Pathologocal changes in the middle ear joints

Influence of ambient air pressure changes on vestibular symptoms after stapes surgery

OBJECTIVE

To examine if vestibular irritation after stapes surgery may be provoked by pressure changes across the tympanic membrane, which consecutively results in displacements of the ossicular chain and the piston prosthesis suspended to it.

METHODS

In this prospective study 15 patients (13 female, 2 male) received unilateral stapes surgery (4 left, 11 right ear) with stapedotomy (n=14) or stapedectomy (n=1) at an academic tertiary referral center. Surgery was performed under local anesthesia via a transmeatal approach with a piston prosthesis 0.4×4.5mm. The fixation of the stapes, the exclusion of a malleus head fixation, and the gliding capacity of the malleus-incus joint were examined intraoperatively. A pure tone audiogram at four frequencies, a tympanometry with simultaneous video-oculography (VOG), caloric testing, and posturography with and without simultaneous tympanometry were performed six days before surgery, six weeks and three months after surgery, respectively.

RESULTS

The mean air bone gap improved significantly from 25 (±8) dB preoperatively to 10 (±6) dB after surgery. In the tympanometry with simultaneous VOG only two patients showed nystagmus beats into the operated ears during only one of the two follow-up appointments. All other patients did not show any vestibular symptoms or nystagmus during any of the follow-up appointments. In the combined testing of posturography and tympanometry no patient showed any pathological findings.

CONCLUSION

In patients who underwent stapes surgery with a piston prosthesis no vestibular symptoms can be provoked by pressure changes in the external auditory canal.

Human ossicular-joint flexibility transforms the peak amplitude and width of impulsive acoustic stimuli

The role of the ossicular joints in the mammalian middle ear is still debated. This work tests the hypothesis that the two synovial joints filter potentially damaging impulsive stimuli by transforming both the peak amplitude and width of these impulses before they reach the cochlea. The three-dimensional (3D) velocity along the ossicular chain in unaltered cadaveric human temporal bones (N = 9), stimulated with acoustic impulses, is measured in the time domain using a Polytec (Waldbronn, Germany) CLV-3D laser Doppler vibrometer. The measurements are repeated after fusing one or both of the ossicular joints with dental cement. Sound transmission is characterized by measuring the amplitude, width, and delay of the impulsive velocity profile as it travels from the eardrum to the cochlea. On average, fusing both ossicular joints causes the stapes velocity amplitude and width to change by a factor of 1.77 (p = 0.0057) and 0.78 (p = 0.011), respectively. Fusing just the incudomalleolar joint has a larger effect on amplitude (a factor of 2.37), while fusing just the incudostapedial joint decreases the stapes velocity on average. The 3D motion of the ossicles is altered by fusing the joints. Finally, the ability of current computational models to predict this behavior is also evaluated.

Flexibility within the middle ears of vertebrates

INTRODUCTION AND AIMS

Tympanic middle ears have evolved multiple times independently among vertebrates, and share common features. We review flexibility within tympanic middle ears and consider its physiological and clinical implications.

COMPARATIVE ANATOMY

The chain of conducting elements is flexible: even the 'single ossicle' ears of most non-mammalian tetrapods are functionally 'double ossicle' ears due to mobile articulations between the stapes and extrastapes; there may also be bending within individual elements.

SIMPLE MODELS

Simple models suggest that flexibility will generally reduce the transmission of sound energy through the middle ear, although in certain theoretical situations flexibility within or between conducting elements might improve transmission. The most obvious role of middle-ear flexibility is to protect the inner ear from high-amplitude displacements.

CLINICAL IMPLICATIONS

Inter-ossicular joint dysfunction is associated with a number of pathologies in humans. We examine attempts to improve prosthesis design by incorporating flexible components.

Otosclerosis and stapedoplasty in older adults

OBJECTIVES

To evaluate the efficacy of stapedoplasty in patients aged 60 and older, based on audiometric data and a questionnaire about quality of life.

DESIGN

A retrospective (1994-2000) study.

SETTING

People living in southern and central Italy.

PARTICIPANTS

Sixty-three patients: 32 consecutive patients aged 60 and older (group 1) and 31 consecutive patients younger than 60 (group 2).

MEASUREMENTS

In each patient, we evaluated the pre- and postoperative auditory thresholds. Each patient answered a questionnaire about postoperative quality of life.

RESULTS

When comparing the pre- and postoperative air conduction thresholds and air-bone gap in the patients aged 60 and older, a statistically significant (P <.001) improvement at each frequency was observed. When elaborating the answers to the questionnaire about postoperative quality of life, we noticed that the older patients experienced a greater improvement.

CONCLUSION

The results show that stapedoplasty offers greater improvement in quality of life for selected adults aged 60 and older than for younger adults. The operation also appears to be as safe for adults aged 60 and older as for younger adults. Stapedoplasty provides subjects with satisfactory social hearing level (hearing capacity sufficient for normal social relations) and slows the progression of otosclerosis. Providing older patients with good auditory functionality improves their state of health, quality of life, and cognitive processes.

Luetic hearing loss: clinical presentation, diagnosis, and treatment

Luetic hearing loss, a relatively rare disorder, is significant because it is one of the few forms of progressive sensorineural hearing loss that may be reversed if diagnosed early and accurately and treated aggressively. With the increased incidence of systemic syphilis over the past few decades, the otolaryngologist can expect otosyphilis to appear more frequently. This report reviews the clinical presentation, histopathology, diagnostic workup, and current therapy for this disorder.

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)

Predictive value of serologic tests for syphilis in otology

Otologic syphilis (luetic inner ear disease) usually is diagnosed by positive serologic tests and by exclusion of other possible causes. Because the FTA-ABS for syphilis is exquisitely sensitive in all but early primary cases, a positive FTA-ABS result and coincident inner ear disease often are thought to be diagnostic of syphilitic inner ear disease. The result is a management dilemma: are there false-positive results in misdiagnosed cases? Over 4 years, the authors performed a prospective study with time-matched controls to determine the predictive value of serologic tests and prevalence of syphilis in otology. Thirty-one cases of otologic syphilis were diagnosed in 5,439 new (different) patients with otologic complaints. In the geographic area studied, this prevalence (570/100,000) was 25-fold greater than that of all reported cases of syphilis in the general population (22.7/100,000). The defined sensitivity of the FTA-ABS (100%) was nearly twofold greater than the measured sensitivity of the rapid plasma reagin (RPR, 55%) in otologic syphilis. Specificities were comparable; therefore, a positive FTA-ABS had higher predictive value than a positive RPR. The prevalence-related predictive value of a positive FTA-ABS (22%) was more than twice that of the RPR (9%) in otology. The predictive value of a positive FTA-ABS in otology was 11-fold greater than that of the FTA-ABS in the general population (2%). Therefore, in suspect cases the FTA-ABS should be used to screen for otologic syphilis in an otologic practice. At a prevalence of 570 cases in 100,000 patients, only 22% of otologic patients with positive FTA-ABS results actually have otologic syphilis. Because disease morbidity can be far worse than treatment morbidity, however, positive results should be considered true-positives to avoid misdiagnosis in potentially infected patients. In suspect cases with positive FTA-ABS, therefore, treatment should be recommended unless specific contraindications exist.

Alterations in auditory processing of speech stimuli during aging in healthy subjects

Studies of auditory processing during aging in man have not provided a consensus on whether aging affects the ability to process speech stimuli. To evaluate the relationship between speech recognition tasks and age, we examined 36 male subjects between the ages of 21 and 83 years, who were screened for the absence of disease, particularly in the cardiovascular and neurologic systems. Measures were obtained on the following tests: pure tone thresholds, speech reception threshold, speech discrimination, low-pass filtered speech, and binaural fusion. A statistically significant correlation was found between pure tone thresholds and age for all frequencies. When the effect of peripheral hearing loss was taken into account, speech measures did not correlate with age, with the exception of low-pass filtered speech in the left ear. Our findings suggest that the aging process in healthy man is not necessarily accompanied by deficits in the processing of speech stimuli beyond those which are due to peripheral hearing loss.

Auditory brainstem responses (ABR) in the aged

86 male subjects, aged between 60 and 86 years (M = 69.5), underwent pure-tone audiometry, impedance tests and brainstem response audiometry (BRA). Subjects have been classified into four age-related groups: 1) 34 subjects, aged between 60 and 65; 2) 22, aged between 66 and 70; 3) 22 aged between 71 and 75; 4) 8, aged between 76 and 86. They have also been classified into four groups on the basis of their mean auditory threshold at 0.5, 1, 2, 4 and 8 kHz: 1) 14 subjects with mean auditory threshold less than or equal to 30 dB HL; 2) 16, between 31 and 40; 3) 24, between 41 and 50; 4) 32, with mean auditory threshold greater than or equal to 51 dB HL. 19 normally hearing adults, aged between 28 and 42, were chosen as controls. Statistically significant correlations have been found between age and mean auditory threshold (P less than or equal to 0.001), between wave latency V and age (P less than or equal to 0.001), between wave latency V and the mean pure-tone auditory threshold at 0.5, 1, 2, 4 and 8 kHz (P less than or equal to 0.001) and between the V-I interval and age (P less than or equal to 0.001). The discrepancy between the mean auditory threshold and the ABR waveform, the overall amplitude's reduction of ABR waves and the progressive lengthening of V-I interval values, seem to indicate that age-related changes involve not only the end organ but also the brainstem auditory structures.

Pathology of congenital syphilitic labyrinthitis

An alarming increase in the incidence of syphilitic labyrinthitis has prompted us to review the pathology of this condition. The temporal bones of two patients with congenital syphilis of the ear were studied histopathologically. They showed diffuse osteitic changes in the otic capsule associated with severe hydrops and degeneration of the membranous labyrinth. The posterosuperior wall of the external auditory canal as well as the auditory ossicles showed numerous connective tissue filled spaces surrounded by thin bony trabeculae. These lesions probably represent healed luetic osteitis. There was severe degeneration of the sensorineural structures in the cochlea. A finding of particular interest was the infiltration and fibrous obliteration of the ductus endolymphaticus in both cases. The significance of these findings in relation to the pathophysiology and treatment of syphilitic labyrinthitis is emphasized.