This study assessed the incidence of this phenomenon in a cohort of patients with treatment-naïve sporadic vestibular schwannomas. A retrospective review of 20 patients with presumed vestibular schwannoma based on characteristic imaging findings and with dedicated internal auditory canal imaging, including postcontrast T1W1 and postcontrast FLAIR, was performed. Tumor size and location were recorded, as was the presence or absence of a fundal fluid cleft. Images were reviewed for the presence of peritumoral hyperintense signal on FLAIR images (a "halo") and for both subjectively and objectively elevated signal in the ipsilateral cochlea and fundus. Patients were randomly selected from an institutional vestibular schwannoma registry. Eleven (55.0%) were women. A peritumoral halo was present in 90% of patients, averaging 1.0 (SD, 0.2) mm in thickness. The maximum mean FLAIR signal in the ipsilateral fundus (205.9 [SD, 110.2]) was significantly greater than on the contralateral side (121.6 [SD, 27.8]) (P = .02). Maximum mean ipsilateral intracochlear signal (167.8 [SD, 104.5]) was also significantly greater than on the contralateral side (113.4 [SD, 40.1]) (P = .04). A peritumoral halo on postcontrast FLAIR images was present in 90% of our cohort with randomly selected, treatment-naïve sporadic vestibular schwannomas. Although its mechanism is unknown, this signal is hypothesized to represent gadolinium extravasation, given an ipsilateral increased signal in the adjacent internal auditory canal fundus and cochlea.

Nervus intermedius: Microsurgical and anatomic relationships to the cerebellopontine angle neurovascular complex.

The nervus intermedius (NI) comprises fibers originating from the trigeminal, superior salivary, and solitary tract nuclei, which join the facial nerve (cranial nerve [CN] VII). Neighboring structures include the vestibulocochlear nerve (CN VIII), the anterior inferior cerebellar artery (AICA), and its branches. Microsurgical procedures at the cerebellopontine angle (CPA) benefit from understanding NI anatomy and relationships, especially for the microsurgical treatment of geniculate neuralgia, where the NI is transected. This study sought to characterize common relationships between the NI rootlets, CN VII, CN VIII, and the meatal loop of AICA at the internal auditory canal (IAC). Seventeen cadaveric heads underwent retrosigmoid craniectomy. Following complete unroofing of the IAC, the NI rootlets were individually exposed to identify their origins and insertion points. The AICA and its meatal loop were traced to assess their relationship with the NI rootlets. Thirty-three NIs were identified. The median number of NI rootlets was 4 per NI (interquartile range, 3-5). The rootlets mainly originated from the proximal premeatal segment of CN VIII (81 of 141, 57%) and inserted onto CN VII at the IAC fundus (89 of 141, 63%). When crossing the acoustic-facial bundle, the AICA most frequently passed between the NI and CN VIII (14 of 33, 42%). Five composite patterns of neurovascular relationships were identified regarding NI. Although certain anatomical trends can be identified, the NI has a variable relationship with the adjacent neurovascular complex at the IAC. Therefore, anatomical relationships should not be used as the sole method of NI identification during CPA surgery.

Topographic Anatomy of the Medial Labyrinthine Wall: Implications for the Transcanal Endoscopic Approach to the Internal Auditory Canal.

To characterize transcanal endoscopic landmarks of the medial labyrinthine wall and correlate these with anatomical features of the fundus of the internal auditory canal (IAC). The transcanal transpromontorial approach (TTA) enables minimally invasive access to the IAC. The establishment of a landmark-based dissection technique for the approach is crucial to avoid injury to the facial nerve. Twenty temporal bones were dissected endoscopically through the TTA. Furthermore, high-resolution computed tomography (CT) scans from ten adult normal temporal bones were analyzed and three-dimensionally reconstructed. A stepwise dissection technique for the TTA was demonstrated depending on a newly described landmark used in the identification of the facial nerve. The proposed landmark, which was named the intervestibulocochlear crest (IVCC), is an integrated part of the otic capsule. It can be differentiated after the excision of the lateral labyrinthine wall as a laterally based bony pyramid between the cochlea and the vestibule. Its medially directed apex blends with the central part of the falcifrom crest and points to the distal part of the meatal facial nerve. The IVCC is best detected on axial CT images at the level of the tympanic facial nerve. The union between the IVCC and the falciform crest appears radiologically as a short stem or mini-martini glass. The proposed IVCC is a novel landmark with a consistent relationship to the IAC fundus and the facial nerve. It may be utilized in conjunction with the falciform crest to identify the facial nerve during minimally invasive transcanal surgeries.

Radial spoiled gradient T1 weighted imaging of the internal auditory canal: Is Scarpa's ganglion now an expected finding and source of fundal enhancement?

StarVIBE is a 3D gradient-echo sequence with a radial, stack-of-stars acquisition having spatial resolution and tissue contrast. With newer sequences, it is important to be familiar with sequence tissue contrasts and appearance of anatomical variants. We evaluated 450 patients utilizing this sequence; 35 patients demonstrated fluffy "cotton wool" enhancement at the internal auditory canal fundus without clear pathology. We favor this represents anatomic neurovascular enhancement that StarVIBE is sensitive to and is a touch-me-not finding.

Imaging Case of the Month: Internal Auditory Canal Fundus Arachnoid Cyst.

Imaging Case of the Month: Internal Auditory Canal Fundus Arachnoid Cyst.

3D Real IR MR Findings in Acoustic Neuromas: Altered Perilymph Metabolism.

This study aimed to investigate the perilymph metabolism by analyzing the 3D real IR MR findings in acoustic neuroma (AN) after intravenous administration of gadolinium (Gd). Eleven patients (6 men and 5 women) diagnosed with AN were included, and 3D real IR MRI was performed 4hours after intravenous Gd injection. The signal intensity and details of inner ear, tumor, and internal auditory canal (IAC) by MRI were analyzed. Four patients had tumors confined to the IAC, and 5 had tumors that extended to the cerebellopontine angle cistern. The signal intensity of the cochlea, vestibule, and IAC fundus was conspicuously enhanced in 3D real IR images than the control side. One patient had a tumor in the cochlea, in which the signal intensity of the semicircular canal and vestibule was increased. One patient had an intravestibular tumor in which the signal intensity of the semicircular canal was increased and the cochlea had endolymphatic hydrops in the affected ear. The synchronously increased signal intensity in the inner ear and IAC may indicate that IAC may serve as a channel for removal of the perilymph in the inner ear; the blockage by the tumor may have changed the hydrodynamics of the perilymph to cause a longer retention of Gd in the inner ear.

Endoscopic intracanalicular vestibular schwannoma excision via middle ear corridors a surgical options

Background With more intracanalicular vestibular schwannoma (ICVS) diagnosed, treatment options are limited either to wait-and-see or surgery. The transpromontorial and infrapromontorial approaches allow direct route to the fundus of internal auditory canal with certain advantages in preserving facial nerve and even cochlear nerve. Objectives To describe the middle ear corridor approach for ICVS excision. Methodology All transpromontorial and infrapromontorial approaches for ICVS excision were recruited. The surgeries were performed at an otologic center by a single experienced otologist. Results Three cases of ICVS Koos Type I were included in this review. Two cases were operated with exclusive endoscopic transcanal transpromontorial approach excision of tumor. One case underwent concurrent transcanal excision of ICVS through infrapromontorial approach with cochlear implantation. Two of them developed facial nerve paresis. The last patient recovered fully with viable cochlear nerve enabling hearing restoration with cochlear implant. Conclusion The potential of surgery in ICVS via middle ear approach is a safe and direct route with promising outcome. This approach offers removal of the ICVS without interrupting facial and cochlear nerves. Hence, the preservation of facial function and hearing are possible.

Internal Auditory Canal Diverticula among Pediatric Patients: Prevalence and Assessment for Hearing Loss and Anatomic Associations.

Internal auditory canal diverticula are focal lucencies along the anterior-inferior aspect of the internal auditory canal fundus. Studies in adults report conflicting data on the etiology and clinical relevance of this finding. We would expect a pediatric study to help elucidate the significance of internal auditory canal diverticula. The primary goals of this study were to determine the temporal bone CT prevalence of diverticula among pediatric patients and to assess possible hearing loss and anatomic associations. For this retrospective study including 283 pediatric temporal bone CTs, 4 neuroradiologists independently assessed for diverticula. Discrepancies were resolved by consensus. One neuroradiologist assessed for an enlarged vestibular aqueduct, labyrinthine dysplasia, cochlear cleft, and otospongiosis. Patient demographics, audiologic data, and pertinent clinical history were recorded. One-way analysis of variance and the Fisher exact test were used to assess possible associations between diverticula and specific patient characteristics. Diverticula were observed in 42/283 patients (14.8%) and were more commonly bilateral. There was no significant association with age, sex, hearing loss, enlarged vestibular aqueduct, labyrinthine dysplasia, or cochlear cleft. A statistically significant association was observed with otospongiosis (P = .013), though only 1 study patient had this disease. Internal auditory canal diverticula are a common finding on pediatric temporal bone CT. In the absence of clinical or imaging evidence for otospongiosis, diverticula likely fall within the range of a normal anatomic variation. Familiarity with these findings may prevent neuroradiologists from recommending unnecessary additional testing in pediatric patients with isolated internal auditory canal diverticula.

Correlation of cochlear nerve cross-sectional area and auditory performance after cochlear implantation in prelingual children with bilateral profound hearing loss

ObjectiveTo assess whether cochlear nerve (CN) cross-sectional area as measured with parasagittal magnetic resonance imaging (MRI) in prelingual pediatric deaf patients correlates with auditory performance after cochlear implantation. Study designProspective Cohort study. MethodsThirty-two prelingual children with bilateral profound sensorineural hearing loss (SNHL) who received unilateral cochlear implant were included in this study. Diameters of CN at Internal auditory canal (IAC) fundus and mid-point of IAC were retrospectively measured on parasagittal images of FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence MRI by two independent observers. Cross-sectional areas [π (Height/2) (Width/2)] were then correlated with post-operative CAPS (Categories of Auditory Performance) and IT-MAIS (Infant-Toddler Meaningful Auditory Integration Scale) scores regularly assessed at 3 monthly intervals post device activation. ResultsThe cochlear nerve was identified in all the 32 patients. Mean cross-sectional areas (CSA) of cochlear nerve were 0.71 ± 0.16 mm2 at IAC fundus and 0.73 ± 0.18 mm2 at mid-point of IAC. The correlation value between CSA at mid-point of IAC and CAPS score at 6 months was 0.271 (p-value- 0.140) and correlation value between CSA at mid-point of IAC and IT-MAIS score at 6 months was 0.282 (p-value- 0.124) which were statistically not significant. ConclusionThere was no significant correlation between the cross-sectional areas of the cochlear nerve on MRI and postoperative auditory scores as measured by CAPS and IT-MAIS scores at six months from the device activation. Hence, we conclude that above an adequate diameter, which can affect the minimum required neurons, the changes in the diameter do not have significant bearing on auditory outcomes after cochlear implantation.

Imaging Features Differentiating Vestibular Ganglion from Intracanalicular Schwannoma on Single-Sequence Non-Contrast Magnetic Resonance Imaging Study

This study aimed to identify imaging features on single-sequence noncontrast magnetic resonance imaging (MRI) that differentiate the vestibular ganglion from small intracanalicular schwannomas. Ninety patients (42 men and 48 women; age: 24‒87 years old) with 102 internal auditory canal (IAC) nodules (59 vestibular ganglia and 43 intracanalicular schwannoma) who underwent both single-sequence T2-weighted (T2W) non-contrast enhanced MRI studies and contrast-enhanced T1-weighted (T1W) MRI studies between May 2012 and April 2017 were evaluated. The length, width, distance to the IAC fundus and length/width ratios for all lesions were obtained and compared among groups. Diagnostic performance and cutoff values of the parameters were evaluated with receiver operating characteristics curve analysis. Area under the curve (AUC) value was calculated. Vestibular ganglia have significantly smaller lengths and widths compared to intracanalicular vestibular schwannomas (1.7 ± 0.4 mm and 1.0 ± 0.2 mm versus 5.6 ± 3.0 mm and 3.7 ± 1.5 mm). They are more fusiform in shape compared to vestibular schwannomas (length/width ratio: 1.8 ± 0.4 versus 1.5 ± 0.4). The lesion width demonstrated the highest diagnostic performance (AUC: 0.998). Using a cutoff width of <1.3 mm, the sensitivity, specificity and overall accuracy for diagnosing vestibular ganglia were 97% (57/59), 100% (43/43) and 98% (100/102), respectively. Vestibular ganglia may mimic intracanalicular vestibular schwannomas on a single-sequence T2W MRI. However, a fusiform shape and width <1.3 mm increases confidence in the diagnosis of ganglia. Identifying the vestibular ganglion on single-sequence T2W MRI studies may obviate the need for a contrast-enhanced MRI, reducing the risks of contrast administration, additional scanning time and cost.

Prognostic Factors of Long-Term Hearing Preservation in Small and Medium-Sized Vestibular Schwannomas After Microsurgery.

The authors evaluated the long-term hearing outcomes of patients with vestibular schwannoma (VS) to explore appropriate surgical treatment. Retrospective study. Tertiary referral center. A total of 138 patients diagnosed with small and medium-sized VS with serviceable hearing from January 2006 to December 2015. All patients underwent microsurgery via retrosigmoid (RSA) or middle cranial fossa approach (MFA) and were followed up for over 2 years. Pre- and postoperative hearing, including pure tone audiometry, speech discrimination score, and auditory brainstem response (ABR), were analyzed. The mean tumor size and volume were 16.6 ± 3.4 mm and 1711.8 ± 918.5 mm, respectively. Preoperative hearing levels were Class A in 42, Class B in 67, and Class C in 29 patients. Patients with a tumor from the superior vestibular nerve (SVN) had better hearing at diagnosis. Postoperative hearing levels were Class A, B, C, and D for 28, 17, 32, and 61 patients. Hearing outcomes were significantly better in patients with normal intraoperative I wave on ABR. Hearing loss within 6 months had a positive effect on postoperative hearing. Better preoperative hearing and tumors from SVN were correlated with better postoperative hearing outcomes. Tumor size, cystic variation, or extension to the fundus of internal auditory canal had no influence on hearing preservation. Better preoperative hearing, shorter hearing loss period, tumors from SVN, and normal intraoperative I wave are prognostic factors for serviceable hearing. RSA and MFA are effective and safe for tumor removal and hearing preservation.

Cochlear basal turn patency in unrecognized perilymph gushers

ObjectivesPerilymph gusher (PLG), an uncommon complication of otologic surgery, has been attributed to communication between the cochlea and the internal auditory canal (IAC). Subtle osseous defects may be missed on routine review of computed tomography (CT). This study aimed to quantify cochlear basal turn patency not seen on axial CT in patients with PLG and compare those against patients without intraoperative PLG. MethodsEars that underwent cochlear implantation or stapedotomy with preoperative helical CT that was interpreted as “normal” at a tertiary referral center. An otologist and a radiologist independently and in a blinded fashion measured the dimensions of cochlear basal turn patency on CT images in oblique plane and parasagittal planes along the interface of the cochlea and IAC fundus. ResultsSixty-one ears were reviewed, including 3 with surgically confirmed PLGs and 12 with apparent dehiscence without a PLG. Mean defect width with PLG was 0.83 mm (range 0.75–0.9 mm) and without PLG was 0.43 mm (range 0.3–0.65 mm, p = 0.011). A greater proportion of PLGs occurred in ears with defects (3 of 15) than in ears without (0 of 46, p = 0.013). Using a cutoff of 0.75 mm, a greater proportion of PLGs occurred with defect width >0.75 mm (3 of 3) than in defects <0.75 mm (0 of 12, p = 0.022). ConclusionsCT dehiscence between the IAC and cochlear basal turn, particularly with a width > 0.75 mm, should be considered a risk for PLG with stapedotomy or cochlear implantation.

Microsurgical and Endoscope Assisted Resection of a Right Intracanalicular Vestibular Schwannoma Two-Dimensional Operative Video.

A 36-year-old lady presented with tinnitus and hearing loss for 1 year which was progressively worsening. A hearing test revealed pure tone average (PTA) between 48 to 65 dB and speech discrimination of 56% at 95 dB. Brain magnetic resonance imaging (MRI) showed a right vestibular schwannoma 5 × 8 mm ( Fig. 1 ) which extended far laterally to the fundus of internal auditory canal (IAC). A translabyrinthine approach was suggested by another neurosurgeon/neurotologist team, but the patient decided to undergo operation by retrosigmoid approach with attempted hearing preservation. She underwent a right retrosigmoid craniotomy, craniectomy, and mastoidectomy with far lateral approach. We performed petrous transcanalicular microsurgical approach with the assistance of neuroendoscope. Intraoperatively, the internal auditory artery was looping into the IAC between cranial nerves VII and VIII, and coming out inferiorly. The IAC was opened by the diamond drill, ultrasonic bone curette, and fine rongeurs. The tumor was grayish in color with filling the lateral aspect of the IAC. After circumferential dissection of the tumor capsule, the tumor was removed completely. It was arising from the inferior vestibular nerve which was stretched. The patient had vertigo and nausea postoperatively but it is steadily improving. Her hearing test has improved to a PTA of 22 dB and speech discrimination of 100% at 70 dB at 6 weeks. The postoperative MRI showed total resection. This two-dimensional video shows the technical nuances of microsurgical retrosigmoid approach and endoscopic assisted resection of an intracanalicular vestibular schwannoma and the value of attempting hearing preservation in all vestibular schwannomas ( Fig. 2 ). The link to the video can be found at: https://youtu.be/KHrO_iDI2tw .

Role of Endoscopy in Resection of Intracanalicular Vestibular Schwannoma via Middle Fossa Approach: Technical Nuances

Surgical resection of vestibular schwannomas (VS) located within the internal auditory canal (IAC) is challenging, especially those located very laterally in the IAC. Various transcranial approaches have been described for resection of intracanalicular VS including retrosigmoid, translabyrinthine, and middle fossa approaches. Each approach has its indications, advantages, and limitations. The middle fossa approach (MFA) is considered by many authors as the gold standard approach for resection of small intracanalicular VS in young patients with serviceable hearing; however, there is often a limitation in complete visualization of the tumor. The authors present an illustrative case to highlight the technical nuances of complementary use of endoscopy in MFA for complete resection of intracanalicular VS located at the IAC fundus, preserving preoperative hearing status and mainting intact facial nerve function. In our experience, the combined use of the endoscope and the microspe as described here and illustrated in our case, improves visualization of the IAC and its contents, improving ressection and outcomes. MFA allows for a direct yet safe surgical corridor to small intracanalicular VS. The implementation of endoscopy with MFA, especially for VS located laterally in the IAC, allows for better opportunity for complete resection of the tumor with improved preservation of hearing and facial nerve function.

Maximizing Exposure of the Internal Auditory Canal Via the Retrosigmoid Approach: An Anatomical, Radiological, and Surgical Study.

The purpose of this study was to identify anatomic landmarks and surgical techniques that maximize bone removal for exposure of the distal internal auditory canal (IAC) to avoid labyrinthine injury during retrosigmoid removal of tumors within the IAC. Anatomic dissection, radiological assessment and retrospective case series. Tertiary referral center. On the basis of previously conducted temporal bone anatomic dissections of the temporal bone, the authors performed intraoperative measurement of the undissected distal IAC, performed pre- and postoperative radiological assessment of vestibular schwannoma (VS) patients. The surgical and anatomic information was used to determine the anatomic limits of labyrinth sparing bone dissection and the landmarks most critical to maximal IAC exposure. The authors describe surgical techniques using these data. An edited video of representative surgery highlights important principles. Review of 251 patients requiring IAC bony dissection for tumor removal from January 2005 through October 2017 is described. Achieving complete exposure of the IAC fundus is not possible, without labyrinthine injury, via retrosigmoid approach. Anatomic dissection, intraoperative photography, and postoperative radiographs demonstrate that bone removal within 2 to 3 mm of the fundus is routinely possible. The endolymphatic sac and duct is the optimal landmark for optimizing IAC exposure. The course of the endolymphatic sac and duct in the posterior petrous bone is the most important landmark determining the lateral limit of bony removal during IAC exposure for tumor resection. Surgical techniques based on these anatomic findings facilitate tumor resection while preserving the labyrinth.

Quantitative Analysis of Surgical Freedom and Area of Exposure in Minimal-Invasive Transcanal Approaches to the Lateral Skull Base.

We aim to provide objective data regarding the area of exposure (AOE) and the surgical freedom (SF) offered by the transcanal approaches to the lateral skull base. Minimal-invasive transcanal lateral skull base procedures have been recently developed and their clinical feasibility demonstrated. The reduced access size requires careful analysis and selection of suitable cases, qualifying for a minimal-invasive approach. We performed the mentioned approaches in standardized dissection using human whole heads. Surgical freedom is defined as the degree of movement liberty of the surgical instrument at predefined landmarks. We assessed SF at anatomical landmarks throughout the lateral skull base. Moreover, we measured the AOE, defined as the surface on the lateral skull base reached by every approach. We performed a total of 48 dissections under stereotactic image guidance in a total of 12 sides. The mean SF was assessed for the inferior petrous apex 602 mm, for the geniculate ganglion 1,916 mm, and for the fundus of internal auditory canal 1,337 mm. The AOE was measured for the infracochlear approach 55 mm, suprageniculate approach 67 mm, transpromontorial approach 11 mm, and for the expanded transpromontorial approach 93 mm at the fundus and 108 mm at the porus of the internal auditory canal. This study provides a quantitative description of minimal-invasive transcanal approaches to the lateral skull base. The AOE offered by the expanded transcanal transpromontorial approach is inferior but comparable to the reported AOE of transmastoidal approaches. The reported objective measurements may provide important information for future preoperative planning and patient counseling.

Transcanal Endoscopic Lateral Skull Base Surgery

Presutti and Marchioni’s transcanal exclusive endoscopic transpromontorial approach represents a new surgical technique to remove diseases that involve cochlea and fundus of internal auditory canal in selected cases, thus avoiding extensive bone drilling, brain, meningeal, and neurovascular manipulation. The advantage of this endoscopic technique is that direct access to internal auditory canal allows the creation of a minimally invasive route through the cochlea with a consequent improved safety during intraoperative and postoperative management. Surgeons who start with this surgical procedure must possess some fundamental prerequisites, like confidence with other inner ear techniques and previous experience with endoscopic middle ear surgery and endoscopic cadaveric dissections. Owing to the reduced invasiveness of the transpromontorial transcanal approach, there is no need for an intensive care unit stay after the operation and patient hospitalization is shorter.

Lessons Learned from Intraoperative Monitoring of Hearing in EMFA Using ECoCh

Introduction: Small acoustic neuroma can be removed by EMFA and by retrosigmoid approach. Hearing monitoring during those operations should be a routine procedures. Material and Method: Authors presented their own experience since 2006 and defined changes in intraoperative behavior of surgeon based on monitored hearing during removal of AN by ETLA. Total material of EMFA includes 150 cases. Forty cases were operated with monitoring. Authors analyzed surgical issues causing signs/changes in ECoCh traces and possibly lowering chances for hearing preservation. Results: First signs deteriorating ECoCh traces appeared during localization of landmarks on temporal bone. In this situation, low-speed micromotors with 30,000 rpm. solved problems. Accidentally opening of SSC resulted in lowering of the amplitude in ECoCh. Immediate sealing caused good recovery. More difficult problems encountered during AN resection. When latency elongated of more than 0.10 milliseconds a break in dissection lasting at least 5 minute was recommended. Recurrent latency elongations lowered the chance for hearing preservation. The most vulnerable part of tumor resection was fundus of IAC. Coagulation close to the operating field always influenced on ECoCh morphology. Conclusion: Hearing loss during AN operation can occur in every stage of EMFA. Monitoring of hearing helps in the explanation of dangerous moments of intervention. Most hazardous steps are drilling the roof of IAC, accidentally opening of SSC and dissection close to fundus of internal auditory canal.

A novel mutation in POU3F4 in a Chinese family with X-linked non-syndromic hearing loss

ObjectiveBased on the clinical manifestations of a hearing loss patient, the POU3F4 gene was tested for diagnosis of etiology. MethodsA comprehensive physical examination was performed on the proband to exclude abnormalities of other organs, and detailed audiological testing and temporal bone CT scan were also performed. Genomic DNA was extracted using the proband's peripheral blood leukocytes. Polymerase chain reactions (PCR) were performed in the coding sequence of the POU3F4 gene. Direct DNA sequencing was subsequently applied to screen the entire coding region of the POU3F4 gene. ResultsThe proband had severe sensorineural hearing loss. Temporal CT showed bilateral cochlear incomplete partition, vestibule dysplasia, internal auditory canal fundus expansion, and cochlear interlink with the internal auditory canal fundus. A novel mutation (c.530C > A (p.S177X)) in the POU3F4 gene was found in this patient, creating an new stop codon and was predicted to result in a truncated protein lacking normal POU3F4 transcription factor function. ConclusionThrough analysis of the POU3F4 gene and clinical manifestations in the patient, we conclude that a novel mutation may have resulted in a premature stop codon, contributing to the mutation of POU3F4 gene.

Cochlear nerve diameters on multipoint measurements and effects of aging in normal-hearing children using 3.0-T magnetic resonance imaging

ObjectiveThe aim of this study was to determine differences in diameter of cochlear nerves (CN) among three measurement points at the midpoint of the internal auditory canal (IAC), IAC fundus and cochlear aperture, and to evaluate whether nerve size varies with age. MethodsA total of 336 normal-hearing ears of 201 children were assessed, who were underwent 3D-Fiesta sequence scanning of inner ear. All subjects were divided into 12 groups at one year interval. The diameter measurements of CN were obtained in the midpoint of the IAC, IAC fundus and cochlear aperture respectively on the axial and oblique sagittal images of 3.0-T MRI. SPSS 18.0 statistics software was applied for data analysis, and all of the data showed a normal distribution and expressed in x¯±s. ResultsThe diameters of normal-hearing children's CN at the midpoint of the IAC, IAC fundus and cochlear aperture were respectively: 1.12±0.08mm, 1.05±0.06mm, 0.87±0.14mm, and there were significant differences among the three measuring points (F=527.57, p<0.05). The diameters of the CN had no significant difference (p>0.05) in age groups, gender and sides (p>0.05), and there was no correlation between the diameters of normal children's CN and age (r is −0.129, 0.128 and −0.113, respectively). ConclusionThe diameters of normal-hearing children's CN change with different points of the internal auditory canal, of which the maximum value is in the midpoint of the IAC, followed by the IAC fundus, and the cochlear aperture is at the minimum; moreover the normal size doesn’t change with age.