Surgical anatomy and pathology of the round window

A study of the surgical anatomy and pathology of the round window was performed on a total of 292 serially sectioned temporal bones. The surgical approach to the round window is discussed with consideration of the anatomical findings. In the pathological study obliteration of the round window niche occurred as a congenital anomaly, in otosclerosis, chronic otitis media and as an end result in suppurative labyrinthitis. Clinical reports seem to indicate that obliteration of the window is associated with a significant hearing loss, contrary to the findings in experimental animals. In chronic otitis media the round window is a pathway for spread of infection to the labyrinth, but also the finding of perilymphatic precipitates adjacent to the window in some ears suggests that certain inflammatory products may enter the scala tympani through the round window and so lead to high tone sensorineural hearing loss.     

Sensorineural hearing loss in experimental purulent otitis media due to Streptococcus pneumoniae

Sensorineural hearing loss (SNHL) has been described clinically following chronic otitis media with effusion, but to the best of our knowledge, no studies have demonstrated SNHL in an animal model of otitis media. Using the chinchilla model of pneumococcal otitis media, significant SNHL was demonstrated after purulent otitis media, especially at higher frequencies. Animals with otitis media received penicillin G procaine treatment for five days after otitis media with effusion (OME) was first documented; resolution of middle ear infection was confirmed by middle ear effusion culture in all animals. Both the inoculated and uninoculated ears were examined by tone burst-elicited compound action potential at threshold. The inoculated ear showed a marked hearing loss of 13 to 36 dB three to four days after OME was first documented; a hearing loss up to 24 dB persisted two to five weeks after inoculation. The change in the compound action potential was highly significant at all frequencies studied. Conductive losses were largely ruled out because there was no middle ear effusion at death and the tympanogram was normal. Purulent labyrinthitis was ruled out by histopathological study. These results indicate that purulent pneumococcal otitis media in the chinchilla model causes significant SNHL and suggest that the pathogenesis of SNHL associated with chronic OME in humans may be studied in this model.     

以听力突然下降为特征的分泌性中耳炎（附24例报告）

目的：提高对以听力突然下降为特征的分泌性中耳炎的确诊率。方法：回顾性分析24例（28耳）以听力突然下降为特征的分泌性中耳炎的临床资料,结果：11例患者被误诊或漏诊,各频率的平均气导阈值在60．2－66．5dBHL,平均骨导阈值在40．5－58．6dBHL,听力图示感音神经性聋9耳,混合性聋19耳,鼓室压图为B型,治疗后听力明显改善,结论,鼓室积液影响圆窗及卵圆窗间的相位差,导致听力突下降,它们的听力图无特征,并对产生误诊的原因进行了讨论。     

Permeability of the normal round window membrane to Haemophilus influenzae type b endotoxin.

Sensorineural hearing loss associated with otitis media may be due to passage of ototoxic substances such as bacterial toxins and antibiotics, from the middle ear into the inner ear. The round window membrane is the most likely route for such transport. The aim of this study was to analyze the extent of endotoxin passage through the normal round window membrane. The round window membranes of 19 chinchillas were exposed in vivo to Gelfoam soaked in purified Haemophilus influenzae type b endotoxin at a concentration of 45,000 endotoxin units per ml (EU/ml) during 3 to 24 h. Endotoxin levels in the perilymph were measured with Limulus Amaebocyte Lysate or Quantitative Chromogenic Limulus Amaebocyte Lysate. Endotoxin was detected in half of the inner ears at concentrations close to the detection limit (approximately 4 EU/ml). The results suggest that the normal round window membrane efficiently protects the inner ear against the passage of bacterial endotoxins from the middle ear cavity. It is unlikely that endotoxin at concentrations found in the middle ear secretion during otitis media can traverse the round window membrane in sufficient amount to cause inner ear deterioration.     

Histopathology of chloroform-induced inner ear damage

Inner ear function loss was caused in guinea pigs and rats by injecting chloroform into the middle ear. After symptoms for cochlear and vestibular deficit had been registered, the animals were permitted to survive for one day to five months. Ear histopathology was then studied in celloidin sections. In both species, hair cells and afferent nerve fibers were intact at all survival times. The acute stage of functional loss in guinea pigs was associated with inner ears of normal histological appearance. Within days after chloroform injection a severe otitis media developed which led to fibrous occlusion of the round window and eventually to new bone growth in the middle ear space around the otic capsule. A secondary labyrinthitis was also observed, resulting in endolymphatic hydrops at longer survival times. Different histopathological changes were seen in rats. The tectorial membrane appeared swollen in all cases, the swelling being more severe in more apical turns at longer survival times. It is concluded that only secondary sequela of the initial functional insult can be detected by standard light microscopic histopathology. Chloroform does not cause a chemical labyrinthectomy as previously assumed, although it is severely ototoxic.     

Current clinical and pathological features of round window diseases

The round window niche and membrane can be involved in clinical problems including perilymphatic fistulas, sensorineural hearing loss in otitis media, and a variety of others. The background of these problems is documented by a review of the literature and recent experimental evidence on round window grafting and tracer studies. Clinical pathological correlates including recent clinical experience are discussed for perilymphatic fistulas (sudden deafness, chronic progressive fluctuating sensorineural hearing loss, and association with Meniere's disease), sensorineural hearing loss in acute and chronic otitis media, and findings in round window membrane including absent round window reflex in cases of exploratory tympanotomy and otosclerosis. In addition, a new syndrome termed perilymphatic hypertension is described as seen in a subset of patients with sudden sensorineural hearing loss.     

两种内淋巴给药方式对豚鼠耳蜗功能和形态的影响

目的 观察经耳蜗侧壁打孔(侧壁径路)和经圆窗膜、基底膜穿刺(双膜径路)两种内淋巴系统给药方式对豚鼠耳蜗整体形态结构和功能的影响并比较两种方式的优劣.方法 40只正常健康杂色豚鼠分为A、B两组(每组20只),所有动物左侧为给药耳,右侧为非给药耳.A组采用侧壁径路进入中阶灌注携带增强型绿色荧光蛋白基因的5型重组腺病毒(adenovirus5-enhanced green fluorescence protein,AdS-EGFP)5 μl;B组采用双膜径路进入中阶灌注AdS-EGFP 5μl.给药前后行听性脑干反应(ABR)测试,观察听功能改变.耳蜗冰冻切片直接荧光观察腺病毒分布,HE染色观察手术径路的愈合情况.基底膜铺片鬼笔环肽染色观察毛细胞受损情况,扫描电镜观察局部损害情况.结果 所有动物术后均存活.穿刺部位修复良好,耳蜗的完整性得以保持.EGFP在Corti器和血管纹内壁细胞内标记明显,表明两种给药径路都可以将药物成功注入内淋巴系统.A组证实成功14只(70%),手术前后ABR反应阈(声压级)变化[(33.1±10.3)dB]与对侧非给药耳[(9.4±3.9)dB]比较差异具有统计学意义(F=46.34,P=0.0005);B组证实成功8只(40%)手术前后阈值改变[(2.5±3.8)d8]与对侧耳[(2.5±3.8)dB]比较差异无统计学意义(F=0.00,P=1.000).两种方法在部分动物中都有药物渗漏入外淋巴的现象,给药局部产生炎性反应,侧壁径路对毛细胞的损害范围大于双膜径路.结论 两种手术径路都可将药物成功注人豚鼠耳蜗的内淋巴系统中,局部有炎性反应,术后耳蜗的完整性可以获得完全恢复.侧壁径路对豚鼠耳蜗毛细胞缺失和ABR反应阈的影响大于双膜径路,但是经侧壁径路进入中阶的手术成功率高于双膜径路,选择何种灌注径路需要根据实验要求来定.     

Clinical Diagnoses Associated With Histologic Findings of Fibrotic Tissue and New Bone in the Inner Ear

Fibrotic tissue or new bone occurs following inner ear inflammation, fracture, or surgery. The prevalence is unknown and was investigated using the National Temporal Bone, Hearing and Balance Pathology Resource Registry database. A search yielded 264 temporal bones with diagnoses of otosclerosis, tumor, Meniere's disease, meningitis, labyrinthitis, chronic otitis media, autoimmune disease, temporal bone fracture, or sensorineural hearing loss. All autoimmune cases contained some new bone, whereas only 20% to 30% of the labyrinthitis/meningitis cases were reported to contain new bone. Otosclerosis, Meniere's disease, and otitis media had relatively few cases containing new bone. Although new bone may derive from surgical trauma, it is also likely to be a result of the disease process. It seems that all these disease processes may contain a common feature that acts as a stimulus to induce fibrosis or bone growth in the inner ear.     

Labyrinthitis secondary to experimental otitis media

PURPOSE: Analysis of labyrinthitis in a model of otitis media. MATERIALS AND METHODS: Morphologic study in 20 Wistar rats in which otitis media was induced by transbullar inoculation of Pseudomonas aeruginosa with obstruction of the eustachian tube. RESULTS: Seventy percent of rats showed vestibular signs. Histologic changes ranged from nonaffected labyrinths to suppurative labyrinthitis. CONCLUSIONS: Dissemination of infection probably occurs through round window membrane. A thinner round window membrane typical of rodents would be the reason for a more severe clinical and morphologic picture in rats when compared to human beings.     

Image analysis of the inner ear with CT and MR imaging: pre-operative assessment for cochlear implant surgery]

Recent progress in magnetic resonance imaging (MRI) has made it possible to obtain detailed images of the inner ear by delineating the lymphatic fluid within the labyrinth. We analyzed CT scans and MR images in 70 ears manifesting profound deafness owing to inner ear lesions and compared their detective ability for inner ear lesions. The following results were obtained. 1) CT scan examination showed slight to extensive ossification of the labyrinth in six ears (9%), whereas MRI examination revealed low to absent signal intensity of the inner ear in nine ears (13%). Therefore, it was concluded that MRI is more sensitive in detecting abnormalities of the inner ear than CT scan. 2) MRI provided useful information as to whether the cochlear turn is filled with lymphatic fluid or obstructed. This point was one of the greatest advantages of MRI over CT scan. 3) Abnormal findings in either or both the CT scan and the MRI were detected in suppurative labyrinthitis occurring secondary to chronic otitis media, bacterial meningitis and in inner ear trauma. However, such abnormal findings were not detected in patients with idiopathic progressive sensorineural hearing loss, ototoxicity or sudden deafness. These findings should be taken into consideration in pre-operative assessment of cochlear implant candidates.     

Round window membrane rupture and acquired sensorineural hearing loss in children

Round window membrane rupture and acquired sensorineural hearing loss in children The aetiology of acquired sensorineural hearing loss includes many conditions. The disparity between the number of children affected by the conditions which are supposed to cause hearing loss and the number of children who are actually deaf, has never been satisfactorily explained. Clinical features observed in children with surgically proven round window membrane rupture have been noted in all conventional aetiological groups. These features include otitis media, doubt about the hearing status in early life, disturbance of balance and other occasional neurological phenomena. Wide variation in the appearance of round window niche has been observed in children with secretory otitis and similar appearances have been observed in children with proven round window membrane rupture. The appearances may represent a reaction to perilymph. Round window membrane rupture is probably common and may prove to be a unifying factor for many cases of acquired sensorineural hearing loss. Occasional neurological phenomena may be related to it.     

Permeability of the middle ear to staphylococcal pyrogenic exotoxin in otitis media

Middle ear permeability after instillation of staphylococcal pyrogenic exotoxin was studied in each of 12 cats, 6 of them with otitis media induced by obstructing their eustachian tubes. This is the first report that there is passage of toxin to the perilymph, cerebrospinal fluid and blood not only in diseased ears, but also in normal controls, 25 min and 12 h after exposure of the middle ear cavity and round window membrane to toxin. The data suggest a pathophysiological explanation for the association of otitis media and sensorineural hearing loss and/or endolymphatic hydrops; potentially both entities can be caused by exotoxins. It also documents the extraordinary capabilities of movement of staphylococcal exotoxin.     

Meningitis resulting in hearing loss and labyrinthitis ossificans - does the causative organism matter?

Our aim was to demonstrate whether one causative agent of meningitis is more likely to cause profound hearing loss and labyrinthitis ossificans. We obtained data from the New South Wales health department for cases of meningitis between 1995 and 2005 (1568 cases) and the Sydney Cochlear Implant Centre for cochlear implant patients with hearing loss secondary to meningitis from 1984 to 2005 (70 ears in 59 patients). The aetiological agents were compared with regard to their ability to cause profound hearing loss and cochlear ossification. Neisseria meningitidis resulted in 56.9% of cases of meningitis and 11.4% of the cases of profound hearing loss resulting in cochlear implantation (incidence of profound hearing loss of 0.4%). Streptococcus pneumoniae, however, caused 41.1% of meningitis but 85.7% of cochlear implantation (incidence of 4.6%). Labyrinthitis ossificans was more common after infection with Streptococcus pneumoniae but there was no statistically significant difference between Streptococcus pneumoniae, Haemophilus influenzae or Neisseria meningitidis for labyrinthitis ossificans (p = 0.45, chi-squared test). In conclusion Neisseria meningitidis meningitis carries a very low risk of profound hearing loss but Streptococcus pneumoniae meningitis a significantly higher risk.     

Temporal bone histopathology in a patient suspected of inner ear extension of otitis media

We report the histopathological findings in the temporal bone of a 30-year-old female who died of cervical esophageal carcinoma. The temporal bone sections revealed severe bilateral suppurative labyrinthitis and otitis media that presumably occurred immediately before her death. Many inflammatory cells were present in the middle ear, particularly around the stapes and the round window niche. They had also infiltrated the inner ear via the annular ligament of the stapes and the round window membrane. Inflammatory cell accumulation was also observed in the peri- and endolymphatic spaces, and it was most severe in the basal turn. Most of the inner and outer hair cells were preserved, but some had degenerated or were missing. Numerous round cells were observed in the modiolus, and some of the spiral ganglion cells had degenerated. On the basis of these findings, we concluded that bacterial otitis media had extended in to the inner ear via the oval window and round window membrane and had resulted in suppurative labyrinthitis. These findings are consistent with those of stage II suppurative labyrinthitis according to the classification of Schuknecht.     

Otitis media (silent): A potential cause of childhood meningitis

Sixteen temporal bones from 8 infants with otitis media, who died of meningitis, and 6 controls from infants with only otitis media, were studied histologically. All bones contained middle ear effusion and residual mesenchyme, but, unlike the controls, the meningitic cases showed considerable histopathological tissue changes of chronic and acute otitis media and chronic inflammatory cells in the round window membrane and within the perilymph, the modiolus, and the cochlear aqueduct, suggesting the latter as likely portals from the inner ear to the meninges. Since all tympanic membranes were intact and 3 were histologically normal, this silent route of infection warrants medical vigilance.     

AM-111 reduces hearing loss in a guinea pig model of acute labyrinthitis

OBJECTIVES/HYPOTHESIS: This study investigated the otoprotective properties of AM-111, an inhibitor of c-Jun N-terminal kinase-mediated apoptosis and inflammation. STUDY DESIGN: A controlled, prospective animal study using a guinea pig model of acute labyrinthitis. METHODS: Acute labyrinthitis was generated by injection of antigen into the scala tympani of sensitized guinea pigs. Treatment groups received 100 microL of AM-111 at concentrations of 100 micromol/L, 10 micromol/L, and 1 micromol/L in a hyaluronic acid gel formulation delivered over the round window niche within 1 hour of antigen challenge. Cochlear function was monitored over 21 days with serial auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) measurements followed by histologic analysis. RESULTS: The ABR results on day 21 demonstrated that untreated control ears for acute labyrinthitis had a mean hearing loss (HL) of 68 +/- 12 dB. In contrast, ears treated with AM-111 (100 micromol/L) had a mean HL of 39 +/- 31 dB. These two groups were statistically different (one-way analysis of variance, P = .03). Secondary outcomes, including DPOAE shift, inner hair cell survival, inflammatory cell counts, and spiral ganglion density, were also statistically significant in favor of an otoprotective effect of AM-111. Lower doses of AM-111 did not produce a statistically significant reduction in HL over controls. CONCLUSION: AM-111 delivered over the round window membrane in a 100 microL hyaluronic acid formulation at a 100 micromol/L concentration immediately after induction of acute labyrinthitis in the guinea pig cochlea protects hearing, reduces hair cell loss, and reduces the number of inflammatory cells at 21 days after treatment.     

Cytotoxic changes in hair cells secondary to pneumococcal middle-ear infection

To determine whether the bacterial toxins associated with otitis media could induce morphologic changes in the organ of Corti, we inoculated the middle-ear cavities of healthy guinea pigs with either Streptococcus pneumoniae or sterile saline and then examined the organ of Corti histologically at 1, 2, and 3 weeks postinoculation. We found that the outer hair cells (OHCs) in the infected ears underwent several changes that were dependent on both the length of time following inoculation and also the position of the OHCs in the cochlea. At 2 weeks postinoculation, 7.0 to 20% of the OHC nuclei from the infected animals became very swollen, with the most significant swelling occurring in the basal turn. At 3 weeks postinoculation, 2.5 to 3.5% of the OHCs were missing in the infected animals, with the most significant loss occurring in the basal and middle turns. These results suggest that bacterial otitis media can produce cytotoxic changes in the cochlea. These changes may be a clinically significant factor in the temporary and permanent sensorineural hearing loss that has been associated with bacterial otitis media.     

豚鼠慢性化脓性中耳炎鼓室硬化模型

目的 研究建立慢性化脓性中耳炎鼓室硬化动物模型豚鼠的方法,为慢性化脓性中耳炎鼓室硬化的动物实验研究提供一种有用的动物模型.方法 采用小鼠腹腔连续传代3次增强毒力的金黄色葡萄球菌,采取反复中耳腔注射的方法,制备豚鼠慢性化脓性中耳炎动物模型,了解化脓性中耳炎对听阈的影响及是否导致鼓室硬化.结果 将钙化斑及局部骨化作为鼓室硬化的标志,接种细菌后1周就可观察到中耳粘连的出现,接种后2周出现钙化斑等鼓室硬化灶,听力较对照耳明显下降.观察到硬化灶最常见的部分是下鼓室,其次是鼓室上隐窝、上鼓室、鼓膜、听骨链间隙和咽鼓管鼓口.结论 豚鼠慢性化脓性中耳炎鼓室硬化动物模型病理变化与人慢性化脓性中耳炎鼓室硬化类似,是研究慢性化脓性中耳炎鼓室硬化较好的动物模型.     

慢性化脓性中耳炎与感音神经性聋

目的：观察慢性化脓性中耳炎（CSOM）对感音神经性聋（SNHL）的影响。方法：测量135例（168耳）CSOM患者的骨导听阈,并以66例单侧患者的健耳为对照,比较不同类型、不同病程的CSOM的骨导听阈。结果：CSOM各组骨导听阈均值明显高于对照组,且与中耳炎的类型和病程相关。结论：CSOM可引起SNHL,且中耳病变越重,病程越长,听力下降越明显     

耳源性细菌性迷路炎研究进展

迷路炎是内耳感染性疾病,其主要临床表现包括发作性头晕、眩晕与感音神经性听力损失。探讨与中耳炎相关的耳源性细菌性迷路炎。根据内耳的病理表现,可以将迷路炎分为局限性迷路炎、浆液性迷路炎和化脓性迷路炎三种。局限性迷路炎也叫做迷路瘘管,常并发于中耳胆脂瘤,好发于水平半规管;浆液性迷路炎是细菌毒素所致的内耳无菌性炎症,常因发病隐袭与其他头晕眩晕疾病混淆造成误诊误判;化脓性迷路炎是发生于内耳的细菌感染性炎症,常造成严重的感音性听力损失和眩晕。目前耳科临床迷路炎并不少见,但并未引起足够的重视。论文结合国内外文献对不同类型的耳源性细菌性迷路炎进行综述,以期为临床对此类患者早诊断早治疗提供帮助。