Superior Canal Dehiscence Similarly Affects Cochlear Pressures in Temporal Bones and Audiograms in Patients.

OBJECTIVES: The diagnosis of superior canal dehiscence (SCD) is challenging and audiograms play an important role in raising clinical suspicion of SCD. The typical audiometric finding in SCD is the combination of increased air conduction (AC) thresholds and decreased bone conduction thresholds at low frequencies. However, this pattern is not always apparent in audiograms of patients with SCD, and some have hearing thresholds that are within the normal reference range despite subjective reports of hearing impairment. In this study, we used a human temporal bone model to measure the differential pressure across the cochlear partition (PDiff) before and after introduction of an SCD. PDiff estimates the cochlear input drive and provides a mechanical audiogram of the temporal bone. We measured PDiff across a wider frequency range than in previous studies and investigated whether the changes in PDiff in the temporal bone model and changes of audiometric thresholds in patients with SCD were similar, as both are thought to reflect the same physical phenomenon. DESIGN: We measured PDiff across the cochlear partition in fresh human cadaveric temporal bones before and after creating an SCD. Measurements were made for a wide frequency range (20 Hz to 10 kHz), which extends down to lower frequencies than in previous studies and audiograms. PDiff = PSV- PST is calculated from pressures measured simultaneously at the base of the cochlea in scala vestibuli (PSV) and scala tympani (PST) during sound stimulation. The change in PDiff after an SCD is created quantifies the effect of SCD on hearing. We further included an important experimental control-by patching the SCD, to confirm that PDiff was reversed back to the initial state. To provide a comparison of temporal bone data to clinical data, we analyzed AC audiograms (250 Hz to 8kHz) of patients with symptomatic unilateral SCD (radiographically confirmed). To achieve this, we used the unaffected ear to estimate the baseline hearing function for each patient, and determined the influence of SCD by referencing AC hearing thresholds of the SCD-affected ear with the unaffected contralateral ear. RESULTS: PDiff measured in temporal bones (n = 6) and AC thresholds in patients (n = 53) exhibited a similar pattern of SCD-related change. With decreasing frequency, SCD caused a progressive decrease in PDiff at low frequencies for all temporal bones and a progressive increase in AC thresholds at low frequencies. SCD decreases the cochlear input drive by approximately 6 dB per octave at frequencies below ~1 kHz for both PDiff and AC thresholds. Individual data varied in frequency and magnitude of this SCD effect, where some temporal-bone ears had noticeable effects only below 250 Hz. CONCLUSIONS: We found that with decrease in frequency the progressive decrease in low-frequency PDiff in our temporal bone experiments mirrors the progressive elevation in AC hearing thresholds observed in patients. This hypothesis remains to be tested in the clinical setting, but our findings suggest that that measuring AC thresholds at frequencies below 250 Hz would detect a larger change, thus improving audiograms as a diagnostic tool for SCD.

Long-term Incidence and Degree of Sensorineural Hearing Loss in Otosclerosis.

OBJECTIVES: 1) To evaluate the long-term incidence and degree of the sensorineural component of hearing loss (SNHL) in patients with otosclerosis after accounting for expected age-related hearing loss. 2) To identify variables that might predict development of sensorineural hearing loss due to otosclerosis. STUDY DESIGN: Retrospective audiometric database and chart review. SETTING: Tertiary referral center. PATIENTS: Consecutive patients with otosclerosis observed between 1994 and 2004, with ≥10 years follow-up, excluding patients with postoperative hearing loss or surgery before the initial audiogram. INTERVENTION: Bone conduction (BC) thresholds at 0.5, 1, 2, and 4 kHz and Word Recognition. MAIN OUTCOME MEASURE: BC threshold change (BCTC) over ≥10 years minus estimated age-related threshold change (ARTC) specific to age and sex for each patient (based on ISO 7029 reference population). RESULTS: Three-hundred fifty-seven ears (290 patients) met study criteria, including 217 ears that had undergone stapedectomy during the study period. Mean follow-up was 14.0 years. The average BCTC after subtracting estimated ARTC was 4.6, 2.6, 3, and 2.7 dB for 0.5, 1, 2, and 4 kHz frequencies, respectively. However, 34% of ears (122 ears) had clinically significant progression of SNHL during the study period (>10 dB BCTC beyond expected ARTC at ≥2 frequencies). Multivariate analysis demonstrated that the probability of developing clinically significant SNHL was higher for women (odds ratio 1.86, p = 0.018) and lower for operated patients (odds ratio 0.46, p = 0.002). CONCLUSION: The average long-term sensorineural hearing loss due to otosclerosis was statistically significantly more than for age alone at each frequency, but these average values (from 2.6 to 4.6 dB for tested frequencies) were clinically insignificant. Approximately one-third of patients with otosclerosis demonstrated a clinically significant progression of the sensorineural component of hearing loss, with the average BCTC above expected age-related changes ranging from 10.2 to 14.6 dB for tested frequencies among this subgroup.

How Often Does Stapedectomy for Otosclerosis Result in Endolymphatic Hydrops?

OBJECTIVES: 1) To evaluate the long-term (≥10 year) clinical incidence of endolymphatic hydrops (EH) after stapedectomy for otosclerosis, using low-frequency sensorineural hearing loss (LFSNHL) as a marker for EH. 2) To determine the histologic incidence of EH in human temporal bone specimens (TBS) with a history of stapedectomy for otosclerosis. 3) To determine the histologic incidence of EH in a control group of human TBS. STUDY DESIGN: Retrospective review and temporal bone study. SETTING: Tertiary medical center and temporal bone pathology laboratory. PATIENTS: Patients with otosclerosis, human TBS with otosclerosis, and human TBS with presbycusis as the control group. INTERVENTION: Pure-tone audiometry, temporal bone pathology. MAIN OUTCOME MEASURES: 1) LFSNHL, defined as >10 decibel elevation of bone conduction thresholds at 250 and 500 Hz, after correcting for age-related hearing loss (per ISO 7029). 2) Histologic assessment of EH. RESULTS: In patients with otosclerosis, 8 of 110 (7.3%) operated patients versus 3 of 123 (2.4%) nonoperated patients developed LFSNHL (p = 0.08). No patients with LFSNHL had other symptoms of EH. In TBS with otosclerosis, 11 of 93 (11.8%) operated TBS versus 3 of 156 (1.9%) nonoperated TBS had evidence of EH (p <0.001). In the control group of TBS with presbycusis, 9 of 253 (3.5%) had EH. CONCLUSION: The long-term incidence of LFSNHL, a marker for EH, in patients with otosclerosis was not significantly higher in those who underwent stapedectomy. The histologic incidence of EH, however, was significantly higher in TBS that had undergone stapedectomy compared with nonoperated TBS or a control group of TBS.

The Audiometric and Mechanical Effects of Partial Ossicular Discontinuity.

OBJECTIVES: Ossicular discontinuity may be complete, with no contact between the disconnected ends, or partial, where normal contact at an ossicular joint or along a continuous bony segment of an ossicle is replaced by soft tissue or simply by contact of opposing bones. Complete ossicular discontinuity typically results in an audiometric pattern of a large, flat conductive hearing loss. In contrast, in cases where otomicroscopy reveals a normal external ear canal and tympanic membrane, high-frequency conductive hearing loss has been proposed as an indicator of partial ossicular discontinuity. Nevertheless, the diagnostic utility of high-frequency conductive hearing loss has been limited due to gaps in previous research on the subject, and clinicians often assume that an audiogram showing high-frequency conductive hearing loss is flawed. This study aims to improve the diagnostic utility of high-frequency conductive hearing loss in cases of partial ossicular discontinuity by (1) making use of a control population against which to compare the audiometry of partial ossicular discontinuity patients and (2) examining the correlation between high-frequency conductive hearing loss and partial ossicular discontinuity under controlled experimental conditions on fresh cadaveric temporal bones. Furthermore, ear-canal measurements of umbo velocity and wideband acoustic immittance measurements were investigated to determine the usefulness regarding diagnosis of ossicular discontinuity. DESIGN: The authors analyzed audiograms from 66 patients with either form of surgically confirmed ossicular discontinuity and no confounding pathologies. The authors also analyzed umbo velocity (n = 29) and power reflectance (n = 12) measurements from a subset of these patients. Finally, the authors performed experiments on six fresh temporal bone specimens to study the differing mechanical effects of complete and partial discontinuity. The mechanical effects of these lesions were assessed via laser Doppler measurements of stapes velocity. In a subset of the specimen (n = 4), wideband acoustic immittance measurements were also collected. RESULTS: (1) Calculations comparing the air-bone gap (ABG) at high and low frequencies show that when high-frequency ABGs are larger than low-frequency ABGs, the surgeon usually reported soft-tissue bands at the point of discontinuity. However, in cases with larger low-frequency ABGs and flat ABGs across frequencies, some partial discontinuities as well as complete discontinuities were reported. (2) Analysis of umbo velocity and power reflectance (calculated from wideband acoustic immittance) in patients reveal no significant difference across frequencies between the two types of ossicular discontinuities. (3) Temporal bone experiments reveal that partial discontinuity results in a greater loss in stapes velocity at high frequencies when compared with low frequencies, whereas with complete discontinuity, large losses in stapes velocity occur at all frequencies. CONCLUSION: The clinical and experimental findings suggest that when encountering larger ABGs at high frequencies when compared with low frequencies, partial ossicular discontinuity should be considered in the differential diagnosis.

Comparison of ear-canal reflectance and umbo velocity in patients with conductive hearing loss: a preliminary study.

OBJECTIVE: The goal of the present study was to investigate the clinical utility of measurements of ear-canal reflectance (ECR) in a population of patients with conductive hearing loss in the presence of an intact, healthy tympanic membrane and an aerated middle ear. We also sought to compare the diagnostic accuracy of umbo velocity (VU) measurements and measurements of ECR in the same group of patients. DESIGN: This prospective study comprised 31 adult patients with conductive hearing loss, of which 14 had surgically confirmed stapes fixation due to otosclerosis, 6 had surgically confirmed ossicular discontinuity, and 11 had computed tomography and vestibular evoked myogenic potential confirmed superior semicircular canal dehiscence (SCD). Measurements on all 31 ears included pure-tone audiometry for 0.25 to 8 kHz, ECR for 0.2 to 6 kHz using the Mimosa Acoustics HearID system, and VU for 0.3 to 6 kHz using the HLV-1000 laser Doppler vibrometer (Polytec Inc, Waldbronn, Germany). We analyzed power reflectance |ECR| as well as the absorbance level = 10 × log10(1 - |ECR|). All measurements were made before any surgical intervention. The VU and ECR data were plotted against normative data obtained in a companion study of 58 strictly defined normal ears (). RESULTS: Small increases in |ECR| at low-to-mid frequencies (400-1000 Hz) were observed in cases with stapes fixation, while narrowband decreases were seen for both SCD and ossicular discontinuity. The SCD and ossicular discontinuity differed in that the SCD had smaller decreases at mid-frequency (∼1000 Hz), whereas ossicular discontinuity had larger decreases at lower frequencies (500-800 Hz). SCD tended to have less air-bone gap at high frequencies (1-4 kHz) compared with stapes fixation and ossicular discontinuity. The |ECR| measurements, in conjunction with audiometry, could successfully separate 28 of the 31 cases into the three pathologies. By comparison, VU measurements, in conjunction with audiometry, could successfully separate various pathologies in 29 of 31 cases. CONCLUSIONS: The combination of |ECR| with audiometry showed clinical utility in the differential diagnosis of conductive hearing loss in the presence of an intact tympanic membrane and an aerated middle ear and seems to be of similar sensitivity and specificity to measurements of VU plus audiometry. Additional research is needed to expand upon these promising preliminary results.

Ear-canal reflectance, umbo velocity, and tympanometry in normal-hearing adults.

OBJECTIVE: This study compares measurements of ear-canal reflectance (ECR) to other objective measurements of middle ear function including audiometry, umbo velocity (VU), and tympanometry in a population of strictly defined normal-hearing ears. DESIGN: Data were prospectively gathered from 58 ears of 29 normal-hearing subjects, 16 females and 13 males, aged 22 to 64 yr. Subjects met all of the following criteria to be considered as having normal hearing: (1) no history of significant middle ear disease; (2) no history of otologic surgery; (3) normal tympanic membrane on otoscopy; (4) pure-tone audiometric thresholds of 20 dB HL or better for 0.25 to 8 kHz; (5) air-bone gaps no greater than 15 dB at 0.25 kHz and 10 dB for 0.5 to 4 kHz; (6) normal, type-A peaked tympanograms; and (7) all subjects had two "normal" ears (as defined by these criteria). Measurements included pure-tone audiometry for 0.25 to 8 kHz, standard 226 Hz tympanometry, ECR for 0.2 to 6 kHz at 60 dB SPL using the Mimosa Acoustics HearID system, and umbo velocity (VU) for 0.3 to 6 kHz at 70 to 90 dB SPL using the HLV-1000 laser Doppler vibrometer (Polytec Inc). RESULTS: Mean power reflectance (|ECR|) was near 1.0 at 0.2 to 0.3 kHz, decreased to a broad minimum of 0.3 to 0.4 between 1 and 4 kHz, and then sharply increased to almost 0.8 by 6 kHz. The mean pressure reflectance phase angle (∠ECR) plotted on a linear frequency scale showed a group delay of approximately 0.1 msec for 0.2 to 6 kHz. Small significant differences were observed in |ECR| at the lowest frequencies between right and left ears and between males and females at 4 kHz. |ECR| decreased with age but reached significance only at 1 kHz. Our ECR measurements were generally similar to previous published reports. Highly significant negative correlations were found between |ECR| and VU for frequencies below 1 kHz. Significant correlations were also found between the tympanometrically determined peak total compliance and |ECR| and VU at frequencies below 1 kHz. The results suggest that middle ear compliance contributes significantly to the measured power reflectance and umbo velocity at frequencies below 1 kHz but not at higher frequencies. CONCLUSIONS: This study has established a database of objective measurements of middle ear function (ECR, umbo velocity, tympanometry) in a population of strictly defined normal-hearing ears. These data will promote our understanding of normal middle ear function and will serve as a control for comparison to similar measurements made in pathological ears.

Oral vs intratympanic corticosteroid therapy for idiopathic sudden sensorineural hearing loss: a randomized trial.

CONTEXT: Idiopathic sudden sensorineural hearing loss has been treated with oral corticosteroids for more than 30 years. Recently, many patients' symptoms have been managed with intratympanic steroid therapy. No satisfactory comparative effectiveness study to support this practice exists. OBJECTIVE: To compare the effectiveness of oral vs intratympanic steroid to treat sudden sensorineural hearing loss. DESIGN, SETTING, AND PATIENTS: Prospective, randomized, noninferiority trial involving 250 patients with unilateral sensorineural hearing loss presenting within 14 days of onset of 50 dB or higher of pure tone average (PTA) hearing threshold. The study was conducted from December 2004 through October 2009 at 16 academic community-based otology practices. Participants were followed up for 6 months. INTERVENTION: One hundred twenty-one patients received either 60 mg/d of oral prednisone for 14 days with a 5-day taper and 129 patients received 4 doses over 14 days of 40 mg/mL of methylprednisolone injected into the middle ear. MAIN OUTCOME MEASURES: Primary end point was change in hearing at 2 months after treatment. Noninferiority was defined as less than a 10-dB difference in hearing outcome between treatments. RESULTS: In the oral prednisone group, PTA improved by 30.7 dB compared with a 28.7-dB improvement in the intratympanic treatment group. Mean pure tone average at 2 months was 56.0 for the oral steroid treatment group and 57.6 dB for the intratympanic treatment group. Recovery of hearing on oral treatment at 2 months by intention-to-treat analysis was 2.0 dB greater than intratympanic treatment (95.21% upper confidence interval, 6.6 dB). Per-protocol analysis confirmed the intention-to-treat result. Thus, the hypothesis of inferiority of intratympanic methylprednisolone to oral prednisone for primary treatment of sudden sensorineural hearing loss was rejected. CONCLUSION: Among patients with idiopathic sudden sensorineural hearing loss, hearing level 2 months after treatment showed that intratympanic treatment was not inferior to oral prednisone treatment. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00097448.

Tinnitus, diminished sound-level tolerance, and elevated auditory activity in humans with clinically normal hearing sensitivity.

Phantom sensations and sensory hypersensitivity are disordered perceptions that characterize a variety of intractable conditions involving the somatosensory, visual, and auditory modalities. We report physiological correlates of two perceptual abnormalities in the auditory domain: tinnitus, the phantom perception of sound, and hyperacusis, a decreased tolerance of sound based on loudness. Here, subjects with and without tinnitus, all with clinically normal hearing thresholds, underwent 1) behavioral testing to assess sound-level tolerance and 2) functional MRI to measure sound-evoked activation of central auditory centers. Despite receiving identical sound stimulation levels, subjects with diminished sound-level tolerance (i.e., hyperacusis) showed elevated activation in the auditory midbrain, thalamus, and primary auditory cortex compared with subjects with normal tolerance. Primary auditory cortex, but not subcortical centers, showed elevated activation specifically related to tinnitus. The results directly link hyperacusis and tinnitus to hyperactivity within the central auditory system. We hypothesize that the tinnitus-related elevations in cortical activation may reflect undue attention drawn to the auditory domain, an interpretation consistent with the lack of tinnitus-related effects subcortically where activation is less potently modulated by attentional state. The data strengthen, at a mechanistic level, analogies drawn previously between tinnitus/hyperacusis and other, nonauditory disordered perceptions thought to arise from neural hyperactivity such as chronic neuropathic pain and photophobia.

Medical record documentation of patients' hearing loss by physicians.

BACKGROUND: Anecdotal evidence suggests that hearing loss, even when sufficient to prevent full access to spoken communication, often is underreported by patients and not documented by physicians. No published studies have investigated this issue quantitatively. OBJECTIVE: To assess the documentation of hearing loss in comprehensive physician notes in cases where the patients are known to have substantial binaural loss. DESIGN: Electronic medical record (EMR) notes for 100 consecutive patients with substantial binaural hearing loss were reviewed retrospectively at a large academic medical center. All records reviewed were created within 2 years before the patient's audiometry. Comprehensive physician notes containing the headings "History" and "Physical Exam" were examined for documentation of hearing loss and scored as: no mention of loss; finding of loss; or hearing reported as normal. PARTICIPANTS: Consecutive adult patients with substantial binaural hearing loss by audiometry who also had a comprehensive medical assessment in their electronic medical record created within 2 years before audiometry. RESULTS: Thirty-six percent of EMRs had no mention of hearing loss, 28% reported some loss, and 36% percent indicated that hearing was normal. CONCLUSIONS: Substantial hearing loss, sufficient to prevent effective communication in the medical setting, often is underdocumented in medical records.