Robert F. Labadie

Intratympanic Dexamethasone for Sudden Sensorineural Hearing Loss After Failure of Systemic Therapy

Objective: Intratympanic steroids are increasingly used in the treatment of inner ear disorders, especially in patients with sudden sensorineural hearing loss (SNHL) who have failed systemic therapy. We reviewed our experience with intratympanic steroids in the treatment of patients with sudden SNHL to determine overall success, morbidity, and prognostic factors.

Horizontal-Plane Localization of Noise and Speech Signals by Postlingually Deafened Adults Fitted With Bilateral Cochlear Implants *

Objectives: The main purpose of the study was to assess the ability of adults with bilateral cochlear implants to localize noise and speech signals in the horizontal plane. A second objective was to measure the change in localization performance in these adults between approximately 5 and 15 mo after activation. A third objective was to evaluate the relative roles of interaural level difference (ILD) and interaural temporal difference (ITD) cues in localization by these subjects. Design: Twenty-two adults, all postlingually deafened and all bilaterally fitted with MED-EL COMBI 40+ cochlear implants, were tested in a modified source identification task. Subjects were tested individually in an anechoic chamber, which contained an array of 43 numbered loudspeakers extending from –90° to +90° azimuth. On each trial, a 200-msec signal (either a noise burst or a speech sample) was presented from one of 17 active loudspeakers (span: ±80°), and the subject had to identify which source from the 43 loudspeakers in the array produced the signal. Subjects were tested in three conditions: left device only active, right device only active, and both devices active. Twelve of the 22 subjects were retested approximately 10 mo after their first test. In Experiment 2, the spectral content and rise-decay time of the noise stimulus were manipulated. Results: The relationship between source azimuth and response azimuth was characterized in terms of the adjusted constant error (Ĉ). (1) With both devices active, Ĉ for the noise stimulus varied from 8.1° to 43.4° (mean: 24.1°). By comparison, Ĉ for a group of listeners with normal hearing ranged from 3.5° to 7.8° (mean: 5.6°). When subjects listened in unilateral mode (with one device turned off), Ĉ was at or near chance (50.5°) in all cases. However, when considering unilateral performance on each subjects better side, average Ĉ for the speech stimulus was 47.9°, which was significantly (but only slightly) better than chance. (2) When listening bilaterally, error score was significantly lower for the speech stimulus (mean Ĉ = 21.5°) than for the noise stimulus (mean Ĉ = 24.1°). (3) As a group, the 12 subjects who were retested 10 mo after their first visit showed no significant improvement in localization performance during the intervening time. However, two subjects who performed very poorly during their first visit showed dramatic improvement (error scores were halved) over the intervening time. In Experiment 2, removing the high-frequency content of noise signals resulted in significantly poorer performance, but removing the low-frequency content or increasing the rise-decay time did not have an effect. Conclusions: In agreement with previously reported data, subjects with bilateral cochlear implants localized sounds in the horizontal plane remarkably well when using both of their devices, but they generally could not localize sounds when either device was deactivated. They could localize the speech signal with slightly, but significantly better accuracy than the noise, possibly due to spectral differences in the signals, to the availability of envelope ITD cues with the speech but not the noise signal, or to more central factors related to the social salience of speech signals. For most subjects the remarkable ability to localize sounds has stabilized by 5 mo after activation. However, for some subjects who perform poorly initially, there can be substantial improvement past 5 mo. Results from Experiment 2 suggest that ILD cues underlie localization ability for noise signals, and that ITD cues do not contribute.

Interaural time and level difference thresholds for acoustically presented signals in post-lingually deafened adults fitted with bilateral cochlear implants using CIS+ processing.

Objectives: The main purpose of the study was to measure thresholds for interaural time differences (ITDs) and interaural level differences (ILDs) for acoustically presented noise signals in adults with bilateral cochlear implants (CIs). A secondary purpose was to assess the correlation between the ILD and ITD thresholds and error scores in a horizontal-plane localization task, to test the hypothesis that localization by individuals with bilateral implants is mediated by the processing of ILD cues. Design: Eleven adults, all postlingually deafened and all bilaterally fitted with MED-EL COMBI 40+ CIs, were tested in ITD and ILD discrimination tasks in which signals were presented acoustically through headphones that fit over their two devices. The stimulus was a 200-msec burst of Gaussian noise bandpass filtered from 100 to 4000 Hz. A two-interval forced-choice adaptive procedure was used in which the subject had to respond on each trial whether the lateral positions of the two sound images (with the interaural difference favoring the left and right sides in the two intervals) moved from left-to-right or right-to-left. Results: In agreement with previously reported data, ITD thresholds for the subjects with bilateral implants were poor. The best threshold was ∼400 &mgr;sec, and only five of 11 subjects tested achieved thresholds <1000 &mgr;sec. In contrast, ILD thresholds were relatively good; mean threshold was 3.8 dB with the initial compression circuit on the implant devices activated and 1.9 dB with the compression deactivated. The ILD and ITD thresholds were higher than previously reported thresholds obtained with direct electrical stimulation (generally, <1.0 dB and 100 to 200 &mgr;sec, respectively). When the data from two outlying subjects were omitted, ILD thresholds were highly correlated with total error score in a horizontal-plane localization task, computed for sources near midline (r = 0.87, p < 0.01). Conclusions: The higher ILD and ITD thresholds obtained in this study with acoustically presented signals (when compared with prior data with direct electrical stimulation) can be attributed—at least partially—to the signal processing carried out by the CI in the former case. The processing strategy effectively leaves only envelope information as a basis for ITD discrimination, which, for the acoustically presented noise stimuli, is mainly coded in the onset information. The operation of the compression circuit reduces the ILDs in the signal, leading to elevated ILD thresholds for the acoustically presented signals in this condition. The large magnitude of the ITD thresholds indicates that ITDs could not have contributed to the performance in the horizontal-plane localization task. Overall, the results suggest that for subjects using bilateral implants, localization of noise signals is mediated entirely by ILD cues, with little or no contribution from ITD information.

Multicenter U.S. bilateral MED-EL cochlear implantation study: Speech perception over the first year of use

Objective: Binaural hearing has been shown to support better speech perception in normal-hearing listeners than can be achieved with monaural stimulus presentation, particularly under noisy listening conditions. The purpose of this study was to evaluate whether bilateral electrical stimulation could confer similar benefits for cochlear implant listeners. Design: A total of 26 postlingually deafened adult patients with short duration of deafness were implanted at five centers and followed up for 1 yr. Subjects received MED-EL COMBI 40+ devices bilaterally; in all but one case, implantation was performed in a single-stage surgery. Speech perception testing included CNC words in quiet and CUNY sentences in noise. Target speech was presented at the midline (0 degrees), and masking noise, when present, was presented at one of three simulated source locations along the azimuth (−90, 0, and +90 degrees). Results: Benefits of bilateral electrical stimulation were observed under conditions in which the speech and masker were spatially coincident and conditions in which they were spatially separated. Both the “head shadow” and “summation” effects were evident from the outset. Benefits consistent with “binaural squelch” were not reliably observed until 1 yr after implantation. Conclusions: These results support a growing consensus that bilateral implantation provides functional benefits beyond those of unilateral implantation. Longitudinal data suggest that some aspects of binaural processing continue to develop up to 1 yr after implantation. The squelch effect, often reported as absent or rare in previous studies of bilateral cochlear implantation, was present for most subjects at the 1 yr measurement interval.

Outcome of cochlear implantation in pediatric auditory neuropathy

Objective Auditory neuropathy, characterized by absence or abnormality of auditory brainstem responses and normal otoacoustic emissions, is often associated with particularly poor response to amplification. Outcome data from four such pediatric patients who received cochlear implants are discussed. Study Design Four patients from the Carolina Childrens Communicative Disorders Program were identified as having received a diagnosis of auditory neuropathy before implantation with a Clarion cochlear implant. Speech data collected after implantation were compared with data from control pediatric implant patients, matched for age at implantation and duration of implant use. Electrically evoked auditory brainstem response data and electrically evoked acoustic reflex data were also obtained. Methods Routine clinical procedures were used to obtain speech outcome data. A 75-&mgr;s biphasic 21.1-Hz pulse train served as the eliciting stimulus for both evoked auditory brainstem responses and reflex measures, which were obtained contralateral to the implant. Results Speech data were comparable with those obtained from the general population of pediatric patients receiving cochlear implants at this center. Identifiable evoked auditory brainstem response data were obtained in all subjects on at least two of the three electrodes tested, and variability was comparable with that observed in other children with implants. A robust electrically evoked acoustic reflex with no decay was observed at estimated M-level in all children. Conclusion The data gathered to date suggest that the outcome of cochlear implantation in these four patients is not significantly different from that in other pediatric implant patients. Physiologic data suggest that the implant was able to overcome the desynchronization hypothesized to underlie auditory neuropathy.

Treatment of benign positional vertigo using the semont maneuver: efficacy in patients presenting without nystagmus.

Objective To evaluate and compare the efficacy of the Semont liberatory maneuver on “objective” benign paroxysmal positional vertigo (BPPV) defined as vertigo with geotropic nystagmus in Dix‐Hallpike positioning versus “subjective” BPPV defined as vertigo without nystagmus in Dix‐Hallpike positioning.

Impact of electrode design and surgical approach on scalar location and cochlear implant outcomes

Three surgical approaches: cochleostomy (C), round window (RW), and extended round window (ERW); and two electrodes types: lateral wall (LW) and perimodiolar (PM), account for the vast majority of cochlear implantations. The goal of this study was to analyze the relationship between surgical approach and electrode type with final intracochlear position of the electrode array and subsequent hearing outcomes.

Automatic Segmentation of Intracochlear Anatomy in Conventional CT

Cochlear implant surgery is a procedure performed to treat profound hearing loss. Clinical results suggest that implanting the electrode in the scala tympani, one of the two principal cavities inside the cochlea, may result in better hearing restoration. Segmentation of intracochlear cavities could thus aid the surgeon to choose the point of entry and angle of approach that maximize the likelihood of successful implant insertion, which may lead to more substantial hearing restoration. However, because the membrane that separates the intracochlear cavities is too thin to be seen in conventional in vivo imaging, traditional segmentation techniques are inadequate. In this paper, we circumvent this problem by creating an active shape model with micro CT (μCT) scans of the cochlea acquired ex vivo. We then use this model to segment conventional CT scans. The model is fitted to the partial information available in the conventional scans and used to estimate the position of structures not visible in these images. Quantitative evaluation of our method, made possible by the set of μCTs, results in Dice similarity coefficients averaging 0.75. Mean and maximum surface errors average 0.21 and 0.80 mm.

Cochlear implant performance in senior citizens

Cochlear implants are indicated for elderly patients with severe-to-profound hearing loss (sensorineural hearing loss ≥ 70 dB). Their use has been limited, possibly by the misconception that elderly patients will perform poorly. To document the performance of older adults (≥65 years old), we undertook a retrospective analysis of our postlingually deafened adult patients who underwent implantation with the CLARION Multi-Strategy Cochlear Implant and underwent formal audiologic analysis (sentence recognition [Central Institute for the Deaf, CID] and monosyllabic word recognition [consonant-noun-consonant, CNC]). Both younger (n = 20; mean age = 46.9 years) and older (n = 16; mean age = 71.5 years) adults showed statistically significant increases in CID and CNC scores after cochlear implantation. No statistically significant difference could be detected in operative time, anesthesia time, length of hospitalization, or CID or CNC scores between the two age groups. We conclude that age should not be a criterion for deciding who should receive cochlear implants. (Otolaryngol Head Neck Surg 2000;123:419-24.)

Image-guided surgery: what is the accuracy?

Purpose of review Use of image-guided surgery (IGS) systems in otolaryngology, particularly rhinology, has grown exponentially in recent years. Central to their use is the understanding of the accuracy of each system. The purpose of this review is to discuss the error inherent in all IGS systems. A standardized technique (currently used in the engineering literature) for understanding and reporting error in IGS systems is reviewed. Using this technique, the error of commercially available IGS systems is reviewed. Recent findings The most commonly used IGS systems depend on the conformation of the skin, as opposed to relying on bone-implanted devices. For these systems, mean accuracies 2 mm or less are routinely reported. This finding is independent of fiducial markers (eg, proprietary headsets, skin-affixed markers, or laser scanning of skin surfaces). Techniques of fiducial localization and registration of CT scans to intraoperative anatomy are proprietary to each company. As such, there is great variability in reporting system specifications-particularly error of IGS systems. This lack of standardization makes comparison of one system to another difficult if not impossible. Summary Image-guided surgery systems commonly used in rhinology report mean accuracies of 2 mm or less. Surgeons must be aware that this value represents a mean of a distribution of errors. As such, 95% of the time error can be expected to be less than approximately 1.7 times its mean value. However, outliers (errors much larger and much smaller than the mean) may exist for each IGS intervention. As noted, IGS systems function to complement-not replace-knowledge of surgical anatomy.