Patterns of Long-term Hearing Loss in Hearing Preservation Cochlear Implant Surgery.

OBJECTIVE: To describe patterns of hearing loss in patients with low-frequency residual hearing after cochlear implantation. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary referral center. PATIENTS: Cochlear implant candidates with immediate postoperative residual low-frequency hearing. INTERVENTIONS: Hybrid or traditional cochlear implant. MAIN OUTCOME MEASURE: Audiograms to measure postoperative hearing. RESULTS: Of the 166 patients reviewed, 17 ears met the inclusion criteria. The age ranged from 3 years 2 months to 86 years. Etiology was unknown (n = 6), presbycusis (n = 5), genetic (n = 4), acoustic trauma (n = 1), and measles virus (n = 1). The Nucleus Hybrid S8 and S12 (n = 7) was the most common electrode array, and then Nucleus 422 (n = 6), Nucleus Contour Advance (n = 2), Med-El Flex 28 (n = 2), and Advanced Bionics Mid Scala (n = 1). Cochleostomy was performed in nine, and round window approach in nine patients. Average follow-up was 28 months (2-68 mo). Postoperative loss was mixed in eight and purely sensorineural in eight. The most common patterns of hearing loss were gradual decline (n = 7), and then fluctuating hearing (n = 6), stable (n = 3), and sudden loss (n = 1). One patient only had one postoperative audiogram. CONCLUSION: Some long-term hearing preservation was achieved in 94% of patients with immediate postoperative hearing preservation. Patients developed both mixed and sensorineural loss postoperatively. A majority of patients with mixed hearing loss had a supra-preoperative bone curve. Gradual decline and fluctuating hearing loss were the most common patterns of hearing loss; few patients had stable hearing and one had a sudden loss.

Spectral and temporal measures in hybrid cochlear implant users: on the mechanism of electroacoustic hearing benefits.

OBJECTIVE: Compare auditory performance of Hybrid and standard cochlear implant users with psychoacoustic measures of spectral and temporal sensitivity and correlate with measures of clinical benefit. STUDY DESIGN: Cross-sectional study. SETTING: Tertiary academic medical center. PATIENTS: Hybrid cochlear implant users between 12 and 33 months after implantation. Hybrid recipients had preservation of low-frequency hearing. INTERVENTIONS: Administration of psychoacoustic, music perception, and speech reception in noise tests. MAIN OUTCOME MEASURES: Performance on spectral-ripple discrimination, temporal modulation detection, Schroeder-phase discrimination, Clinical Assessment of Music Perception, and speech reception in steady-state noise tests. RESULTS: Clinical Assessment of Music Perception pitch performance at 262 Hz was significantly better in Hybrid users compared with standard implant controls. There was a near significant difference on speech reception in steady-state noise. Surprisingly, neither Schroeder-phase discrimination at 2 frequencies nor temporal modulation detection thresholds across a range of frequencies revealed any advantage in Hybrid users. This contrasts with spectral-ripple measures that were significantly better in the Hybrid group. The spectral-ripple advantage was preserved even when using only residual hearing. CONCLUSION: These preliminary data confirm existing data demonstrating that residual low-frequency acoustic hearing is advantageous for pitch perception. Results also suggest that clinical benefits enjoyed by Hybrid recipients are due to improved spectral discrimination provided by the residual hearing. No evidence indicated that residual hearing provided temporal information beyond that provided by electric stimulation.

Development and validation of the University of Washington Clinical Assessment of Music Perception test.

OBJECTIVES: Assessment of cochlear implant outcomes centers around speech discrimination. Despite dramatic improvements in speech perception, music perception remains a challenge for most cochlear implant users. No standardized test exists to quantify music perception in a clinically practical manner. This study presents the University of Washington Clinical Assessment of Music Perception (CAMP) test as a reliable and valid music perception test for English-speaking, adult cochlear implant users. DESIGN: Forty-two cochlear implant subjects were recruited from the University of Washington Medical Center cochlear implant program and referred by two implant manufacturers. Ten normal-hearing volunteers were drawn from the University of Washington Medical Center and associated campuses. A computer-driven, self-administered test was developed to examine three specific aspects of music perception: pitch direction discrimination, melody recognition, and timbre recognition. The pitch subtest used an adaptive procedure to determine just-noticeable differences for complex tone pitch direction discrimination within the range of 1 to 12 semitones. The melody and timbre subtests assessed recognition of 12 commonly known melodies played with complex tones in an isochronous manner and eight musical instruments playing an identical five-note sequence, respectively. Testing was repeated for cochlear implant subjects to evaluate test-retest reliability. Normal-hearing volunteers were also tested to demonstrate differences in performance in the two populations. RESULTS: For cochlear implant subjects, pitch direction discrimination just-noticeable differences ranged from 1 to 8.0 semitones (Mean = 3.0, SD = 2.3). Melody and timbre recognition ranged from 0 to 94.4% correct (mean = 25.1, SD = 22.2) and 20.8 to 87.5% (mean = 45.3, SD = 16.2), respectively. Each subtest significantly correlated at least moderately with both Consonant-Nucleus-Consonant (CNC) word recognition scores and spondee recognition thresholds in steady state noise and two-talker babble. Intraclass coefficients demonstrating test-retest correlations for pitch, melody, and timbre were 0.85, 0.92, and 0.69, respectively. Normal-hearing volunteers had a mean pitch direction discrimination threshold of 1.0 semitone, the smallest interval tested, and mean melody and timbre recognition scores of 87.5 and 94.2%, respectively. CONCLUSIONS: The CAMP test discriminates a wide range of music perceptual ability in cochlear implant users. Moderate correlations were seen between music test results and both Consonant-Nucleus-Consonant word recognition scores and spondee recognition thresholds in background noise. Test-retest reliability was moderate to strong. The CAMP test provides a reliable and valid metric for a clinically practical, standardized evaluation of music perception in adult cochlear implant users.

Clinical assessment of music perception in cochlear implant listeners.

OBJECTIVE: Cochlear implants (CI) have provided tremendous benefit for speech recognition in quiet for patients with severe and profound hearing impairment, but implant users still have great difficulty perceiving music. The purpose of this study was to develop a test to quantify music perception by CI listeners in a clinically practical manner that could be standardized for administration at any implant center. STUDY DESIGN: Prospective convenience sample. SETTING: Hearing research center at an academic hospital. PATIENTS: Eight CI listeners, including 5 men and 3 women with implant experience ranging from 0.5 to 6 years, participated in this study. They represented a variety of implant devices and strategies. INTERVENTION: Administration of the Clinical Assessment of Music Perception test in a standardized sound field. MAIN OUTCOME MEASURES: Music perception was assessed using a computerized test comprising pitch direction discrimination, melody identification, and timbre identification. The pitch subtest used a 2-alternative forced-choice adaptive procedure to determine a threshold interval for discrimination of complex pitch direction change. The melody and timbre subtests assessed recognition of 12 isochronous melodies and 8 musical instruments, respectively. RESULTS: Testing demonstrated a broad range of perceptual accuracy on all 3 subtests. Test duration averaged less than 45 minutes. CONCLUSION: Clinical Assessment of Music Perception is an efficient computerized test that may be used to measure 3 different aspects of music perception in CI users in a standardized and clinically practical manner.