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The mobility of the malleus and incus with varying middle ear pressures.

The mobility of the malleus and incus was studied in two fresh human temporal bones. Various pressure gradients were applied across the intact tympanic membrane and the movement of the ossicles examined, firstly with the incus in situ and secondly, with the incus removed. The displacement of the long process of the incus was less than 100 microns at the extremes of pressure gradient. However, this mobility increased by over twofold when the posterior incudal ligament was divided. With removal of the incus, the mobility of the umbo with pressure changes was further increased and can be as much as half a millimetre. In all cases the maximal rate of ossicular excursion was noted with pressure gradients of less than 100 daPa (mmH2O) across the tympanic membrane.

Ear Ossicles↗

Incus window in transposition.

In aiding the positioning of the incus in incus transposition, a hole, the incus window, is drilled completely through the body of the incus. Through the window the surgeon has a visual as well as a tactile reference to the head of the stapes. At one year results show that 182 of 201 patients closed the air-bone gap to within 20 dB of the preoperative bone level.

Bone Transplantation↗

Computed tomography of the disarticulated incus.

Complete incus disarticulation may be a complication of trauma, chronic otitis, or prosthetic stapedectomy. Purposeful incus disarticulation (with incus interposition) is used as a method of ossicular reconstruction. CT has been a valuable diagnostic tool for preoperative location of the incus in the former disorders and for determination of the status of the ossiculoplasty in the latter.

Ear Ossicles↗

Considerations of isolated destruction of the short process of the incus in a case of cholesteatoma.

Cholesteatoma occurs frequently with the destruction of the ossicles. The most commonly eroded ossicle has been reported to be the incus. Many studies report destruction of the long process and body of the incus. However, isolated erosion of the short process of the incus is an unusual finding. We present such a case with a slight conductive hearing loss that remained unchanged at 2 1/2 years postoperatively. The short process of the incus may contribute to hearing up to 10-15 dB. It is also possible that it plays a role in epitympanic aeration by supplying an attachment surface to the incudal folds.

Adult↗

Incus and stapes necrosis associated with diabetes mellitus.

Chronic otitis media is often associated with ossicular defects, the most frequent being necrosis of the long process of incus. Except for infection and cholesteatoma; trauma and local pressure by chorda tympani are uncommon causes leading to incus erosion. In the literature, no case of incus necrosis has been reported associated with type II diabetes mellitus (DM). A patient is presented in this report with incus and stapes suprastructure necrosis and associated type II DM who was admitted to the out-patient clinic with complaints of conductive hearing loss.

Adult↗

Congenital absence of the long process of the incus.

OBJECTIVE/HYPOTHESIS: To review the case reports of three generations of one family, suffering from bilateral conductive hearing loss due to congenital absence of the long process of the incus. STUDY DESIGN: Review of the literature regarding hereditary congenital absence of the long process of the incus to determine its mode of inheritance such as autosomal dominant or X-linked. Also document the types and results of surgical repairs performed by previous investigators of this defect and compare them with the present study. METHODS: Three female patients of direct lineage. Mother, daughter, and granddaughter, who were personally seen, operated on, and followed up over a period of 26 years. RESULTS: All three female patients presented with similar symptoms and findings of hearing impairment since birth, with no history of ear infections, and with normal appearing tympanic membranes. However, they had severe conductive hearing loss with normal bone conduction and discrimination. Operative findings were identical in all three patients, with the incus ending in a blind stub, and with absence of the capitulum of the stapes. The type of ossicular reconstruction varied with the changing of times and advances in otologic surgery, as well as the prosthetic materials used. All three patients received improvement in their hearing, and this improvement has been maintained over the 26-year span of the study. CONCLUSIONS: Hearing loss due to congenital absence of the incus is uncommon but not rare. Interestingly, no other instance of inherited cases were reported in the literature. In this family the defect appears to be an inherited trait either due to an autosomal dominant mutation or an X-linked dominant inheritance. This abnormality is amendable to surgery, and any well-executed technique usually gives good hearing results.

Adult↗

Bone cement ossiculoplasty: incus to stapes versus malleus to stapes cement bridge.

OBJECTIVE: In this study, our purpose was to evaluate results of our experience with bone cement repair of ossicular discontinuity between the incus and stapes and between the malleus and stapes. METHODS: Medical records of patients who underwent surgery for chronic otitis media between March 2000 and December 2002 were evaluated retrospectively. Fifty-seven patients who underwent bone cement ossiculoplasty and had appropriate follow-up data were included in the study. Bone cement reconstruction of the ossicular chain was performed 1) from incus to stapes (I-S) in the absence of long arm or lenticular process of the incus and 2) from malleus to stapes (M-S) in the absence of the incus. The clinical data of the patients were evaluated by otoscopic examination and audiometry. RESULTS: The graft take rate was 84.1%. I-S procedure was performed in 42 and M-S in 8 patients. Pre- and postoperative PTAs of all patients were compared, which showed a significant improvement in air PTA (p < 0.001) while bone PTA did not change (p > 0.05). In I-S and M-S groups, successful hearing restoration could be achieved in 78.6.1% and 87.5% of the patients, respectively. Hearing results of different aural pathologies (chronic otitis media and conductive hearing loss) and surgeries (tympanotomy and tympanoplasty with or without mastoidectomy) were not significantly different (p > 0.05). CONCLUSION: Bone cement ossiculoplasty offers cost effective and significant improvement in conductive hearing loss.

Adult↗

Ossiculoplasty using incus interposition: hearing results and analysis of the middle ear risk index.

OBJECTIVE: To determine the immediate hearing result and the long-term stability of sculpted incus interposition in ossiculoplasty and evaluate the utility of the middle ear risk index in predicting hearing outcome in these cases. PATIENTS: One hundred thirty-seven surgical patients. STUDY DESIGN: Review of 137 patients who underwent ossiculoplasty using autologous or homologous sculpted incus interposition. INTERVENTIONS: Ossiculoplasty using autologous or homologous sculpted incus interposition. METHODS: Retrospective chart review, using the guidelines delineated by the Committee on Hearing and Equilibrium of the Academy of Otolaryngology-Head and Neck Surgery for the evaluation of results for the treatment of conductive hearing loss. RESULTS: The mean preoperative air bone gap was 26.8 dB, and the mean postoperative gap was 18.6 dB. Twenty-seven percent of patients were closed to within 10 dB, and 66.4% were brought to within 20 dB of the postoperative bone conduction line. Average time to the last postoperative audiometric testing was 15.8 months, with a range of 2 to 62 months. A mean air bone gap change of -0.2 dB was noted. Four patients had more than a 10 dB deterioration in conductive hearing loss. There were no cases of graft extrusion. Each ear operated upon in our series was fully scored using the middle ear risk index, and an index total was calculated. No statistical associations could be demonstrated in any group between the postoperative air bone gap and the middle ear risk index subcategories or total. CONCLUSIONS: Sculpted autologous or homologous incus interposition provides hearing success comparable with current allograft prosthesis studies, has a very low extrusion rate, and remains stable over time. We were not able to demonstrate an association between the middle ear risk index and hearing results in this subset of patients.

Adolescent↗

The histopathology of the incus after stapedectomy.

Twenty-two temporal bones subjected to stapedectomy were examined by light microscopy for histological changes in the long process of the incus. In 19 cases a stainless steel wire technique had been used and in three a polyethylene tube operation had been performed. Twenty healthy unoperated ears were examined as controls. In all operated ears fibrosis and reduced vascularity of the mucosa was noted. In the polyethylene tube group, 1 ear showed the growth of new bone into the lumen of the tube and 1 showed minor resorption of the long process of the incus. In the stainless steel wire group bone resorption of the long process of the incus. In the stainless steel wire group bone resporption was seen in 5 cases and 1 incus also showed an area of necrosis adjacent to the tip; 2 of the 5 incudes showed some loss of the lenticular process. The main factor relating to bony resorption in this group was the presence of other histological changes resulting from postoperative inflammation. These findings represent a critical histological examination; the hearing results obtained appear to be good, although full audiometry is lacking.

Adult↗

Virtual image of the incus from a saline lens: an aid to safe dissection of the mastoid antrum.

Dissection of the antrum requires judicious visualization of the tegmen, horizontal canal, incus, and facial nerve. Inadvertent contact with the incus by the power drill may cause significant acoustic trauma. An effective "early warning device" accurately predicting exposure of the incus may be constructed with the saline irrigation fluid. The formation of the meniscus at the antrum permits visualization of the image of the incus around the corner of the bony canal wall overhang. A thin-lens model of this phenomenon has been created for first-order analysis of the optics, and it provides useful criteria for using this image. Image minification, displacement, and distortion were analyzed. A more complex model was then created to assess the impact of changing meniscus shape. The latter helped in understanding an added "swinging-door effect" noted as the meniscus was altered. The model predicted accurately the phenomena as observed in the temporal bone preparation. Illustrative examples of the optics and photographic demonstrations of the phenomena are presented.

Dissection↗

Bone tissue kinetics in the surgically disarticulated dog incus.

The incus of the right ear from 4 growing mongrel dogs was surgically disarticulated and left in the middle ear space. The external auditory canal was then filled with teflon paste and sutured. After 6 weeks (D-6 group) and 13 weeks (D-13 group) the animals were sacrificed. The right experimental incus and the left control one were embedded in methyl methacrylate and sectioned in single 50-microns-thick sections according to the principal axis of the two processes. On the microradiographs of each section we evaluated the thickness of the body and of both processes and the percentage area of the primary channels of the secondary osteons and that of the appositional bone tissue. The thickness of the body and of the two processes was more pronounced in all the experimental incuses, in which 6% (in D-6) and 8% (in D-13) of the total area were occupied by new appositional woven bone. In the body of the D-13 group, 9% of the pre-existing bone was substituted by secondary osteons. The results indicate that the incus react to the variations of mechanical stimuli.

Animals↗

Incus interposition and ossiculoplasty with hydroxyapatite prostheses.

This article traces the evolution of transplant material in ossicular reconstruction of the middle ear. The first transplant consisted of the body and short process of the homograft incus. It was repositioned or wedged between the stapes head and the manubrium of the malleus. Further modification consisted of the sculpture of prostheses from homograft incudes; these were known as the notched incus with short or long process. By means of a notch in the short process, they were locked in place. The final phase is the use of hydroxyapatite as a biocompatible material from which similar prostheses may be precisely manufactured. These hydroxyapatite prostheses, known as the incus and incus-stapes replacement prosthesis, appear to be well tolerated and to produce excellent hearing results.

Biocompatible Materials↗

Physiologic reestablishment of ossicular continuity during excision of retraction pockets: use of hydroxyapatite bone cement for rebridging the incus.

OBJECTIVE: To analyze the results obtained from hydroxyapatite bone cement repair of ossicular discontinuity between the incus and stapes during surgery of retraction pockets. DESIGN: Clinical study of a case series. SETTING: Otolaryngology Department, Tanta University Hospitals, Tanta, Egypt. PATIENTS: A total of 62 previously untreated patients (82 ears) with retraction pockets. INTERVENTIONS: Hydroxyapatite bone cement was used to repair defects at the incudostapedial connection in 82 ears with retraction pockets. The ears were divided into 2 groups: group 1 included 48 ears with a small defect in the long process of the incus; group 2 included 34 ears with a large defect in the long process of the incus. In addition, 20 control patients underwent surgery using plastipore partial ossicular replacement prostheses. Hearing results were reported in 4 frequencies (0.5, 1, 2, and 3 kHz). Analysis of the results was performed using the paired t test with significance level at .05. MAIN OUTCOME MEASURES: Anatomic and audiologic results. RESULTS: Significant postoperative improvement of pure-tone air conduction threshold averages and air-bone gap averages were reported in the 3 studied groups. The postoperative air-bone gap averages showed significantly better outcome in groups 1 and 2 compared with controls (P<.001), while there was no statistically significant difference between groups 1 and 2 (P>.05). CONCLUSIONS: Bone cement ossiculoplasty offers cost-effective and significant improvement in conductive hearing loss. It provides an excellent alternative to ossiculoplasty with preformed prostheses. We believe the indications for bone cement were validated by these results.

Adult↗

Allograft stapes-incus assembly. A new ossiculoplasty.

In 45 patients with absence of the stapedial arch, including 24 with a history of radical surgery and without ossicles, the head of an allograft stapes was placed on the patient's footplate and on top of this an incus body, either as allograft or autograft. The results of this assembly, judging by different methods of analysis, are the same as in 45 ears having approximately the same pathologic condition treated by an autograft or allograft incus as the columella between the footplate and eardrum. The allograft stapes-incus assembly is an alternative method to the commonly used incudal columella, particularly in patients previously subjected to radical surgery in whom all ossicles are absent.

Ear Ossicles↗

Allograft stapes-incus assembly. Long-term results.

In 35 patients with absence of the stapedial arch, with a history of radical surgery, and without ossicles, the head of an allograft stapes was placed on the patients' footplates and an allograft incus body on the top of this. The long-term results of this assembly, judging by different methods of analysis, are still somewhat better than those of 98 ears with approximately the same pathologic condition treated by an allograft incus as the columella between the footplate and fascia. The allograft stapes-incus assembly is an alternative method to the commonly used incudal columella. The allograft stapes has not been resorbed to a significant degree during the years after surgery.

Ear Ossicles↗

Acquired atrophy of the long process of the incus.

Various lesions can cause conductive hearing loss in a patient with a normal tympanic membrane. These include congenital ossicular anomaly, otosclerosis, and congenital or acquired ossicular fixation and discontinuity. We had an experience with a patient who presented with a conductive hearing loss in both ears, in which small pieces of the long process of the incus were absent and had been replaced with fibrous tissues in both ears. No other abnormalities, such as postinflammatory changes or fixation of the ossicles, were found. Because the long process of the incus undergoes remodeling through resorption and rebuilding throughout life, failure of the remodeling or impaired vascular supply to the long process of the incus may have been the cause of the conductive hearing loss in this patient.

Atrophy↗

An anatomically shaped incus prosthesis for reconstruction of the ossicular chain.

An anatomically shaped incus replica prosthesis has been designed to reconstruct the ossicular chain. A series of in vitro studies on human temporal bones evaluated the acoustic performance of this prosthesis and compared it with a Causse partial ossicular replacement prosthesis (PORP). Pure tones in the frequency range 0. 125-8 kHz stimulated the tympanic membrane at sound pressure levels of 80, 90 and 100 dB. Measurements of the stapes footplate velocity were made with a laser interferometer. The acoustic function of the ossicular chain reconstructed with the incus replica prosthesis was found to be within 10 dB of that of the original intact ossicular chain, when both the upper and lower joints of the implant were rigidly fixed in place. It was shown that a rigid mechanical contact between the ossicular prosthesis and ossicles is a prerequisite for effective sound transmission. The anatomically shaped incus prosthesis gave a 15-dB improvement on the PORP at frequencies below 1.5 kHz.

Acoustic Stimulation↗

Silastic coated incus in tympanoplasty: a preliminary report.

In 54 ears lacking the stapedial arch and the long process of the incus, ossiculoplasty was performed with a shaped auto- or homologous incus as columella. In 29 of the ears, the deep, slender part of the columella was coated with a silastic tube in order to prevent adhesions and dislocation. One year after the operation the functional results were similar in patients with silastic coating of the incus to those without. It is concluded that the less satisfactory results of tympanoplasty in such ears are primarily caused by factors outside the niche of the oval window. Possible ways of improving the results are discussed.

Adolescent↗