Carlton J. Zdanski

Cochlear implantation in children with auditory neuropathy spectrum disorder

Objective: To report the patients characteristics, preoperative audiological profiles, surgical outcomes, and postoperative performance for children with auditory neuropathy spectrum disorder (ANSD) who ultimately received cochlear implants (CIs). Design: Prospective, longitudinal study of children with ANSD who received CIs after a stepwise management protocol that included electrophysiologic and medical assessment, documentation of behavioral audiometric thresholds and subsequent fitting of amplification according to Desired Sensation Level targets, auditory-based intervention with careful monitoring of skills development and communication milestones, and finally implantation when progress with the use of acoustic amplification was insufficient. Results: Of 140 children with ANSD, 52 (37%) received CIs in their affected ears (mean duration of use of 41 mos). Many of these children were born prematurely (42%) and impacted by a variety of medical comorbidities. More than one third (38%) had abnormal findings on preoperative magnetic resonance imaging of the brain and inner ear, and 81% had a greater than severe (>70 dB HL) degree of hearing loss before implantation. Although 50% of the implanted children with ANSD demonstrated open-set speech perception abilities after implantation, nearly 30% of them with >6 months of implant experience were unable to participate in this type of testing because of their young age or developmental delays. No child with cochlear nerve deficiency (CND) in their implanted ear achieved open-set speech perception abilities. In a subgroup of children, good open-set speech perception skills were associated with robust responses elicited on electrical-evoked intracochlear compound action potential testing when this assessment was possible. Conclusions: This report shows that children with ANSD who receive CIs are a heterogeneous group with a wide variety of impairments. Although many of these children may ultimately benefit from implantation, some will not, presumably because of a lack of electrical-induced neural synchronization, the detrimental effects of their other associated conditions, or a combination of factors. When preoperative magnetic resonance imaging reveals central nervous system pathology, this portends a poor prognosis for the development of open-set speech perception, particularly when CND is evident. These results also show that electrical-evoked intracochlear compound action potential testing may help identify those children who will develop good open-set speech perception. Instead of recommending CI for all children with electrophysiologic evidence of ANSD, the stepwise management procedure described herein allows for the identification of children who may benefit from amplification, those who are appropriate candidates for cochlear implantation, and those who, because of bilateral CND, may not be appropriate candidates for either intervention.

Auditory neuropathy characteristics in children with cochlear nerve deficiency.

Objective: To describe a group of children exhibiting electrophysiologic responses characteristic of auditory neuropathy (AN) who were subsequently identified as having absent or small cochlear nerves (i.e., cochlear nerve deficiency). Design: A retrospective review of the clinical records, audiological testing results, and magnetic resonance imaging (MRI) studies. Fifty-one of 65 children with AN characteristics on auditory brain stem response (ABR) testing had MRI available for review. Nine (18%) of these 51 children with ABR characteristic of AN have been identified as having small (N = 2; 4%) or absent (N = 7; 14%) cochlear nerves on MRI. Results: Of the nine children with cochlear nerve deficiency, five (56%) were affected unilaterally and four (44%) bilaterally. Eight of nine presented after failing a newborn infant hearing screening, whereas one presented at 3 yr of age. On diagnostic ABR testing, all 9 children (9 of 13 affected ears; 69%) had evidence of a cochlear microphonic (CM) and absent neural responses in at least one ear. In the unilateral cases, AN characteristics were detected in all affected ears. In bilateral cases, at least one of the ears in each child demonstrated the AN phenotype, whereas the contralateral ear had no CM identified. Only one ear with cochlear nerve deficiency had present otoacoustic emissions as measured by distortion-product otoacoustic emissions. In children with appropriate available behavioral testing results, all ears without cochlear nerves were identified as having a profound hearing loss. Only 4 (31%) of the 13 ears with cochlear nerve deficiency had a small internal auditory canal on MRI. Conclusions: Children with cochlear nerve deficiency can present with electrophysiologic evidence of AN. These children frequently refer on newborn screening examinations that use ABR-based testing methods. Similar to other causes of AN, diagnostic ABR testing will show a CM with absent neural responses. Given that 9 (18%) of 51 children with available MRI and electrophysiologic characteristics of AN in our program have been identified as having cochlear nerve deficiency makes this a relatively common diagnosis. These findings suggest that MRI is indicated for all children diagnosed with AN. Moreover, electrophysiologic evidence of unilateral AN in association with a profound hearing loss should make the clinician highly suspicious for this problem. Although children with cochlear nerve deficiency who have a small nerve may benefit from cochlear implantation or amplification, these interventions are obviously contraindicated in children with completely absent cochlear nerves.

Internal auditory canal morphology in children with cochlear nerve deficiency

Objective: To describe the internal auditory canal (IAC) and inner ear morphologic characteristics of children with cochlear nerve (CN) deficiency. Study Design: Retrospective case series. Setting: Tertiary referral center. Patients: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution magnetic resonance imaging (MRI). Interventions: MRI of the brain. Clinical evaluation. Main Outcome Measures: Review of medical records, audiological testing results, and imaging studies. Images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs and inner ears. Audiometric thresholds were evaluated in all subjects. Methods: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution MRI. A review of the medical records, audiologic testing results, and imaging studies was undertaken. The images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs, and inner ears. The audiometric thresholds were evaluated in all subjects. Results: Among the 14 patients, 5 had known syndromes. MRI allowed an exact specification of the nervous structures within all ears with normal-size IACs. Precise characterization of the nerves in ears with small IACs was more difficult, requiring a consideration of both imaging findings and functional parameters. Five children had bilateral deficient CNs, whereas the remaining 9 subjects were affected unilaterally. Thus, 19 ears had CN deficiency (absent CN, 16; small CN, 3). Eleven ears had normal-size IACs and deficient CNs. Of the 9 ears with small IACs, 8 had deficient CNs (absent, 7; small, 1) on the basis of both MRI and functional assessments. Two ears with small IACs had clear morphologic and/or functional evidence for the presence of a CN: one had a small-size CN on MRI, whereas another had a single nerve in a small IAC with present facial and auditory functions. Conclusion: The findings of this study suggest that CN deficiency is not an uncommon cause of congenital hearing loss. The findings that most ears with CN deficiency had normal IAC morphology and that two ears with small IACs had CNs present indicate that IAC morphology is an unreliable surrogate marker of CN integrity. On the basis of these findings, we think that high-resolution MRI, rather than CT imaging, should be performed in all cases of pediatric hearing loss, especially in those cases where profound hearing loss has been documented. For ears with small IACs, the resolution of MRI currently remains limiting. In these cases, the determination of CN status frequently requires a variety of anatomic (CT and MRI) and functional tests (auditory brainstem response, otoacoustic emissions, behavioral audiometry, and physical examination).

Nitric oxide synthase is an active enzyme in the spiral ganglion cells of the rat cochlea

Nitric oxide (NO) mediates the effects of the excitatory amino acids in the central nervous system. Excitatory amino acids, in particular L-glutamate, are thought to be the neurotransmitter(s) present at the cochlear hair cell-afferent nerve synapse. To our knowledge, no studies to date have documented the presence of NO in the cochlea nor attempted to elucidate the role of NO in hearing. Rat cochlea frozen sections were examined for the presence of nitric oxide synthase (NOS) by NADPH diaphorase histochemistry. Vibratome sections of rat cochlea were examined by immunocytochemistry with an antibody to citrulline, an indication of NOS activity. Spiral ganglion cells in the rat cochlea were positive by NADPH diaphorase histochemistry and by anti-citrulline immunocytochemistry. These results indicate that NOS is present and that the enzyme actively produces nitric oxide in the spiral ganglion cells of the rat cochlea. Given our current understanding of neurotransmission in the cochlea, it is reasonable to postulate that the actions of NO in cochlear neuronal tissue are similar to the actions of NO in the CNS and that NO acts as a neurotransmitter/neuromodulator in the cochlea. In addition, because NO has been implicated as a mediator of excitotoxicity in the CNS, NO may play a role in neurotoxicity in the cochlea.

Cochlear implantation in children with labyrinthine anomalies and cochlear nerve deficiency: implications for auditory brainstem implantation.

Compare outcomes among children with inner ear malformations and/or cochlear nerve deficiency (CND) who have received a cochlear implant (CI).

Cochlear implantation for children with GJB2-related deafness.

Objectives/Hypothesis: Mutations in GJB2 are a common cause of congenital sensorineural hearing loss. Many children with these mutations receive cochlear implants for auditory habilitation. The purpose of the study was to compare the speech perception performance of cochlear implant patients with GJB2‐related deafness to patients without GJB2‐related deafness.

β-Blockers for Infantile Hemangiomas: A Single-Institution Experience

Propranolol has become first-line therapy for the treatment of infantile hemangiomas in many centers. Of 302 children with hemangiomas seen at the University of North Carolina from 2008 through 2010, 15.6% were treated with oral propranolol alone, 5.6% with topical timolol (a propranolol derivative) alone, and 2.3% with both. The use of these agents increased over time from 7% of patients seen in 2008 to 54% of patients first seen in 2010. Starting doses of propranolol ranged from 0.25 to 1 mg/kg/d, with target doses of 1 to 4 mg/kg/d. Serious side effects, noted in 6/54 (10.9%) patients, included somnolence, bradycardia, hypotension, hypoglycemia, and mottling of extremities.The authors confirm the variation in use of propranolol for vascular lesions and extend experience with timolol. They suggest daily home monitoring of patients for the first 2 weeks of initiating or increasing doses. Frequent feeding of infants and young children on this drug is recommended.

Cochlear implants in Waardenburg syndrome.

Objective: Waardenburg syndrome is an autosomal‐dominant syndrome characterized by dystopia canthorum, hyperplasia of the eyebrows, heterochromia irides, a white forelock, and sensorineural hearing loss in 20% to 55% of patients. This patient population accounts for approximately 2% of congenitally deaf children. The purpose of this retrospective case review was to describe the outcomes for those children with Waardenburg syndrome who have undergone cochlear implantation.

Multicenter Interrater and Intrarater Reliability in the Endoscopic Evaluation of Velopharyngeal Insufficiency

OBJECTIVE To explore interrater and intrarater reliability (R (inter) and R (intra), respectively) of a standardized scale applied to nasoendoscopic assessment of velopharyngeal (VP) function, across multiple centers. DESIGN Multicenter blinded R (inter) and R (intra) study. SETTING Eight academic tertiary care centers. PARTICIPANTS Sixteen otolaryngologists from 8 centers. MAIN OUTCOME MEASURES Raters estimated lateral pharyngeal and palatal movement on nasoendoscopic tapes from 50 different patients. Raters were asked to (1) estimate gap size during phonation and (2) note the presence of the Passavant ridge, a midline palatal notch on the nasal surface of the soft palate, and aberrant pulsations. Primary outcome measures were R (inter) and R (intra) coefficients for estimated gap size, lateral wall, and palatal movement; kappa coefficients for the Passavant ridge, a midline palatal notch on the nasal soft palate, and aberrant pulsations were also calculated. RESULTS The R (inter) coefficients were 0.63 for estimated gap size, 0.41 for lateral wall movement, and 0.43 for palate movement; corresponding R (intra) coefficients were 0.86, 0.79, and 0.83, respectively. Interrater kappa values for qualitative features were 0.10 for the Passavant ridge; 0.48 for a notch on the nasal surface of the soft palate, 0.56 for aberrant pulsations, and 0.39 for estimation of gap size. CONCLUSIONS In these data, there was good R (intra) and fair R (inter) when using the Golding-Kushner scale for rating VP function based on nasoendoscopy. Estimates of VP gap size demonstrate higher reliability coefficients than total lateral wall, mean palate estimates, and categorical estimate of gap size. The reliability of rating qualitative characteristics (ie, the presence of the Passavant ridge, aberrant pulsations, and notch on the nasal surface of the soft palate) is variable.

Pediatric Sensorineural Hearing Loss, Part 2: Syndromic and Acquired Causes

SUMMARY: This article is the second in a 2-part series reviewing neuroimaging in childhood SNHL. Previously, we discussed the clinical work-up of children with hearing impairment, the classification of inner ear malformations, and congenital nonsyndromic causes of hearing loss. Here, we review and illustrate the most common syndromic hereditary and acquired causes of childhood SNHL, with an emphasis on entities that demonstrate inner ear abnormalities on cross-sectional imaging. Syndromes discussed include BOR syndrome, CHARGE syndrome, Pendred syndrome, Waardenburg syndrome, and X-linked hearing loss with stapes gusher. We conclude the article with a review of acquired causes of childhood SNHL, including infections, trauma, and neoplasms.