Biomedical subjects

B Cone-Wesson

Publications and source records attributed to B Cone-Wesson.

26 records · Page 2Linked to original sources

PubMed1997

Effect of stimulus level and frequency on ABR and MLR binaural interaction in human neonates.

Auditory brainstem (ABR) and middle latency (MLR) responses were evoked by click and tone-burst stimuli from human neonates. Electrophysiologic evidence of binaural interaction was measured by subtracting waveforms obtained for binaural stimulus conditions from waveforms obtained for the sum of right ear monaural and left ear monaural stimulus conditions. The effects of stimulus level and stimulus frequency on binaural interaction were evaluated by measuring the number, latency and amplitude of components found in the derived binaural interaction waveform, that is, binaural interaction components (BIC). BICs were more prevalent in the latency range of ABRs than for MLRs. Click and tonal stimuli were equally effective for deriving ABR-BICs, while tone-bursts were somewhat less effective than clicks for deriving MLR-BICs. Stimulus-response dependencies for ABR and MLR component latencies were apparent in monaural, binaural and binaural interaction waveforms. Normalized amplitudes for BICs showed that low-frequency tone-burst stimuli resulted in the largest values compared to click and high-frequency tonal stimuli. Comparison of these results with published results from adults demonstrated immaturity of binaural interaction in neonates.

Acoustic Stimulation↗

PubMed1997

Hearing sensitivity in newborns estimated from ABRs to bone-conducted sounds.

This study focused on the problem of estimating hearing sensitivity in newborns from auditory brainstem responses (ABRs) evoked by clicks and 500 Hz and 4000 Hz tonebursts presented by a bone-conduction (BC) oscillator. The effects of acoustic energy transmitted to the ear canal, gender, and ear differences were also investigated. ABR thresholds for BC stimuli were 56, 52, and 53 dB (re 1 microN) or -5, -14, and 0 dB nHL (re adult psychophysical threshold) for click and 500 Hz and 4000 Hz tonebursts, respectively. For newborns, ear canal SPLs generated by the BC stimuli were as much as 21 dB greater than those in adults. Gender-related threshold differences were significant, with female infants having lower thresholds than males; however, ear differences were not. The findings of this study can be used to set appropriate BC stimulus levels for screening or assessment of newborns.

Auditory Threshold↗

PubMed1991

Intraoperative recurrent laryngeal nerve monitoring.

Intraoperative nerve monitoring has become common for surgical procedures in which cranial or peripheral nerves may be compromised. Intraoperative monitoring of recurrent laryngeal nerve function can be accomplished by recording electromyographic activity from fine-wire electrodes placed in the vocalis muscle. The technique and instrumentation for this are adapted from those used in intraoperative facial nerve monitoring for acoustic neuroma excision. Specifically, a commercially available instrument, the XOMED-NIM provides the capability for monitoring the vocalis muscle electromyogram by means of visual and auditory display. It also provides the capability for performing evoked electromyographic tests of nerve integrity. Intraoperative monitoring of the recurrent laryngeal nerve during thyroidectomy may assist in the more precise dissection of the nerve as well as in verification of nerve integrity during the operative procedure, thus reducing the risk of injury.

Electrodes↗

PubMed1988

Effects of maternal cocaine abuse on the neonatal auditory system.

Eighteen neonates born to cocaine-abusing mothers were tested for peripheral and brainstem auditory dysfunction using auditory brainstem responses (ABR). Their data were compared to ABRs from 18 normal neonates. The ABR data were analyzed to determine if ABR parameters were abnormal in neonates born to cocaine-abusing mothers in comparison to normal neonates. ABRs from neonates exposed to maternal cocaine abuse show prolonged interpeak latencies and prolonged absolute latencies. These abnormalities indicate neurologic impairment or dysfunction that warrants further audiologic and neurologic follow-up.

Audiometry, Evoked Response↗

PubMed1987

Electrophysiologic assessment of auditory pathways in high risk infants.

This study evaluated auditory processing in a group of 59 infants at risk for subsequent hearing and language disorders due to low birthweight and/or perinatal asphyxia. Auditory system integrity was evaluated electrophysiologically by recording the auditory brainstem response (ABR), middle latency response (MLR) and the cortical auditory evoked potential (CAEP). 63% of the babies had normal peripheral function or slight unilateral impairment; 84% had normal brainstem auditory system function; 82% showed normal MLRs; and 81% showed normal CAEPs. Fifty-three percent of the babies were normal on all tests and only 3% were deviant on all tests. The remaining infants showed diverse patterns of peripheral, brainstem and cortical abnormalities.

Auditory Cortex↗

PubMed1987

Bone conduction masking for brainstem auditory-evoked potentials (BAEP) in pediatric audiological evaluations. Validation of the test.

A brainstem auditory-evoked potential (BAEP) protocol for testing pediatric patients at risk for conductive hearing impairment was evaluated. The protocol used was: air-conducted click stimuli masked by bone-conducted wide-band noise. The specificity and sensitivity values for the test were determined by means of a blind cross-sectional trial including an active group of patients with an aural malformation and an age-matched control group with a sensorineural impairment. The bone-conducted masking of air-conducted BAEP showed high specificity and sensitivity and was easily administered despite pediatric difficulty. It was useful in differentiating sensorineural from conductive impairment and provided a rough estimate of the cochlear reserve in presumptive conductive hearing loss as great as 60 dB hearing loss. It is concluded that the bone-conducted masking procedure appears to be a great help in the binary decision whether middle ear surgery should be performed in patients at risk for conductive hearing loss, specially children with aural malformations.

Adolescent↗

PubMed1985

Neurological complications in infants and children with acquired immune deficiency syndrome.

Neurological complications occurred in 6 children, aged 6 months to 5 years, with acquired immune deficiency syndrome who were followed for 14 months. The most frequent manifestations included encephalopathies, acquired microcephaly, and pyramidal tract signs. Computed tomographic examinations showed variable degrees of cortical atrophy with ventricular dilatation and calcification. Electrophysiological abnormalities were demonstrated. Two children had documented central nervous system infections. Neurological deterioration resulted in dementia in 3 children. Cognitive impairment and developmental delays were evident in the other 3. Postmortem examination of the 3 children who died showed subacute cytomegalovirus encephalitis in 1; nonspecific hemispheric white matter changes, calcific vasopathy of the basal ganglia, and striking bilateral corticospinal tract degeneration in the second; and extensive calcific vasopathy of the basal ganglia and frontal centrum semiovale, and bilateral attenuation of the frontopontine and corticospinal tracts in the third.

Acquired Immunodeficiency Syndrome↗

PubMed1985

Developmental abnormalities in infants and children with acquired immune deficiency syndrome (AIDS) and AIDS-related complex.

Children with acquired immune deficiency syndrome (AIDS) display two types of clinical picture: a full-blown AIDS characterized by the presence of opportunistic infections and/or Kaposi's sarcoma and a prodromal stage now identified as AIDS-related complex (ARC). Neurological complications have been identified in infants and children with the disease. This paper discusses the developmental abnormalities in 16 pediatric patients, seven with AIDS and nine with ARC, ranging in age from six months to six years. In all cases, the mothers of these children either had ARC, AIDS and/or used intravenous drugs. Developmental histories showed delayed acquisition of milestones in most children following the diagnosis of AIDS or ARC, with delayed motor milestones consistently noted in both groups. Several children with AIDS actually lost milestones as their illness progressed; this has not occurred in the ARC group. Psychometric testing revealed more severe cognitive dysfunction in the group with AIDS. Involvement of the central nervous system was documented clinically, radiologically, and/or electrophysiologically in all patients with AIDS. In the ARC group the course of the illness has shown greater variability. Medical and social factors that may contribute to the developmental abnormalities are discussed.

Acquired Immunodeficiency Syndrome↗