Ossicular chain defects in adults with chronic otitis media.

BACKGROUND AND OBJECTIVE: Chronic otitis media (COM) is a common condition characterized by the perforation of the tympanic membrane and inflammation of the mucosal lining the hollow space in the middle ear and airy spaces of the temporal bone for at least 2-6 week. This study was carried out to find out the status of the middle ear ossicles in patients with COM and to correlate their status with clinical parameters. METHODS: This retrospective clinical study was conducted on 107 COM patients (52 males and 55 females; age range: 18 to 75 years) submitted to surgery in the Otology Clinic at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran. Initially, a comprehensive case-history was obtained from patients and their hearing thresholds were recorded. Then, ossicles status and their junction condition were evaluated intraoperatively. RESULTS: The malleus was found intact in 70 (65.42%), absent in 10 (9.34), and eroded in 27 (25.24%) patients. Our results revealed that the incus was intact in 33 (30.84%), eroded in 55 (51.41%) and absent in 19 (17.75%) subjects. Stapes was found intact in 54 (50.46%) cases and eroded in 53 (49.54%) cases. The mean Pure Tone Average (PTA) and Air-Bone Gap (ABG) comparisons in "intact" and "discontinuous" ossicular chain groups was not significant (Independent sample t-test, p>0.05). CONCLUSION: Our results demonstrated that incus was the most susceptible middle ear ossicle to erosion in COM, whereas the malleus was the most resistant ossicle. Furthermore, ABG and PTA values cannot be considered as a potential preoperative predictor for ossicular chain status.

The pattern of Fos expression in the rat auditory brainstem changes with the temporal structure of binaural electrical intracochlear stimulation.

The immediate-early-gene c-fos with its protein product Fos has been used as a powerful tool to investigate neuronal activity and plasticity following sensory stimulation. Fos combines with Jun, another IEG product, to form the dimeric transcription factor activator protein 1 (AP-1) which has been implied in a variety of cellular functions like neuronal plasticity, apoptosis, and regeneration. The intracellular emergence of Fos indicates a functional state of nerve cells directed towards molecular and morphological changes. The central auditory system is construed to detect stimulus intensity, spectral composition, and binaural balance through neurons organized in a complex network of ascending, descending and commissural pathways. Here we compare monaural and binaural electrical intracochlear stimulation (EIS) in normal hearing and early postnatally deafened rats. Binaural stimulation was done either synchronously or asynchronously. The auditory brainstem of hearing and deaf rats responds differently, with a dramatically increasing Fos expression in the deaf group so as if the network had no pre-orientation for how to organize sensory activity. Binaural EIS does not result in a trivial sum of 2 independent monaural EIS, as asynchronous stimulation invokes stronger Fos activation compared to synchronous stimulation almost everywhere in the auditory brainstem. The differential response to synchronicity of the stimulation puts emphasis on the importance of the temporal structure of EIS with respect to its potential for changing brain structure and brain function in stimulus-specific ways.

Experimental study of vibrations of gerbil tympanic membrane with closed middle ear cavity.

The purpose of the present work is to investigate the spatial vibration pattern of the gerbil tympanic membrane (TM) as a function of frequency. In vivo vibration measurements were done at several locations on the pars flaccida and pars tensa, and along the manubrium, on surgically exposed gerbil TMs with closed middle ear cavities. A laser Doppler vibrometer was used to measure motions in response to audio frequency sine sweeps in the ear canal. Data are presented for two different pars flaccida conditions: naturally flat and retracted into the middle ear cavity. Resonance of the flat pars flaccida causes a minimum and a shallow maximum in the displacement magnitude of the manubrium and pars tensa at low frequencies. Compared with a flat pars flaccida, a retracted pars flaccida has much lower displacement magnitudes at low frequencies and does not affect the responses of the other points. All manubrial and pars tensa points show a broad resonance in the range of 1.6 to 2 kHz. Above this resonance, the displacement magnitudes of manubrial points, including the umbo, roll off with substantial irregularities. The manubrial points show an increasing displacement magnitude from the lateral process toward the umbo. Above 5 kHz, phase differences between points along the manubrium start to become more evident, which may indicate flexing of the tip of the manubrium or a change in the vibration mode of the malleus. At low frequencies, points on the posterior side of the pars tensa tend to show larger displacements than those on the anterior side. The simple low-frequency vibration pattern of the pars tensa becomes more complex at higher frequencies, with the breakup occurring at between 1.8 and 2.8 kHz. These observations will be important for the development and validation of middle ear finite-element models for the gerbil.

Malleostapedotomy in tympanosclerosis patients.

OBJECTIVES: 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. METHODS: Prospective study. RESULTS: 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. CONCLUSIONS: 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.

Malleus head fixation: histopathology revisited.

CONCLUSIONS: Malleus head fixation is a rare but not exceptional pathology. It may be apparently congenital or acquired, and can be associated with stapes fixation. In the acquired secondary process two histological types of malleus head fixation were found: the first corresponded to non-tympanosclerotic bone remodeling and the second to localized tympanosclerosis. OBJECTIVE: To describe the histopathologic features of malleus head fixation and to correlate them with its clinical appearance. MATERIAL AND METHODS: Ten patients with surgically proven malleus head fixation were included in this series. A fixed malleus head was resected via a transcanal approach in six patients, and attic bony fragments fixing the malleus head were removed via a mastoidectomy without disruption of the ossicular chain in four. Histopathologic studies were performed for both types of malleus head fixation. RESULTS: Three types of acquired malleus head fixation were defined in accordance with the surgical and histopathological findings. Histologically, the first type presented with normal bone tissue, the second was characterized by non-tympanosclerotic bone remodeling and the third presented with a localized tympanosclerotic focus in the tympanic cavity.

Tonic contractions of the tensor tympani muscle: a key to some non-specific middle ear symptoms? Hypothesis and data from temporal bone experiments.

CONCLUSIONS: The results of this study show that in clinical practice it will not be easy to diagnose tonic contractions of the tensor tympani muscle and only a combination of findings will be helpful. Based on these experimental results a clinical study will be started which should clarify the diagnostic relevance of indicators of tonic tensor muscle contractions. OBJECTIVES: There are indications from the literature and from personal experience that tonic contractions of the tensor tympani muscle may play a role in some ear symptoms, such as fullness, certain cases of tinnitus, slight hearing loss or Ménière's disease-like findings. In order to prove this theory we looked for indicators, either visual or functional, to help clinically diagnose the functional state of the muscle, particularly its tonic contraction. MATERIAL AND METHODS: Experiments simulating tensor contractions were carried out on temporal bone specimens. Traction was applied either to the isolated muscle, to its tendon or to the malleus neck. Effects were observed either visually via an endoscope or by impedance audiometry using multiple-frequency tympanometry. RESULTS: During simulated tensor traction the aspect of the tympanic membrane changed slightly, i.e. there was some inward movement of the umbo. However, such effects were only identifiable during the pulling action or by directly comparing the "contracted" and "relaxed" states. Tympanometry revealed a decrease in the peak amplitudes and a shift in the middle ear resonance towards higher frequencies during contractions.

Experimental and clinical studies of malleus fixation.

OBJECTIVES/HYPOTHESIS: Preoperative clinical diagnosis of malleus fixation can be difficult. "Fixation" of the malleus can be caused by various disorders or diseases: fibrous tissue, bony spurs, and neo-osteogenesis around the malleus head or stiffening of the anterior malleal ligament. The conductive hearing loss produced by these disorders or diseases has not been well characterized. The study goals were 1) to determine the effects of various types of malleus fixation using a cadaveric temporal bone preparation and 2) to assess the clinical utility of umbo velocity measurements in preoperative differential diagnosis of malleus fixation and stapes fixation. METHODS: Umbo and stapes velocity were measured in 18 fresh cadaveric human temporal bones with laser vibrometry before and after controlled application of adhesives to the malleus, stapes, or both ossicles. RESULTS: Each simulated pathological condition produced a specific degree of loss in stapes velocity: stiffening of anterior malleal ligament, 0 to 8 dB; fibrous tissue around malleus head, less than 10 dB; bony bar to malleus head, 10 to 30 dB; and extensive neo-osteogenesis around malleus head, greater than 35 dB. Simulated malleus fixations generally produced similar reductions in both umbo and stapes velocity. Stapes fixation reduced stapes velocity with little change in umbo velocity. Because the change in stapes velocity would be similar to conductive hearing loss, experimental results were directly compared with clinical measurements of umbo velocity in surgically confirmed cases of malleus or stapes fixation. The effects of malleus and stapes fixations between the clinical and experimental data were similar. CONCLUSION: The study showed that measurements of umbo velocity and air-bone gap can enable one to diagnose malleus fixation and specifies how to differentiate malleus from stapes fixation.

[Failure of regain full function after surgery for otosclerosis: causes, diagnosis and treatment]. / Echecs fonctionnels dans la chirurgie de l'otospongiose: causes, diagnostic et traitement.

OBJECTIVE: The aim of this study was to evaluate the causes, the diagnosis, the treatment and the results obtained by revision surgery, in cases of stapedectomy failures. MATERIALS AND METHODS: Retrospective study of 50 recent cases operated on between January 1997 and December 2001. DIAGNOSIS OF THE FAILURE: All reoperated patients had clinical and audiological assessment; CT scan with virtual endoscopy. RESULTS: The mean time of onset of failure was 23 months. The mean preoperative air bone gap was 25.5 dB. Otoscopy revealed a retraction pocket caused by poor eustachian tube function in 9 cases. CT scan proved to be very effective at differentiating the cause of the failure. OPERATIVE FINDINGS: In 11 cases the prosthesis was too short, in 8 cases the prosthesis had migrated out of the hole of stapedotomy and in 6 cases the piston was fixed in the stapedotomy hole. A partial or complete lysis of the long process of the incus was frequently associated, but in 9 cases it was the only cause of the failure. In all the cases when the piston was displaced, the stapedotomy was found to be covered by a thin mucous membrane, avoiding labyrinthine fistula. In 3 cases, the failure was due to recurrent otosclerosis. In 5 cases the failure was due to a local anomaly at the level of the oval window niche, 2 cases of failure were due to a malleus ankylosis. In 5 cases fibrous adhesion was found between the incus and the mucosa of the promontory. In one case a reparative granuloma was found at the level of the oval window. TREATMENT: In cases of partial lysis of the long process of the incus, a new prosthesis was placed in a 0.4 mm diameter stapedotomy, performed using a KTP laser. A 0.4 mm diameter piston was extended 0.2 mm below stapedotomy to avoid a new extrusion. Indeed some prosthesis extrusion could be due to increased movements of the ossicular chain in cases of eustachian tube dysfunction. In cases of complete lysis of the long process of the incus, or in cases of a very short long process of the incus, a piston was put in the stapedotomy and attached to the malleus manubrium. The results of revision stapedotomy were favorable in the absence of associated fibrous tissue adhesion or local malformation. The air bone gap was found to be less than 10 dB in 40 cases and between 10 and 20 dB in 8 cases. An impairment of the air bone gap was found in 2 cases. No case of bone conduction impairment was found in this series.

[Auditory brainstem responses evoked by direct mechanical stimulation of the ossicular chain. Objective preoperative testing of candidates for implantable hearing aids]. / Frühe akustisch evozierte Potenziale bei direkter mechanischer Stimulation der Gehörknöchelchenkette. Objektive Eignungsdiagnostik vor Implantation von Hörsystemen.

BACKGROUND AND OBJECTIVE: The function of several implantable hearing systems is based on the vibratory excitation of the ossicular chain. For preoperative testing, malleus vibration audiometry has been described [7]. In special cases, it could be desirable to perform objective testing before implantation. We therefore studied the auditory brainstem responses (ABR) evoked by vibratory stimulation of the ear drum. METHOD: The ABR evoked by vibratory and acoustical click stimulation were recorded in 20 subjects with normal hearing at four different stimulus intensities. For the vibratory stimulation (v-ABR), the transducer rod was brought into mechanical contact with the eardrum under microscopic control. This setup was further used for the determination of the individual subjective threshold. The v-ABR were compared to conventional ABR recordings. RESULTS: In all subjects, the v-ABR could clearly be identified. At high stimulus levels, the complete wave pattern was observed in 15 of 20 cases. There is no essential difference between v-ABR and conventional ABR with respect to the incidence and parameters of the potentials. At high stimulus levels, a pronounced stimulus artefact impedes the identification of wave I in some cases. Moreover, the quality of v-ABR is limited by the uncomfortable situation and incomplete relaxation of the subject. CONCLUSIONS: The measurement of vibratory evoked ABR is practicable without hazards for the patient and it yields reliable results. The hearing threshold for click stimuli can be determined from the incidence and amplitude of the responses. The loudness associated with the click stimuli can be estimated from the response latency. Therefore, the investigation of v-ABR not only gives evidence of the individual suitability for implantable hearing aids but its outcome may also be useful as an orientation for the postoperative fitting.

Laser-assisted tympanoplasty for preservation of the ossicular chain in cholesteatoma.

We report the use of potassium titanyl phosphate laser-assisted tympanoplasty in amputations of the malleus and incus in 2 patients with cholesteatoma medial to those ossicles that had not destroyed the ossicular chain continuity. In both cases, the laser successfully removed portions of the ossicles to allow removal of the cholesteatoma; importantly, the laser preserved certain ossicular ligaments, thus keeping the ossicular chain continuous. Postoperatively, both patients showed satisfactory hearing. Although the prevalence of cholesteatoma medial to the ossicles with maintained ossicular continuity is limited, the laser-assisted procedure described here is useful for maintaining hearing ability in these cases.

[Fixed mallear head syndrome]. / Le syndrome de la tête du marteau fixée.

Fixed head malleus syndrome is a rare anatomoclinical entity first described by Goodhill in 1966. We present a series of 9 patients who underwent surgery between 1991 and 1997 and discuss the technical procedures used and functional outcome. Ossicular mobility can be re-established with two surgical methods. The more simple method consists in a classical incus transposition with malleus neck section. The more physiological method consists in drilling the synostosis fixing the malleus without disrupting the ossicular chain; stapedotomy is associated in certain cases (Type III).

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

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

Middle ear involvement in children with chronic rheumatoid juvenile arthritis.

In a selected sample of patients affected by juvenile rheumatoid arthritis (JRA) little is known about middle ear involvement, even though many synovial joints are affected. Multifrequency tympanometry was used to measure admittance, conductance, susceptance and phase angle at different probe frequencies and resonant frequencies. In all, 35 children with JRA and a control group (30 children) were studied. Findings showed that mean resonant frequency values in all children with JRA were greater than in the control children. The multifrequency tympanometry parameters measured in acute JRA subjects are not different from parameters of remission JRA subjects except for a change in the phase angle. The changes found are due to involvement of the incudomalleolar and incudostapedial joints.

Middle ear transmission disorders--tympanic membrane vibration analysis by laser-Doppler-vibrometry.

Laser-Doppler-vibrometry is a useful method to measure vibrations of the tympanic membrane. It is suitable to objectively diagnose the middle ear. In comparison to tympanometry, laser-Doppler-vibrometry has greater sensitivity. Temporal bone specimens were specially prepared to simulate middle ear disorders like middle ear effusion, fixation of the malleus head, fixation of the stapes footplate and removal of the incus. A correlation between the displacement function of the umbo and the experimentally produced middle ear disorders could be demonstrated. For the first time it was possible to measure the vibration of the tympanic membrane by using a laser-Doppler-vibrometer in a healthy 25-year-old male.

Malleus head fixation: association with pseudohypoparathyroidism.

Pseudohypoparathyroidism (PHP) is a heterogenous syndrome resulting from bone and renal resistance to parathyroid hormone (PTH). Hypocalcemia and hyperphosphatemia occur despite elevated PTH levels. Head and neck manifestations of PHP include tetany, laryngeal spasm, and ectopic calcification in the eye, dentition, subcutaneous tissue and brain. The first case of malleus head fixation caused by ectopic calcification in a PHP patient is reported. Normalization of serum calcium and phosphate levels does not appear to retard or correct this abnormality. Ossiculoplasty or amplification is currently the recommended treatment in PHP patients with malleus head fixation.

The mechanics of the middle-ear at static air pressures: the role of the ossicular joints, the function of the middle-ear muscles and the behaviour of stapedial prostheses.

In an experimental study, the mechanical behaviour of the ossicle-chain during changes of the static air pressure was analyzed microscopically and with a radiographic magnification technique in temporal bone preparations. Several preliminary experiments served to pinpoint methodological problems, like exsiccation-artifacts, storage procedures, preparation defects, missing air-cushion effect with the opened middle-ear cavity, absent labyrinthine pressure, relation of the optical axis to middle-ear structures and statistical reproducibility of the measured values. Variations of the static air pressure in the external ear canal ranging from 0 to +/- 400 mmH2O induce an inward-outward movement of the malleus. In the regular middle-ear, the direction of this movement is changed within the ossicular chain into a predominantly upward-downward direction of the lenticular process, due to a gliding function of the incudo-malleal (IM) joint. This results in a gliding movement of the surfaces of the incudostapedial joint (IS). In this way, the stapes and the inner-ear are decoupled from the excessive displacements of the drum membrane and malleus. This change in the mode of motion explains many former results of ossicle vibration, aroused by unphysiologically high sound pressures, like v. Békésy's description of the tilting footplate. This mode of motion, however, changes completely if the gliding function of the IM-joint is cancelled by experimental ankylosis. In that case, the predominant direction of movement at the incus and stapes is inward and outward, too. This mode of motion has been the generally accepted concept of the ossicle-chain mechanics up to now. This isodirectional motion also occurs with progressive exsiccation of the temporal bone preparations, explicable with drying and shrinking of the capsular ligament of the IM-joint. It is conceivable, therefore, that our concepts of the mechanics of the ossicle-chain were partly based on experiments with insufficiently moistened temporal bone preparations, as the methodological problem of the exsiccation became known only during recent decades. In further experiments with static air pressure, the mechanics of the reconstructed ossicle-chain, i.e. tympanoplasty and stapedial prostheses, were studied. In the columella-like chain reconstruction, the displacement of the stapes equals the values measured with the ankylosed IM-joint. This displacement is limited by the strength of the annular ligament, whose function, however, is eliminated in the case of stapedial prostheses. Now the displacement is limited by the friction of the piston at the perforation in the footplate.(ABSTRACT TRUNCATED AT 400 WORDS)

Attenuation and protection provided by ossicular removal.

Behavioral studies of hearing loss produced by exposure to ototraumatic agents in experimental animals, combined with the anatomical evaluation of end-organ pathology, have provided useful information about the relation between dysfunction and pathology. However, in order to attribute a given hearing loss to some pattern of cochlear damage, it is necessary to test each ear independently. The objective of the present study was to evaluate attenuation measured behaviorally and protection to the cochlea provided by removal of the malleus and incus in noise-exposed chinchillas. Results from one behaviorally trained chinchilla with ossicular removal indicated a conductive hearing loss that varied from 41 dB at 0.125 kHz to 81 dB at 4.8 kHz and averaged 60 dB. Counts of missing sensory cells in ears of seven chinchillas with unilateral ossicular removal and exposure to noise (octave band centered at 0.5 kHz, 95 dB SPL, for durations up to 216 days, or centered at 4.0 kHz, 108 dB SPL, for 1.75 h) showed no more cell loss on the protected side than in age-matched control ears. From these data it is concluded that ossicular removal provides enough attenuation to protect the chinchilla cochlea from damage during these noise exposures, and that it will insure monaural responses behaviorally as long as the hearing loss in the test ear does not exceed that in the ear with ossicular removal by approximately 50 dB at any frequency.

Sound pickup utilizing an implantable piezoelectric ceramic bimorph element: application to the cochlear implant.

The degree of sound pickup possible with a piezoelectric ceramic bimorph element ( PCBE ) was tested as part of research on a total implantation system for a cochlear prosthesis. The PCBE functions as an electromechanical transducer and can be utilized as a device to sense vibration in the tympanic membrane by touching it to the malleus head. This method lends itself to the miniaturization and simplification required by an implantable device for sound pickup. The ability of the PCBE to function as a device to pick up sound was investigated using three normal human temporal bones. The sensitivity of the PCBE when coupled to the malleus was calculated as the ratio of the voltage generated by the PCBE to the sound pressure in front of the tympanic membrane, when these factors were processed with a spectrum analyzer. The best sensitivities registered with the three temporal bone specimens were -63, -61, -59 dB re 1 V/Pa, respectively, at 1 kHz. The frequency response curves had resonant frequencies at about 2 kHz and declined beyond 5 kHz. These results indicate that a PCBE coupled to the malleus head performs satisfactorily in regard to sound pickup and shows promise as a component of a totally implanted hearing system.

Malleus handle probe: a middle ear diagnostic procedure.

Manual probing of the malleus handle (MH) of 477 patients suggests a protective middle ear reflex with a variable tonic contraction of the tensor tympani muscle (TTM). The degree and type of MH retraction suggests three stages of progressive middle ear inflammation. Prediction accuracy of 250 myringotomy findings was 60% with impedance audiometry and 92% with MH probing. Mechanical pressure gauge readings (grams) of 202 ears correlated with finger pressure estimations. The TTM tendons were sectioned in ten children with persisting otitis media with effusion (OME) and seven obtained benefit. The three diagnostic methods, pneumatic otoscopy, impedance audiometry and MH probing, assess similar and separate perimeters and are complementary. Malleus handle probing alone detects attic loculation of OME, 54 of 954 ears (5.6%). it extends the diagnostic range to the TTM activities.