Incudomalleolar Joint Research Articles

The atretic plate – a conduit for drill vibration to the inner ear?

Conclusion: In the presence of simulated congenital aural atresia with fixation of the ossicular chain to the surrounding bone, access to the chain for placement of a middle ear prosthesis using the rotating burr is not associated with significant stapes movement that would cause vibrational trauma to the cochlea. Objectives: To determine the energy transmitted to the cochlea while drilling the mastoid in an ear with simulated congenital aural atresia and fixation of the ossicular chain to the surrounding bone. Methods: Eight human cadaveric temporal bones were used. Cement was placed in the external auditory canal and on the incudomalleolar joint and surrounding epitympanum, to simulate congenital aural atresia and ossicular fixation, respectively. Stapes vibration was measured with the Laser Doppler Vibrometer using acoustic then drill stimulation by touching the wall of the epitympanum with a running burr. Results: Using acoustic stimulation, all bones showed frequency-specific reduction of stapes motion of up to 17 dB with fixation of the ossicular chain to the surrounding bone. There was no measurable stapes motion when the external auditory canal was filled with cement. On drill stimulation, there was no difference in stapes velocity between the normal bone and the bone with simulated congenital aural atresia.

Experimental Study on Admissible Forces at the Incudomalleolar Joint

The forces that cause rupture of the incudomalleolar joint during the fixation of stapedial prostheses can be determined by means of load-deflection measurements at the long process of the incus. As in other tissues, 3 ranges of forces can be defined: micro rupture, rupture, and short-term maximum. A crucial step in stapes surgery is the attachment of the stapedial prosthesis to the long process of the incus. It is unknown which forces occur during the crimping process that increase the risk of damage to the incudomalleolar joint or incus luxation. The goal of this study was to assess the admissible range of forces at the long process of the incus that would be tolerable before damaging the structures and to compare them with the forces occurring during surgery. Load-deflection curves in the lateral-medial and anterior-posterior direction were measured in 9 freshly frozen or fresh temporal bones. The force was measured with a load cell, and displacement was taken from the encoder information of the electrically driven translation stage on which the load cell was mounted. The long process of the incus was coupled to the load cell via a customized needle. We also monitored with video recordings for visual confirmation of findings. The rupture force at which the middle ear was found to be severely injured was 894 (724-1018) mN in the anterior-posterior direction and 695 (574-771) mN in the lateral-medial direction. Micro-ruptures occurred at forces around 568 (469-686) mN in the anterior-posterior direction and in the lateral-medial direction at 406 (254-514) mN. Short-term maximum forces of 1,321 (1,051-1,533) mN were measured in the anterior-posterior direction and 939 (726-1,132) mN in the lateral-medial direction. Rupture forces of the incudomalleolar joint could be defined with high accuracy. These results were used to calculate risks of incus luxation or subluxation during stapes surgery. Compared with the use of clip and SMA prostheses, the risk of damage from a crimping procedure is significantly higher.

Synovial Chondromatosis of the Middle Ear: A Case Report

Synovial chondromatosis is a rare pathology of unknown etiology characterized by multinodular cartilaginous proliferation in the synovium. When it does occur, it usually develops in the large synovial joints (e.g., the knee, hip, elbow, and shoulder). Only rarely does it occur in the head and neck (most often in the temporomandibular joint). We report a case of synovial chondromatosis of the middle ear (i.e., the incudomalleolar joint) in a 64-year-old woman, and we describe the clinical, radiologic, and intraoperative findings in this case. To the best of our knowledge, this is the first reported case of synovial chondromatosis in the middle ear.

Malleostapedotomy in tympanosclerosis patients

To present our personal experience of a series of 10 patients suffering from tympanosclerosis with functional blocking of the stapes or footplate, who underwent malleostapedotomy surgery. The criteria for patient selection for this type of operation, and its results and complications, are discussed. Prospective study. Incus and malleus dysfunction was observed in 70 per cent of cases, either alone or combined with fixation of the stapes. The post-operative hearing results were considered to be satisfactory (i.e. within 20 dB) in 80 per cent of cases. Only one patient had sensorineural hearing loss over 10 dB. Malleostapedotomy has proved its practicability in the treatment of patients with fixed footplate or stapes complicated by ankylosis of the incudomalleolar joint. This procedure can be considered a further, valid technique within the otologist's surgical armamentarium.

Preoperative evaluation of the congenital aural atresia on computed tomography; an analysis of the severity of the deformity of the middle ear and mastoid

Objective To compare the development of temporal bone in normal and atretic ears and to assess some radiological landmarks that could be important in the hearing restoration interventions in such patients. Material and methods Thirty-five patients with 40 atretic external ears were evaluated with temporal bone CT and compared to a control group of 40 normal ears retrospectively. Using comparable slice levels in all patients, the course and the caliper of the facial canal, the surface area of the incus and malleus, the level of mastoid aeration, the location and anteroposterior diameters of the jugular bulb and sigmoid sinus, the direction and the caliber of the tympanic bony part of the Eustachian tube, area of the middle ear cavity, distance from facial nerve to incudomalleolar joint, to the vestibule and to the jugular bulb were included in the assessment. Non-parametric and parametric statistical tests were used for comparison. Results In atretic ears middle ear sectional area was found to be smaller at the equivalent plane as compared to control subjects (mean area index: 19.3 mm 2 versus 47.4 mm 2). Mastoid aeration was low in general and the ossicles in the atretic ears were hypoplastic (mean ossicular sectional area: 8.3 mm 2 versus 11 mm 2). The distance from the jugular bulb to the facial nerve was significantly lower (mean: 6.2 mm versus 6.8 mm) ( p < 0.05) in the atretic ears. Facial canal caliber, distance from the facial canal to the incudomalleolar joint and distance from the facial canal to the vestibule in the atretic ears (means: 1.49, 2.93 and 1.82, respectively) did not show statistically significant difference from the control subjects (means: 1.44, 2.91 and 1.83, respectively) ( p > 0.05 for all). Conclusion External ear atresia is significantly associated with middle ear and mastoid abnormalities. The ossicles were underdeveloped which always have to be considered during reconstructive surgery. Radiologically, in the atretic ears anterior–posterior length of the temporal bone was more influenced as compared to superior–inferior portion, which justifies abnormal route of the facial nerve canal. However, there is no abnormality in the development of the facial nerve as the caliper is similar to the control subjects.

Multidetector row CT demonstration of inner and middle ear structures

The aim of this study is to evaluate the anatomical details of the inner ear and middle ear, using multidetector row CT. Temporal bone CT scans were obtained using 16-detector row CT scanner (Lightspeed 16, General Electric Medical Systems, Milwaukee, WI) in 30 patients with dizziness, vertigo, or hearing loss. The three-dimensional (3D) images were reconstructed with volume rendering techniques. The 3D images were reviewed by two radiologists and scored by using a three-point quality rating for qualitative assessment of the 23 representative structures of the middle and inner ear. The malleus, incus, and facial nerve canal were identified in all patients. The incudomalleolar joint appeared fused in all patients. The stapes were seen clearly in 27 (90%) of 30 patients except in three patients. Among the three remaining patients, there was one who had effusions in the middle ear cavity. Another patient had left cholesteatoma. The third patient had normal middle ear cavity. The cochlea and the three semicircular canals (anterior, posterior, and lateral) were well demonstrated in 29 (97%) of 30 patients except for one old woman with osteoporosis. Sixteen-detector row CT imaging of temporal bone with advanced 3D reformation yields state-of-the-art anatomical details of the temporal region useful to address anatomical localization issues and ease conceptual structural learning.

Experimental ossicular fixations and the middle ear’s response to sound: Evidence for a flexible ossicular chain

A human temporal-bone preparation was used to determine the effects of various degrees of artificial ossicular fixation on the sound-induced velocity at the input-side (the umbo of the malleus) and the output-side (the stapes) of the ossicular chain. Construction of various degrees of attachment between an ossicle and the surrounding temporal bone provided a range of reduction in ossicular mobility or “fixations”. The results demonstrate different effects of the fixations on the umbo and stapes velocity: fixations of the stapes or incus produce larger reductions in sound-induced stapes velocity (as much as 40–50 dB with extensive stapes fixation), than reductions in umbo velocity (typically less than 10 dB). Fixations of the malleus produce similar-sized changes in both umbo and stapes velocity. These differential effects are consistent with significant flexibility in the ossicular joints (the incudo-malleolar joint and the incudo-stapedial joint) that permits relative motion between the coupled ossicles. The existence of flexibility in the ossicular joints indicates that joints in the ossicular chain can effect a loss of sound-induced mechanical energy between the umbo and the stapes, with a concomitant reduction in the sound-induced motion of the stapes. The introduction of such losses in sound transmission by the joints raises questions concerning the utility of three ossicles in the mammalian ear. The consequences of ossicular flexibility to ossicular-chain reconstruction is discussed. Also, as examined in a more clinically directed paper [Laryngoscope 115 (2005) 147], the different effects of the various ossicular fixations on the motion of the umbo and malleus may be useful in the diagnosis of the site of fixations in humans with conductive hearing losses caused by such pathologies.

The incudo-malleolar joint and sound transmission losses

The question as to whether the incudo-malleolar joint (IMJ) is mobile or immobile at moderate sound pressure levels (SPLs) is addressed. Referring to the mechanical properties of elastic tissue, we suggest that the IMJ is mobile at any SPL. In order to test this hypothesis, we investigated the dynamics of the IMJ in nine temporal bones by means of laser scanning doppler vibrometry. The dynamic behavior of both ossicles is described by three degrees of freedom, and transfer functions (TFs) are shown for each of them. We show that there is indeed relative motion between the malleus and the incus. This transmission loss affects the middle ear TF and results in a frequency dependent sound transmission loss. Some characteristics of our results are in agreement with middle ear TFs described in the literature. The increasing transmission loss towards higher frequencies is caused by relative motion between malleus and incus at the IMJ. The concept that the IMJ is functionally mobile is consistent with the physical properties of elastic tissues which most likely define the mechanics of this joint. Since the IMJ is indeed mobile at moderate sound intensities and audible frequencies the theory of the lever ratio being responsible for the characteristics of the middle ear TF must be reconsidered.

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.

Investigations on protein metabolism in malleus and incus (author's transl)

Protein and mucopolysaccharide metabolism was studied in the auditory ossicles of rabbits after administration of tritiated amino acids to three and of S35 to two animals. No differences between S35 and aminoacid turnover was seen, indicating a parallelmetabolism of proteins and mucopolysaccharides of the intercellular substance. The tissue, cartilage and bone, shows a metabolism on the molecular level. Areas of cartilage ground substance adjacent to the incudomalleolar joint and the interglobular spaces are not labelled by the radioactive substances. They are excluded from metabolical turnover, while the adjacent cells remain vital. This observation indicates a change of cellular properties, from cartilage to bone cell. The subperiostal bone has lower metabolism than the underlying skeinlike bone. Few osteones were found.

Tympanoplasty in blast-induced perforation.

Tympanoplasties were performed on 107 blast-induced tympanic membrane ruptures. An air-bone gap of less than 10 dB, or a speech reception threshold of less than 30 dB was obtained on 80.6% of cases. An intact tympanic membrane was achieved in 86.9% of cases. The most frequent form of ossicular abnormality was disruption of the incudomalleolar joint and adhesion of the malleus tip to the promontory. This occurred in approximately 25% of cases. Incudostapedial joint abnormality occurred in 8.4% of cases. Medial placement of graft material had both lower graft failure rate and better hearing result than lateral placement.

Development of Auditory Function in the Mongolian Gerbil

The gerbil ear is not mature at birth. The sound-conducting apparatus as well as inner-ear structures continue to develop over a period of at least 16 to 20 days postparturition. This circumstance allows a unique opportunity to examine relationships between morphology and function in the auditory apparatus. Mongolian gerbils were vitally perfused at various ages ranging from 20 min to more than 23 days. Serial sections were done and observations made on the developmental status of the external, middle, and inner parts of the ear. Cochlear potentials were recorded from some animals. The presence of reflex activity to sound was noted. Our observations indicate that the earliest reflex response to sound (whole body) occurred at 16 days. Electrical activity could be recorded from the round window niche by day 14. Maturation of the organ of Corti was questionable by day 10, and the limbus and spiral sulci were not well differentiated. By day 16, all parts of the organ of Corti appeared well developed. Ossicular ossification was almost complete by day 16, but mesenchyme was still present in the region of the incudomalleolar joint. [Work supported by NIH.]

Middle-ear characteristics of anesthetized cats.

Ossicular motion was measured visually with stroboscopic illumination. Tonal stimulation ranged from 30 to 10 000 Hz. Up to 130 dB SPL (sound-pressure level), the motion of the stapes is predominantly piston-like, and its displacement amplitude is linearly related to sound pressure. At frequencies under 3000 Hz, the ossicles move as one rigid body; at higher frequencies, the stapes and incus displacements lag behind the malleus displacement, which suggests that the incudo-malleolar joint flexes. From measurements of stapes displacement at known sound pressures, we calculate a transfer characteristic for the middle ear with the tympanic cavities open. The effects of closing the tympanic cavities on the transfer characteristic were determined from measurements in which the electric response recorded from the round window was used as an indicator of middle-ear output. By combining these data, we obtain a transfer characteristic for the middle ear with the tympanic cavities intact. An attempt is made to compare middle-ear characteristics of cat and man.

Experimental Studies on the Mechanism of Sound Couduction of the Ossicular Chain

In order to make clear the mechanism of sound couduction of the ossicular system, the author investigated the alteration of the cochlear potentials after the partial adhesion at different points of the ossicular chain of many cats by the use of tissue adhesives (α-cyano-acrylate-monomer=Aron Alpha).The following results were obtained:(1) After adhesion of the manubrium of the malleus to the eardrum, there appeared the reduction in C. M. response even to 15-20dB in the range from 0.2 to 2kcps.(2) Stiffness of incudo-malleolar joint resulted in no reduction in C. M. response. But adhesion of the incudo-malleolar joint to the epitympanum led to a loss of 10-20dB in the range from 0.2 to 1kcps.(3) Adhesion of the incudo-stapedial joint improved the C. M. response up to 5dB in the range from 0.2 to 1kcps while there was no reduction in the higher frequency range.(4) After stapedial fixation, a loss in the low to middle frequency range, was larger than high frequency range and the notchs were observed in 0.2 and 1kcps. It is persumed that the notch of 0.2kcps is largely due to the inner impedance while that of 1kcps indicates the resonant point of the stapes.(5) Stiffness of the all ossicular chain by the partial adhesion at several different points showed that the resonant point of the all ossicular system is centered around 1kcps, and the loss of C. M. response is about 40dB in the low range, about 50dB in the middle range, and about 20dB in the higher frequency range.