Reliability and Validity of a Korean Version of the Tinnitus Primary Function Questionnaire.

Purpose The aim of this study was to evaluate the reliability and validity of a Korean version of the Tinnitus Primary Function Questionnaire (K-TPFQ). Method A total of 79 subjects participated in the study. All participants completed the K-TPFQ, and the Korean versions of the Pittsburgh Sleep Quality Index ( Buysse, Reynolds, Monk, Berman, & Kupfer, 1989 ; Sohn, Kim, Lee, & Cho, 2012 ), the Beck Depression Inventory ( Beck, Ward, Mendelson, Mock, & Erbaugh, 1961 ; Jo, Park, Jo, Ryu, & Han, 2007 ), the State-Trait Anxiety Inventory questionnaire ( Cho & Choi, 1989 ; Spielberger & Gorsuch, 1983 ), and the Tinnitus Handicap Questionnaire ( Kuk, Tyler, Russell, & Jordan, 1990 ). Results The K-TPFQ exhibited good or high internal consistency and reliability (Cronbach's alpha range: .91-.95, item-total correlation range: .50-.82). The total score derived from the items of the K-TPFQ and its subcategories was moderately correlated with that of questionnaires that measure similar parameters (Pearson correlation coefficient range: .50-.79). Conclusions Overall, the results of this study indicate that the K-TPFQ is reliable and valid. Therefore, the current translated version of the K-TPFQ is applicable to subjects with Korean as their 1st language and proves to be a useful tinnitus questionnaire.

Clinical effect of intratympanic dexamethasone injection in acute unilateral tinnitus: A prospective, placebo-controlled, multicenter study.

OBJECTIVE: The purpose of this study was to investigate the effectiveness of intratympanic dexamethasone injection (ITDI) in acute tinnitus of presumed cochlear origin. STUDY DESIGN: A prospective, randomized, placebo-controlled, double-blinded, multicenter study. METHODS: Between August 2013 and December 2015, 54 patients with unilateral tinnitus were enrolled at four different centers. Patients were assigned either to an ITDI (n = 27) or an intratympanic normal saline injection (ITNI; n = 27) group through block randomization. Intratympanic injections were administered four times over 2 weeks. At 4 weeks after initial injection, we analyzed the improvement rates of tinnitus using the tinnitus handicap Inventory (THI) and visual analogue scale (VAS) for loudness, awareness, and annoyance. We defined improvement as the reduction of more than 7 points or of more than 20% in the final THI score compared to the initial THI score. RESULTS: The initial mean hearing thresholds and VAS and THI scores of the two groups did not differ significantly. At 4 weeks after initial injection, the mean VAS and THI scores of both groups had significantly reduced. However, the improvement rate did not differ significantly between the groups (ITDI, 51.9%; ITNI, 59.3%). CONCLUSION: The results indicate that ITDI might not be more effective than ITNI for the treatment of acute unilateral tinnitus. Therefore, ITDI should not be considered as the main treatment for patients presenting with acute tinnitus as the primary symptom. LEVEL OF EVIDENCE: 1b. Laryngoscope, 128:184-188, 2018.

Surgical and Audiologic Comparison Between Sophono and Bone-Anchored Hearing Aids Implantation.

OBJECTIVES: Bone-anchored hearing aids (BAHA) occasionally cause soft tissue problems due to abutment. Because Sophono does not have abutment penetrating skin, it is thought that Sophono has no soft tissue problem relating to abutment. On the other hand, transcutaneous device's output is reported to be 10 to 15 dB lower than percutaneous device. Therefore, in this study, Sophono and BAHA were compared to each other from surgical and audiological points of view. METHODS: We retrospectively reviewed the medical records of 9 Sophono patients and 10 BAHA patients. In BAHA cases, single vertical incision without skin thinning technique was done. We compared Sophono to BAHA by operation time, wound healing time, postoperative complications, postoperative hearing gain after switch on, and postoperative air-bone gap. RESULTS: The mean operation time was 60 minutes for Sophono and 25 minutes for BAHA. The wound healing time was 14 days for Sophono and 28 days for BAHA. No major intraoperative complication was observed. Skin problem was not observed in the 2 devices for the follow-up period. Postoperative hearing gain of bilateral aural atresia patients was 39.4 dB for BAHA (n=4) and 25.5 dB for Sophono (n=5). However, the difference was not statistically significant. In all patients included in this study, the difference of air-bone gap between two groups was 16.6 dB at 0.5 kHz and 18.2 dB at 4 kHz. BAHA was statistically significantly better than Sophono. CONCLUSION: Considering the audiologic outcome, BAHA users were thought to have more audiologic benefit than Sophono users. However, Sophono had advantages over BAHA with abutment in cosmetic outcome. Sophono needed no daily skin maintenance and soft tissue complication due to abutment would not happen in Sophono. Therefore, a full explanation about each device is necessary before deciding implantation.

Advantages of binaural amplification to acceptable noise level of directional hearing aid users.

OBJECTIVES: The goal of the present study was to examine whether Acceptable Noise Levels (ANLs) would be lower (greater acceptance of noise) in binaural listening than in monaural listening condition and also whether meaningfulness of background speech noise would affect ANLs for directional microphone hearing aid users. In addition, any relationships between the individual binaural benefits on ANLs and the individuals' demographic information were investigated. METHODS: Fourteen hearing aid users (mean age, 64 years) participated for experimental testing. For the ANL calculation, listeners' most comfortable listening levels and background noise level were measured. Using Korean ANL material, ANLs of all participants were evaluated under monaural and binaural amplification with a counterbalanced order. The ANLs were also compared across five types of competing speech noises, consisting of 1- through 8-talker background speech maskers. Seven young normal-hearing listeners (mean age, 27 years) participated for the same measurements as a pilot testing. RESULTS: The results demonstrated that directional hearing aid users accepted more noise (lower ANLs) with binaural amplification than with monaural amplification, regardless of the type of competing speech. When the background speech noise became more meaningful, hearing-impaired listeners accepted less amount of noise (higher ANLs), revealing that ANL is dependent on the intelligibility of the competing speech. The individuals' binaural advantages in ANLs were significantly greater for the listeners with longer experience of hearing aids, yet not related to their age or hearing thresholds. CONCLUSION: Binaural directional microphone processing allowed hearing aid users to accept a greater amount of background noise, which may in turn improve listeners' hearing aid success. Informational masking substantially influenced background noise acceptance. Given a significant association between ANLs and duration of hearing aid usage, ANL measurement can be useful for clinical counseling of binaural hearing aid candidates or unsuccessful users.

A case of auditory neuropathy with recovery of normal hearing.

Newborn hearing screening test is very important in the early diagnosis of childhood hearing loss because it affects language development. Auditory neuropathy is a spectrum disorder characterized by abnormal auditory brainstem response but preserved otoacoustic emission and cochlear microphonics. In general, auditory neuropathy patients have poor word discrimination and variable patterns of pure tone audiometry. We report on a patient with auditory neuropathy diagnosed at 16 months of age and started wearing hearing aids, but showed normal pure tone and speech audiometric findings 3 years later. Close follow-up for patients with auditory neuropathy is recommended.

Genetic Screening of GJB2 and SLC26A4 in Korean Cochlear Implantees: Experience of Soree Ear Clinic.

OBJECTIVES: Genetic hearing loss is highly heterogeneous and more than 100 genes are predicted to cause this disorder in humans. In spite of this large genetic heterogeneity, mutations in SLC26A4 and GJB2 genes are primarily responsible for the major etiologies of genetic hearing loss among Koreans. The purpose of this study is to investigate the genetic cause of deafness in Korean cochlear implantees by performing a genetic screening of the SLC26A4 and GJB2 genes. METHODS: The study cohort included 421 unrelated Korean patients with sensorineural hearing loss (SNHL) and who had received cochlear implants (CI) at Soree Ear Clinic from July 2002 to December 2010. Among 421 CI patients, we studied 230 cases who had received the genetic screening for SLC26A4 or GJB2 genes. Written informed consent was obtained from all participants. All patients had severe to profound, bilateral hearing loss. For 56 patients who showed enlarged vestibular aqueduct on their computed tomography (CT) scan, we analyzed SLC26A4. For 174 CT negative patients, GJB2 gene was sequenced. RESULTS: For the 56 SLC26A4 patients, 32 (57.1%) had two pathogenic recessive mutations in SLC26A4. A single recessive SLC26A4 mutation was identified in 14 patients (25%). H723R and IVS7-2A>G were the most commonly found mutations, accounting for 60.3% (47/78) and 30.8% (24/78) of the mutated alleles, respectively. For the 174 GJB2 patients, 20 patients (11.5%) had two pathogenic recessive mutations in GJB2. 235delC was the most common mutation, accounting for 43.0% (31/72) of mutant alleles. CONCLUSION: The two major genes, SLC26A4 and GJB2, contribute major causes of deafness in CI patients. Continuous studies are needed to identify new genes that can cause hearing loss to Korean CI patients.

Classification of external auditory canal cholesteatoma by computed tomography.

OBJECTIVES: We propose here a classification system for external auditory canal cholesteatoma (EACC). We classified the EACC by the computed tomography findings and clinical findings of the patients, and we evaluated the EACC characteristics by the proposed staging system. METHODS: Stage classification was done according to the results of temporal bone computed tomography and the clinical findings of the patients. Stage I indicates that the EACC lesion is limited to the external auditory canal. Stage II indicates that the EACC lesion invades the tympanic membrane and middle ear. Stage III indicates that the EACC lesion creates a defect of the external auditory canal and it involves the air cells in the mastoid bone. Stage IV indicates that the EACC lesion is beyond the temporal bone. Between 1996 and 2006, 29 patients with EACC and who underwent surgery were prospectively collected. This study was comprised of 16 males and 13 females with a mean age of 22.8+/-15.0 yr. We reviewed the characteristics and results of surgery by our proposed staging system. RESULTS: A total of 29 patients who underwent operation due to EACC were classified by this system, and the number of stage I, II, III, and IV cases was 14, 3, 10, and 2, respectively. Symptoms such as otorrhea, hearing impairment and otalgia occurred in 12, 17, and 17 cases, respectively. The most common wall invaded by EACC was the inferior wall. The number of cases that had a spontaneous, congenital, post-traumatic, post-inflammatory or tumorous origin was 14, 9, 2, 2, and 1, respectively. Cholesteatoma recurred in 2 patients after surgery. Both cases were stage 1 and both were caused by congenital disease. There were 3 cases with meatal stenosis after surgery, and their primary disease was congenital. CONCLUSION: This proposed staging is simple and easily applicable for use when deciding the treatment plan for patients with EACC.

Clinical presentation and management of jugular foramen paraganglioma.

OBJECTIVES: Jugular foramen paraganglioma is a locally invasive, benign tumor, which grow slowly and causes various symptoms such as pulsatile tinnitus and low cranial nerve palsy. Complete surgical resection is regarded as the ideal management of these tumors. The goal of this study is to identify the clinical characteristics and most effective surgical approach for jugular foramen paraganglioma. METHODS: Retrospective analysis of 9 jugular foramen paraganglioma patients who underwent surgical resection between 1986 and 2005 was performed. Clinical records were reviewed for analysis of initial clinical symptoms and signs, audiological examinations, neurological deficits, radiological features, surgical approaches, extent of resection, treatment outcomes and complications. RESULTS: Most common initial symptom was hoarseness, followed by pulsatile tinnitus. Seven out of 9 patients had at least one low cranial nerve palsy. Seven patients were classified as Fisch Type C tumor and remaining 2 as Fisch Type D tumor on radiologic examination. Total of 11 operations took place in 9 patients. Total resection was achieved in 6 cases, when partial resection was done in 3 cases. Two patients with partial resection received gamma knife radiosurgery (GKS), when remaining 1 case received both GKS and two times of revision operation. No mortality was encountered and there were few postoperative complications. CONCLUSION: Neurologic examination of low cranial nerve palsy is crucial since most patients had at least one low cranial nerve palsy. All tumors were detected in advanced stage due to slow growing nature and lack of symptom. Angiography with embolization is crucial for successful tumor removal without massive bleeding. Infratemporal fossa approach can be considered as a safe, satisfactory approach for removal of jugular foramen paragangliomas. In tumors with intracranial extension, combined approach is recommended in that it provides better surgical view and can maintain the compliance of the patients.

Correlation between enhanced MRI and surgical findings in herpes zoster oticus.

CONCLUSION: This study demonstrates good correlation between enhanced MRI and surgical findings. OBJECTIVES: This study investigated the reliability of enhanced magnetic resonance imaging (MRI) to make a surgical decision on the strategy for facial nerve decompression in herpes zoster oticus, by determining the degree of correlation between contrast enhancement in MRI and the pathologic change in the facial nerve. SUBJECTS AND METHODS: This retrospective study of 13 patients, who underwent facial nerve decompression with herpes zoster oticus, was designed to compare gadolinium-enhanced segment of facial nerve on MRI and the pathologically changed segment confirmed by surgical exploration, grouping them by the timing of operation after onset of facial paralysis. RESULTS: Commonly enhanced segments on MRI were the labyrinthine, intracanalicular, and geniculate ganglion, found in 84%, 69%, and 69% of all patients, respectively. The most common pathologic segment was the labyrinthine segment (92%), followed by the geniculate ganglion (84%).

Clinical significance of quantitative analysis of facial nerve enhancement on MRI in Bell's palsy.

CONCLUSIONS: Quantitative analysis of the facial nerve on the lesion side as well as the normal side, which allowed for more accurate measurement of facial nerve enhancement in patients with facial palsy, showed statistically significant correlation with the initial severity of facial nerve inflammation, although little prognostic significance was shown. OBJECTIVES: This study investigated the clinical significance of quantitative measurement of facial nerve enhancement in patients with Bell's palsy by analyzing the enhancement pattern and correlating MRI findings with initial severity of facial palsy and clinical outcome. SUBJECTS AND METHODS: Facial nerve enhancement was measured quantitatively by using the region of interest on pre- and postcontrast T1-weighted images in 44 patients diagnosed with Bell's palsy. The signal intensity increase on the lesion side was first compared with that of the contralateral side and then correlated with the initial degree of facial palsy and prognosis. RESULTS: The lesion side showed significantly higher signal intensity increase compared with the normal side in all of the segments except for the mastoid segment. Signal intensity increase at the internal auditory canal and labyrinthine segments showed correlation with the initial degree of facial palsy but no significant difference was found between different prognostic groups.

Surgical treatment and outcomes of temporal bone chondroblastoma.

Chondroblastoma is an uncommon primary benign bone tumor that usually arises in the epiphyses of the long bones. Temporal bone chondroblastoma is a rare primary bone tumor that affects the floor of the middle cranial fossa and temporomandibular joint (TMJ). The biological nature of temporal bone chondroblastoma is occasionally aggressive because of local invasion and is known to have a high recurrence after curettage. Therefore, complete resection is recommended. However, the literature provides little information regarding long-term surgical outcomes and complications after surgical resection. The authors have retrospectively analyzed four cases of temporal bone chondroblastoma that had been completely excised by a single surgeon with an eventual long-term follow-up. A single surgeon operated on four patients, two males and two females, with a mean age of 34 years, at the Department of Otorhinolaryngology, Severance Hospital. In all cases, the tumor involved the middle cranial fossa dura and the mandibular fossa with variable degree of infiltration. All patients have had no tumor recurrence to date (mean follow-up period of 5 years). Complete surgical resection of the temporal bone chondroblastoma is the gold standard for treatment. Precise preoperative image evaluation of tumor extension and proper management of the dura mater and temporomandibular joint (TMJ) are the major important features in complete surgical removal that minimize complications in temporal bone chondroblastoma treatment.

Jugular foramen schwannoma: analysis on its origin and location.

OBJECTIVE: To examine the microsurgical anatomy of the jugular foramen and correlate anatomical findings to clinical manifestations of jugular foramen schwannomas concerning tumor origin and location. STUDY DESIGN: Anatomical analysis of jugular foramen was performed by dissection of 25 cadavers (50 sides). By retrospective review of 9 cases of jugular foramen schwannomas surgically treated, the origin and location of tumor were studied. SETTING: Tertiary referral center. MAIN OUTCOME MEASURES: The anatomical characteristics of jugular foramen, lower cranial nerves, and inferior petrosal sinus were correlated with the origin and growth pattern of jugular foramen schwannomas. RESULTS: The superior and inferior ganglions of the glossopharyngeal nerve and the superior ganglion of the vagus nerve were located within the jugular foramen. The superior ganglions of the glossopharyngeal and vagus nerves were located superiorly, whereas the inferior ganglion of the glossopharyngeal nerve was found inferiorly in relation to the inferior petrosal sinus orifice. In our series of 9 cases of jugular foramen schwannoma, the most common nerve of origin was the vagus nerve, followed by the glossopharyngeal nerve. CONCLUSION: The reason for the predilection of the jugular foramen schwannoma for the glossopharyngeal and vagus nerves may be associated with the presence of their ganglions within the jugular foramen. Also, the inferior petrosal sinus may act as a barrier to tumor growth, and the location of the ganglion of tumor origination within the jugular foramen in relation to the inferior petrosal sinus may be correlated to the predominant direction of tumor extension.

Statistical analysis of pure tone audiometry and caloric test in herpes zoster oticus.

OBJECTIVES: Pure tone audiometry and caloric test in patients with herpes zoster oticus were performed to determine the biologic features of the varicella zoster virus (VZV) and the pathogenesis of vestibulocochlear nerve disease in herpes zoster oticus. STUDY DESIGN: A retrospective chart review of 160 patients with herpes zoster oticus was designed in order to determine the classic characteristics of vestibulocochlear nerve disease associated with the syndrome. Speech frequency and isolated high frequency acoustic thresholds were analyzed based on severity of facial paralysis and patient age. Patients without cochlear symptoms were selected randomly, and audiological function was evaluated. Patients with symptoms of vestibular dysfunction underwent the caloric test, and canal paresis was analyzed according to the severity of facial paralysis and the age of each patient. RESULTS: Among the 160 patients, 111 exhibited pure tone audiometry; 26 (79%) of the patients with cochlear symptoms and 44 (56%) of the patients without cochlear symptoms had abnormal audiological data. Among the patients without cochlear symptoms, 15 (19%) had hearing loss at speech frequency, and 42 (54%) had hearing loss isolated to high frequency. The incidence of cochlear symptoms in herpes zoster oticus was not related to the severity of facial paralysis. The incidence of patients with isolated high frequency hearing loss statistically increased with age, however the incidence of patients with speech frequency hearing loss did not increase. Thirteen patients complained vertigo, and the incidence of vestibular disturbances and the value of canal paresis in the caloric test increased to statistical significance in parallel with increasing severity of facial paralysis. CONCLUSION: Mild or moderate cochlear symptoms with high frequency hearing loss were related to age, and severe vestibular symptoms were related to the severity of facial paralysis after onset of herpetic symptoms. This study might suggest us a clue to the pathogenesis of vestibulocochlear nerve disease in herpes zoster oticus.

A cochlear schwannoma presenting with sudden hearing loss.

A cochlear schwannoma is a rare tumor that arises from the cochlear nerve. Clinically, a cochlear schwannoma mimics the clinical features of sudden deafness or Meniere's disease. We report a case of cochlear schwannoma that presented with sudden hearing loss, which was diagnosed with gadolinium-enhanced magnetic resonance imaging and removed using a transotic approach.

Correlation between MRI and operative findings in Bell's palsy and Ramsay Hunt syndrome.

PURPOSE: To investigate the correlation between gadolinium enhanced magnetic resonance image (MRI) results and surgical findings of facial nerves in Bell's palsy and Ramsay Hunt syndrome. MATERIALS AND METHODS: From 1995 to 2004, MRI was performed on 13 patients with Bell's palsy or Ramsay Hunt syndrome, who were offered with surgical decompression of the facial nerve through the middle cranial fossa approach. Gadolinium enhanced MRI was performed on all patients and the enhancement of the facial nerve was evaluated by radiology specialists. Operative findings including the degree of the facial nerve segment swelling were examined. Furthermore, the time interval from the onset of palsy to surgery was evaluated. RESULTS: Swelling of facial nerve segments was found in patients with enhanced facial nerves from MRI. The swelling of the facial nerve in the labyrinthine segment in particular was identified in all patients with enhanced labyrinthine segments in MRI. The intraoperative swelling of geniculate ganglion of facial nerve was found in 78% of patients with enhanced facial segment in MRI (p=0.01). The intraoperative swelling of tympanic segment was observed from fourth to ninth weeks after the onset of palsy. CONCLUSION: MRI enhancement of facial nerves in Bell's palsy and Ramsay Hunt syndrome is associated with the extent of intratemporal lesions of facial nerves, especially in the labyrinthine segment.

Intracanalicular facial nerve schwannoma.

OBJECTIVE: To investigate the capability of preoperative evaluations in predicting the precise anatomic origin of intracanalicular tumors. STUDY DESIGN: We conducted a retrospective case review. SETTING: Tertiary referral center. PATIENTS: A total of 11 patients (8 men and 3 women, 26-70 years old) with intracanalicular tumors who were treated surgically were included. INTERVENTIONS: Pure-tone average, auditory brainstem response, caloric test, and temporal magnetic resonance imaging were done in all 11 patients. Electroneuronography has only been performed since 2003, and only 3 patients were evaluated. MAIN OUTCOME MEASURE: Preoperative symptoms, pure-tone average, auditory brainstem response, caloric test, electroneuronography, and magnetic resonance imaging were compared between patients with facial nerve schwannomas and patients with vestibular schwannomas. RESULTS: Postoperatively, facial nerve schwannomas were diagnosed pathologically in 2 (18%) of 11 patients. There were not any clues suggesting facial nerve schwannoma in preoperative evaluations. CONCLUSION: A facial nerve schwannoma may be misdiagnosed as a vestibular schwannoma, especially when the tumor is confined to the internal auditory canal. There are no useful preoperative evaluation tools in predicting the precise nerve origin of intracanalicular tumors. These emphasize the need to fully inform the patient preoperatively.

Management of facial nerve schwannoma in patients with favorable facial function.

OBJECTIVE: We report six cases of facial nerve schwannomas in which surgical management allowed the preservation of facial nerve function. Specifically, this paper reports that a stripping surgery may provide favorable functional outcomes. STUDY DESIGN: A retrospective review of preoperative and postoperative data for six patients with facial nerve schwannoma that had normal facial nerve function or a House-Brackmann grade II facial palsy before the surgery. METHODS: Stripping surgery, which removed the schwannoma from the remaining nerve fascicle, was attempted on the six patients. Postoperative facial nerve function and imaging (magnetic resonance imaging) were evaluated. RESULTS: Stripping surgery with gross total tumor removal of the mass was performed in four cases. In the two remaining cases, the stripping surgery was not possible, and decompression alone was performed. Favorable preservation of facial function was achieved in all six cases. CONCLUSION: It was possible to preserve facial function after surgery to remove facial nerve schwannoma. We suggest that stripping surgery, focused on the preservation of continuity of the facial nerve, may be attempted for facial nerve schwannoma in which favorable facial function has been preserved.

Hearing results after ossiculoplasty using Polycel prosthesis.

CONCLUSIONS: Polycel is an effective material to use in ossiculoplasty. Good prognostic factors for hearing improvement after ossiculoplasty were healthy middle ear mucosa and the presence of stapes superstructure. OBJECTIVE: During the last decade, the surgical use of alloplasts has become increasingly widespread among otologists. This study aimed to evaluate the hearing results after ossiculoplasty using Polycel prosthesis. MATERIALS AND METHODS: We retrospectively reviewed 188 patients who underwent ossicular chain reconstruction using Polycel prosthesis and were followed up postoperatively for more than 12 months at Severance Eye-ENT Hospital from 1998 to 2002. Postoperative hearing results were assessed by measuring the postoperative air-bone gap (ABG) and closure of the ABG. Successful postoperative ABG criteria were defined as the following three measurements: ABG of

Wheel-shaped cartilage-perichondrium composite graft for the prevention of retraction pocket development.

CONCLUSION: Our technique can decrease the formation of retraction pockets and improve hearing function. The wheel-shaped cartilage-perichondrium composite graft (Wheel CPCG) can be considered a good material for a drum graft, and it is easy to insert a ventilation tube, in case of initial drum retraction. OBJECTIVE: The purpose of this study was to introduce the novel surgical technique of a Wheel CPCG with one-stage ossiculoplasty to prevent a retraction pocket and subsequent cholesteatoma after intact canal wall tympanomastoidectomy. PATIENTS AND METHODS: A total of 47 patients were reviewed; 43 cases were selected for audiologic testing. The results of operations were evaluated by comparing preoperative and postoperative hearing results and postoperative drum findings. RESULTS: A retraction pocket was observed in three cases (6.7%). Slight protrusion of partial ossicular replacement prosthesis (PORP) and lateral healing of drum was observed in one case each, and there were two cases of postoperative infection. The number of cases with an air-bone gap (ABG)<20 dB increased from 9 (23%) cases before operation, to 20 cases (51%) after operation. The ABG average statistically decreased from 30.0 dB to 24.0 dB, and the mean air conduction thresholds decreased from a preoperative level of 47.3 dB to a level of 35.7 dB.

New method of identifying the internal auditory canal as seen from the middle cranial fossa approach.

OBJECTIVES: The middle cranial fossa approach allows one to remove acoustic tumors and preserve the facial nerve and hearing. However, there are no consistent landmarks on the surface of the temporal bone to identify the internal auditory canal. This study was designed to identify the internal auditory canal by use of external and internal references as seen during the middle cranial fossa approach. METHODS: We dissected 32 temporal bones using the middle cranial fossa approach and measured the distances from the posterior origin of the zygomatic arch to an imaginary coronal line between the foramen spinosum and the foramen ovale. We measured the angle between the lines drawn from the posterior origin of the zygomatic root to the foramen spinosum and from the foramen spinosum to the porus of the internal auditory canal. RESULTS: The distances were 14.7 mm and 22.9 mm, respectively, and the angle was roughly 90 degrees. CONCLUSIONS: In this study, we found external and internal landmarks that help to locate the internal auditory canal.