Tissue reactions to glass ceramics in the middle ear*

The bioactive glass ceramic ‘Ceravital’ was used to fashion protheses for the replacement of various ossicles in the middle ear. They were tested in 70 rabbit ears, where they were accepted in osseous areas without formation of surrounding fibrous tissue. Histological examinations regularly showed an osseous bond with the surrounding bony tissue. Mucous membrane covered these ossicular chain prostheses and showed no evidence of inflammatory reactions. Glass ceramic implants were also used to reconstruct the ossicular chain and the posterior wall of the outer ear canal in 100 patients. The functional results were satisfactory in all cases.     

How useful is tricalcium phosphate ceramic in middle ear surgery?

In our experiments on the hypotympanum of the pig, resorbable porous tricalcium phosphate ceramic has proved to be serviceable for reducing radical mastoidectomy cavities and as a substitute for osseous walls. For our initial clinical trials with porous tricalcium phosphate ceramic in middle ear surgery, we had implants made especially for the purposes of replacing osseous walls and reducing radical mastoidectomy cavities. When implants have been used to replace osseous walls, insufficient ventilation of the tympanic cavity has frequently coincided with complications in the covering between implant and auditory canal. Follow-up operations have afforded opportunities for histologic examination of fifteen implants, which served as wall replacements for nine to thirty months. There were only the slightest traces of resorption and replacement by bone. In contrast with our findings on the replacement of walls with ceramic implants, postoperative observation for periods of up to four years has shown that granules of porous tricalcium phosphate ceramic are well suited to reducing radical mastoidectomy cavities.     

International consensus on middle ear implants

Conclusion. Our anatomical findings place special emphasis on the requirement to follow an infero-anterior approach to the round window, to expose the scala tympani safely for ‘normal’ cochlear implantation. It is also known how easily the basilar membrane may be accidentally damaged, despite exercising considerable caution in the approach used. With regard to an ‘endosteal electrode’ it can be stated that there are no really specific indicators to locate the spiral ligament, or each of the scalae, on the lateral aspect of the tissue layer encasing the cochlea. For the concept of an endosteal electrode, however, the soft tissue layer of the lateral aspect of the cochlea is considered to be sufficiently thick to serve as a physical barrier between the electrode and the inner ear fluid. Objectives. To re-evaluate surgical techniques of gaining access to the scala tympani for cochlear implantation (cochleostomy, ‘fenestration’). There are two reasons for this study. First, recent publications show that in a significant number of patients the electrode array was unintentionally inserted into the ‘wrong’ scala (sc. vestibuli). Second, dealing with an alternative concept proposed by Lehnhardt for patients with residual hearing (‘endosteal electrode’), the anatomical site of the spiral ligament should be known. In a study on human temporal bones the topography of the middle and inner ear is revised with regard to the presence of anatomical or surgical landmarks that may guide the surgeon. Materials and methods. Anatomical examinations were performed on 10 temporal bones (5 fresh specimens and 5 fixed in formalin), in which the bone of the promontory was carefully milled. The consistency of identification and the relative location of specific surgical indicators or landmarks such as ‘blue lines’ and ‘gray lines’ were evaluated for 10 temporal bones. Furthermore, the projection of the lateral attachment of the basilar membrane on the promontory was determined with regard to round window anatomy. Results. In all cases, a major blue line indicated the lateral aspect of the basal cochlear turn while milling the promontorial bone. In a limited number of cases (20%), an additional gray line potentially indicated the spiral ligament before the last shell of bone was removed. In 80% of the cases it was possible to remove the bony layer and leave the endosteum intact as a precondition for a potential endosteal electrode insertion. In addition, through the examination of these models, the relative anatomical location of structures, such as the scala vestibuli, scala tympani, spiral ligament, and basilar membrane, is reviewed.     

Biocompatibility of vitallium as ossicular reconstruction material in the middle ear: experimental animal study

Conclusion Although long-term data will be necessary for confirmation, the result of this preliminary study indicates that vitallium may be a good alternative material for ossicular replacement prostheses in the middle ear.

Objectives To investigate the biocompatibility of vitallium (Co–Cr–Mo) as ossicular reconstruction material in the rabbit middle ear, and to compare the results with those obtained with titanium, well known as a highly biocompatible material, and non-implanted control groups.

Material and methods Eighteen female New Zealand White rabbits were anesthetized. The tympanomeatal flap was elevated and 12 vitallium and 12 titanium implants were placed in the bulla away from the ossicles in 24 middle ears. Six rabbits were used as non-implanted controls. All animals were sacrificed under general anesthesia on the 180th day after implantation. The temporal bones were removed, fixed in 10% buffered paraformaldehyde and decalcified for a week in EDTA. Tissue samples were then prepared using an Autotechnicon and embedded in paraffin. Sections (30-μm thick) were cut with a microtome, stained with hematoxylin–eosin, von Gieson's stain and fibroblast growth factor (FGF) and examined under a light microscope. The numbers of lymphocytes, collagen fibers and FGF-positive cells were determined in all three groups.

Results There was no significant difference in the numbers of collagen fibers between the groups (p>0.05). No significant differences were found in the numbers of lymphocytes and FGF-positive cells between the titanium and vitallium groups (p>0.05). The differences in the numbers of lymphocytes and FGF-positive cells between the control and other groups were found to be significant (p<0.05).     

Linear measurements in middle ear surgery

Present methods of linear measurement in micro-surgical procedures in the middle ear are crude when judged in relation to the delicate structure and functioning of the normal ear. Alternative methods of measurement employing the operating microscope are described. These depend on recording the travel of the microscope between two selected focal points and can be employed in both vertical and horizontal planes. Oblique distances can readily be calculated from the information provided. Minor alterations to existing microscopes would be required to ensure precise recording by electronic or linear methods.     

Glucocorticoids reduce nitric oxide concentration in middle ear effusion from lipopolysaccharide induced otitis media

Objective

Otitis media with effusion (OME) is a common childhood disease that is characterized by an accumulation of fluid in the middle ear. Chronic OME can also lead to sensorineural hearing loss (SNHL). Nitric oxide (NO), an inflammatory mediator (IM) of OME, is a free radical known to regulate cell proliferation, cell death, and angiogenesis. Previous studies have shown that nitric oxide may cause SNHL through outer hair cell (OHC) cytotoxicity. This experiment was designed to determine whether glucocorticoids, dexamethasone, fluticasone propionate, or rimexolone, can reduce the concentration of NO in middle ear effusion (MEE).

Methods

Fifty-three chinchillas were divided into 7 groups, vehicle vs. each glucocorticoid at 0.1% and 1.0% concentrations. Due to anesthesia complications, N ranged from 6 to 9 per group. Two hundred microlitres of each test article was injected into the bullae of each animal. Two hours later, lipopolysaccharide (LPS) (0.3 mg in solution) was added. Test articles were re-administered at 24 and 48 h post-LPS induction. After 96 h, animals were euthanized and the MEE was collected.

Results

All three glucocorticoids numerically reduced NO concentration in the middle ear when administered at 0.1%, but only FP showed a significant reduction. At 1.0% concentrations, all 3 steroids significantly reduced NO concentration.

Conclusion

This study suggests that glucocorticoid treatment reduces NO concentration in the MEE and may protect the ear from the SNHL caused by NO.     

成功保护听骨链的中耳耳印模异物取出联合鼓膜成形术1例

1病例报告患者,女,59岁,因＂发现左中耳异物2d＂入院。患者双耳反复流脓伴听力下降20余年,多次在耳鼻咽喉科检查均提示鼓膜紧张部大穿孔。半个月前验配助听器取左耳印模时,不慎将制印模材料落入中耳腔,患者听力损失较前加重,在外院门诊取出部分左耳印模后转入我科。耳内镜检查示：双侧鼓膜紧张部大穿孔,中鼓室黏膜肿胀,无明显充血及分泌物,左耳前上鼓室、残留鼓膜内侧见浅绿色异物,边缘呈不规则毛刺状。颞骨高分辨率     

Optimum tension for partial ossicular replacement prosthesis reconstruction in the human middle ear

OBJECTIVE: Hearing results from ossiculoplasty are unpredictable. There are many potentially modifiable parameters. One parameter that has not been adequately investigated in the past is the effect of tension on the mechanical functioning of the prosthesis. Our goal was to investigate this parameter further, with the hypothesis that the mechanical functioning of partial ossicular replacement prostheses (PORP) from the stapes head to the eardrum will be affected by the tension that they are placed under. METHODS: Fresh temporal bones were used to reconstruct a missing incus defect with a PORP-type prosthesis. Three different lengths of PORP were used, and the stapes vibrations were measured with a laser Doppler vibrometer using a calibrated standard sound in the ear canal. Eight temporal bones were used. RESULTS: Tension had a very significant effect on stapes vibration. In general, loose prostheses resulted in the best overall vibration transmission. The effects were most marked at the lower frequencies. There was a slight advantage to tight prostheses in the higher frequencies, but much less than the decrement in lower frequencies with tight prostheses. CONCLUSION: In ossicular reconstruction, best stapes vibration results in our model are achieved by shorter prostheses, which result in lower tension.     

Fibrin glue and tricalcium phosphate implants in middle ear surgery. An animal experiment study

Tricalcium phosphate (TCP) with and without heterologous fibrin glue has been used for obliteration of the mastoid cavity in middle ear surgery. The use of TCP with a homologous fibrin glue has not been described so far. Obliteration of 22 epitympanic and 51 femoral defects in rabbits by means of TCP-granulates without and with homologous fibrin glue was performed in 18 animals. Follow-up was for 2 weeks to 6 months. Histological osteo-integration was studied microscopically. Fibrin glue induces the development of soft tissue impeding osseous integration of the calcium phosphate for at least 6 weeks.     

inflammatory responses to hydroxyapatite implants in middle ear in rats

Objective To study local inflammatory response after implantation of hydroxyapatite synthetic ossicular prosthesis. Methods Hydroxyapatite gantries were implanted in the bulla in 32 rats. Sham surgical procedures were performed in 10 rats as the control. Animals were sacrificed at 1 to 300 days after surgery. Bulla sections, stained with HE and Mallory's azan, were examined for numbers and percentages of various inflammatory cell types. Results Slightly more inflammatory reaction was seen in animals with the implant than in the controls, mostly during the early stage following the implantation procedure. Few inflammatory cells were observed at later times. There were satisfactory fibrosis in both implanted and control ears. Conclusion The results indicate that hydroxyapatite synthetic prosthesis is a biocompatible implantation material in the middle ear. Nonetheless, the presence of inflammatory reaction immediately following implantation implies that control of infection is important in the early times after the implantation procedure.     

Bone allografts in reconstructive middle ear surgery

The authors present their current experience with stored bone grafts, using allografts shaped from the cortices of long bones for reconstructing the tympano-ossicular chain. The materials and the methods are described. The anatomical results have been good in 97% of the cases, while the functional results are as satisfactory as those obtained with bioceramics. In addition to ossiculoplasty, the bone allografts can also be used in otology for reconstructing large bony defects of the temporal bone.     

Results of homografts in middle ear surgery

Anatomical and hearing results following the use of the homograft tympanic membrane and ossicles either in combination or separately are reported for the period 1968 through 1975. The study is divided into two parts, the first covering the primary years 1968 through 1971, and the latter covering the last four years, 1972 through 1975. The original technique was to cover completely the homograft tympanic membrane with a canal skin graft. During the year 1969 new and different techniques were attempted. Unfortunately this resulted in a marked increase of graft failures; therefore, there was a prompt return to the original technique, which has been used without change throughout the study. The graft take rate for the first four years which included 1969 was 92%. There was a slight increase to 96% during the second part of the study. The hearing results show a greater discrepancy for the two periods with 89% of the patients receiving a satisfactory hearing result during the last four years, compared to 77% for the earlier period.