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1/8. Electrical status epilepticus in slow wave sleep: prospective case study of a cortical hearing impairment.

    The development of a central hearing impairment is described in a young girl with risk factors for hearing impairment that included mosaic down syndrome, leukemia, and chemotherapy. This case is unusual in the prospective regularity with which hearing was assessed from birth. The diagnosis is electrical status epilepticus in slow wave sleep, a rare childhood disorder, which was associated with lack of responsiveness to auditory signals, regression of emerging speech and language and other cognitive skills, and abnormal electroencephalographic (EEG) activity in both hemispheres. Treatment of the disorder with anticonvulsant medications and steroids has ameliorated the condition by suppressing the abnormal EEG activity and allowing substantial improvements in cognitive and social skills, although communication skills are improving more slowly.
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keywords = wave
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2/8. SPET monitoring of auditory cortex activation by electric stimulation in a patient with auditory brainstem implant.

    auditory cortex activation following multifrequency acoustic stimulation has been evaluated by means of single photon emission tomography (SPET) in one patient before and after an auditory brainstem implant (ABI). No activation could be observed after acoustic stimulation before ABI. After ABI stimulation in the coronal and axial slices, the activation within the temporal cortex contralateral to the stimulated ear was twice (43.76%) that of normal controls (23.94 /- 2.74%). This marked difference was not present in other selected cortical auditory areas (homolateral temporal, homolateral and contralateral parietal cortices). The temporal cortex was also examined with six consecutive sagittal slices from 18.75 mm up to 56.25 mm lateral to the midline. A very strong activation (51.20%) compared with that of normal controls (9.94 /- 7.45%) was detected in the 25.26-mm sagittal slice of the temporal cortex contralateral to the stimulated side. The remaining sagittal slices showed an almost normal post-stimulatory activation. As the 25.26-mm sagittal slice corresponds to the medial part of the auditory temporal cortex, its activation suggests that electrode stimulation is concentrated on the region of the cochlear nucleus in which the neurons that transduce high frequencies are located. SPET can be considered useful, in combination with electric auditory-evoked potentials, to obtain information on ABI placement and function, effectiveness of acoustic stimulation, degree of cortical stimulation and tonotopic spatial distribution of auditory cortex activation.
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ranking = 0.0052455226039914
keywords = frequency
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3/8. Auditory brainstem responses elicited by 1000-Hz tone bursts in patients with sensorineural hearing loss.

    Auditory brainstem responses were measured in response to 1000-Hz tone bursts from 115 patients with sensorineural hearing loss, presumably of cochlear origin. Mean wave V latencies and variability were comparable to those observed in normal hearing subjects for similar stimuli. The range of interaural differences in wave V latencies for 1000-Hz tone bursts were slightly greater than those observed for clicks, which may not be surprising, given the greater variability in wave V latencies for tonal stimulation, even in normal-hearing subjects. These differences, however, were not affected either by the magnitude or symmetry of hearing loss for frequencies at and above 1000 Hz. These data suggest that tone burst ABRs might be useful in otoneurologic evaluations, especially for patients with asymmetric hearing loss.
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ranking = 0.6
keywords = wave
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4/8. Evidence of central vestibulo-auditory dysfunction in atypical Cogan's syndrome: a case report.

    Auditory and vestibular functions were investigated in a patient with atypical Cogan's Syndrome. The brainstem auditory evoked response revealed bilateral severe distortion of morphology and voltage diminution after potential I, greater in right ear recordings. Interwave latency I-III was increased bilaterally. Electronystagmographic studies showed nonfatigable direction changing positional nystagmus greater with right ear undermost and bilateral failure of optic suppression. Findings suggested bilateral pontocerebellar dysfunction. Correlation was found with the side of greater clinical manifestations. The patient had excellent recovery of auditory and vestibular functions with administration of corticosteroids within 2 weeks of the onset of hearing impairment. She was followed up with auditory and vestibular studies for 30 months.
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keywords = wave
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5/8. Detection v discrimination of brief-duration tones. Findings in patients with temporal lobe damage.

    Based on earlier experiments with cats, we have developed two new hearing tests to evaluate the ability of patients with temporal lobe damage to discriminate tones of short temporal duration. Earlier published studies suggested that patients exhibit notably increased thresholds for detecting tone pulses shorter than 200 ms in length when the signals are presented to the ear located contralateral to the damaged hemisphere. Our experiments with cats indicated that auditory cortex lesions had no effect on the cats' ability to detect brief tones but did impair their ability to discriminate small changes in the frequency of such signals. In giving the brief-tone tests to seven patients with temporal lobe damage, we found a similar behavioral dissociation. All patients exhibited normal detection thresholds in conjunction with substantially elevated frequency difference limina.
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keywords = frequency
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6/8. Ototoxicity of erythromycin in man: electrophysiologic approach.

    Ototoxicity is probably the least acknowledged adverse reaction of erythromycin. The mechanism of erythromycin ototoxicity is still unknown. Here we report on two new cases of erythromycin-induced hearing loss. In both of them, serial evoked auditory brainstem potentials (EABPs) were obtained. The recorded EABPs showed absence of waves I to III during treatment with erythromycin, and normalization of all EABP waves after the administration of erythromycin had been stopped. Our findings support the hypothesis that erythromycin-induced hearing loss is attributable to a functional disorder in the peripheral parts of the auditory system.
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keywords = wave
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7/8. Cortical auditory disorder caused by bilateral temporal infarctions.

    We present a 55-year-old man who suddenly became afflicted with a bilateral auditory disturbance. Auditory acuity was preserved relatively well. Brainstem auditory evoked potentials (BAEPs) were normal. Middle latency auditory evoked potentials (MLAEPs) revealed the total absence of all waves. Brain computed tomography (CT) showed infarctions of the temporal lobes bilaterally, involving the superior temporal and transverse temporal gyri. The recognition of verbal and nonverbal sounds was also impaired. Brain CT, MLAEPs and auditory recognition tests were useful in diagnosing the cortical auditory disorder.
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keywords = wave
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8/8. Reversing click polarity may uncover auditory neuropathy in infants.

    OBJECTIVE: To identify patients with primary auditory neuropathies whose cochlear potentials to a 100 microsec click persist after click cessation and simulate synchronous auditory brain stem responses (ABRs) at high intensities. DESIGN: ABRs to condensation and rarefaction clicks, as well as Maximum Length Sequence ABRs and one transtympanic electrocochleogram (ECochG), were collected from five infants with absent middle ear muscle reflexes and normal or near normal otoacoustic emissions. These infants failed ALGO screens, which used alternating polarity clicks, and/or failed full ABRs done elsewhere with alternating polarity clicks. RESULTS: When ABRs were collected in response to a single polarity pulse, they revealed robust and reproducible wave forms over 4 to 6 msec that initially were mistaken for a normal ABR by the referring agents. However, when condensation and rarefaction click data are compared, the waveforms change polarity when the stimulus is inverted. Furthermore, the waveforms fail to shift in latency as the intensity of the stimulation is reduced. Transtympanic ECochG on one of the children revealed the same polarity reversal and fixed latency functions, confirming that they were cochlear rather than neural responses. CONCLUSIONS: Comparing responses with positive versus negative polarity clicks may help separate ABRs from cochlear potentials and alert clinicians to the possibility of an auditory neuropathy. Therefore, absent or abnormal ABRs in the presence of normal otoacoustic emissions need not always implicate a purely "central disorder," but might be consistent with dysfunction between outer hair cells and primary afferent fibers.
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