Clutton, D. B., Gordon, K. A. Hospital for Sick Children, Toronto, Ontario, CANADA Conclusions: 1. C-levels were more likely to exceed eSRTs in N22 than N24 users. 2. Absolute differences between eSRT and C’s do NOT change with years of implant use. 3. CI children cannot accurately predict maximum loudness levels. References: 1. Jerger, J., Oliver, T. A., & Chmiel, R. A. (1988). Prediction of dynamic range from stapedius reflex in cochlear implant patients. Ear Hear, 9, 4-8. 2. Hodges AV, Balkeny TJ, Ruth RA, Lambert PR, Dolan-Ash S, Schloffman JJ. (1997). Electrical middle ear muscle reflex: use in cochlear implant programming. Otolaryngol Head Neck Surg, 117, 255-261. 3. Shallop, J. K., & Ash, K. R. (1995). Relationships among comfort levels determined by cochlear implant patient’s self-programming, audiologist’s programming, and electrical stapedius reflex thresholds. Ann Otol Rhinol Laryngol Suppl, 166, 175-6. 4. Spivak, L.G., Chute, P. M., (1994). The relationship between electrical acoustic reflex thresholds and behavioral comfort levels in children and adult cochlear implant patient. Ear Hear, 15, 184-192. 5. Stephan, K., & Welzl-Muller, K. (1994). Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant. Audiology, 33, 143-51. Previous studies have shown that the eSRT is a valid approximation of C-levels in adult cochlear implant recipients 1 . Objective eSRTs have also been used to estimate C-levels in pediatric recipients 2,4 . We demonstrate that in a large sample of pediatric implant recipients, the eSRT is strongly influenced by behavioral C-levels and implant device, but not by duration of device use. Discussion: Figure 5: (eSRT – C) by Duration of Implant Use -100 -50 0 50 100 150 -2 0 2 4 6 8 10 12 Duration of Use Difference (eSRT-C) N22 N24 Contour In Figure 5 Differences between eSRT and C-levels are shown for all electrodes tested by duration of implant use. Each device is represented by a different color. C-levels exceeded ESRTs in Nucleus 22 users more often than in Nucleus 24M or Contour users (p<0.0001). A wider range of ESRTs and C-levels were found in users of bipolar stimulation (primarily Nucleus 22 users) than monopolar stimulation (primarily Nucleus 24M and Contour users). Figure 4: /C-eSRT/ by Device 6.62 3.59 1.03 0 5 10 15 20 25 30 35 40 n22 n24 contour Device Absolute Difference -12 -9 -6 -3 0 3 6 9 Duraiton of Implant Use (Years) Absolute Difference (Clinical Units) Duration of Implant Use (Years) Figure 4 demonstrates that although children using Nucleus 22 devices had the longest duration of implant use (p<0.0001) and children using Nucleus Contour devices had a mean duration of implant use of only 1.0  1.2 years, absolute differences between ESRT and C-levels were not significantly different between devices (p>0.05). Results: R = 0.77 0 50 100 150 200 250 300 0 50 100 150 200 250 300 C-level (cu) eSRT level (cu) Data was obtained for 914 electrodes. Stepwise multiple linear regression analyses indicated that C-levels explained 60.0% of ESRT variability while the type of device explained another 8.6% of ESRT variability. Figure 2 demonstrates that there was a strong positive correlation between behavioral C-levels and eSRT (R= 0.77). Figure 3 demonstrates that eSRT levels were significantly higher than behavioral C-levels (p<0.0001). 150 160 170 180 190 200 210 N 22 N 24M Contour Device Clinical Units C-level eSRT Figure 3: Comparison of C-levels vs. eSRT by Device Figure 2: Correlation between C-levels and eSRTs Measures: Stimulus levels were increased and children were asked to indicate when the sound was very loud. C-levels were set 1 – 10 clinical units below this level. For children who could not perform this task, observation of behavioral or physiological changes were used to estimate C-levels. The electrically evoked stapedius reflex was obtained using immittance measures in the ear contralateral to the cochlear implant. Pulses of 500 ms each were presented at the same stimulation rate used in the child’s MAP and delivered at 1 Hz. Table 1. Demographics Gender: - male 35 - female 29 Re-Implanted Subjects 2 Device: - CI22M 22 - CI24M 24 - CI24R(CS) 18 Age at Implant (years): 4.9 + 2.5 Age at eSRT (years) 8.9 + 3.9 Duration of Use at eSRT 3.9 + 2.8 Figure 1. Etiology of 64 Children congenital mondini/hypoplasia meningitis hereditary waardenburg progressive/unknown consanguinity cytomegalovirus ototoxicity Sixty-four children participated in this prospective study. Demographics are shown in Table 1. Etiology of hearing loss is shown in Figure 1. Method: Before receiving a cochlear implant, children with severe to profound sensorineural hearing loss may not have been able to perceive loudness through their hearing aids. Because of this lack of experience, such children may not be able to make accurate judgments of loudness which are needed in order to provide optimal stimulation levels for their cochlear implants. We asked if maximum stimulation levels (C-levels) obtained by behavioral responses from children provide a reliable measure of loudness. Objective: Are Children Who Use Implants Able to Accurately Judge Loudness?