An Analysis of the Acoustic Input Impedance of the Ear

Ear canal acoustics was examined using a one-dimensional lossy transmission line with a distributed load impedance to model the ear. The acoustic input impedance of the ear was derived from sound pressure measurements in the ear canal of healthy human ears. A nonlinear least squares fit of the model to data generated estimates for ear canal radius, ear canal length, and quantified the resistance that would produce transmission losses. Derivation of ear canal radius has application to quantifying the impedance mismatch at the eardrum between the ear canal and the middle ear. The length of the ear canal was found, in general, to be longer than the length derived from the one-quarter wavelength standing wave frequency, consistent with the middle ear being mass-controlled at the standing wave frequency. Viscothermal losses in the ear canal, in some cases, may exceed that attributable to a smooth rigid wall. Resistance in the middle ear was found to contribute significantly to the total resistance. In effect, this analysis “reverse engineers” physical parameters of the ear from sound pressure measurements in the ear canal.     

Anterior Canal benign paroxysmal positional Vertigo following surgical Management of superior canal dehiscence

Objective

Benign paroxysmal positional vertigo (BPPV) is a common post-surgical finding in patients managed for superior semicircular canal dehiscence (SSCD). The posterior semicircular canal has been reported as the involved canal in the majority of cases of post-surgical BPPV, with only two cases reported of lateral canal involvement. The objective of this report is to present a case in which an anterior semicircular canal BPPV response was identified in a patient following surgical management for SSCD.

半规管阻塞技术的初步临床应用

目的初步探讨临床应用半规管阻塞技术治疗位置性眩晕与梅尼埃病的安全性与有效性。方法回顾性分析1994-2000年间半规管阻塞技术临床应用的资料,其中,后半规管位置性眩晕2例,水平半规管位置性眩晕1例,内淋巴囊阻塞术后5年复发的梅尼埃病1例,男1例,女3例,年龄39-58岁。梅尼埃病患者行三半规管阻塞及内淋巴乳突腔分流术,位置性眩晕患者行相应的半规管阻塞术。结果位置性眩晕患者术后随访1.5-7年,全部患者位置性眩晕得到解除,术后纯音测听、中耳功能分析、听觉脑干电反应测试、耳声发射等听觉功能检查结果显示耳蜗功能与术前完全一致,水平半规管阻塞的患者双耳冷热试验结果显示手术消除了水平半规管的功能,后半规管阻塞的患者双耳冷热试验结果显示手术后以水平半规管为代表的其它前庭末梢器官的功能得到良好的保存。内淋巴囊阻塞术后5年复发的梅尼埃病患者术后随访2年,眩晕得到完全控制。结论半规管阻塞技术可有效控制位置性眩晕与梅尼埃病患者的眩晕,半规管阻塞对患者耳蜗功能及所阻塞半规管以外的其它前庭末梢器官功能没有影响,半规管阻塞技术可望成为位置性眩晕和梅尼埃病安全、有效的治疗手段,符合现代外科学对手术微创的要求。     

Facial canal dehiscence in the initial operation for chronic otitis media without cholesteatoma

OBJECTIVE: To evaluate the risk of the facial nerve injury during operations for chronic otitis media without cholesteatoma by analysis of the intraoperative findings of the facial canal dehiscence. METHODS: We retrospectively reviewed operative findings of 152 patients who underwent tympanoplasty with mastoidectomy for chronic otitis media. We examined every segment of the facial canal from the geniculate ganglion to the mastoid segment. Facial canal dehiscence was confirmed by palpation with a Rosen pick after inspection with a surgical microscope. RESULTS: The rate of facial canal dehiscence was 8.6% (13 of 152 cases), and the tympanic segment was the most commonly found region at 84.6% (11 of 13 cases). Of the 11 cases of tympanic segment dehiscence, 9 cases were involved the lateral aspect of the facial canal in the oval window area. There was one case each of facial canal dehiscence in the geniculate ganglion and the mastoid segment, respectively. CONCLUSION: The rate of facial canal dehiscence of 8.6% is not a low incidence rate, so even though performing a routine chronic ear operation, surgeons may encounter facial canal dehiscence at any time and should be prepared for the emergence of such a situation.     

外耳道阻塞性角化病的临床特点

目的总结外耳道阻塞性角化病的临床特点。方法对30例外耳道阻塞性角化病患者的临床资料进行回顾性分析。结果外耳道阻塞性角化病的临床主要特点有：剧烈的耳痛;嵌塞物有较硬的核心;嵌塞物呈灰白色或者污灰色;嵌塞物和耳道皮肤粘连紧密;外耳道皮肤炎症较重。结论外耳道阻塞性角化病的5个特点可以作为诊断外耳道阻塞性角化病以及与外耳道胆脂瘤区别的参考。     

A case of osteoma with cholesteatoma in the external auditory canal

Osteoma in the external auditory canal (EAC) is an uncommon benign lesion, which presents as a solitary, unilateral, and slow-growing pedunculated mass in the outer half of the bony canal. It is usually asymptomatic; but symptoms can arise if a canal obstruction occurs. External canal cholesteatoma is also a rare lesion of the external auditory canal. Cholesteatoma of the external auditory canal may arise via several mechanisms. However, an occlusion or narrowing of the external auditory canal is the basic pathogenesis. The association of an osteoma with a cholesteatoma is extremely rare, and there have been very few reports published. We encountered a rare case of a 49-year-old man with an osteoid osteoma that was complicated by a cholesteatoma in the external auditory canal. The canal wall down mastoidectomy and tympanoplasty successfully removed the osteoma and the cholesteatoma, and no recurrence or complications had occurred in the first 6 months postoperatively.     

Triple semicircular canal occlusion in guinea pigs with endolymphatic hydrops.

HYPOTHESIS: Triple semicircular canal occlusion will eliminate rotatory stimulation to the vestibular peripheral system (as it blocks endolymphatic fluid movement) and therefore release rotatory vertigo attack. This surgery is safe in ears with endolymphatic hydrops. BACKGROUND: Semicircular canal occlusion has been used as an alternative treatment of intractable benign paroxysmal positional vertigo with varied success. Triple semicircular canal occlusion in animal models blocks the responses of the semicircular canals to rotation and spares cochleae and the otolithic apparatus. This result suggests that triple semicircular canal occlusion is a prospective method in vertigo management for patients with Ménière's disease. However, the effectiveness and safety of triple semicircular canal occlusion has not been fully evaluated in ears with endolymphatic hydrops. METHODS: Endolymphatic hydrops was established in 20 guinea pigs by endolymphatic sac obliteration. Triple semicircular canal occlusion was performed in 12 of them 120 days after endolymphatic hydrops surgery, whereas 8 others were killed for morphologic observation to confirm endolymphatic hydrops. Auditory and vestibular functions were monitored from the time before endolymphatic hydrops until 1 month after triple semicircular canal occlusion. Endolymphatic hydrops and canal occlusion were confirmed by morphologic observation. RESULTS: Successful establishment of endolymphatic hydrops was indicated by mild elevation of the auditory brainstem response threshold and tentative asymmetry in nystagmus. Endolymphatic hydrops was confirmed by cochlear morphology in all eight animals that were killed 120 days after endolymphatic hydrops surgery. After triple semicircular canal occlusion, all 12 animals showed spontaneous nystagmus with a slow component toward the side that had been operated on, head tilt, rotated walking, and tentative asymmetry in rotatory nystagmus. The static symptoms disappeared within 1 month after triple semicircular canal occlusion. Caloric nystagmus was only slightly reduced after endolymphatic hydrops as compared with the contralateral ears but could not be elicited at all after triple semicircular canal occlusion. No significant elevation in auditory brainstem response threshold was found after triple semicircular canal occlusion. The canal occlusion and endolymphatic hydrops were confirmed in all surgical ears. CONCLUSION: Triple semicircular canal occlusion is effective for eliminating the response of semicircular canals to rotation and caloric stimulation and is safe in ears with endolymphatic hydrops. Also, the static compensation to the disequilibrium is quick and complete. These results suggest that triple semicircular canal occlusion should be an option for controlling rotatory vertigo in Ménière's disease.     

The facial nerve canal in patients with Bell’s palsy: an investigation by high-resolution computed tomography with multiplanar reconstruction

Facial nerve edema is an important finding in Bell’s palsy patients. Inflammation may cause facial nerve edema, and mechanical compression and ischemic change of the facial nerve may occur in the facial nerve canal. A few studies have reported the dimensions of the facial nerve canal using conventional computed tomography or human temporal bone sections. However, the cross-sectional area of the facial nerve canal has not been fully understood. Therefore, the cross-sectional area of the facial nerve canal was measured in patients with unilateral Bell’s palsy by computer tomography with multiplanar reconstruction. Sixteen patients with unilateral Bell’s palsy were enrolled. Computed tomography of the temporal bone was performed, and perpendicular images to the facial nerve canal were reconstructed by the multiplanar reconstruction technique. The cross-sectional area of the facial nerve canal on the affected and unaffected sides was measured at the labyrinthine segment, the horizontal segment, and the mastoid segment. Both in the labyrinthine and horizontal segments, the mean cross-sectional area of the facial nerve canal was significantly smaller on the affected side than on the unaffected side. There was no significant difference between the affected and unaffected sides in the cross-sectional area of the facial nerve canal in the mastoid segment. The labyrinthine segment was the narrowest segment in the facial nerve canal. These findings suggest that the facial nerve is vulnerable, especially in the labyrinthine segment of the facial nerve canal, and a narrow facial nerve canal may be one of the risk factors for Bell’s palsy.     

Radiological classification of the infraorbital canal and correlation with variants of neighboring structures

This study aims to classify the infraorbital canal according to its position related to the maxillary sinus as observed by axial CT. It is a retrospective, cross-sectional study. This study was performed in a tertiary referral center. In this study, axial and coronal CTs of 750 patients were examined and infraorbital canals and neighboring structures were evaluated. Infraorbital canals were then classified according to their positions in relation to the maxillary sinus as seen in axial sections. Morphologic variations of neighboring structures were also noted and their correlations with specific canal types were investigated. Three types of infraorbital canal configurations were identified according to the canal’s relationship with the maxillary sinus: Type 1, the infraorbital canal was totally protruding into the maxillary sinus (12.3 %); Type 2, the infraorbital canal was located at the floor of the maxillary sinus or was partially protruding into the maxillary sinus (51.2 %); Type 3, the infraorbital canal was totally embedded in the maxillary corpus or was bulging on the external face of the maxillary sinus (36.4 %). Concurrence of maxillary sinus septa and infraorbital canal type-1 was found to be statistically significant on both sides (right side p = 0.00, left side p = 0.00). The study radiologically classified the infraorbital canal according to its position as related to the anterior wall of the maxillary sinus, and found that the type where the canal was totally protruding into the maxillary sinus (type-1) had a significant rate of 12.3 %. The rate of the protruded infraorbital canal was doubled with the presence of maxillary sinus septa (25 %).     

Preservation of hearing after removal of the membranous canal with a cholesteatoma

Normal cochlear function was preserved in a patient after excision of the membranous canal from a huge fistula at revision surgery eight years after the primary procedure. A recurrent cholesteatoma had eroded the entire prominence of the horizontal canal and surrounded its membranous portion. The cholesteatoma, including the membranous canal, was removed in a one-stage procedure. The open ends of the bony canal were sealed with a fascia soaked in fibrin glue. After initial dizziness and severely reduced hearing, the patient quickly recovered, with normal bone conduction and a stable 30-dB hearing level by air conduction. The lumen of the membranous canal was patent, and only the ampullar end was atretic. Presumably, the fistula became separated from fluid spaces by formation of perilymphatic partitions and by collapse of the membranous labyrinth adjacent to the fistula.     

Semicircular canal dehiscence in HR multislice computed tomography: distribution,frequency, and clinical relevance

The literature about bony defects in the semicircular canal system is highly inconsistent. Therefore, we analyzed a series of 700 high-resolution multislice CT examinations of the temporal bone for semicircular canal dehiscencies. An unselected group of ENT patients with different clinical symptoms and variable age was chosen. We found semicircular canal dehiscence in 9.6% of temporal bones, superior semicircular canal was affected mostly (8%), less common posterior semicircular canal (1.2%); only in 3 cases (0.4%), lateral semicircular canal showed dehiscence. In 60% of SSC dehiscence, we registered bilateral manifestation. The so-called “third mobile window” in semicircular canal dehiscence causes a great variety of clinical symptoms like vertigo, nystagmus, oscillopsies, hearing loss, tinnitus and autophonia. Comparison with anatomic studies shows that CT examination implies the risk of considerable overestimation; this fact emphasizes the important role of clinical and neurophysiological testing.     

Paroxysmal positional vertigo syndrome.

INTRODUCTION: This study was initiated to investigate the differential diagnosis of patients with benign paroxysmal positional vertigo (BPPV) of different canals' origin. METHODS: The eye movements of 292 patients were evaluated with the use of Frenzel glasses and infrared video cameras after positional tests. Epley's canal repositioning procedure (CRP) was conducted, with appropriate modifications for individual cases, on every patient. RESULTS: Two different types of positional nystagmus were observed corresponding to the presence of otoliths in the lumen of each of the semicircular canals and on the cupola of the horizontal semicircular canal. The posterior canal was involved in 250 patients unilaterally and 23 patients bilaterally. The anterior canal variety was observed in four patients. In the horizontal canal, nine were of the cupulolithiasis and six of the canalithiasis variety. In seven patients. the affected canal converted to a different location. The canal repositioning procedure eliminated vertigo and abnormal eye movements in 88% of the unilateral posterior canal variety. The success rate of the procedure in the other varieties was 50%. CONCLUSION: Positional vertigo can have characteristics corresponding to the presence of otolith particles in each of the semicircular canals. The treatment requires different strategies to move the otoliths, depending on their location in the vestibule.     

Evaluation of canal wall down tympanoplasty with canal reconstruction for draining ear with middle ear cholesteatoma

OBJECTIVES: We studied the postoperative stability of canal wall down tympanoplasty with canal reconstruction for middle ear cholesteatoma with preoperative otorrhea. SUBJECTS AND METHODS: 155 ears with middle ear cholesteatoma treated with canal wall down tympanoplasty with canal reconstruction were evaluated retrospectively. A comparison was made between the group of 80 ears which showed otorrhea, preoperatively, and the group of 75 without preoperative otorrhea. Problems observed in the tympanic membrane or reconstructed external auditory canal were evaluated both at the postoperative initial stage and more than 1 year after surgery. Postoperative hearing prognosis was also studied. RESULTS: 1) In the postoperative initial stage, local infection and necrosis of materials for canal reconstruction were significantly more likely to be observed in ears with preoperative otorrhea. 2) In ears with postoperative local infection, necrosis of materials for canal reconstruction occurred more frequently, and the period until drying of the reconstructed external auditory canal was significantly extended. 3) No significant difference was seen in postoperative status of the tympanic membrane and reconstructed ear canal at least 1 year after surgery. 4) The presence of preoperative otorrhea had no influence on hearing prognosis. CONCLUSIONS: When canal wall down tympanoplasty with canal reconstruction is used for ears with preoperative otorrhea, careful attention should be paid to local treatment at the postoperative initial stage. However, no significant problem occurred in the outcome of preoperative ear draining at least 1 year after surgery.     

Tooth anatomy risk factors influencing root canal working length accessibility

The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases (amounting to a total of 1 005 root canals) were examined. The anatomy risk factors assessed in each case included: tooth type (tooth location), root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type (tooth location), root canal curvature, canal calcification, and endodontic retreat- ment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility (P<0.05). Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.     

Effect of vitamin A on the growth and differentiation of rat external auditory canal epithelium in organ culture.

Intact rat external ear canal explants were maintained either in retinoid-deficient or retinoid-supplemented medium for 7, 10, 14, and 21 days. The morphology of the external ear canal epidermis was well maintained, including the presence of sebaceous glands even after 21 days in culture with retinoid-deficient medium. However, after culturing in retinoid-supplemented medium, the external ear canal epithelium showed both a loss of keratohyalin granules and the formation of keratin. Extensive microvilli formation occurred, even though the desquamation process continued from the superficial layer after 7, 10, and 14 days in culture with retinoid-enriched medium. After 21 days in culture with retinoid-supplemented medium, the ear canal epithelium contained well-developed Golgi apparatus and secretory granules as well. It was concluded that the ear canal epithelium was transformed into a secretory-like mucosal epithelium by retinoid supplementation.     

中耳胆固醇肉芽肿手术治疗策略探讨

目的:探讨中耳胆固醇肉芽肿手术治疗的策略。方法:对19例中耳胆固醇肉芽肿患者的临床资料进行回顾性分析。其中4例行单纯鼓膜置管术,8例行完壁式乳突切除+后鼓室切开+鼓膜置管术,7例行开放式乳突切除+鼓膜置管术。结果:术后随访0.5～3.3年。4例行单纯鼓膜置管术的患儿中,2例术后复发;8例行完壁式乳突切除+后鼓室切开+鼓膜置管术的患者中,3例术后复发;7例行开放式乳突切除+鼓膜置管术的患者无一例复发。在目前情况良好的14例患者中,有12例患者听力较术前明显改善。结论:对初发、病变范围局限的青少年患者,术前应完善检查以排除咽鼓管机械性阻塞因素,可选择单纯鼓膜置管术,术后定期观察;对症状反复发作、单纯置管或完壁式乳突切除+后鼓室切开+鼓膜置管术无效、病程较长或病变范围广泛的患者,应选择做保留鼓室完整性的开放式乳突切除+鼓膜置管术。     

大腿内侧Thiersch皮瓣在小耳畸形耳廓成形并外耳道重建术中的应用

目的探讨小耳畸形患者采用大脚内侧Thiersch皮瓣在耳廓成形并外耳道重建术中的应用。方法 总结2000年1月-2012年5月先天性小耳畸形并外耳道闭锁的患者105例（115耳）临床资料,所有患者在全麻下行耳廓成形并外耳道重建术,在重建的外耳道内采用大腿内侧Thiersch皮瓣移植,术后10-12 d局部换药,3-4周后外耳道用透明质酸和膨胀海绵填塞,3-6个月后取出填塞物。结果耳廓外形满意,外耳道皮肤上皮化良好,112耳外耳道口直径6-10 mm,外耳道口宽敞;3例患者因未定期复诊出现外耳道狭窄。结论大腿内侧Thiersch皮瓣可满足于先天性小耳畸形术后外耳道植皮需要,术后定期复查可有效预防外耳道狭窄。     

Influence of Canal Paresis and Compensation on Gain and Time Constant of Nystagmus Slow-phase Velocity to Yaw-axis Rotation

In order to assess the influence of canal paresis and compensation on the yaw-axis rotatory chair test parameters gain and time constant, a study was conducted in 435 patients diagnosed with unilateral peripheral vestibulopathy. Patients were grouped according to the amount of canal paresis found in the caloric test and by the result of a bedside examination of the vestibulo-ocular reflex (VOR). The time constant of the VOR diminishes as canal paresis increases and, when using a high-velocity sinusoidal test, there is a similar reduction in gain. Mean time constant was reduced when rotations were to the side of the lesion (ipsilesional) and to the normal (contralesional) and differences between both rotations were found for 21-80% canal paresis. Ipsilesional gain was significantly less than contralesional gain, which had a normal result independent of the amount of canal paresis; differences between them were significant when canal paresis was > 41%. Spontaneous nystagmus significantly influenced the appearance of asymmetries in gain and time constant in the tests performed while, with high-velocity sinusoidal rotation, gain was found to be significantly different for ipsilesional and contralesional rotations in non-acute symptomatic patients.     

Influence of canal paresis and compensation on gain and time constant of nystagmus slow-phase velocity to yaw-axis rotation.

In order to assess the influence of canal paresis and compensation on the yaw-axis rotatory chair test parameters gain and time constant, a study was conducted in 435 patients diagnosed with unilateral peripheral vestibulopathy. Patients were grouped according to the amount of canal paresis found in the caloric test and by the result of a bedside examination of the vestibulo-ocular reflex (VOR). The time constant of the VOR diminishes as canal paresis increases and, when using a high-velocity sinusoidal test, there is a similar reduction in gain. Mean time constant was reduced when rotations were to the side of the lesion (ipsilesional) and to the normal (contralesional) and differences between both rotations were found for 21-80%, canal paresis. Ipsilesional gain was significantly less than contralesional gain, which had a normal result independent of the amount of canal paresis; differences between them were significant when canal paresis was > 41%. Spontaneous nystagmus significantly influenced the appearance of asymmetries in gain and time constant in the tests performed while, with high-velocity sinusoidal rotation, gain was found to be significantly different for ipsilesional and contralesional rotations in non-acute symptomatic patients.     

Application of modified transmastoid approach methods to congenital atresia of the external ear canal with middle ear infection

OBJECTIVE: To present our surgical technique for congenital atresia of the external ear canal with middle ear infection. METHODS: A modified transmastoid approach to congenital atresia of the external ear canal with middle ear infection was applied. Our method is to visualize the landmarks of the mastoid cavity such as the antrum, sinodural angle and digastric ridge by the canal-open method to avoid facial nerve injury and then prepare a relatively large external ear canal with reconstruction of the posterior wall of the external ear canal. RESULTS AND CONCLUSION: This method is suitable not only for treating congenital atresia of the external ear canal with middle ear infection, but also for avoiding facial nerve injury and postoperative complications such as re-stenosis of the new ear canal and postoperative middle ear infection.