Bony ossicular fixation using 2-cyano-butyl-acrylate adhesive

We investigated the effects of 2-cyano-butyl-acrylate (Histoacryl) on the ossicles of 11 of 12 adult guinea pigs. A small amount of the adhesive, placed precisely between the incus and its bony fossa in each middle ear, fixed the ossicles. Light microscopic investigation of the ears of animals killed at 3, 6, 9, and 12 months after surgery showed a bony union of the ossicle to its surrounding niche in 11 of 12 operated-on ears. Negligible inflammatory reaction was seen in areas of the middle ear not in contact with the adhesive. These observations suggest that 2-cyano-butyl-acrylate may be used to achieve a durable bony union in ossiculoplastic surgery with minimal side effects in the middle ear.     

The use of tissue adhesive (isobutyl cyanoacrylate) and topical steroid (0.1 percent dexamethasone) in experimental tympanoplasty

Two main purposes in the present study were: 1. to determine the feasibility of using the tissue adhesive isobutyl 2-cyanoacrylate in reconstructive middle ear surgery; and 2. to learn whether a potent topical corticosteroid (0.1 percent dexamethasone) would have beneficial anti-inflammatory effects when placed in the tympanic cavity at the time of middle ear surgery. Tympanoplastic surgery was performed on 26 cat ears and six squirrel monkey ears; the animals were followed for six weeks to nine months postoperatively. The conclusions to be drawn from this experimental study are that presently the tissue adhesive isobutyl cyanoacrylate appears too toxic for use on the delicate middle ear structures; likewise, corticosteroids placed in the middle ear do not appear to have any beneficial effects in tympanoplasty surgery.     

Titanium oxide ceramic as an implantation material in otosurgery: animal experimental results and surgical technique

BACKGROUND: For the experimental animal study to evaluate a new ossicular chain replacement prosthesis, we developed a new technique for surgical implantation into the middle ear of rabbits. The selection of the species was based on its similarity to human middle ear anatomy and the favored, standardized, microsurgical approach to the middle ear cavity. METHOD: For the study we included a total of 34 approximately 6-month-old female white rabbits (New Zealand) with a weight of 3.2 to 4.4 kg. The implants used were constructed of ceramic materials TiO(2) (titania) with different pore size. Directly before the implantation of the TORPs, as well as at 28, 84 and 300 days after implantation, electric response audiometry was used to determine the hearing thresholds of the animals (bone conduction click stimulus nHL). The Erbium Yag-Laser was used to cut out the originally ossicular chain. RESULTS: After implantation we could not detect any stenosis of the outer ear canal or perforation of the tympanic membrane. The conductive hearing threshold was in the range of 4.21 +/- 6.68 dB nHL (n = 131). The hearing level showed no significant difference before and after surgery (p > 0.05). CONCLUSIONS: The laser surgery is a very safe procedure for prosthesis implantation in the middle ear of rabbits..     

中耳感染性疾病Ⅰ期和分期人工耳蜗植入病例分析

目的总结中耳感染性疾病患者人工耳蜗植入(Cochlear Implant,CI)的临床经验。方法对2000年12月-2019年3月在解放军总医院行CI伴中耳感染性疾病患者的临床资料进行回顾性研究。对Ⅰ期或Ⅱ手术患者的中耳病变性质和范围、手术方式、术腔填塞物种类、手术疗效以及术后并发症等进行总结分析。结果术后随访9个月-10年,Ⅰ期植入11例,其中,慢性化脓性中耳炎静止期5例,活动期2例,中耳胆脂瘤4例(胆脂瘤范围较小,或有完整包膜)。Ⅱ期植入9例,其中,慢性化脓性中耳炎活动期6例,静止期1例;中耳胆脂瘤2例(胆脂瘤范围较大,或包绕正常组织,不易完整清除)。分期植入组中有1例耳蜗植入术后9年电极脱出。其余病例通过结合病例特点,采用不同手术方式均取得满意的治疗效果。结论对于中耳感染性疾病的患者,人工耳蜗分期植入相对于同期植入更加安全。Ⅰ期植入应尽可能选择病变较轻,病灶局限易完整清理的病例,术式选择应在彻底清除病灶的基础上尽量选择损伤范围较小的术式。     

Octylcyanoacrylate: a new medical-grade adhesive for otologic surgery

HYPOTHESIS: The adhesive octylcyanoacrylate is not associated with significant inner ear toxicity in a guinea pig model. BACKGROUND: Many cyanoacrylate adhesives have been investigated for use in otologic surgery, but variable ototoxicity has been reported. Octylcyanoacrylate is a medical-grade adhesive with many properties that make it ideal for use in the ear. It is free of contaminants; it forms a strong, flexible bond; and it inhibits the growth of gram-positive organisms in culture. This is the first study to assess the ototoxicity of this new adhesive. METHODS: Fourteen adult guinea pigs were used. Preoperative auditory brainstem responses (ABRs) were determined. Bilateral antrotomies were performed, and the ears were randomized to adhesive and control (saline) groups. In the adhesive ears. 0.5 or 0.1 mL of octylcyanoacrylate was instilled into the middle ear. Eight weeks later, postoperative ABRs were determined, the animals were killed, and the temporal bones were removed. Middle ear changes were noted, and the ossicular chain was assessed. Cochlear hair cell analyses were performed. Histologic assessment of the middle ear mucosa was performed. RESULTS: There was a higher incidence of conductive hearing loss in the adhesive group secondary to fixation of the ossicular chain, but there was no significant difference in bone conduction thresholds. The median postoperative bone conduction thresholds (dB peak sound pressure level) was 15.0 in the control group and 17.5 in the adhesive group, p = 0.89. There was also no significant difference in inner hair cell counts (0.4% vs. 0.5% median hair cell loss, p = 0.72) or outer hair cell counts (3.7% vs. 3.0% median hair cell loss, p = 0.23) for the adhesive and control groups, respectively. Histopathologic analysis of the middle ear mucosa demonstrated variable mild to moderate foreign body reaction with no evidence of mucosal ulceration or necrosis. CONCLUSIONS: A large amount of octylcyanoacrylate placed in the middle ear of the guinea pig did not cause any morphologic or functional evidence of inner ear toxicity. This new adhesive is a promising tool for otologic surgery.     

Pneumococcal meningitis threshold model: A potential tool to assess infectious risk of new or existing inner ear surgical interventions.

HYPOTHESIS: A minimal threshold of Streptococcus pneumoniae is required to induce meningitis in healthy animals for intraperitoneal (hematogenous), middle ear, and inner ear inoculations, and this threshold may be altered via recent inner ear surgery. BACKGROUND: There has been an increase in the number of reported cases of cochlear implant-related pneumococcal meningitis since 2002. The pathogenesis of pneumococcal meningitis is complex and not completely understood. The bacteria can reach the central nervous system (CNS) from the upper respiratory tract mucosa via either hematogenous route or via the inner ear. The establishment of a threshold model for all potential routes of infection to the CNS in animals without cochlear implantation is an important first step to help us understand the pathogenesis of the disease in animals with cochlear implantation. METHODS: Fifty-four otologically normal adult Hooded Wistar rats (27 receiving cochleostomy and 27 controls) were inoculated with different amounts of bacterial counts via three different routes (intraperitoneal, middle ear, and inner ear). Rats were monitored during 5 days for signs of meningitis. Blood, cerebrospinal fluid, and middle ear swabs were taken for bacterial culture, and brains and cochleae were examined for signs of infection. RESULTS: The threshold of bacterial counts required to induce meningitis is lowest in rats receiving direct inner ear inoculation compared with both intraperitoneal and middle ear inoculation. There is no change in threshold between the group of rats with cochleostomy and the control (Fisher's exact test, p < 0.05). CONCLUSION: A minimal threshold of bacteria is required to induce meningitis in healthy animals and is different for three different routes of infection (intraperitoneal, middle ear, and inner ear). Cochleostomy performed 4 weeks before the inoculation did not reduce the threshold of bacteria required for meningitis in all three infectious routes. This threshold model will also serve as a valuable tool, assisting clinicians to quantitatively analyze if the presence of a cochlear implant or other CNS prostheses alter the risk of meningitis.     

先天性内耳畸形并中耳畸形患者多通道人工耳蜗植入术3例报告

目的：探讨先天性内耳畸形并中耳畸形患者行多通道人工耳蜗植入术的方法及效果。方法：1995年5月-2002年5月我院为3例罕见的先天性内耳畸形并中耳畸形患者经乳突进路行人工耳蜗植入术,分别植入27、28、32个电极,植入后3个月行声场测听。结果：3例患者均成功地行人工耳蜗植入,术中、术后无严重并发症发生,术后声场测听听阈达35-40dBHL。结论：罕见的先天性内耳畸形并中耳畸形患者也可行人工耳蜗植入术,术后效果满意。     

A novel microperfusion system for the long-term local supply of drugs to the inner ear: implantation and function in the rat model.

Local therapy is practiced for middle and inner ear diseases but is usually restricted to cases of ear drum perforation or repeated invasive intratympanic drug application. Perfusion of drugs on the round window or through the scalae of animals using a pump system suggests that the chronic local drug treatment might also be feasible in humans. However, drug delivery systems that are currently on the market involve repeated reimplantation if they are to be used for long-term drug supply. A bone-anchored, totally implantable micro-drug delivery system (MDS) for patient-controlled drug supply has been developed [Lehner et al., 1997]. In this study, we show the first successful long-term in vivo test of the MDS micro-pump in rats. The process of implantation and first functional tests will be described. The biomaterial used to manufacture the delivery system did not cause any inflammation reaction in any of the 9 animals successfully implanted. After activation of the micro-pump, the drug reservoir and port was found to be fluid-tight. Bolus applications of tetrodotoxin (TTX) to the round window induced a transient decrease of evoked brainstem responses. In 2 animals which carried the MDS for more than 8 months the proper functioning of the pumping device was examined in a 2-3 week interval over a 3 month period. The MDS can be autoclaved even after long-term implantation and can then be reused for subsequent implantations. Designed for life-long implantation in humans, the demonstration of an effective long-term drug supply to the inner ear using the MDS provides an encouraging first step towards future long-term drug treatment of the inner ear in humans.     

Morphological sequence of Plastipore extrusion in experimental otitis media

OBJECTIVES: Plastipore prostheses are still used by many surgeons, although the functional results are controversial. The aim of this study was the morphological analysis of Plastipore material performance in the middle ear of rats, with special attention to extrusion. METHODS: Twenty-four Wistar rats were given implants made of commercially available Plastipore and assigned to 3 groups: group A, with implantation in a healthy middle ear; group B, with implantation and cauterization of the nasopharyngeal orifice of the eustachian tube (hypoventilation); and group C, with implantation, cauterization of the eustachian tube, and bacterial inoculation with Pseudomonas aeruginosa. RESULTS: The pathological study showed in nearly all cases the disintegration of the biomaterial. Adhesion between the biomaterial and bone could be seen in 1 rat from group C (hypoventilation and infection). In group C, the Plastipore was in contact with the tympanic membrane in 1 case and was extruding in 2 animals. Different phases of extrusion were defined. No extrusion was observed in the other groups. CONCLUSIONS: The sequential stages of Plastipore extrusion are demonstrated. Infection seems to be the most important factor in Plastipore extrusion in our model.     

可吸收医用膜预防和治疗中耳粘连的实验研究

目的探讨可吸收医用膜(粘克)对耳科术后中耳粘连的预防作用。方法选取听阈正常、无耳科疾病的正常豚鼠36只, 随机分为3组,均通过堵塞咽鼓管来诱发中耳黏膜炎性渗出改变,在豚鼠的中耳鼓岬部植入粘克阻隔材料(试验组1),并在另外两组的豚鼠中耳内植入硅胶片(试验组2)和不植入任何材料(对照组)作为对照,每组豚鼠分别在术后15 d和90 d各处死6只,以了解可吸收医用膜阻隔中耳粘连的作用。结果植入粘克材料的豚鼠听力阈值改变较小,与其他两组比较差异具有统计学意义(P<0.05)。对植入阻隔材料后豚鼠的听泡进行病理形态学观察显示：与其他两组形成大量纤维肉芽组织和大片坏死相比,粘克材料组形成的纤维肉芽组织较少,且形成局限性包裹,并有腔隙形成,有效的阻隔了粘连。结论粘克材料具有更好的生物相容性,是很好的阻隔中耳粘连的生物材料。     

Auditory brain-stem responses in guinea pigs following middle ear implantation of Ceravital

Summary The effects on auditory function caused by implantation of the bioactive glass ceramic Ceravital in the middle ear of guinea pigs was investigated. Auditory brain-stem responses (ABR) were used to measure hearing function. A threshold shift due to a conductive hearing loss was observed immediately post-operatively. This threshold shift increased towards the 20th post-operative day and improved thereafter. Surgical manipulation of the middle ear and biochemical reactions between the Ceravital granules and the middle ear wall may have contributed respectively to the immediate and late temporary ABR threshold shift recorded. However, cochlear function was not affected by middle ear implantation of Ceravital. These results correlate well with morphological studies of Ceravital implanted in the middle ear and give further support to the safe use of Ceravital as an implantation material in middle ear reconstructive surgery. Offprint requests to: D. Zikk, Department of Otorhinolaryngology, Tel Aviv Sourasky Medical Center, Ichilov Hospital, 6 Weizman St., Tel Aviv 64239, Israel     

Experimental middle ear cholesteatoma originated from free skin graft of the external ear

The pathogenesis of middle ear cholesteatoma has been thought to be invasion of squamous epithelium originated from the external ear skin including the tympanic membrane. There is no evidence, however, that the external ear skin has more potential to form cholesteatoma than that of other sites. In this report experimental middle ear cholesteatoma of guinea pigs originated from the external ear skin was histologically compared with that originated from the auricular skin. Cholesteatoma as dermal cyst was seen in the middle ear of almost all animals (25/28 = 89.3%), using a free skin graft (3 x 3 mm), regardless of the skin taken from superior (group A) or inferior (group B) part of the external ear, or the auricle (group C) eight weeks after skin implantation. The activity of epithelium such as keratinization was evident in group C. There is, however, no obvious difference in surrounding granulation tissues among group A, B, and C. In a half of this series, cyst wall was broken and its contents (debris) mainly consisted of keratin were put on surrounding granulation tissues three weeks after skin implantation. Striking keratinized epithelium and subepithelial inflammations in relation to the amount of debris were observed at the eighth week. These findings suggest that the external ear skin does not have specific potential to form cholesteatoma and keratin plays some roles in growth of cholesteatoma.     

颞骨高分辨率CT在中、内耳手术中的应用

目的分析颞骨高分辨率CT在中、内耳手术中的应用。方法回顾分析近3年的600例中、内耳手术前颞骨CT和术中病变情况。结果术前CT诊断慢性化脓性中耳炎、中耳胆脂瘤、中耳炎后遗症(包括鼓膜穿孔、粘连性中耳炎、鼓室硬化症)、耳硬化症和中耳畸形及恶性肿瘤的符合率分别为98.7%(221/224耳)、94.4%(319/302耳)、94.1%(32/38耳)、66.7%(16/24耳)和100%(12/12耳)。结论颞骨CT提供了大量关于中、内耳的信息,临床医师术前应该认真阅读分析颞骨CT片,充分利用CT提供的信息,做好手术的个体化设计,提高治疗质量。     

Experimental use of fibrin tissue adhesive in middle ear surgery

The biocompatibility of a new tissue adhesive was tested. Its major advantages are adhesions, hemostasis, and the promotion of wound healing. In experimental surgery on 43 middle ears of chinchillas, documented by histological evidence obtained 45 days after operation, the validity of the following two hypotheses was established. That fibrin tissue adhesive placed upon the footplate of the stapes is biologically compatible, biodegradable and does not cause toxic, inflammatory or foreign body reactions, or other tissue damage to middle ear structures. That a small piece of bone glued on the long process of the incus with fibrin tissue adhesive shows permanent tissue union. In addition, in cases where the inner ear was accidentally opened by surgically subluxating the stapes and adhesive was free to enter the vestibule, evidence was obtained that there was no damage to inner ear structures. This finding deserves further investigation.     

Eustachian tube malfunction and middle ear disease in new perspective

Our traditional concepts relating to the development of middle ear disease are based on the assumption that obstruction of the Eustachian tube with reduced ventilation of the middle ear space leads to the development of high negative pressure in the middle ear and, ultimately, to the development of middle ear disease. This hypothesis, which focuses on Eustachian tube opening failure, has not been verified satisfactorily. Results of recent studies indicate that another approach to the problem can lead to a better understanding of the Eustachian tube pathophysiology leading to the development of ear disease. Direct measurements of middle ear pressure in patients with manifest ear disease have revealed that high negative intratympanic pressure is generated by the voluntary act of sniffing. This type of Eustachian tube malfunction is thus characterized by Eustachian tube closing failure. The repetitive barotrauma induced by sniffing or reverse Valsalva maneuvers seems to be a basic predisposing factor in the development of recurrent middle ear effusion and chronic middle ear disease, including adhesive otitis and cholesteatoma.     

Middle ear mucosa regeneration by grafting of artificial mucosa

CONCLUSION: Artificial middle ear mucosa (AMEM), a sheet of mucosal cells grown on collagen gel populated with fibroblasts, is useful as graft material that is able to promote mucosal regeneration after middle ear surgery. OBJECTIVES: Regeneration of the middle ear mucosa and pneumatization of the mastoid cavity is critical for good prognosis. We examined whether implantation of AMEM into damaged middle ear cavity would promote mucosal regeneration. MATERIALS AND METHODS: AMEM was prepared as described previously using epithelial cells and fibroblasts isolated from the rabbit middle ear. We implanted AMEM into rabbit middle ear from which mucosa had been surgically removed and evaluated its histological and functional recovery 8 weeks later. Three other groups were used for comparison: a normal control group, a mucosa-eliminated group, and a collagen-implanted group. RESULTS: AMEM grew to be morphologically similar to the native middle ear mucosa. Electron microscope studies showed that implanted AMEM has basal lamina and cilia. AMEM implantation suppressed bone hyperplasia and granulation, leading to better mucosal regeneration. Mucosal gas exchange was also significantly improved after implantation.     

Effects of middle ear ventilation on cholesteatoma development in experimental animals

This study was designed to evaluate the effect of middle ear ventilation on cholesteatoma formation following propylene glycol application in experimental animals. Fifteen chinchillas had stainless steel ventilation tubes chronically implanted in their bullae and 60% propylene glycol was subsequently instilled into the middle ear cavities. The animals were kept alive for 4 weeks, during which time the middle ear pressure was monitored tympanometrically and the tubes were frequently inspected to verify patency. Of the 30 ears in the study, 20 (66.6%) developed middle ear cholesteatoma--a rate of occurrence comparable to that found in earlier studies in which middle ear ventilation was not provided. These results indicate that negative middle ear pressure is not a necessary factor for cholesteatoma development following application of chemical irritants in experimental animals.     

The effect of experimental tubal obstruction on the middle ear. Preliminary report

The rat was used as a model for studying the effect of tubal obstruction on the middle ear. Animals raised under conventional conditions, SPF- and germ-free animals were used. The predominant findings were: (1) Tubal occlusion causes an effusion of serous fluid into the middle ear cavity and promotes the pathological behaviour of pathogen and non-pathogen symbionts of the middle ear cavity. (2) The germ-free animal is an excellent model for studying the isolated effect of tubal obstruction without the interference of infectious disease. (3) The middle ear reacts towards tubal obstruction by a tendency to resorb and to organize the fluid by phagocytosis and fibrosis of the cavity. Transformation of the epithelium into mucus-producing cells was observed only in those animals which developed a middle ear infection after occlusion. (4) The final result shows a near-totally obliterated middle ear cavity resembling the atelectatic middle ear in humans.     

Middle ear pressures in eustachian tube malfunction: manometric studies

We made direct measurements of the difference in pressure between the middle ear and the ambient atmosphere in 300 ears affected with chronic adhesive otitis media (CAOM), serous otitis media (SOM), and similar disorders of the ear caused by eustachian tube malfunction. We utilized a narrow bore, open U-tube manometer made of No. 205 polyethylene tubing which was connected to a 20 or 22 gauge spinal needle. The needle was passed through the intact tympanic membrane and the displacement of the column of 95 percent alcohol in the manometer was noted and recorded. Our results showed that in 101 ears with CAOM, the average negative pressure difference between the middle ear and the ambient atmosphere was 9 mm 95 percent alcohol, equivalent to 7 mm of H₂O. In 136 ears with SOM, the average negative middle ear pressure was 8 mm 95 percent alcohol, equivalent to 6.5 mm H₂O. In 80 of the 300 diseased ears we tested, the middle and ambient atmospheric pressures were equal. Direct readings of the middle ear pressure tell us the status of the middle ear ventilation at the moment of the measurement.     

The development of the middle ear in neonatal chinchillas II. Two weeks to adulthood.

Studies of auditory function in the human neonate indicate adult-like hearing sensitivity, mature cochlear function and well-developed responses in the auditory pathway. Paradoxically, measurements of middle ear function are characterized by responses that would be interpreted as abnormal in older subjects. Consequently, there is not an accepted clinical test for middle ear disease in the newborn population. Like human neonates, chinchillas have normal hearing sensitivity at birth, but middle ear function tested by multifrequency tympanometry is abnormal compared to the adult. A previous study from our laboratory indicated that the newborn chinchilla middle ear is free of mesenchyme and other debris. Over the first 2 weeks of life there were no significant changes in tympanic membrane thickness and diameter, tympanic membrane to promontory distance and stapes footplate length. There were small changes in mastoid bulla area and perimeter and in mastoid bulla bone thickness. The most striking difference between the newborn and adult temporal bone was in bone composition, the newborn bone having a less dense, spongy appearance. Impedance characteristics of the newborn chinchilla ear, measured by multifrequency tympanometry, were abnormal relative to adult animals and did not change over the first 2 weeks of life. This investigation is an extension of the previous study, designed to better understand the relationship between middle ear function, hearing sensitivity and the structural changes of the newborn chinchilla middle ear. Twenty animals, aged 2-8 weeks, were studied. Additional adult animals were used as controls. Middle ear function was assessed by a wideband reflectance impedance system. Hearing sensitivity was measured by auditory brainstem response in 2- and 8-week-old animals. Structural characteristics of the temporal bone were analyzed using histopathologic preparations. There was an orderly progression in middle ear impedance and reflectance characteristics as the chinchilla ear matured from 2 to 8 weeks of age. At 8 weeks of age, impedance and reflectance patterns approached, but did not match, those of the adult animal. Hearing sensitivity was unchanged throughout this maturational period. Finally, histological analysis demonstrated no age-related changes in distance from the tympanic membrane (TM) to the promontory and in stapes footplate length. There was a small significant decrease in the TM thickness from 2 weeks to adulthood. The most significant developmental changes were a reduction in mastoid bone thickness and concomitant increases in the perimeters and areas of the middle ear and posterior bulla.