Characterization of mechanical behaviour of healthy and injured human incus by eigenfrequency evaluation.

The usage of finite element method techniques gives a possibility to replace time-consuming experiments or imitate physical process in the ear by numerical simulation. Especially, the research of spatial motion of ossicular chain in the middle ear is of high interest for the oto-surgeons and engineers. It is known that the most affected bone from the ossicular chain is the incus. After the cholesteatoma operation and tympanoplasty, the affected incus is removed or sacrificed; thus, the possibility of transducing noise lays on the stapes, new titanium or other material prosthesis. In this case, the affected incus was removed because of the cholesteatoma that was lying in front of it in the tympanic cavity. The removed incus with the affected long process passed micro-computed tomography. The computer-aided design systems allowed redesigning a 'healthy' incus with an intact long process. In this way, it was possible to evaluate the influence of damaged long process of incus in the vibrational analysis. This article analyses the problems of mechanical behaviour of injured and healthy human incus. The numerical simulation has demonstrated that the features of healthy incus and analysed injured incus do not differ significantly, especially at low (about 500 Hz) frequencies. It explains why there is no impact of cholesteatoma on hearing for a long time in the audiogram.

Misplaced incus: an unusual complication of a temporal bone fracture.

A 24-year-old man sustained significant injuries as a result of a motor bicycle accident. CT scans demonstrated multiple intracranial injuries including bilateral temporal bone fractures. On emergence from sedation, the patient reported right-sided hearing loss which was attributed to ossicular chain disruption after the incus was found to be in the external auditory canal. Unexpectedly, the initial conductive hearing loss resolved with conservative management and an ossicular chain reconstruction was not required. This is an unusual case of impressive long-term good hearing outcomes following complete dislocation of the incus and extrusion from the middle ear.

Fracture of the Incus Caused by Digital Manipulation of the Ear Canal and its Diagnosis Using Wideband Acoustic Immittance.

OBJECTIVE: To describe the first reported case of a fracture of the long process of the incus due to digital manipulation of the ear canal and to discuss diagnostic markers for ossicular fractures. PATIENT: A 46-year-old woman with incessant clicking and crunching in her left ear, and hearing loss after digital manipulation of the ear canal. INTERVENTION: Diagnostic evaluation and therapeutic ossiculoplasty. MAIN OUTCOME MEASURE(S): Audiometric and wideband acoustic immittance (WAI) measurements were made before surgery to investigate the cause of clicking sounds and mild conductive hearing loss (CHL). RESULTS: The clinical suspicion of a loose ossicular chain was confirmed by a large narrow-band decrease in power reflectance (calculated from WAI) at frequencies between 600 and 700 Hz, and a mid- to high-frequency air-bone gap. Exploratory tympanotomy revealed an ossicular fracture of the distal aspect of the long process of the incus. Ossiculoplasty with bone cement resolved bothersome clicking sounds. CONCLUSION: A finger inserted into the ear canal can produce an air seal, and subsequent quick removal of the finger can result in the fracture of an ossicle. Clinicians should be cognizant of this form of trauma because insertion of a finger, ear plug, and earphone into the ear canal are common. Ossicular fractures can result in high-frequency CHL, and can be misdiagnosed as sensorineural loss because bone conduction thresholds are not measured above 4 kHz. As in this case, an ossicular fracture may be misdiagnosed and result in inappropriate treatment. Here, WAI, a non-invasive measure of ear mechanics, diagnosed a loose ossicular chain.

Drill-induced Cochlear Injury During Otologic Surgery: Intracochlear Pressure Evidence of Acoustic Trauma.

HYPOTHESIS: Drilling on the incus produces intracochlear pressure changes comparable to pressures created by high-intensity acoustic stimuli. BACKGROUND: New-onset sensorineural hearing loss (SNHL) following mastoid surgery can occur secondary to inadvertent drilling on the ossicular chain. To investigate this, we test the hypothesis that high sound pressure levels are generated when a high-speed drill contacts the incus. METHODS: Human cadaveric heads underwent mastoidectomy, and fiber-optic sensors were placed in scala tympani and vestibuli to measure intracochlear pressures (PIC). Stapes velocities (Vstap) were measured using single-axis laser Doppler vibrometry. PIC and Vstap were measured while drilling on the incus. Four-millimeter diamond and cutting burrs were used at drill speeds of 20k, 50k, and 80k Hz. RESULTS: No differences in peak equivalent ear canal noise exposures (134-165 dB SPL) were seen between drill speeds or burr types. Root-mean-square PIC amplitude calculated in third-octave bandwidths around 0.5, 1, 2, 4, and 8 kHz revealed equivalent ear canal (EAC) pressures up to 110 to 112 dB SPL. A statistically significant trend toward increasing noise exposure with decreasing drill speed was seen. No significant differences were noted between burr types. Calculations of equivalent EAC pressure from Vstap were significantly higher at 101 to 116 dB SPL. CONCLUSION: Our results suggest that incidental drilling on the ossicular chain can generate PIC comparable to high-intensity acoustic stimulation. Drill speed, but not burr type, significantly affected the magnitude of PIC. Inadvertent drilling on the ossicular chain produces intense cochlear stimulation that could cause SNHL.

Traumatic ossicle extrusion into the external auditory canal.

We report a rare case of incus dislocation into the external auditory canal following a head injury. The patient was a 35-year-old man who presented to the surgical emergency unit with a head injury that he had sustained during a traffic accident. An x-ray of the skull detected a longitudinal fracture of the right temporal bone. The ENT examination revealed the presence of a bony structure and a blood clot in the right external auditory canal. Computed tomography identified a disruption of the ossicular chain, with an incus-like bony shadow in the external canal. The wide opening of the fracture line and the impact of the accident were believed to have pushed the incus through the fracture and into the external canal. The patient was successfully treated with exploratory tympanotomy and ossiculoplasty.

Normal hearing after trauma with completely ectopic incus -- how possible?.

OBJECTIVES: To report the rare case of a patient with complete incus dislocation after trauma showing normal hearing. METHODOLOGY: Physical examination, audiometry, CT of temporal bone, and detection during operation. RESULTS: The incus had become remotely located in the mastoid cavity, but the patient showed normal hearing because fibrous connections had preserved bony continuity. CONCLUSION: This case demonstrates that disruption of the ossicular chain does not always require ossicular reconstruction.

Traumatic dislocation of the incudostapedial joint repaired with fibrin tissue adhesive.

We present a case of traumatic dislocation of the incudostapedial joint (ISJ) and a simple method for controlled application of the glue using commercial fibrin tissue adhesive. A 26-year-old female presented to our ENT clinic for hearing impairment to her left ear 2 months after a head trauma due to a motorcycle accident. The audiogram revealed a 40- to 50-dB HL conductive hearing loss with a notch configuration in bone conduction curve on the left ear. Computed tomography of the left temporal bone revealed a longitudinal fracture line. An exploratory tympanotomy was performed under general anesthesia. The ISJ was found dislocated while the incus was trapped by the edges of the bony lateral attic wall fracture. A small bony edge that impeded incus movement was removed and a small amount of the glue was precisely applied to the lenticular process of the incus with an angled incision knife. The long process of the incus was firmly pressed over the stapes for 30 seconds with a 90° hook and 60 seconds after the application of the glue the ISJ was repaired. One year after our patient achieved full airbone gap (ABG) closure (ABG, ≤10 dB HL), while she demonstrated overclosure in frequencies 2 and 4 kHz. Fibrin tissue glue allowed safe, rapid, and accurate repair of the ISJ and resulted in an anatomically normal articulation as the mass and shape of the ossicles was preserved. Moreover, our patient achieved full ABG closure.

Fisch's reversal steps stapedotomy: when to use it?

OBJECTIVE: To determine that the use of Fisch's reversal steps stapedotomy is recommended only when the visible portion of the footplate is blue in all its points before removing the stapes superstructure. STUDY DESIGN: Prospective study. MATERIALS AND METHODS: This study started on January 2007 and ended on June 2007, when the statistical data reached significance. Fifty patients with otosclerosis were examined. Four otosclerosis were excluded from the study following the exclusion criteria indicated by Fisch (obliterative otosclerosis and narrow oval niche). Finally, 46 otosclerosis patients were considered for the study. For all patients, stapedotomy procedures using the reversal steps technique by Fisch were planned. The study group was divided into 2 groups (A and B) on the basis of the footplate color before removing the stapes superstructure. Group A included otosclerosis with blue footplate (n = 34). Group B included otosclerosis with white footplate (n = 12). We estimated whether the reversal steps stapedotomy proposed by Fisch significantly avoids incus complications (luxation and subluxation) and stapes footplate complications (luxation and fracture) both in blue and white otosclerosis. MAIN OUTCOME MEASURES: Footplate color, incidence of complications. RESULTS: The footplate fenestration had not caused fractures or luxation of footplate in both groups. The fracture of the anterior crus had caused 5 footplate complications (2 luxations and 3 fractures) in Group B, but none in Group A. This difference was significant. In Group A, we had no subluxation/luxation of the incus. In Group B, we had 3 incus subluxations. This difference was significant. CONCLUSION: The use of Fisch's reversal steps stapedotomy is recommended only when the visible portion of the footplate, before removing the stapes superstructure, is blue in all its points, that is, "blue otosclerosis," because only in this case that the original idea of Fisch avoids incus and footplate complications. When the visible portion of the footplate, before removing the stapes superstructure, is white in all or in most of its points, that is, "white otosclerosis," the reversal steps technique by Fisch is not recommended because it does not avoid incus luxation/subluxation and footplate complications (fracture and luxation of the anterior half).

Incudostapedial joint arthroplasty using temporalis fascia/perichondrium ties.

Incudostapedial joint dislocation is the most frequently found ossicular chain defect. In these cases reconstitution of joint capsule is important in maintaining joint integrity. But reconstruction of dislocated incudostapedial joint is a challenging procedure as this joint is devoid of any muscular or soft tissue support. Here we describe a technique designed to reposition the incudostapedial joint in its anatomical position using temporalis fascia or perichondrium. Data have been collected and analyzed from 42 patients with incudostapedial joint discontinuity. The fascial ties used for reconstruction of joint capsule ensure a dynamic union of the repositioned incus with stapes, leading to a significant improvement in conductive hearing loss.

Traumatic stapes fracture with rotation and subluxation into the vestibule and pneumolabyrinth.

A 41-year-old man presented after forceful penetrating ear injury. He had incapacitating vestibular symptoms. Computed tomography revealed pneumolabyrinth with a fractured stapes that was >90 degrees rotated and subluxed into the vestibule, such that the crura and capitulum could be seen in the vestibule. Surgical repair reversed the vestibular symptoms, but there was persistent hearing loss. Stapes fractures are unusual and rarely associated with subluxation into the vestibule. When this does occur, there is usually simple footplate depression. This case demonstrates a rare stapes fracture with pneumolabyrinth and >90 degrees stapes rotation, then subluxation into the vestibule. Laryngoscope, 2009.

Unusual middle-ear mischief: trans-tympanic trauma from a hair grip resulting in ossicular, facial nerve and oval window disruption.

A case of piercing of the tympanic membrane, resulting in unusual consequences, is described. This is the first reported case of the long process of a dislocated incus resulting in trauma to the horizontal portion of a dehiscent facial nerve. Simultaneous depression of the stapes footplate resulted in a perilymph leak, but with delayed presentation.

Ossicular chain dislocation with normal hearing.

We report a unique case of an ossicular chain injury in a young man. Despite the fact that the patient's incus was dislocated into the external auditory canal while remaining attached to the stapes, his hearing was not affected and remained nearly normal. We discuss the patient's presenting features and our diagnostic and management strategy in this case.

[Experimental joint incus-stapedial injuries in scanning electron microscopy]. / Doswiadczalne uszkodzenia stawu kowadelkowo-strzemiaczkowego w skaningowej mikroskopii elektronowej.

Because all machines and vibration devices also produce noise, the combined activities of both factors are usually examined together. The opinion dominates that vibration exerts only a weak, additionally traumatic influence on the hearing organ. The aim of our investigation was to determine the influence of long-term, whole-body vibration on the incudo-stapedial joint which integrity is indispensable for the protection of the inner ear from the effect of noise. To realize the experimental conditions, sinusoidal vertical shaking (10 Hz, 5 mm, 1.4 g rms), an own noiseless apparatus was consisted. The experiment was carried out on 30 young, healthy, colored guinea pigs. They were subjected to vibration over 1, 3, and 6 months (132, 396, and 792 hours). The investigation was based on examination of the structures of the incudo-stapedial joint in the scanning electron microscopy. Among experimental animals two kinds of changes were ascertained which can be attributed to the activity of vibration. One was an extensive damage to the surfaces of the incudo-stapedial joint itself. The other was an often observed thickening of the bursa of the joint. The frequencies of occurrence and stages of advancement of both were in direct relationship to the duration of the experiment. The evaluation of the observed changes permits an explanation of the mechanism of the damage to hearing of persons subjected to noise and vibration. Whole-body vibration damages the incudo-stapedial joint, making its separation difficult. This may, than, facilitate the transfer of noise and its injurious influence to the inner ear.

Incus subluxation and luxation during stapedectomy.

Stapedectomy is a safe surgical procedure used in patients with otosclerosis. However, complications may occur and decrease hearing gain after the operation. The aim of the work was to analyze hearing results in patients with incus subluxation during stapedectomy. In 15 (5%) of 292 patients with otosclerosis, the incus was unintentionally luxated during surgery. In one patient the incus was completely dislocated and malleovestibulopexy with autoincus had to be applied. In 14 stapedectomies the incus was subluxated and though it was pathologically mobile it was held in position by its ligaments. This situation allowed delicate reposition of the incus and insertion of the piston prosthesis on the long incus process. Mean AC threshold improved by 24 dB. Mean ABG improved from 34.6+/-8.3 dB before to 13.1+/-6.3 dB 8 months after stapedectomy (t=9.7; p<0.0001). Ten years after surgery average ABG was 10.6+/-4.4, which means stable hearing result. In 6 patients including the individual with complete incus luxation, postoperative ABG was less than 10 dB. In 9 patients postoperative ABG was between 10 and 15 dB. When the incus is subluxated good hearing results can be expected after insertion of the prosthesis on the repositioned incus.

Management of incus dislocation by physiological repositioning of the incus.

Data have been collected prospectively from 11 patients (12 affected ears) with traumatic disruption of the ossicular chain. Isolated dislocation of the incus is the most common finding in our cases, but two had stapes arch features and two had fractures of the tympanic bone. The most common cause of the injuries was a road traffic accident. We describe a technique designed to reposition the incus in its physiological position. This involves a combination of a tympanotomy and a posterior approach to the attic region. The results in five patients (six ears) treated in this way are presented.