Prenatal Iron Deficiency and Auditory Brainstem Responses at 3 and 10 Months: A Pilot Study.

PURPOSE: To examine whether prenatal iron deficiency delays auditory brainstem response (ABR) maturation in infancy. METHODS: One hundred and fifteen full-term healthy Chinese infants with maternal and cord blood haemoglobin and serum ferritin determinations were recruited into this study. Forty-eight infants received ABR testing at 3 months, and 45 infants were tested at 10 months. Comparison of the ABR variables were made between infants with and those without evidence of prenatal iron deficiency (maternal 3rd trimester haemoglobin <110 g/L, cord blood ferritin <75 µg/L); or anaemia at 10 months (haemoglobin <110 g/L). RESULTS: Latencies for wave V and wave III-V and I-V intervals were prolonged at 3 months in infants of anaemic mothers (effect sizes 1.02-1.19 SD). At 10 months, infants with low cord blood serum ferritin (indicating low iron stores at birth) showed longer wave I latency and possibly wave V latency also, besides demonstrating a smaller wave V amplitude (effect sizes 0.58-0.62 SD). Infants with low ferritin at birth and anemia at 10 months had longer wave III-V latency than other groups. CONCLUSION: In full-term healthy infants, prenatal iron deficiency appears to have adverse effects on the developing central nervous system and auditory system as assessed by ABRs at 3 and/or 10 months.

Pediatric cochlear implant patient performance as a function of age at implantation.

OBJECTIVE: The objective of this study was to examine the effect that age at implantation has on performance of children who received multichannel cochlear implants. STUDY DESIGN: This is a retrospective study of 295 children who were broken down into 5 age groups based on age at implantation: 1-3 years, 3-5 years, 5-7 years, 7-9 years, and 9-11 years. Speech perception test scores obtained 12, 24, and 36 months postactivation were compared for the 5 groups using repeated-measures analysis of variance. SETTING: This study was carried out at a tertiary academic medical center. PATIENTS: Subjects consisted of 295 children who ranged in age from 12 months to 10 years 11 months at the time they obtained their cochlear implant. INTERVENTION: All patients received their cochlear implant at a single implant facility. MAIN OUTCOME MEASURES: Performance on several speech perception tests was compared 12, 24, and 36 months postactivation. Performance was evaluated as a function of age at implantation. RESULTS: Patients in all 5 groups demonstrated improved scores when compared with scores obtained preoperatively with hearing aids. Repeated-measures analysis of variance (ANOVA) revealed a significant group by time interaction for 3 of the 5 measures. For all three of these measures, children implanted at younger ages demonstrated greater gains in speech perception over time than children implanted at older ages. CONCLUSIONS: These results are in agreement with those of previous studies indicating that early implantation facilitates improved development of speech perception skills in profoundly deaf children.

Selective cricothyroid muscle reinnervation by muscle-nerve-muscle neurotization.

OBJECTIVE: To determine if selective reinnervation of the cricothyroid muscle could be achieved with muscle-nerve-muscle neurotization. DESIGN: Case series. SETTING: Tertiary referral center. PATIENTS: Three consecutive patients with high vagal lesions that resulted in unilateral laryngeal paralysis. INTERVENTIONS: Patients underwent laryngeal reinnervation with ansa hypoglossi to recurrent laryngeal nerve anastomosis. In addition, patients underwent selective cricothyroid muscle reinnervation by muscle-nerve-muscle neurotization technique. MAIN OUTCOME MEASURES: Objective and subjective improvement in voice quality and electromyographic evidence of selective reinnervation of the cricothyroid muscle. RESULTS: All patients recovered normal or near-normal speaking voice and had normal objective measures of voice quality. They also showed electromyographic evidence of cricothyroid muscle reinnervation. CONCLUSION: The muscle-nerve-muscle neurotization technique was successful in providing selective reinnervation of the cricothyroid muscle in our 3 patients.

Adult cochlear implant patient performance with evolving electrode technology.

OBJECTIVE: In 1998, clinical trials were initiated to evaluate the CLARION Multi-Strategy Cochlear Implant (Advanced Bionics Corp., Sylmar, CA, U.S.A.), a precurved electrode with an electrode positioning system (EPS) in adults with severe to profound hearing impairments. In 1999, clinical trials were initiated to assess the CLARION HiFocus electrode with EPS in a similar group of adults. The purpose of this retrospective study was to evaluate and compare the preoperative and 1-, 3-, and 6-month postoperative speech perception scores obtained by the first 56 patients implanted with the precurved electrode with EPS and the first 56 patients implanted with the HiFocus electrode with EPS. Speech strategy preferences were additionally noted and compared at each test interval for each group. STUDY DESIGN: All subjects participated in preoperative testing with hearing aids and postoperative (1, 3 and 6 months) testing with either the precurved electrode with EPS or the HiFocus electrode with EPS. Demographic characteristics and preoperative and postoperative speech perception results were compared within and between the 2 groups. SETTING: Data presented here were collected at cochlear implant programs affiliated with tertiary medical centers located in the United States and Canada that participated in the clinical trials. PATIENTS: Patients were postlinguistically deafened adults who received a CLARION cochlear implant. RESULTS AND CONCLUSION: Within-group evaluations revealed that both groups demonstrated significant improvements on all speech perception measures when 1-month postoperative scores were compared with scores obtained preoperatively with hearing aids. Between-group comparison of demographic data showed that the HiFocus group had a significantly higher mean age at implant and a significantly longer mean duration of deafness than the precurved electrode with EPS group. Statistical comparison of mean speech perception scores showed no significant difference between subjects using the precurved electrode with EPS versus the HiFocus electrode with EPS at the preoperative, 1-, and 3-month test intervals. At the 6-month test interval, the mean CNC Monosyllabic Word Test score obtained by the HiFocus with EPS group was significantly better than the mean score obtained by the group with the precurved electrode with EPS (p < 0.05).

Motion-specific laryngeal reinnervation using muscle-nerve-muscle neurotization.

There is no current treatment method that can reliably restore physiologic movement to a paralyzed vocal fold. The purposes of this study were to test the hypotheses that 1) muscle-nerve-muscle (M-N-M) neurotization can be induced in feline laryngeal muscles and 2) M-N-M neurotization can restore movement to a paralyzed vocal fold. Muscle-nerve-muscle neurotization can be defined as the reinnervation of a denervated muscle via axons that are induced to sprout from nerves within an innervated muscle and that then traverse a nerve graft interposed between it and the target denervated muscle. A paralyzed laryngeal muscle could be reinnervated by axons from its contralateral paired muscle, thus achieving motion-specific reinnervation. Eighteen adult cats were divided into sham, hemilaryngeal-denervated, and M-N-M-reinnervated thyroarytenoid muscle groups. Five of the 6 reinnervated animals had histologic evidence of axons in the nerve graft, 4 of the 6 had evoked electromyographic evidence of crossed reinnervation, and 1 of the 6 had a return of appropriately phased adduction. This technique has great potential and should be further investigated.

The influence of age at implantation on performance with a cochlear implant in children.

OBJECTIVE: This study involved the assessment of speech recognition abilities as a function of age at implantation and length of cochlear implant use in children who received the Nucleus CI22M cochlear implant. STUDY DESIGN: Two separate analyses were performed. The first analysis involved the assessment of speech recognition performance as a function of length of time with a cochlear implant in 48 patients evaluated at 7 years of age. The second analysis involved the assessment of speech recognition performance as a function of age at implantation in 53 patients evaluated 36 months after implantation. Patients were divided into four groups based on length of implant use or age at implantation, and the results were analyzed by a repeated-measures analysis of variance. SETTING: This study was carried out at a tertiary academic medical center. PATIENTS: Patients consisted of children implanted with a Nucleus Multi Channel cochlear implant programmed with the SPEAK encoding strategy. Their ages at the time of evaluation ranged from 5.5 to 7.8 years. Their ages at implantation ranged from 2.4 to 14.5 years. INTERVENTIONS: All patients received a Nucleus Multi Channel cochlear implant programmed with the SPEAK encoding strategy. Word and sentence recognition tests were administered at various ages and at several postimplantation intervals. MAIN OUTCOME MEASURES: Performance as a function of length of cochlear implant use and as a function of age at implantation. RESULTS: Patients performed significantly better as length of cochlear implant use increased and age at implantation decreased. When patients were tested at a fixed postimplantation time interval (36 months), there was an overall trend for patients who received the implant at a younger age to perform better in spite of being younger at the time of evaluation. However, these effects were not statistically significant for all speech recognition tests that were administered. CONCLUSIONS: These results confirm previous findings indicating continued improvement of speech recognition with time in implanted children. Furthermore, the results support the concept of the advantage of a younger age at implantation.

Longitudinal effects of botulinum toxin injections on voice-related quality of life (V-RQOL) for patients with adductory spasmodic dysphonia.

Adductory spasmodic dysphonia is a focal dystonia of laryngeal muscles. Patients with this disorder typically have severe vocal difficulties, with significant functional, social, and emotional consequences. There is no widely accepted cure for this condition, however, botulinum toxin injections of the thyroarytenoid muscles are considered by most voice clinicians to be the state of the art treatment. Based on extensive experience treating patients for adductory spasmodic dysphonia, we feel that traditional means of voice assessment do not adequately measure either the disease severity or the treatment outcomes. That is, listening to or acoustically analyzing limited phonatory samples does not capture the functional, social, and emotional consequences of this disorder. These consequences will be reflected in a patient's voice-related quality of life (V-RQOL). Using a validated voice outcomes instrument, the V-RQOL Measure, the purpose of this study was to quantify longitudinal changes in the V-RQOL of patients with adductory spasmodic dysphonia who are undergoing botulinum toxin injections. Twenty-seven consecutive new patients presenting with dysphonia to our institution during an 18-month period were diagnosed with adductory spasmodic dysphonia, and treated patients were evaluated prospectively using the V-RQOL Measure. Results indicated that (1) V-RQOL was initially very low for these patients, (2) botulinum toxin injections improved it significantly for each injection cycle studied, and (3) the magnitude of the treatment effect appears to change across injections.

Auditory brain stem response in small acoustic neuromas.

OBJECTIVE: The auditory brain stem response (ABR) has been criticized recently as an insensitive measure for the detection of small acoustic neuroma (AN). This study was undertaken to evaluate our experience with the efficacy of ABR in detection of small tumors. STUDY DESIGN: Retrospective case review. Twenty-five patients with surgically proven small ANs measuring 1 cm or less were reviewed. In addition, 568 patients who underwent screening ABR were reviewed to evaluate the rate of false positive results at our institution. RESULTS: ABR was abnormal in 92% of patients with small AN in this series. Screening ABR was abnormal in approximately 19% of cases, one-third of which were found to have AN on magnetic resonance imaging testing. CONCLUSION: With strict adherence to optimal technique and evaluation criteria, the ABR remains a viable option for AN screening, especially in elderly patients or when there is a low index of suspicion.

Audiovestibular phenotype associated with a COL11A1 mutation in Marshall syndrome.

BACKGROUND: Marshall syndrome is a dominant disorder characterized by craniofacial and skeletal abnormalities, sensorineural hearing loss, myopia, and cataracts, and is associated with splicing mutations in COL11A1. OBJECTIVE: To determine the auditory and vestibular phenotypes associated with a COL11A1 splicing. DESIGN: Clinical otolaryngologic, audiologic, vestibular, and radiologic evaluations of the auditory and vestibular systems. SUBJECTS: Three affected individuals from a family cosegregating Marshall syndrome and a COL11A1 splice site mutation. RESULTS: The study subjects have progressive sensorineural hearing loss that is predominantly cochlear in origin and asymptomatic dysfunction of the central and peripheral vestibular systems. Computed tomography detected no malformations of temporal bone structures. CONCLUSIONS: The observed auditory and vestibular abnormalities are not caused by defective morphogenesis of the osseous labyrinth, but by more direct effects of the COL11A1 mutation on the membranous labyrinth and the central nervous system. The onset and degree of hearing loss associated with COL11A1 mutations are useful clinical features to differentiate Marshall syndrome from the phenotypically similar Stickler syndrome.

Outcome of newborn hearing screening by ABR compared with four different DPOAE pass criteria.

The purpose of this study is to compare the effectiveness and utility of distortion product otoacoustic emission (DPOAE) and auditory brain stem response (ABR) testing as screening methodologies suitable for universal application at a large birthing hospital. Five hundred sixty-nine neonates (1184 ears) without risk indicators for hearing loss underwent DPOAE and ABR screening before hospital discharge at birth. All ears (100%) passed the ABR screening. DPOAE results were categorized on the basis of the number of frequencies at which emissions were obtained as well as presence versus absence of a replicated response at each test frequency. Pass and refer rates varied widely, on the basis of whether the presence of DPOAE response at 2000 Hz or replication were required. With the most stringent criteria, only 64.44% of ears passed, whereas with the least stringent criteria 88.94% passed. Given that 100% of ears passed according to the gold standard of the ABR screening, these results indicate false-positive rates ranging from 11% to 35% by DPOAE screening. This discrepancy in pass and refer rates when various criteria are applied indicates the need for standardization and further comparison of appropriate pass criteria for newborn hearing screening programs.

Hearing loss and automobile airbag deployments.

In an on-going research program, on the causation of injuries in motor vehicle accidents, at the University of Michigan Transportation Research Institute, crashes with airbags have been, and are continuing to be, investigated. In order to determine the occurrence, if any, of 'hearing problems' associated with airbag deployments, drivers and passengers who had been involved in 'airbag' automobile crashes were interviewed by telephone. From the crashes investigated, 225 attempts were made to contact drivers who were exposed to airbag deployments. From these telephone interviews, contacts were made with 177 car occupants. Only three reported that they had experienced any type of hearing-related problems subsequent to their crash. One other case is reported of a driver who had pre-crash hearing loss. It appears that permanent hearing deficit due to airbag deployment, both in cars with the steering wheel airbag alone, and in those with a passenger side airbag, is an infrequent event (1.7%) from the data of this study.

ABR hearing screening for high-risk infants.

OBJECTIVE: The goals of this investigation were to determine the outcome of a high-risk newborn auditory brainstem response hearing screening program at this institution and to determine the clinical characteristics of the target population with special emphasis on the relationship between risk criteria and hearing status. STUDY DESIGN: This study involved the prospective screening of newborns with risk indicators and a retrospective analysis of results accumulated over a 10-year period. SETTING: The study was conducted either in the newborn nursery or outpatient audiology clinic of a tertiary health care center. PATIENTS: Patients were 2,103 newborns presenting with one or more risk indicators for significant congenital hearing loss or delayed onset/progressive sensorineural hearing loss. INTERVENTIONS: Diagnostic interventions involved auditory brainstem response screening at two intensity levels (25 dB and 65 to 75 dBnHL). MAIN OUTCOME MEASURES: The main outcome measure was incidence of significant, nonmedically treatable hearing loss in this population. A secondary outcome measure was determination of incidence of hearing loss in association with different risk indicators. RESULTS: One hundred fourteen (5.4%) infants were diagnosed with bilateral hearing loss. Twenty-three infants (1%) presented with unilateral hearing loss. Sixty seven (49%) of the 137 infants diagnosed with hearing loss presented with greater than moderate hearing loss. Nine (13.4%) of these 67 patients presented with delayed onset hearing loss that was diagnosed at appointments subsequent to the initial screening. The largest percentage of diagnosed hearing loss was found in the "craniofacial anomalies" category. CONCLUSIONS: Auditory brainstem response hearing screening of newborns at risk for significant hearing loss is a clinically efficient and cost effective approach to early detection of significant hearing loss. For this program, the calculated cost to diagnose one hearing impaired infant from this population is $3000.

Successful cochlear implantation in a patient with MELAS syndrome.

OBJECTIVE: To describe methods of assessing cochlear implant candidacy in patients with potentially significant peripheral and central nervous system (CNS) degeneration. STUDY DESIGN: A patient with a degenerative CNS disease (MELAS syndrome) undergoing evaluation for cochlear implantation is described. SETTING: This study took place at a tertiary care center. PATIENT: A patient with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) who had cortical blindness and profound sensorineural hearing loss was evaluated and rehabilitated with cochlear implantation. INTERVENTIONS: Pure-tone audiogram, behavioral responses to promontory stimulation electrical auditory brainstem response, and electrically evoked middle-latency responses (MLRs) were used to assess eighth nerve, auditory brainstem, and cortical auditory pathways. Cochlear implantation with Cochlear Corporation mini 22 implant was performed. RESULTS: Repeatable electrically evoked MLRs and behavioral responses to promontory stimulation documented the presence of auditory cortical responses. Successful implantation resulted in open set speech recognition and communication using the auditory/oral mode. CONCLUSION: This report describes successful implantation in a patient with MELAS syndrome and demonstrates the ability to preoperatively confirm the integrity of brainstem and cortical auditory pathways despite significant CNS degeneration.

Hearing improvement after resection of cerebellopontine angle meningioma: case study of the preoperative role of transient evoked otoacoustic emissions.

In a retrospective case study of a patient with a right-sided cerebellopontine angle mass lesion, transient evoked otoacoustic emissions were robustly present despite a severe to profound sensorineural hearing loss and abnormal auditory brainstem response. These results were interpreted as suggestive of a neural site of lesion, and the potential for planned, preserved, or improved hearing by a suboccipital surgical craniotomy was considered. A gross total resection was successful. Three years postoperatively, the patient has normal hearing sensitivity and word recognition ability.

Performance with the 20 + 2L lateral wall cochlear implant.

OBJECTIVE: The purpose of this study was to investigate the operating characteristics of the Nucleus 20 + 2L lateral wall cochlear implant including speech recognition results. STUDY DESIGN: This was a prospective randomized study involving five different modes of stimulation. SETTING: This study was carried out in an academic, tertiary referral center. PATIENTS: The patients included in this study were adult cochlear implant candidates ages 44-74 years. Length of deafness ranged from 1 to 58 years with a variety of etiologies. INTERVENTIONS: All patients were implanted with a 20 + 2L implant, which includes an intrascalar electrode array and an apically placed extracochlear, titanium encased ball electrode in contact with the endosteum of the apical turn. All patients underwent psychophysical and speech recognition testing in five different modes of electrode configuration. MAIN OUTCOME MEASURE(S): The main outcome measures included thresholds, comfort levels, dynamic ranges, and speech recognition results obtained in five electrode configuration modes. RESULTS: Thresholds were significantly lower (repeated measures ANOVA) in both monopolar conditions when compared to bipolar mode of stimulation. A binomial statistical analysis indicated that in five of nine patients activated in all five modes of stimulation, the monopolar modes of stimulation resulted in improved speech recognition scores. CONCLUSIONS: The results of the study demonstrate the feasibility of the use of an apical lateral cochlear wall electrode in conjunction with an intrascalar electrode array. It further demonstrated the superiority of monopolar stimulation in selected patients.

Electrically evoked auditory potentials: current clinical applications in children with cochlear implants.

OBJECTIVE: To summarize the current applications of auditory evoked potential in children with cochlear implants and candidates for implantation. PATIENTS AND METHODS: Perioperative transtympanic EABR is used routinely for ear selection and to establish the electrical stimulability of the ear intended to be implanted. The perioperative transtympanic EABR is supplemented with EABR obtained immediately following the insertion of the electrode array and the seating of the implant's receiver. Postoperatively, EABR and averaged electrode voltages are used effectively to properly adjust the implant stimulus parameters and to determine whether the implant is functioning adequately. Postoperatively, cognitive evoked potentials to speech and tonal stimuli may also be obtained. RESULTS: EABR results have contributed to effective implant placement and function. There were several significant correlations between speech recognition and cognitive evoked potential. CONCLUSION: These measures help assure proper implant function and effective stimulus delivery.

Clinical outcome of continuous facial nerve monitoring during primary parotidectomy.

OBJECTIVES: To assess whether continuous facial nerve monitoring during parotidectomy is associated with a lower incidence of facial nerve paresis or paralysis compared with parotidectomy without monitoring and to assess the cost of such monitoring. DESIGN: A retrospective analysis of outcomes for patients who underwent parotidectomy with or without continuous facial nerve monitoring. SETTING: University medical center. PATIENTS: Fifty-six patients undergoing parotidectomy in whom continuous electromyographic monitoring was used and 61 patients in whom it was not used. MAIN OUTCOME MEASURES: (1) The incidence of early and persistent facial nerve paresis or paralysis and (2) the cost associated with facial nerve monitoring. RESULTS: Early, unintentional facial weakness was significantly lower in the group monitored by electromyograpy (43.6%) than in the unmonitored group (62.3%) (P=.04). In the subgroup of patients without comorbid conditions or surgeries, early weakness in the monitored group (33.3%) remained statistically lower than the rate of early weakness in the unmonitored group (57.5%) (P=.03). There was no statistical difference in the final facial nerve function or incidence of permanent nerve injury between the groups or subgroups. After multivariate analysis, nonmonitored status (odds ratio [OR], 3.22), advancing age (OR, 1.47 per 10 years), and longer operative times (OR, 1.3 per hour) were the only significant independent predictive variables significantly associated with early postoperative facial weakness. The incremental cost of facial nerve monitoring was $379. CONCLUSIONS: The results suggest that continuous electromyographic monitoring of facial muscle during primary parotidectomy reduces the incidence of short-term postoperative facial paresis. Advantages and disadvantages of this technique need to be considered together with the additional costs in deciding whether routine use of continuous monitoring is a useful, cost-effective adjunct to parotid surgery.

Cognitive evoked potentials to speech and tonal stimuli in children with implants.

We investigated late and cognitive (mismatch negativity, P300) auditory potentials in 14 children with cochlear implants between the ages of 4 and 12 years. Length of cochlear implant use ranged from 7 to 84 months. Three types of stimulus contrasts were used: (1) a loudness contrast consisting of a 1500 Hz tone burst presented at 75 (standard) and 90 dB sound pressure level (deviant); (2) a frequency contrast consisting of a 1500 Hz tone burst (standard) and a 3000 Hz tone burst (deviant) presented at 80 dB sound pressure level; and (3) a speech contrast consisting of "heed" (standard) and "who'd" (deviant) delivered with a roving loudness paradigm involving a randomized variation of the levels of the standard and deviant stimuli. Latencies and amplitudes of components N1, P2, N2, and P3 and a mismatch negativity were measured. Overall, there were very few missing or unidentifiable components. P3 and mismatch negativity components were identified for all subjects and all stimuli. The latencies of most components were affected by stimulus type. There was a trend for longer latencies for the speech contrast compared with the loudness or frequency contrasts. This may be a reflection of the increased processing time required for the speech stimuli because of its higher complexity. There were several significant correlations between speech recognition and cognitive evoked potential latencies. These results indicate that the clinical use of cognitive evoked potentials in children with cochlear implants is feasible and informative.