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Although human bone conduction (BC) hearing is well investigated, there is a lack of information about BC hearing in most other species. In humans, the amount of conductive loss is estimated as the difference between the air conduction (AC) and BC thresholds. Similar estimations for animals are difficult since in most species, the normal BC hearing thresholds have not been established. In the current study, the normal BC thresholds in the frequency range between 2 kHz and 20 kHz are investigated for the Guinea pig. Also, the effect of a middle ear lesion, here modelled by severing the ossicles (ossicular discontinuity) and gluing the ossicles to the bone (otosclerosis), is investigated for both AC and BC. The hearing thresholds in the Guinea pigs were estimated by a regression of the amplitude of the compound action potential (CAP) with stimulation level and was found robust and gave a high resolution of the threshold level. The reference for the BC thresholds was the cochlear promontory bone velocity. This reference enables comparison of BC hearing in animals, both intra and inter species, which is independent on the vibrator and stimulation position. The vibration was measured in three orthogonal directions where the dominating vibration directions was in line with the stimulation direction, here the ventral direction. The BC thresholds lay between -10 and 3 dB re 1 μm/s. The slopes of CAP growth function were similar for AC and BC at low and high frequencies, but slightly lower for BC than AC at frequencies between 8 and 16 kHz. This was attributed to differences in the stimulus levels used for the slope estimation and not a real difference in CAP slopes between the stimulation modalities. Two kinds of middle ear lesions, ossicular discontinuity and stapes glued to the surrounding bone, gave threshold shifts of between 23 and 53 dB for AC while it was below 16 dB when the stimulation was by BC. Statistically different threshold shifts between the two types of lesions were found where the AC threshold shifts for a glued stapes at 2 and 4 kHz were 9-18 dB greater than for a severed ossicular chain, and the BC threshold shifts for a glued stapes at 4 and 12 kHz were 8-9 dB greater than for a severed ossicular chain., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives:: The development of pneumolabyrinth without previous head trauma is a rare event; the associated symptoms may be nonspecific, and they can simulate various cochleo-vestibular pathological entities. The aim of the present study is to describe one of these rare occurrences, characterized by a peculiar onset., Methods:: We report a case of stapes fracture secondary to ear pick penetration into the middle ear with a pneumolabyrinth that caused a recurrent paroxysmal positional vertigo (PPV) mimicking a canalolithiasis., Results:: The patient developed a profound left sensorineural hearing loss and an intractable PPV with "migrant" features. A pneumolabyrinth was visualized with high-resolution computed tomography. A perilymphatic fistula (PLF) with stapes fracture was found while performing an explorative tympanotomy. After the surgical treatment of the PLF, the patient no longer complained of vestibular symptoms., Conclusions:: To our knowledge, this is the fifth case of traumatic pneumolabyrinth simulating a canalolithiasis without previous history of temporal bone trauma and/or middle ear surgery. A pneumolabyrinth should be suspected in case of patients presenting recurrent intractable PPV after ear trauma.

Introduction: Temporal bone fractures are frequently associated with ossicular dislocations or fractures, most commonly involving the incus. To our knowledge, isolated fracture of the posterior crus of the stapes has not been previously reported., Case Report: A 20-year-old man consulted for persistent left hypoacusis several months after a head injury. Initial computed tomography of the temporal bone showed a simple temporal bone fracture with no other associated abnormalities. The diagnosis of stapes fracture was suggested by increased compliance on tympanometry, leading to a second thin-section temporal bone computed tomography, which suggested a fracture of the posterior crus of the stapes. Endaural surgical exploration confirmed the diagnosis and allowed placement of ionomer cement in the posterior crus., Discussion: The possibility of ossicular dislocation or fracture must be considered in patients with persistent conductive hearing loss associated with increased compliance on tympanometry, even when computed tomography of the temporal bone does not show dislocation of the ossicular chain or ossicular fracture. Hearing rehabilitation can be performed by hearing aid or surgical reconstruction of the ossicles., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Objective: Stapediovestibular luxations are rare lesions that are most commonly caused by direct, penetrating trauma to the external ear canal. In this type of ossicular dislocation, disruption of the annular ligament or footplate fracture may lead to a perilymphatic fistula (PLF) presenting with cochleovestibular symptoms including (progressive) sensorineural hearing loss, tinnitus, and vestibular symptoms. The objective of this article is to define the optimal treatment of stapediovestibular luxations and review the literature on this topic., Patient: We present a case of internal stapediovestibular dislocation and pneumolabyrinth after penetrating trauma with predominantly conductive hearing loss and incapacitating vertigo., Intervention: Middle ear inspection with removal of the luxated incus, repositioning of the stapes with a "stapedial strut" and closure of the tympanic membrane., Main Outcome Measures: Hearing outcome and vestibular symptoms of this patient are presented, and all comparable cases in the literature are reviewed., Results: Complete resolution of the vestibular symptoms and stabilization of the bone conduction thresholds., Conclusion: In patients with pneumolabyrinth after middle ear trauma with mild symptoms, we recommend initial conservative treatment with close monitoring of hearing. In patients with severe, persisting, or progressive vestibulocochlear symptoms, exploratory tympanotomy should be performed to check for and treat PLF. Oval window fistula repair is reported to have variable hearing outcomes but offers complete resolution of vestibular symptoms in most cases. The stapedial strut is one of the possible surgical techniques in case of an internally luxated stapes.

Introduction: Temporal bone fracture is a common complication of high-energy cranial trauma. Labyrinth involvement is rare, but there is a risk of perilymphatic rupture that is often underestimated on initial clinical examination due to the predominance of neurological and/or somatic symptoms., Case Report: A patient presented with overlooked perilymphatic fistula, decompensated by hyperpressure effort due to poorly adapted management., Discussion: Following a review of the literature on post-traumatic pneumolabyrinth, overall management (from diagnosis to treatment, via prevention advice) was analyzed. A constructive critique of the patient's treatment was thus made., Conclusion: We argue for a systematic management protocol in cranial trauma with temporal bone fracture, comprising ENT examination, millimetric-scale cross-sectional imaging of the fracture site, and standardized counseling to prevent late complications., (Copyright © 2013. Published by Elsevier Masson SAS.)

Background: Hearing loss in Paget's disease of bone (PDB) is typically mixed and bilateral. Although different mechanisms have been proposed, the pathophysiology of hearing impairment remains unclear., Objective: The purpose of this study is to describe the histopathologic findings of temporal bones in patients with PDB and elucidate possible pathologic mechanisms related to hearing impairment., Methods: This is an archival human temporal bone study of 8 subjects diagnosed with Paget's disease from the temporal bone collection of the UCL Ear Institute., Results: A fractured stapes footplate was observed in 1 temporal bone and stapes footplate fixation in 2 other specimens. Obliteration of Cotugno's canal by extensive bone remodeling was observed in 78% of temporal bones. An intracochlear vestibular schwannoma was observed in 1 specimen (previously reported in the literature). Other findings include microfissures and microfractures of the otic capsule, bleeding in the scalae, strial atrophy, and cystic lesions in the spiral ligament., Conclusion: This study is the first to report a fractured stapes footplate, as a causative lesion of conductive hearing loss in PDB. Extensive bone remodeling around Cotugno canal also was a frequent finding, not reported before in the literature. We hypothesize that sensorineural hearing loss in patients with PDB of the temporal bone may, in some cases, be attributed to obliteration of Cotugno's canal by remodeling pagetoid bone, thus obstructing the venous drainage of the cochlea, with a subsequent effect on the function of stria vascularis and spiral ligament. This seems to be consistent with experimental studies in animals.

Objective: To describe 3 cases of pneumolabyrinth after penetrating injury to the middle ear and to review previously reported cases, comparing precipitating factors and hearing outcomes., Data Sources: Three cases we encountered and the PubMed and Japan Medical Abstracts Society databases., Study Selections: In addition to our 3 cases, we identified 48 cases from 41 articles regarding pneumolabyrinth. DATA EXTRACTIONS: All articles describing cases of pneumolabyrinth were used for this review., Data Synthesis: Among the 51 cases, audiologic evaluation was not available in 16 cases. In the remaining 35 cases, hearing outcomes were analyzed focusing on 3 factors: 1) differences in and interval until medical intervention, 2) existence of stapes lesions, and 3) extension of air bubble into the inner ear. We failed to find any significant differences in interventions, although operation less than 2 weeks after injury tended to be associated with a higher rate of hearing recovery (54%) than operation 2 weeks or longer after injury (25%). Furthermore, 11 (48%) of 23 cases with pneumolabyrinth limited to the vestibule or semicircular canals showed improved hearing, whereas none of 6 cases (0%) with pneumolabyrinth extending from the vestibular organs to the cochlea showed hearing recovery. This difference was statistically significant (p < 0.05)., Conclusion: Assessment of the location and extension of pneumolabyrinth appears important in predicting hearing outcomes and planning the management of middle and inner ear trauma.

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., (Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.)

We report the first case of isolated stapedial dislocation caused by indirect head trauma, and present imaging and surgical findings in the case of a 25-year-old woman who suffered hearing loss and dizziness after head trauma caused by a traffic accident. The pure tone average was 60 dB, with an air-bone gap of 50 dB. The stapedial reflex was positive with the probe on the affected ear. Computed tomography scans revealed a longitudinal fracture of the temporal bone and a dislocated stapedial superstructure in the tympanic cavity, adhering to the tympanic membrane. During surgery, it was found that the stapes was broken at the base of the posterior crus and at the anterior one third of the footplate and that the stapedial superstructure was dislocated outward and downward, with the anterior one third of the footplate adhering to the tympanic membrane. The stapedial tendon was connected to the superstructure. Ossicular chain reconstruction was performed with success. In the present case, two mechanisms may have acted together: 1) an increase in perilymphatic pressure that caused the footplate to fracture, and 2) a distorting force that broke the posterior crus, disconnecting the incudostapedial joint, and finally dislocating the stapedial superstructure together with the anterior part of the footplate.

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.

Acquired perilymphatic fistulae can be the result of direct or indirect trauma to the temporal bone, barotraumas, infections or a complication of stapedectomy surgery. We report a case of accidental stapedectomy causing a perilymphatic fistula in an ear with inactive chronic noncholesteatomatous otitis media. This patient had an oval window perilymphatic fistula for 6 weeks prior to surgery without significant permanent sensorineural hearing loss.

Traumatic luxation of the stapes into the vestibule is a rare entity, and the disease complicated with pneumolabyrinth is extremely rare. We report the case of a 72-year-old woman with pneumolabyrinth associated with a stapediovestibular dislocation. The patient presented with vertigo and nystagmus following penetrating trauma to the middle ear. High resolution computed tomography scans demonstrated air in the vestibule and dislocation of the stapes. Exploratory tympanotomy demonstrated oozing of the perilymph from the oval window and depression of the stapes into the vestibule. Pneumolabyrinth and stapes luxation detected by high resolution computed tomography should be predictive of a perilymphatic fistula.

Background: A columella-prosthesis is the typical reconstruction procedure of the ossicular chain in cases with a destroyed stapedial arch. Lightweight titanium prostheses are commonly used for this type of surgery. The smaller the prosthesis foot the lower the risk of dislocation and friction of the prosthesis with the bony rim of the oval niche. However, using a smaller prosthesis foot, fracture of the footplate and penetration of the prosthesis into the inner ear are conceivable., Methods: Using fresh temporal bone preparations, lacking the stapedial arch, in conjunction with a load cell, the force needed to fracture the footplate was measured. Different prostheses with different foot diameters (0.2 - 0.8 mm) were used in these experiments. Furthermore, a human stapes was evaluated morphologically by scanning electron microscopy., Results: The forces leading to fracture of the footplate were measured to be between 250 mN and 980 mN. Statistical analysis showed no significant difference between 0.2 mm and 0.8 mm prosthesis foots. Moreover, different forces were attributed to varying thickness of the stapes footplate. In scanning electron microscopy the rough and uneven bony surface of the footplate could be demonstrated., Conclusion: Due to the uneven footplate, only punctual contact of the prosthesis foot can be achieved. Hence, the risk of footplate fracture is not considerably higher by using smaller diameters. However, the use of smaller feet in upcoming generations of TORPs seems to be appropriate.

Objectives: To describe the value of high resolution computed tomography scan (HRCT scan) in post traumatic hearing loss., Method: HRCT scan of the temporal bone in millimetric cut with axial and coronal views was performed., Results: CT scan confirmed pneumolabyrinth with intact stapes depressed deeply into the vestibule. Surgical exploration was performed and the stapes was gently removed from the vestibule., Conclusion: CT scan confirmed the diagnosis and studied the stapes integrity. Hearing deteriorated postoperatively is increased in case of stapes fracture. When a luxation of the stapes into the vestibule is suspected, it is important to determine how deeply and whether it is fractured. When such a case is encountered, high resolution CT scan of the temporal bone must be performed to confirm the diagnosis and to confirm integrity of the stapes.

We herein report a case of traumatic fracture of the stapes accompanying vestibular window rupture with perilymph fistula, and its diagnosis and surgical procedure were discussed. In the present case, a direct force through the external auditory canal damaged not only the ossicular chain but also the vestibular window. On the exploratory tympanotomy, the complete dislocation and fracture of the stapes with a relatively huge rupture was confirmed. Perilymph fistula was repaired with a connective tissue graft, which was inserted between disrupted vestibular window and the long process of the incus. Vestibular dysfunctions disappeared within 3 days, and a satisfactory audiologic result was obtained one month after surgery.

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.

Pneumolabyrinth can result from traumatic luxation of stapes into the vestibule. The diagnosis of stapes luxation following a head injury can be delayed especially if the otoscopic examination is within normal limits. Here a 15-year-old girl presenting with vertigo and nystagmus following a blunt head injury was presented, whose computerized tomography revealed air in the vestibule and cochlea (pneumolabyrinth) and stapes was found to be luxated into the vestibule.

We report the case of a 60 year old patient suffering from a displacement of her stapes piston after a rear-end collision with whiplash injury. Immediately after the accident she complained hearing loss and tinnitus. During the following days, the patient developed vertigo with lateropulsion. Diagnostic tympanoscopy showed a piston dislocation with migration into the vestibulum as a result of the blunt head trauma.

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.

Traumatic fracture of the stapes occurs rarely following head injury. Ossicular dislocation is more commonly encountered. When present, stapes fractures are usually associated with an underlying temporal bone fracture. A higher incidence has been reported in childhood, possibly because of the greater flexibility of the skull in this age group. This report highlights the fact that these fractures can be associated with a relatively minor head injury. This possibility should be kept in mind when evaluating patients, especially children, who have a persistent conductive deafness of more than 30 dB with an intact tympanic membrane following any form of head injury. An exploratory tympanotomy with appropriate ossicular reconstruction, as described in this case, can yield excellent results.

Background: Injuries of the ossicular chain have various etiologies. Skull traumas from blows to the temporal, parietal or occipital region with or without fracture of the temporal bone are the main causes of the ossicular injury; other modes of injury are rare. It depends on the type of trauma which kind of injury occurs. Mainly subluxations, luxations and fractures are to be observed. The incus is the ossicle which is the most often injured. Mostly, only one ossicle is injured, rarely two or all of them., Patients: From January 1997 to June 1999 we operated 19 patients with traumatic lesions of the membrane and the middle ear. In 4 cases the reason for the operation was an injury of the stapes. We observed 2 cases with broken stapes crura, 1 case with an impression of the stapes into the vestibulum with perilymphatic fistula and 1 case with subluxation of the stapes in the direction of the promontorium. By presenting 4 cases we want to point out the diagnostic possibilities and the operative management of such rare injuries. In all cases we applied the transmeatal approach for the operation of the middle ear. In 2 cases it was possible to place the stapes back in their anatomic position in order to re-establish the ossicular chain. In the other 2 cases we had to use middle ear prostheses which were interpositioned between the manubrium of the malleus and the footplate of the stapes., Results: In all cases the immediate post-operative hearing results and the long-term hearing results after 10 to 28 months were satisfying. We did not notice any post-operative complications, especially no vestibular symptoms. One patient's tinnitus was the same as before the operation., Conclusions: The diagnosis of a stapes injury is despite the use of sophisticated technology, especially the CT-scan of the temporal bone, often very difficult. A sensitive anamnesis seems to be very important. It depends on the kind of injury which operative technique is to be applied in order to re-establish the ossicular chain. In our opinion, it is useful to take - if it is possible - the autolog stapes for the surgical re-establishment of transmission.

Imaging of the window of the temporal bone has became an important tool in the analysis of hearing loss, vertigo, tinnitus in a context of trauma, malformation, otosclerosis, and chronic otitis media. A good knowledge of the anatomy and a good technical procedure are necessary for making an efficient diagnosis. The increased thickness of the footplate may be delineated in otosclerosis, chronic otitis media, malformation, when it is measured at 0.7 mm or more in horizontal computed tomography (CT) sections. The traumatic displacement of the stapes, particularly within the labyrinths, is easily diagnosed in horizontal CT section. Imaging of the round window is now very important for the detection of otosclerotic foci, congenital stenosis, and perilymphatic fistula with or without fracture. Magnetic resonance imaging (MRI) with the high-resolution T2 plays an important role in the detection of a small amount of fluid in the round window recess, confirming the traumatic perilymphatic fistula without fracture.

Three rare cases of sudden high frequency sensorineural hearing loss with longitudinal fracture of the stapes footplate are presented. In two patients it occurred after they suppressed a sneeze. In the third patient after the exertion of parturition. At exploratory tympanotomy all were found to have longitudinal fractures of the stapes footplate and two had a perilymph fistula at that site. The history and audiometric profiles in such patients should raise a high index of suspicion regarding the possibility of a stapes footplate fracture.

A Plastipore (porous polyethylene) Total Ossicular Replacement Prosthesis gave an excellent initial hearing result which was maintained for 14 years. Hearing then began to deteriorate and revision surgery showed disintegration of the prosthesis and a defect in the stapes footplate. Histological examination confirmed previous findings in porous polyethylene with multinucleated foreign body giant cells and breakdown of the material.

The leaking labyrinthine lesion is treated by conservative methods or surgical procedures. With respect to the stapes, the surgical treatment is controversial. Five cases of middle ear injuries accompanying oval window rupture are reported herein. In each case, direct force through the auditory canal damaged not only the ossicular chain but also the oval window. Initial symptoms were sudden hearing loss with significant conductive disturbance and various degrees of unsteadiness. Spontaneous horizontal nystagmus directed toward the uninvolved ear was observed in each case. Tympanic cavities were promptly explored under general anesthesia and oval window injuries were confirmed. In each case, the damaged stapes was temporally removed from the oval window. Perilymphatic leakage was recognized in each case. Two patients had subluxation of the stapes with a paucity leakage. Three had complete luxation of the stapes with a relatively huge oval window fistula. Disrupted oval windows were repaired with temporalis muscle fascial grafts that were inserted under the middle ear mucosae surrounding the oval windows. The stapes were replaced in the repaired oval windows, and the ossicular chains were reconstructed without artificial grafts. Vestibular dysfunctions disappeared within 7 days, and satisfactory audiologic results were obtained in each case.

We present a rare case in which barotrauma led to fracture of the stapes footplate and perilymph fistula, resulting in sudden severe sensorineural hearing loss and tinnitus. Surgical repair in this case resulted in excellent hearing recovery. The aetiology and management of inner ear barotrauma and stapes injury is discussed. We believe that early exploration and repair of suspected perilymph fistulae optimises hearing recovery.

We encountered a case of acquired perilymphatic fistula in which the origin of the disease, namely, the stapes begin medially displaced into the vestibule, was shown by thin-section CT. Accordingly, we recommend that every patient with suspected perilymphatic fistula of traumatic origin undergo high-resolution CT of the petrous bone.

Since 1992 a small air-cooled opthalmological argon laser (Argus system, 3 W max.) equipped with a fiberoptic microhandpiece has been used for stapedotomy at the Inselspital, Berne. The microhandpiece has been developed especially for otological purposes in our electronic laboratory. In order to measure the effect of argon laser pulses applied through the handpiece to the ear, we performed temperature measurements in a saline-filled inner ear model by using ultrathin (2 microns thick), ultrafast (4 ns) thermosensitive rhodamine-coated polyurethane films. Multiple laser pulses of 1-2.5 W and 0.1 s duration - as used in clinical applications - produced a temperature elevation of about 1 degree C in the liquid of the inner ear model. The local laser effect was then examined histologically on the isolated stapes. The thermal damage zone around the stapedotomy perforation was limited to about 100 microns. In a clinical study we compared the results of argon laser stapedotomy (n = 54) with those of a skeeter microdrill stapedotomy (n = 29). Substantial hearing gains were found in all cases in both groups. In the laser stapedotomy group the mean residual air-bone gap (0.5-2 kHz) was 10 dB or less in all cases but one. Inner ear function remained unchanged except for a 40-dB loss at 4000 Hz in one case. Transient vertigo with nystagmus occurred in one case. Facial nerve dysfunction did not occur in any patient. The most important advantage of the laser found was the absence of mechanical trauma to the stapes. Stapes luxation and a floating footplate were avoided. In contrast, thick footplates were more easily perforated with the skeeter. Use of an argon laser equipped with a fiberoptic microhandpiece and a skeeter microdrill as needed seems particularly advantageous for stapedotomy.

The object of the present study was to examine the tissue ablation capacity of various pulsed lasers at the stapes footplate. Isolated human stapes and bovine compact-bone platelets (thickness 90 microns) were used to determine effective laser parameters for achieving a perforation measuring 500 microns to 600 microns in diameter. Apart from achieving the perforation diameters, particular attention was given to the form and quality of the perforations, reproducibility of the perforation effect and the thermally altered border zones occurring at the footplate. Four pulsed laser systems were used: excimer, Ho:YAG, Er:YSGG and CO2 lasers. An adequately large perforation generally could only be achieved by several repeated shots at the same application site, since only a small amount of tissue was ablated per application. The mechanism of the photoablation caused the extent of the thermal side effects to be markedly lower than with the continuous wave (cw) and superpulse systems. For this reason and because of their highly reproducible perforation effect, they were basically better suited for stapedotomy than the cw systems. It was possible, however, that as a result of the longer application time and the need to repeatedly irradiate the same application site, the higher pulse counts could prove to be disadvantageous in clinical practice. Among the pulsed laser systems, the Er:YSGG laser had the highest ablation rate at the stapes and was thus the most effective laser for interventions at the footplate. Although somewhat less effective than the Er:YSGG laser in our studies, the Ho:YAG and pulsed CO2 lasers also appear to be suitable for stapes surgery. On the other hand, we did not consider the excimer laser (308 nm) to be particularly effective at the footplate because of its low ablation rates.

During stapedotomy, the small dimensions and highly sensitive anatomic structures present require the highest degree of precision and safety. The risk of damage to middle and inner ear structures through manipulation with conventional instruments can be reduced by non-contact perforation of the footplate with the laser beam. The present study was devised to clarify which of the presently available laser systems was best suited for use in stapes surgery and thus represent a significant alternative to conventional stapedotomy. Isolated human stapes and bovine compact-bone platelets were used to investigate the connections between the parameters of various laser systems and their effects on bone tissue. The aim was to optimize the laser parameters required to achieve a perforation of 500 microns to 600 microns in diameter. In addition, the thermal effects of laser irradiation were assessed. Three different systems were employed: the argon and CO2 lasers in continuous wave (cw) modes and the CO2 laser in superpulse mode. The lasers investigated offered the advantage of achieving an adequately large perforation with one or a few juxtaposed applications but caused in part extensive thermal side effects at the stapes footplate. To reduce thermal effects, footplate perforation was best performed by several juxtaposed single shots at low power, short pulse duration and small beam diameter. The suitability of the argon laser for stapedotomy was rendered doubtful in view of the lower absorption coefficient of the stapes for the argon laser beam and the considerable influence exerted by the degree of pigmentation of the irradiated tissue sites with a resultant poor reproducibility of the perforation diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Manipulating the mobile stapes is a central procedure during tympanoplasty, i.e., mounting a prosthesis onto the stapedial head or dissecting cholesteatoma matrix off the oval window niche. An excessive displacement of the stapedial suprastructure as caused by these manipulations with hand-held instruments might result in a rupture of the annular ligament. Bacteria invading through this perilymphatic fistula threaten the inner ear. In experiments with temporal bones, the author investigated the rupture mechanisms of the annular ligament with definite stapedial manipulations. Leaks, which became detectable by exerting pressure on the inner ear fluid, occur only when all suspension fibers are completely ruptured. Further clinical aspects with different directions of stapedial manipulations are demonstrated.

During tympanoplasty, the stapes is often exposed to considerable manipulations, i.e. the dissection of cholesteatoma matrix from the oval window niche or the insertion of a prosthesis for ossicular chain reconstruction. Too much strain may rupture the annular ligament resulting in an opening of the inner ear. Furthermore it is conceivable that microperilymphatic fistulas, which remain undetected, may develop prior to a visible luxation of the stapes. Therefore, temporal bone experiments with definite manipulations on the stapes were performed to study the rupturing strength of the annular ligament. Increasing the pressure of the methylene blue dyed perilymphatic fluid facilitated the detection of even smallest ruptures. A leakage occurs only in case of a complete rupture of all fibres. Further findings of clinical interest, gained from these experiments with different directions of stapedial manipulation, are discussed.

The possible occurrence of inner-ear trauma linked to stapedectomy was studied by scanning electron microscopy of the medial (or labyrinthine) side of human stapedial footplates after performing a hole with different instruments. The anatomic variations induced experimentally by the different procedures are presented in detail and discussed. Manual instruments were shown to induce irregularities on the rim of the hole, whilst the utilization of either electric or pneumatic drills produced more regular margins. Finally, laser-produced holes were also examined. Rather neat rims were observed, but the thermal effect produced by this device has to be considered the major parameter involved in a possible inner-ear postoperative trauma.

The author reports on a rare case of direct injury of the middle ear with elective luxation of the stapes in vestibulum, where the rest of the ossicular chain was intact. The patient had a paroxysmal vertigo and combined hearing loss. The stapes was extracted from the vestibulum the same day and was fixed to the incus with fibrin sealant in an anatomical position. The oval window was sealed with connective tissue. The inner ear function recovered immediately. After one year, the audiogram was normal and the stapedial reflex was present.

The symptomatology, especially vestibular, and the surgical findings in traumatic dislocation of the stapes into the oval window are described in 2 patients, one of whom seen 1 3/4 h after the accident and the other after 12 days. The main indication for exploratory tympanotomy was change of the spontaneous nystagmus from an irritative to a paretic type. Special attention should be given to positional nystagmus, which increases on turning onto the affected side, the mechanism for which is apparently similar to the positional vertigo of labyrinthine fistulae. Hearing was preserved in both patients. In one patient, vestibular function recovered considerably whilst in the other, there remained considerable impaired function.

Bone like in otosclerosis from a 34-years-old man, from 33 years and 22 years old women, suffering from osteogenesis imperfecta tarda, with hardness of hearing in both ears were removed with chisel from the lower border of the oval window. After that a stapedectomy was accomplished. The stapedial crura have been genetically interrupted or broken, the footplate attached to the oval window. The bone from the border of the oval window was prepared for the histological examination. The specimens were coloured with Hematoxylin-Eosin and corresponding to Gomöri. In the bone similar cartilage osteoclasia and osteogenesis are rare. There are in the chondroosseous bone rooms filled with connective tissue. The diseased osseous labyrinth in osteo genesis imperfecta tarda must be regarded as a special morphogenetic formation of osteopsathyrosis.

On the basis of the observation of eight cases with traumatisms of the ossicular system, the authors discuss the mechanism of various forms of lesions, which may be primary represented by fractures and luxations or they may be secondary reactions following the traumatism leading to ankylosis the joins. There is underlined the frequency of the luxations of the stapes and the constant ankylosis of the footplate in these cases. The authors argue in favour of an early surgical procedure, the extent of the surgical intervention being conditioned by the lesional aspect.

Isolated fractures of the limbs of the stapes are relatively rare when compared with other traumatic lesions of the ossicula. Diagnosis, as in two recent cases, is suggested by the history of injury and the persistence of a recordable stapes reflex. Surgical re-establishment of transmission is simple but results are not always as spectacular as might be expected.

In guinea pigs the cochlea microphonics (CM) were recorded during and after argon laser stapedotomy. Short termed drastic depression of CM was observed. This effect involved the entire frequency range of the cochlea. The recovery was mostly complete and often started already during laser irradiation or at the end of the laser exposure. A marked sensitivity loss of the cochlea only occurred with large stapedotomy holes followed by massive perilymph leakage. A momentary heat related instability of the entire stapes is suggested to cause the CM depression. In addition we observed a thermoacoustic effect on the CM. This laser evoked response seems to cause no harm to the cochlea.