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Movements of the intact and reconstructed ossicular chain during changes in static pressure.

OBJECTIVE: To investigate the motion of the normal and reconstructed ossicular chain during changes in static pressure. MATERIAL AND METHODS: Experiments were carried out using seven fresh human temporal bones Using digital photography, movements of the malleus were measured during incremental pressure changes between +500 and -500 daPa with the incus in situ and following its removal. The pattern of movement of the ossicles was recorded in the form of digital video clips. This was carried out with the ossicular chain intact and also when it had been reconstructed with an incus graft and four different types of artificial prosthesis. RESULTS: The lateral to medial movement of the malleus during changes in static pressure is converted into a predominantly superior to inferior movement of the incus. Conventional reconstructions using a graft or prosthesis transmit the malleus movement directly to the stapes so that it is pushed in and out of the oval window. Reconstructions with prostheses which restore the mammalian three-ossicle pattern, by contrast, move in a similar manner to the normal incus. CONCLUSION: Ears reconstructed using conventional techniques are more at risk from pressure changes than those in which a "physiological" method is used.

Atmospheric Pressure↗

Middle ear pathology in ancient and modern populations: incudal osteoma.

CONCLUSIONS: Osteomas of the incus were found in surprisingly high numbers in ancient and modern populations. The coexistence of osteoma formation and unique vascularization on the medial surface of the incus alludes to a relationship between the two findings. OBJECTIVE: Osteomas involving the middle ear ossicles are rare. The aim of this study was to compare the incudal pathology of ancient and recent periods using the recent literature. MATERIAL AND METHODS: Pathologies encountered in 1170 human incudes belonging to different populations from ancient and recent periods were studied. Most of the ossicles were found in the middle ear of dry skulls or during dissection. The observations were done with a binocular microscope and a Nikon Profile Projector. RESULTS: A total of 47 incudes (4.01%) presented with a variety of pathologies, osteomas being found in 19 cases (1.62%). The osteomas were noted only on the medial surface of the incus. Other findings, including prominent erosions, multiple nutrient foramina and pitting, were also found on the medial side of the incus. The incidence of osteoma was found to be more common in ancient populations (1.88%) and most prevalent among Bedouins (4.55%).

Ear Neoplasms↗

Human temporal bone study on the postnatal ossification process of auditory ossicles.

OBJECTIVE: In infancy the head of the malleus and body of the incus normally contain bone marrow, which is gradually replaced by bone and converted into vascular channels with age. This study was carried out to clarify the age at which ossification of the ossicles is complete and to examine factors influencing the ossification process. STUDY DESIGN: Human temporal bone sections from 32 infants and children with or without congenital anomalies, aged 1 day to 9 years, who were born at term were studied. METHODS: The percentage bone marrow area occupying the head of the malleus and body of the incus was calculated in three horizontal temporal bone sections for each case, using computer-aided digital processing of images. RESULTS: Bone marrow was observed in both the malleus and incus in children until 25 months of age, while after the age of 25 months no bone marrow tissue was present in either of the ossicles. It appeared that the bone marrow space disappeared somewhat earlier in the malleus than in the incus. The bone marrow space around the otic capsule disappeared much earlier than that within the ossicles. The age at completion of ossification was correlated with neither the presence of congenital anomalies nor the presence of residual mesenchyme in the middle ear. CONCLUSIONS: Ossification of the ossicles seems to occur steadily throughout fetal life and after birth during development of the middle ear. Although the clinical significance of postnatal residual bone marrow within the ossicles is not known, it possibly plays a role as a blood-forming organ in early infancy.

Bone Marrow↗

Malleus-to-footplate versus malleus-to-stapes-head ossicular reconstruction prostheses: temporal bone pressure gain measurements and clinical audiological data.

HYPOTHESIS: Several clinical reports suggest that if the stapes superstructure is intact, ossicular reconstruction should be made to the stapes head rather than the footplate to achieve a better hearing outcome. To test this hypothesis, we compared the in situ mechanical performance of hydroxylapatite (HA) malleus-to-stapes-head (MSH) ossicular reconstruction prosthesis (ORP) with malleus-to-footplate (MFP) ORP, both manufactured by Project HEAR. BACKGROUND: ORPs are commonly used to replace a missing or deficient incus. However, hearing outcomes are highly variable, depending on the ORP material, design, surgical technique, and ORP positioning. METHODS: Cochleo-vestibular pressure measurements in human cadaveric temporal bones for the HA MFP ORP have been reported by Puria et al. (2005). In the present study, the ear canal pressure Pe and cochleovestibular pressure Pv were measured in cadaveric temporal bones with intact incus, removed incus, and MSH ORP reconstruction. The relative loss in gain, Lmsh, is defined as the ratio of Pv with reconstructed MSH ORP to intact incus and compared with Lmfp. A retrospective clinical audit of the pre- and postoperative audiologic results of patients who had undergone ossiculoplasty with either MSH or MFP ORP was conducted for comparison. RESULTS: For the 0.5 to 3 kHz frequency range, Lmsh magnitude is 6.2 dB lower than the Lmfp magnitude (p = 0.05). The retrospective audit of audiologic results after ossiculoplasty with either MSH or MFP ORP revealed a similar difference in gain between the two ORP designs with air-bone gap differences of 7.6 dB (p = 0.04) and air conduction threshold differences of 8.0 dB (p = 0.13) for these patients. CONCLUSION: The MFP ORP showed better average pressure gain compared with the MSH ORP across the speech frequencies. Surgeons performing ossiculoplasty with designs similar to Project HEAR HA ORPs, where there is direct columella-like connection between the malleus and stapes, should consider using the MFP ORP design to achieve a better postoperative audiologic result, even when the stapes superstructure is intact.

Aged↗

A new prosthesis for reconstructing the incudostapedial joint.

OBJECTIVE: This study aimed to evaluate the hearing results obtained using the Silverstein Incus-Stapes Connection in ossicular reconstruction among patients with chronic ear disease. STUDY DESIGN: The study was performed as a retrospective review. A control group consisted of patients undergoing similar surgery but in which no prosthesis was used. SETTING: The Florida Ear and Sinus Center outpatient offices of the senior author. PATIENTS: Forty-seven patients with a mean age of 48 years comprised the treatment group. Thirty-eight patients (mean age, 49.4 years) acted as control subjects. INTERVENTION: All patients underwent surgery for chronic ear disease. Reconstruction surgery for patients requiring separation of the incudostapedial was performed with a Silverstein Incus-Stapes Connection or by reapproximating the joint capsule to allow primary healing. MAIN OUTCOME MEASURE: The patients were categorized according to how the prosthesis was used. Results comparing the preoperative air-bone gap and postoperative air-bone gap were evaluated. The change in air-bone gap was reported according to the guidelines set forth by the Committee on Hearing and Equilibrium. RESULTS: The mean postoperative air-bone gap for reconstruction with the prosthesis was 17.6 dB compared to a mean of 11.8 dB among control subjects. An air-bone gap of 16.5 dB was achieved when the prosthesis was used to bridge an area of lenticular resorption. When a composite prosthesis, made by adding cartilage to the disk, was used to bridge larger defects, an air-bone gap of 14.3 dB was seen. Finally, when the prosthesis was used as a partial ossicular replacement prosthesis and directly contacted the tympanic membrane, the air-bone gap was 9 dB. The prosthesis was found to be stable when re-exploration was required and modification of the prosthesis with cartilage was accomplished easily intraoperatively. CONCLUSION: The Silverstein Incus-Stapes Connection is a middle ear prosthesis that can provide a mechanism for overcoming incus resorption in selected cases. In addition, the prosthesis can be modified easily with the addition of cartilage when needed.

Adolescent↗

A more reliable method for incudostapedial rebridging ossiculoplasty: bone cement and wire.

Polymaleinate glass ionomer cement is a commercially available bone cement (Ketac Cem Radiopaque, ESPE, Germany) that can be used to reconstruct a discontinuity between the incus and the stapes. The popularity of bone cement in otologic surgery is increasing. If the missing part of the incus is too long, the results in the long term could be unsatisfying. Under such circumstances, a new method of incudostapediopexy that uses wire and involves remodeling of the long process of the incus with bone cement is introduced. A retrospective analysis of the outcomes of incudostapedial rebridging ossiculoplasty (ISRO) procedures carried out in 21 patients between June 1999 and September 2003 was performed. A total of 17 patients were treated with bone cement only; in 4 of these patients, hearing loss reoccurred within 6 months. The procedure was repeated in 2 of these patients using both bone cement and wire with satisfactory hearing results (air-bone gaps, 7.5 and 8.8 decibels hearing level [dB HL]) after 1 year. Four patients underwent ISRO wire and bone cement initially. The long-term results of these 6 "wire-and-cement" cases, which were followed for a mean of 21 months, were satisfactory (air-bone gap, 9.8 dB HL). The postoperative air-bone gap in the 15 patients who were treated by ISRO with bone cement only excluding the 2 reoperation cases was 12.1 dB HL. ISRO with bone cement is a cost-effective and safe procedure that yields good hearing results in selected cases. If the distance between eroded incus and stapes is too long to be reconstructed with bone cement alone, the surgeon should consider using wire with bone cement.

Adolescent↗

[Ionomer cement prostheses in reconstructive middle ear surgery].

Animal experiments with microbiologic examinations and studies in cell cultures have shown that ionomer cement is a biocompatible and biostable bone replacement material in the head and neck region. Clinical and functional results of its use in the human middle ear have proven to be satisfactory during a maximal period of 2.5 years observation. The present trial was continued in order to determine the long-term behavior of ionomer cement (Ionos partial and total ossicles) after reconstruction of the ossicular chain. The ossicular chain was reconstructed in 343 cases and included various losses of one or more of the ossicles (i.e., incus, incus and malleus, incus and stapes superstructure, and malleus, incus and stapes superstructure). Follow-up extended over a maximum period of 5.5 years. Patients were examined under a surgical microscope and a pure-tone audiogram was performed at regular intervals. Clinical and audiological results were obtained 3 months postoperatively in all reconstructive procedures performed (partial and total ossicular replacement prostheses). These were mainly stable but revision surgery was necessary in 9% of the cases. In 5% the prosthesis was displaced and in 3% the prosthesis had partially migrated through the eardrum. Complete rejection of the implants was observed in the course of infections in 1% of the cases. Ionomer cement as a bone replacement material was found to have all required criteria for its use in the middle ear (biocompatibility, biostability, stable audiologic results and easy workability). These findings show that ionomer cement can be recommended in all cases of ossicular reconstruction.

Adolescent↗

Use of Mimix hydroxyapatite bone cement for difficult ossicular reconstruction.

OBJECTIVE: To describe the advantages of using Mimix hydroxyapatite (HA) bone cement in reconstructing a variety of ossicular chain abnormalities. STUDY DESIGN AND SETTING: Case series at a tertiary medical center. RESULTS: Twenty-five cases of HA reconstruction are included in this series (ages 23-74; mean, 47 years). The examples presented include (1) HA as the sole reconstructive material for incus erosion, (2) HA for securing a total or partial ossicular replacement prosthesis, (3) incus augmentation after crimping for revision stapedotomy with incus erosion, (4) HA in primary stapedotomy to fix the crimped prosthesis to an intact incus, and (5) other unique situations. Preoperative and postoperative audiograms were evaluated for 4-tone pure tone average (PTA), speech reception thresholds, word recognition scores, and air-bone gaps (AB gaps). Mean follow-up was 11 months (range 2 to 22 months). The mean PTA improved from 57 dB to 37 dB, whereas the mean AB gaps decreased from 33 dB to 16 dB. There were no cases of infection or extrusion. CONCLUSIONS: Hydroxyapatite bone cement is an excellent adjunct or alternative to ossiculoplasty with preformed prostheses. Easily malleable, rapidly setting, and rapidly hardening, Mimix is particularly well suited for middle ear work. SIGNIFICANCE: Definitive fixation with bone cements during difficult ossicular chain reconstruction may ensure a more enduring successful outcome.

Adult↗

A new crimping device for stapedectomy prostheses.

OBJECTIVE: To describe a newly designed microforceps for easy and stable crimping of a prosthesis loop to the incus' long process in stapes surgery RESULTS: We developed a crimping tool with two innovative improvements. First, the tip of the crimping device is arcuated and thus able to span the loop of the prosthesis entirely around the incus long process. Second, a retaining spring is implemented into the handle. This passive opening mechanism of the crimper avoids the switch from flexor to extensor muscle group movements in the forearm of the surgeon while switching from crimping to unclosing the forceps. This maneuver, which is considered the most delicate in ear surgery, can be performed by variations of the flexor muscle group tonus only. CONCLUSION: The new crimping tool has proved to be reliable in firm attachment of the prosthesis' loop to the incus long process. Furthermore, because of the passive open-up mechanism movements of the surgeon's hand, wriggling excursions of the tip of the forceps are minimized and the risk of incus luxation is reduced.

Humans↗

CT appearances of ossicular injuries.

Trauma of the ossicular chain is a frequent complication of temporal bone injury. Skull trauma from blows to the temporal, parietal, or occipital region (with or without fracture of the temporal bone) is the main cause of ossicular injury; other modes of injury are rare. Ossicular injury usually occurs as a dislocation, of which there are five types: incudostapedial joint separation, incudomalleolar joint separation, dislocation of the incus, dislocation of the malleoincudal complex, and stapediovestibular dislocation. Fracture of the malleus, incus, or stapes is uncommon. High-resolution computed tomography is the method of choice for evaluation of ossicular trauma. Joint separation and fracture of the stapes are seen on axial images; coronal images may aid visualization. Both axial and coronal images are needed for evaluation of a dislocated malleus or incus. Fracture of the malleus or incus is detected with axial or coronal images; reformatted images may also be useful.

Adolescent↗

Bapx1 regulates patterning in the middle ear: altered regulatory role in the transition from the proximal jaw during vertebrate evolution.

The middle ear apparatus is composed of three endochondrial ossicles (the stapes, incus and malleus) and two membranous bones, the tympanic ring and the gonium, which act as structural components to anchor the ossicles to the skull. Except for the stapes, these skeletal elements are unique to mammals and are derived from the first and second branchial arches. We show that, in combination with goosecoid (Gsc), the Bapx1 gene defines the structural components of the murine middle ear. During embryogenesis, Bapx1 is expressed in a discrete domain within the mandibular component of the first branchial arch and later in the primordia of middle ear-associated bones, the gonium and tympanic ring. Consistent with the expression pattern of Bapx1, mouse embryos deficient for Bapx1 lack a gonium and display hypoplasia of the anterior end of the tympanic ring. At E10.5, expression of Bapx1 partially overlaps that of Gsc and although Gsc is required for development of the entire tympanic ring, the role of Bapx1 is restricted to the specification of the gonium and the anterior tympanic ring. Thus, simple overlapping expression of these two genes appears to account for the patterning of the elements that compose the structural components of the middle ear and suggests that they act in concert. In addition, Bapx1 is expressed both within and surrounding the incus and the malleus. Examination of the malleus shows that the width, but not the length, of this ossicle is decreased in the mutant mice. In non-mammalian jawed vertebrates, the bones homologous to the mammalian middle ear ossicles compose the proximal jaw bones that form the jaw articulation (primary jaw joint). In fish, Bapx1 is responsible for the formation of the joint between the quadrate and articular (homologues of the malleus and incus, respectively) enabling an evolutionary comparison of the role of a regulatory gene in the transition of the proximal jawbones to middle ear ossicles. Contrary to expectations, murine Bapx1 does not affect the articulation of the malleus and incus. We show that this change in role of Bapx1 following the transition to the mammalian ossicle configuration is not due to a change in expression pattern but results from an inability to regulate Gdf5 and Gdf6, two genes predicted to be essential in joint formation.

Animals↗

[Congenital auditory ossicle malformation without external ear abnormality].

In 29 ears of 24 patients with auditory ossicle malformation, but without external ear abnormalities, who were operated on at our clinic in the 10 years between June 1993 and June 2002, we studied the condition of ossicles, preoperative examination, surgical procedures, and postoperative hearing improvement. Our study did not include patients with cholesteatoma or those with only fixed stapes but without ossicular deformity. Samples were 12 ears of 11 men and 17 ears of 13 women. We clinically distinguished 3 major categories: (i) discontinuity between the incus and stapes with mobile stapes, (ii) congenital fixation of the stapes with ossicular deformity, and (iii) congenital fixation of the malleus and deformity of the incus with mobile stapes. We classified each category into minor abnormalities based on the condition of the long process of the incus, the superstructure of the stapes, and the stapes footplate. We conducted auditory ossicle reconstruction by mobilization of the malleus and incus in 2 ears, by type III tympanoplasty in 5 ears, by type IV tympanoplasty in 13 ears, and by stapes surgery in 8 ears. Improvement in hearing after the operation was observed in 25 of the 29 ears treated. In the classification of the auditory ossicle malformation without external ear abnormalities, we should evaluate discontinuity or fixation of the ossicles and their deformity. This requires that varied ossicular reconstruction be prepared for surgery, but the possibility of hearing improvement is high, so intensive treatment is needed in many cases of auditory ossicle malformation.

Adolescent↗

A new adhesive bonding material for the cementation of implantable devices in otologic surgery.

BACKGROUND: Presently, there are no U.S. Food and Drug Administration (FDA)-approved adhesive bone cements for the surgical fixation of prosthetic materials in the middle ear. A promising new cement, 4-META/MMA-TBB opaque resin, has shown remarkable adhesive properties as a bone cement in vivo. The cement is composed of 4-methacryloyloxyethyl trimellitate anhydride (4-META) and methyl methacrylate (MMA) as monomers and tri-n-butyl borane (TBB) as an initiator. METHODS: An electromagnetic semiimplantable hearing device presently under development was implanted into the middle ear of six cats using 4-META/MMA-TBB resin to cement a titanium-encased magnet to the incus. The animals were subsequently killed (at a mean of 9.6 months) to assess the (temporal bones and specifically the magnet-incus complex in each animal. RESULTS: The titanium-encapsulated magnet was firmly adherent to all incuses without any failure of the cement-bone interface. Histopathologic examination of the implanted temporal bones demonstrated lack of middle ear inflammation. Transmission electron microscopy of the incuses demonstrated a unique "hybrid layer" in the bone-side subsurface of the bone-cement interface that elucidates the mechanism of interfacial adhesion. CONCLUSIONS: Our investigation highlights the special biomechanical properties as well as the biocompatibility of 4-META/ MMA-TBB resin that make it an attractive bone-bonding agent for use in otologic surgery, including its potential usefulness during ossicular reconstruction.

Animals↗

'Tripod' ossiculoplasty in incudal lesions.

A method of ossiculoplasty, in cases where the long process of the incus is eroded, is described. The defect created by the erosion of the incus is bridged by an autogenic or allogenic bone graft that leans on the stapes, the remaining part of the incus, and the side of the malleus. These three contact points allow for stability of the bony graft and account for the name tripod. The method was applied in 30 ears and was successful in all but three cases. All the rest (ie, 27 ears) achieved an average gain of 24.8 dB, leaving an average air-bone gap of 11.1 dB. The postoperative air-bone gap was 20 dB or less in all 27 ears that were successfully operated on; and in 21 of them (77.8%), it was no more than 10 dB. The average period of follow-up was 23.8 months. Operative success depended on both the technique chosen and the favorable selection of cases.

Bone Conduction↗

Laser assisted fixation of ear prostheses after stapedectomy.

Three different lasers (erbium:YAG, holmium:YAG, alexandrite) were used to drill a hole at the end of the long process of the incus in order to fix an ear prosthesis after stapedectomy or small fenestra stapedectomy. The energy was coupled into a 250-microns core diameter zirconium-fluoride fiber. The operations were carried out on human temporal bone models from cadavers. The fiber was guided to the incus under the stereoscopic surgical microscope. The tissue response was examined under the scanning electron microscope, and after decalcification, histologically. These studies suggest the feasibility of using the erbium:YAG laser to improve the anchorage of the prosthesis on the incus and to increase the stability in ossicular chain reconstruction.

Cochlear Implants↗

Tympanoplasty in partial defects of the stapedial arch.

A defective stapedial arch was found among 690 operated patients in 46 ears (6-7 per cent). Most often it was the stapedial head or anterior limb which was absent. The problems and results of ossiculoplasty on a defective stapes are analyzed. Classical interposition of the incudal body on top of a defective stapes did not afford satisfactory results, as the incus had to be placed asymmetrically on top of the stapedial remnant, with a risk of fixation and tilting of the graft. Better results were obtained by interposition of the short process of the incus on the footplate in a way which gives the incus contact also with the remaining parts of the stapedial arch. If the neck and head of the stapes are absent, it is suggested that the ossicles be shaped in relation to the defect in such a way that contact between the stapedial remnant and the malleus will be stable and the risk of secondary fixation minimal. If there are partial defects of the stapedial limbs the columella should be in contact with the footplate as well as with the remaining parts of the limbs.

Ear Ossicles↗

Acoustic effect of malleus head removal and tensor tympani muscle section on middle ear reconstruction.

In the reconstruction of ears with a missing incus, an incus replacement prosthesis (IRP) is commonly used to connect malleus and stapes. In some cases, it is necessary to resect the malleus head and/or section the tensor tympani muscle (TTM) tendon. The acoustic effects of these maneuvers have not been well studied. We performed experiments in a temporal bone model to measure the effect of these maneuvers on middle ear sound transmission. Measurements of umbo and stapes displacement were made before and after malleus head removal and TTM section plus incus replacement with an IRP. After malleus head removal, there was a peak gain in stapes displacement of 6 dB below 0.5 kHz and 8 dB above 2.5 kHz. TTM section had a similar but lesser effect. A clinical example is described.

Acoustic Stimulation↗

A new approach for malleus/incus fixation: no prosthesis necessary.

OBJECTIVE: To describe a novel approach to manage malleus/incus fixation. STUDY DESIGN: Retrospective review of 363 patients with conductive hearing loss operated on since 1996. SETTING: Academic tertiary referral center. PATIENTS: Three hundred sixty-three patients with conductive hearing loss, an intact tympanic membrane, and without history for chronic infection underwent middle ear exploration. Three hundred forty-three had otosclerosis and underwent laser stapedotomy; the remaining 20 patients had laser release of their malleus/incus fixation. INTERVENTION: Twenty patients are presented in this paper. Nineteen patients were diagnosed with malleus fixation before surgery. One patient had a total perforation and mobility of the ossicular chain was not verified preoperatively. This patient was, intraoperatively, noted to have complete ossicular fixation. Conductive hearing loss was identified using audiometry and tuning forks. Nineteen of the 20 patients had the diagnosis confirmed using micropneumotoscopy and noting immobility of the malleus. A transcanal approach was used, and the malleus/incus fixation was released using a laser. This space was expanded upon using a drill. A 1.5-2.0 mm space was created where the ossicular fixation existed, thereby reducing the likelihood of refixation. MAIN OUTCOME MEASURE: Audiometric studies before and after intervention were compared. One to seven years of follow up are provided. RESULTS: Preoperative air-bone gaps ranged from 18 dB to 51 dB and averaged 33 dB. Postoperative air-bone gaps ranged from 1-36 dB and averaged 13 dB. No patients have experienced refixation. There were two complications: one perforation requiring a tympanoplasty and one patient sustaining a 20 dB high-frequency sensorineural loss, most likely secondary to inadvertent drill contact to the ossicular chain. CONCLUSION: When fixation of the malleus and/or incus is found, treatment options exist. A common technique involves removal of the incus and head of the malleus and reconstruction with an incus interposition or a partial ossicular prosthesis. Another technique proposed by the senior author (M.D.S.) is maintenance of the normal anatomy and use of the potassium-titanyl-phosphate laser and drill to free the ossicles and widen the epitympanum. This series shows successful closure of the air-bone gap with this technique.

Adolescent↗