Acoustic Reflexes in Aural Atresia Patients: Evidence of an Intact Efferent System?

OBJECTIVE: To record crossed acoustic reflex thresholds (xART's) postoperatively from patients after surgical repair of unilateral congenital aural atresia (CAA). To seek explanations for when xARTs can and cannot be recorded. We hope to understand the implications for this central auditory reflex despite early afferent deprivation. METHODS: Patients who underwent surgery to correct unilateral CAA at a tertiary academic medical were prospectively enrolled to evaluate for the presence of xART. Preoperative ARTs in the normal (non-atretic) ear, and postoperative ipsilateral ARTs (stimulus in the normal ear) and contralateral ARTs (stimulus in the newly reconstructed atretic ear; record in the normal ear) were measured at 500, 1000, and 2000 Hz. RESULTS: Four of 11 patients with normal ipsilateral reflex thresholds preoperatively demonstrated crossed acoustic reflexes postoperatively (stimulus in reconstructed ear; record from normal ear). Four other patients demonstrated normal ipsilateral thresholds preoperatively but did not have crossed reflexes postoperatively. No reflexes (pre- or postoperatively) could be recorded in 3 patients. Crossed reflex threshold is significantly correlated with the postoperative audiometric threshold. There was no correlation between ipsilateral and contralateral reflex thresholds. CONCLUSION: Crossed acoustic reflexes can be recorded from some but not all postoperative atresia patients, and the thresholds for those reflexes correlate with the postoperative pure tone threshold. The presence of acoustic reflexes implies an intact CN VIII-to-opposite CN VII central reflex arc despite early unilateral sound deprivation.

Quantification of Head Acceleration during Vestibular Rehabilitation Exercises.

PURPOSE: Vestibular rehabilitation exercises have been proven to reduce symptoms and diminish the risk of falls in those with dizziness and balance impairments. The first purpose of this study is to investigate a new method of measuring head movements during habituation vestibular rehabilitation exercises. The second is to explore the relationship between head acceleration measurements during select traditional vestibular rehabilitation exercises and the variables of age, dizziness, and poor balance confidence. RESEARCH DESIGN: A descriptive, cross-sectional study, in a university setting. STUDY SAMPLE: Fifty-two participants, ranging in age from 20 to 96 yr. All were volunteers, with the majority (34) reporting no history of dizziness or balance confidence. DATA COLLECTION: Head accelerations were calculated from linear and angular displacements as measured by magnetometry. RESULTS: Head accelerations decreased with increasing age, dizziness, and low balance confidence during four habituation exercises. CONCLUSIONS: Head acceleration varies as a function of age, dizziness, and low balance confidence during head movement-based vestibular and balance rehabilitation therapy (habituation) exercises. The magnetometry measurement method used could be applied across the course of treatment to establish predictive measures based on change in acceleration over time. More diverse participant sampling is needed to create normative data.

The effect of lead on the avian auditory brainstem.

Lead (Pb) continues to be a significant environmental toxin and remains an integral part of many industrial processes, hobbies, and tobacco smoke. Pb has been shown to be a potent toxin to the CNS and low levels of Pb (below the CDC established toxic blood level of 10 microg/dl) have been correlated with decreases in the IQ of children. Pb exposure is a risk factor for dyslexia, and significantly, dyslexics have deficits in auditory temporal processing, including backward masking and amplitude modulation detection. Importantly, Pb-exposed children have been found to be deficient in various aspects of auditory temporal processing, including backward masking. Auditory temporal information is vital for appropriate speech detection and it is not known where within the auditory axis temporal processing takes place, nor is it understood how Pb exposure modifies the cells of the auditory system. To address these questions, we have developed an animal model of auditory temporal processing using chickens and have established that Pb exposure during development results in deficits in backward masking in avians. The current study was undertaken to identify the cellular changes induced by Pb exposure in the auditory brainstem of chickens that are likely anatomical correlates of the observed deficits in backward masking. We found Pb exposure had no effect on neuron number or glial cells within the auditory brainstem. However, Pb exposure does result in significant decreases in the amount of the medium weight neurofilament protein (NFM) as well as decreased NFM phosphorylation within the axons connecting auditory nuclei in the avian brainstem. Because the amount of neurofilament can affect the conduction velocities of axons, these results may provide an anatomical link between Pb exposure, auditory temporal processing deficits, and dyslexia.

Do former preterm infants remember and respond to neonatal intensive care unit noise?

BACKGROUND: Previous studies have shown that 4-month-old infants have a decrease in heart rate, a component of the orienting reflex, in response to interesting auditory stimuli and an increase in heart rate to aversive auditory stimuli. OBJECTIVE: To compare the heart rate responses of former preterm and term infants at 4-5 months corrected age to a recording of NICU noises. METHODS: 13 former preterm infants and 17 full-term infants were presented NICU noise and another noise of similar level and frequency content in random order. Heart rate 10s prior to the stimulus and for 20s during the stimulus was analyzed. Group differences in second by second heart rate changes in response to the two noise stimuli were compared by analysis of covariance. RESULTS: Both the preterm and term newborns responded similarly to the NICU noise and the control noise. The preterm infants did not alter their heart rate in response to either stimulus. In contrast, the term infants displayed an orienting response to the second stimulus presented regardless of whether it was the NICU or control noise. CONCLUSIONS: Former preterm infants at 4-5 months corrected age have reduced responsiveness to auditory stimulation in comparison to 4- to 5-month-old term infants. Furthermore, they did not respond to the NICU noise as an aversive stimulus.

Emergence of Binaural Summation After Surgical Correction of Unilateral Congenital Aural Atresia.

OBJECTIVE: To investigate the emergence of binaural summation in patients with unilateral congenital aural atresia undergoing surgical correction. STUDY DESIGN: Preoperative and postoperative audiometric testing in a prospective cohort of 10 patients with unilateral congenital aural atresia. SETTING: University-based tertiary care center. PATIENTS: Ten patients (ages 6-53) with an average 69 dB (±9 dB sd) unilateral conductive hearing loss, normal hearing in the nonatretic ear, and normal bone conduction in the atretic ear. INTERVENTIONS: Pre- and postoperative hearing in noise test in quiet and in noise. MAIN OUTCOME MEASURES: Levels of sentences presented from a single central speaker were adaptively varied to determine a speech reception threshold (SRT), first in quiet and then with simultaneous multitalker babble at 65 dB SPL from the same speaker. RESULTS: Preoperative SRT was worse than normal controls in both quiet (p = 0.001) and in noise (p = 0.05), as expected. Postoperative SRT in quiet improved 3.5 dB (marginally significant with one-tailed p value of 0.05); thresholds in noise improved an insignificant 0.8 dB (one-tailed p = 0.2). Converting results to dB-worse-than normal, atresia patients did better in noise (relative to normal) than in quiet (p = 0.008). CONCLUSION: The expected summation effect (3 dB) occurs after atresia surgery in quiet but not in noise. Relative to normal, these patients performed better in noise than quiet, perhaps because these patients develop skills attending to threshold-level speech in noise during their years without binaural benefit.

Pressed scar tissue for tympanic membrane grafting in revision tympanoplasty.

OBJECTIVE: Compare the efficacy of pressed scar tissue grafts to standard fascia and areolar tissue grafts for use in tympanoplasty. STUDY DESIGN: A retrospective review of a prospective computerized database of tympanoplasty and mastoid surgeries at an academic, tertiary care practice was performed. Search parameters were set to find all patients who underwent tympanoplasty with or without mastoidectomy with use of various grafting materials for repair of tympanic membrane perforation from 1996 to 2002. All ages were included. Patients with cholesteatoma at the time of surgery were excluded. The short-term graft take rate was evaluated at 30 to 90 days to identify any differences in results using the standard fascia and areolar grafts vs. pressed scar tissue grafts. Other parameters that may have an influence on outcome were analyzed including mastoidectomy, infection, perforation size, perforation location, age of patient, primary vs. revision surgery, number of previous surgeries, postauricular vs. transcanal approaches, and medial vs. lateral grafting techniques. Hearing results were analyzed to see whether the use of scar tissue grafts resulted in equivalent outcomes compared to standard graft materials. RESULTS: There were no statistically significant differences in short-term tympanic membrane closure rates in subjects undergoing surgery using standard fascia/areolar tissue grafts and pressed scar tissue grafts. Hearing results were also statistically equivalent regardless of graft material used. The only parameter that was somewhat associated with successful closure of tympanic perforation was use of the postauricular approach compared to the transcanal approach. CONCLUSIONS: Pressed scar tissue grafts are as efficacious as standard fascia and areolar tissue grafts when used to repair tympanic membrane perforations. Pressed scar tissue graft can be used successfully in cases such as revision tympanoplasty when standard tissue grafts are not available or difficult to obtain. EBM RATING: B-3.

Dissociation of sensitivity and response bias in children with attention deficit/hyperactivity disorder during central auditory masking.

Forty-three children (ages 7.0-14.5 years old) with and without attention deficit/hyperactivity disorder (ADHD), combined type had thresholds for detection of a 500-Hz pure tone estimated with and without a noise masker in the contralateral ear. The ear receiving the signal in the masked condition was varied randomly. A single-interval maximum-likelihood method estimated thresholds and false-alarm rate. Whereas the increase in threshold in children with ADHD in the presence of contralateral masking was comparable with controls, the increase in false-alarm rate was significantly greater. This dissociation between changes in sensitivity and response bias in the presence of masking noise supports suggestions that children with ADHD have difficulty inhibiting maladaptive responses and indicates that this deficit is quantifiable using psychoacoustic methods.

Auditory temporal processing in children with specific reading disability with and without attention deficit/hyperactivity disorder.

The auditory temporal deficit hypothesis predicts that children with specific reading disability (RD) will exhibit a deficit in the perception of auditory temporal cues in nonspeech stimuli. Tasks assessing perception of auditory temporal and nontemporal cues were administered to children with (a) RD without attention-deficit/hyperactivity disorder (RD/no-ADHD, n = 40), (b) ADHD alone (ADHD/no-RD, n = 33), (c) RD and ADHD (RD/ADHD, n = 36), and (d) no impairment (NI, n = 41). The presence of RD was associated with a specific deficit in detection of a tone onset time asynchrony, but no reduction in performance on other tasks assessing perception of temporal or nontemporal acoustic cues. The presence of ADHD was associated with a general reduction in performance across tasks. The pattern of results did not indicate a pervasive deficit in auditory temporal function in children with RD, but did suggest a possible sensitivity to backward masking in this group. Results also indicated that the comorbid presence of ADHD is a significant factor in the performance of children with RD on psychoacoustic tasks.

Impact of unilateral conductive hearing loss due to aural atresia on academic performance in children.

OBJECTIVES/HYPOTHESIS: This study evaluates the effect of unilateral conductive hearing loss secondary to aural atresia on elementary school children's academic performance. STUDY DESIGN: Case control survey and review of audiometric data. METHODS: One hundred thirty-two surveys were mailed to families of children with aural atresia, and 48 surveys were sent to families of children with unilateral sensorineural hearing loss (SNHL) to identify rates of grade retention, use of any resource, and behavioral problems. Audiometric data of the cohort were tabulated. RESULTS: Of the 40 atresia patients, none repeated a grade, but 65% needed some resources: 12.5% currently use a hearing aid, 32.5% use(d) a frequency-modulated system in school, 47.5% had an Individualized Education Plan, and 45% utilized speech therapy. Compared to the unilateral SNHL group and a cohort of children with unilateral SNHL in an earlier study, children with unilateral atresia were less likely to repeat a grade. Children in both unilateral atresia and SNHL groups were more likely to utilize some resource in the academic setting compared to the unilateral SNHL children in the prior study. CONCLUSIONS: Unilateral conductive hearing loss due to aural atresia has an impact on academic performance in children, although not as profound when compared to children with unilateral SNHL. The majority of these children with unilateral atresia utilize resources in the school setting. Parents, educators, and health care professionals should be aware of the impact of unilateral conductive hearing loss and offer appropriate habilitative services.

Does preoperative hearing predict postoperative hearing in patients undergoing primary aural atresia repair?

OBJECTIVE: The purpose of this study is to explore the correlation between preoperative hearing and early postoperative hearing results in patients undergoing primary aural atresia repair. STUDY DESIGN: Retrospective review of 125 patients. SETTING: Academic tertiary referral center. PATIENTS: One hundred twenty-five patients (5-67 yr old) undergoing 133 primary aural atresia surgeries were included. MAIN OUTCOME MEASURE(S): Spearman correlation coefficients were calculated between preoperative and postoperative (mean, 7.5 wk; range, 3-40 wk after surgery) hearing outcome measures including 3-tone pure-tone average (PTA), speech reception threshold (SRT), speech discrimination scores (SDS), air-bone gap (ABG), change in ABG (ΔABG), and between preoperative SRT and Jahrsdoerfer score. RESULTS: Preoperative PTA, SRT, SDS, and ABG correlated strongly with their respective postoperative values (correlation coefficients rho of 0.356 [p < 0.01], 0.199 [p < 0.05], 0.480 [p < 0.01], and 0.223 [p < 0.05], respectively). Preoperative PTA (0.407; p < 0.01), SRT (0.348; p < 0.01), SDS (-0.247; p < 0.01), and ABG (0.514; p < 0.01) also were correlated with ΔABG. When postoperative results were dichotomized to either normal (SRT, <30dB HL) or abnormal (SRT, ≥30dB HL), preoperative SRT was found to be a positive predictor of normal postoperative hearing (p = 0.05). Probability of normal postoperative hearing was 66% when preoperative SRT was 50 dB HL or lower and 40% when greater than 60 dB HL. Preoperative hearing (SRT) also trended toward a correlation with Jahrsdoerfer score (-0.168 [p = 0.058]). CONCLUSION: Among patients undergoing primary atresia repair, better preoperative hearing strongly predicts better postoperative hearing and correlates with ear anatomy. Preoperative hearing status should be factored when counseling atresia patients on hearing rehabilitation options.

Categorical perception of speech stimuli in children at risk for reading difficulty.

Children determined to be at risk (n = 24) or not at risk (n = 13) for reading difficulty listened to tokens from a voice onset time (VOT) (/ga/-/ka/) or tone series played in a continuous unbroken rhythm. Changes between tokens occurred at random intervals and children were asked to press a button as soon as they detected a change. For the VOT series, at-risk children were less sensitive than not-at-risk children to changes between tokens that crossed the phonetic boundary. Maps of group stimulus space produced using multidimensional scaling of reaction times for the VOT series indicated that at-risk children may attend less to the phonological information available in the speech stimuli and more to subtle acoustic differences between phonetically similar stimuli than not-at-risk children. Better phonological processing was associated with greater sensitivity to changes between VOT tokens that crossed the phonetic boundary and greater relative weighting of the phonological compared to the acoustic dimension across both groups.

Perception of speech and nonspeech stimuli by children with and without reading disability and attention deficit hyperactivity disorder.

The auditory temporal deficit hypothesis predicts that children with reading disability (RD) will exhibit deficits in the perception of speech and nonspeech acoustic stimuli in discrimination and temporal ordering tasks when the interstimulus interval (ISI) is short. Initial studies testing this hypothesis did not account for the potential presence of attention deficit hyperactivity disorder (ADHD). Temporal order judgment and discrimination tasks were administered to children with (1) RD/no-ADHD (n=38), (2) ADHD (n=29), (3) RD and ADHD (RD/ADHD; n=32), and (4) no impairment (NI; n=43). Contrary to predictions, children with RD showed no specific sensitivity to ISI and performed worse relative to children without RD on speech but not nonspeech tasks. Relationships between perceptual tasks and phonological processing measures were stronger and more consistent for speech than nonspeech stimuli. These results were independent of the presence of ADHD and suggest that children with RD have a deficit in phoneme perception that correlates with reading and phonological processing ability. (c) 2002 Elsevier Science (USA).

Functional maps of metastases from breast cancers: proof of the principle that multidimensional scaling can summarize disease progression.

The mathematic technique of multidimensional scaling can create "functional maps" of metastases from breast cancer such that positions of organs in these maps are proportional to the probability of metastases. Areas that are likely to share disease are close together in a functional map, even though they may be physically distant, and vice versa. Two functional maps of breast cancers-one of local metastases to axillary levels I to III and another of distant metastases-are statistically significant and clinically meaningful. The maps accurately reflect the clinical data ( r > 0.97, p < 0.01), and so the progression of disease is revealed in simple visual summaries. As an analogy, the metastatic sites are like buoys on a fluid surface, and cancer spreads from a primary tumor like waves emanating from a point of impact on that surface. Metastases are predicted when the waves swamp the buoys. Because breast cancers do not always spread to the next nearest site, these functional maps do not resemble anatomic maps. The maps are a view of the body as "seen" by the tumor. Several well known clinical features are seen in these maps: most local metastases are to axillary level I; upper-inner primaries spread equally to levels II and III; in-transit metastases in the lymph and blood vessels do not follow the pattern of other distant metastases. Future functional maps can expand these summary diagrams to include biologic parameters (gene-expression profiles or endocrine response) and give valuable insights into patterns of recurrence in different populations.