Examination of Utricular Response Using oVEMP and Unilateral Centrifugation Rotation Testing.

OBJECTIVES: Significant advancements have been made toward the clinical assessment of utricular function through ocular vestibular-evoked myogenic potentials (oVEMP) and unilateral centrifugation (UCF) testing. To date, no study has examined intrasubject relationships between these measures. The study hypothesis was that intrasubject responses from oVEMP and UCF testing would be correlated inasmuch as both tests have been reported to assess utricular function. DESIGN: UCF rotations and oVEMP testing were performed on healthy volunteers, aged 18 to 62 years. A within-subject study design compared and correlated UCF outcome measures of ocular counterroll, subjective visual vertical, and ocular counterroll-gravitational inertial acceleration slope against peak to peak oVEMP N1-P1 amplitude. RESULTS: Correlational analyses failed to reveal any significant relationships between oVEMP amplitude and UCF responses suggesting that these tests may be inciting different response properties within the utricular system. CONCLUSIONS: Various anatomical and physiological differences within the utricle, in addition to the fundamental differences in stimulus properties between the oVEMP and UCF tests, could explain the lack of significant correlations between these measures and suggest that oVEMP and UCF testing may be complimentary in their evaluation of the utricular system. These data reinforce the complexities of the utricular system and provide further insight into the difficulties encountered in its clinical assessment.

Tympanometry in newborn infants--1 kHz norms.

With the rapid implementation of universal newborn hearing screening (UNHS) programs, a test of middle-ear function for infants is urgently needed. Recent evidence suggests that 1 kHz tympanometry may be effective. Normative data are presented for newborn intensive care unit (NICU) graduates tested at a mean age of 3.9 weeks (Study 1) and full-term infants tested at 2-4 weeks (Study 2) who passed an otoacoustic emissions (OAE) screen. Nearly all infants tested had single-peaked tympanograms. The norms are evaluated for a group of full-term infants who were screened with OAE (Study 3) and two groups of infants (NICU patients and well babies) who were not screened by OAE (Study 4). The 5th percentile for static admittance for NICU and full-term babies was identical, allowing a sinngle pass-fail criterion. Using that criterion, well babies who passed an OAE screen (Study 3) yielded a 91% pass rate. Those who passed the OAE screen had substantially higher 1 kHz static admittance than those who failed, suggesting a strong relationship between middle-ear transmission characteristics and OAE responses. The pass rate was lower for newborn well babies and NICU graduates who were not screened by OAE (Study 4).

Auditory profile in superficial siderosis of the central nervous system: a prospective study.

OBJECTIVE: To identify auditory pathology resulting from superficial siderosis of the central nervous system (SSCN), auditory site of lesion, and a clinical profile for differential diagnosis and development of recommendations. STUDY DESIGN: Prospective study. SETTING: Academic clinical center. PATIENTS: Ten participants with SSCN (the largest prospective evaluation of audiologic status reported to date). INTERVENTION(S): Demographics, clinical characteristics and history, audiometric evaluation, and Tinnitus Handicap Inventory (THI). MAIN OUTCOME MEASURE(S): Type and degree of hearing loss, relationship to clinical course of SSCN, and expected results based on age and sex. RESULTS: Sensorineural hearing loss (SNHL) is the most common symptom in SSCN (100%). Tinnitus (100%), imbalance (80%), and gait disorder (80%) were also frequently reported. Hearing loss is typically bilateral, asymmetric, progressive, sloping, and exceeds expected hearing loss related to age and sex. Hearing loss may be cochlear and/or retrocochlear in origin. Decreased word recognition is possible, and traditional amplification may offer limited benefit. CONCLUSION: We observed significant audiometric findings in all participants. SSCN variably and pathologically targets the auditory system without regard for duration of disorder. A long asymptomatic phase and lack of predictive relationship between duration and severity of hearing loss makes suspicion of SSCN based solely on audiometric battery difficult; however, asymmetric hearing loss exceeding expectations, particularly with history of head trauma or previous neurosurgical procedure, should raise a red flag and trigger further medical evaluation including MRI. Diagnosis of SSCN may alter expectations for audiologic prognosis and is a critical component for comprehensive management of SSCN patients.

Does universal newborn hearing screening identify all children with GJB2 (Connexin 26) deafness? Penetrance of GJB2 deafness.

OBJECTIVE: Deafness is the most common neurosensory defect at birth, and GJB2 (connexin 26) mutations are the most frequent genetic cause of hearing loss in many populations. The hearing loss caused by GJB2 mutations is usually congenital in onset and moderate to profound in degree. Considerable phenotypic variation has been noted however, including two anecdotal cases of apparent non penetrance at birth. The objective of this study is to document nine additional children with two pathogenic GJB2 mutations who had non penetrance of hearing loss at birth. DESIGN: Subjects were identified through a national repository which includes deaf probands ascertained primarily from the United States through the Annual Survey of Deaf and Hard of Hearing Children and Youth conducted at the Research Institute at Gallaudet University. The hearing of each of these children had been screened at birth using standard audiologic techniques. Parents were interviewed and available medical records were reviewed. Testing for GJB2 mutations was performed by PCR and sequencing of the entire coding exon in all nine individuals. RESULTS: Using parent interviews and medical records, we documented that all nine children passed newborn audiologic hearing screening. The age at which the hearing loss was subsequently identified in these nine children ranged from 12-60 mo. Of these nine children, 3 were compound heterozygotes and six were homozygous for the 35delG mutation in the GJB2 gene. CONCLUSION: These nine cases demonstrate that current newborn hearing screening does not identify all infants with two GJB2 mutations. These cases suggest that the frequency of non penetrance at birth is approximately 3.8% or higher. It is important to consider connexin deafness in any child with recessive nonsyndromic hearing loss as well as simplex cases with no history of other affected family members even when the newborn hearing screening results were within the normal range.