Age-related hearing loss, vitamin B-12, and folate in elderly women. (1/570)

BACKGROUND: Hearing impairment is 1 of the 4 most prevalent chronic conditions in the elderly. However, the biological basis of age-related hearing loss is unknown. OBJECTIVE: The objective was to test the hypothesis that age-related hearing loss may be associated with poor vitamin B-12 and folate status. DESIGN: A thorough audiometric assessment was conducted in 55 healthy women aged 60-71 y. Hearing function was determined by the average of pure-tone air conduction thresholds at 0.5, 1, 2, and 4 kHz and was categorized into 2 groups for logistic regression analyses: normal hearing (<20 dB hearing level; n = 44) and impaired hearing (> or = 20 dB hearing level; n = 11). RESULTS: Mean age was the same (65 y) for the normal hearing and impaired hearing groups. Pure-tone averages were inversely correlated with serum vitamin B-12 (r = -0.58, P = 0.0001) and red cell folate (r = -0.37, P = 0.01). Women with impaired hearing had 38% lower serum vitamin B-12 (236 compared with 380 pmol/L, respectively, P = 0.008) and 31% lower red cell folate (425 compared with 619 nmol/L, respectively, P = 0.02) than women with normal hearing. Among participants who did not take supplements containing vitamin B-12 or folate, women with impaired hearing had 48% lower serum vitamin B-12 (156 compared with 302 pmol/L, respectively, P = 0.0007) and 43% lower red cell folate (288 compared with 502 nmol/L, respectively, P = 0.001) than women with normal hearing. CONCLUSION: Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.  (+info)

A possible neurophysiological basis of the octave enlargement effect. (2/570)

Although the physical octave is defined as a simple ratio of 2:1, listeners prefer slightly greater octave ratios. Ohgushi [J. Acoust. Soc. Am. 73, 1694-1700 (1983)] suggested that a temporal model for octave matching would predict this octave enlargement effect because, in response to pure tones, auditory-nerve interspike intervals are slightly larger than the stimulus period. In an effort to test Ohgushi's hypothesis, auditory-nerve single-unit responses to pure-tone stimuli were collected from Dial-anesthetized cats. It was found that although interspike interval distributions show clear phase-locking to the stimulus, intervals systematically deviate from integer multiples of the stimulus period. Due to refractory effects, intervals smaller than 5 msec are slightly larger than the stimulus period and deviate most for small intervals. On the other hand, first-order intervals are smaller than the stimulus period for stimulus frequencies less than 500 Hz. It is shown that this deviation is the combined effect of phase-locking and multiple spikes within one stimulus period. A model for octave matching was implemented which compares frequency estimates of two tones based on their interspike interval distributions. The model quantitatively predicts the octave enlargement effect. These results are consistent with the idea that musical pitch is derived from auditory-nerve interspike interval distributions.  (+info)

Auditory and electroencephalographic effects of midazolam and alpha-hydroxy-midazolam in healthy subjects. (3/570)

AIMS: Whereas cortical EEG effects of benzodiazepines are well characterized, information about benzodiazepine effects in other areas of the central nervous system is sparse. This study investigated the action of midazolam and its active metabolite alpha-hydroxy-midazolam on different parts of the auditory pathway in six healthy volunteers in a randomized, double-blind, three-way cross-over study. METHODS: Acoustically evoked short (SLP) and middle (MLP) latency potentials, transitory evoked otoacoustic emissions (TEOAE), and EEG power spectra were analysed after short i. v. injections of placebo, or 0.15 mg kg-1 midazolam, or alpha-hydroxy-midazolam, respectively. RESULTS: All subjects fell asleep during the 4 min infusion of active drug. SLP showed a significant transient increase of Jewett wave V 10 min after injection for midazolam and alpha-hydroxy-midazolam while the latency of wave I was unchanged. Both benzodiazepines induced a marked and long-lasting MLP amplitude decrease for 240 min with slow recovery over the following 360 min. No changes of TEOAE were observed. In agreement with earlier reports, increases in EEG beta activity and decreases in alpha activity were observed after administration of either drug. CONCLUSIONS: Systemically administered benzodiazepines modulate the auditory pathway above the level of the cochlea. While SLP changes were closely associated with sedation and high plasma benzodiazepine concentrations, MLP effects persisted for hours after sedation even at low benzodiazepine plasma levels. Evoked potentials may therefore be more sensitive than EEG as a tool to monitor benzodiazepine effects.  (+info)

Functional specificity in the right human auditory cortex for perceiving pitch direction. (4/570)

Previous lesion and functional imaging studies in humans suggest a greater involvement of right rather than left auditory cortical areas in certain aspects of pitch processing. In the present study, adaptive psychophysical procedures were used to determine auditory perceptual thresholds in 14 neurologically normal subjects, and in 31 patients who had undergone surgical resection from either the right or left temporal lobe for the relief of intractable epilepsy. In a subset of the patients, the lesion encroached significantly upon the gyrus of Heschl or its underlying white matter as determined from MRI analysis. Subjects were asked to perform two different perceptual tasks on the same set of stimuli. In a pitch discrimination task, the subject had to decide whether two elements of a pure tone pair were the same or different. In a task requiring the judgement of direction of pitch change, subjects decided whether pitch rose or fell from the first tone to the second. Thresholds were determined by measuring the minimum pitch difference required for correct task performance. Mean thresholds in the pitch discrimination task did not differ between patient groups and control subjects. In contrast, patients with temporal lobe excisions that encroached upon the gyrus of Heschl in the right hemisphere (but not in the left) showed significantly elevated thresholds when judging the direction of pitch change. These findings support a specialization of function linked to right auditory cortical areas for the processing of pitch direction, and specifically suggest a dissociation between simple sensory discrimination and higher order perception.  (+info)

Incidence of presbycusis of Korean populations in Seoul, Kyunggi and Kangwon provinces. (5/570)

Presbycusis, a bilateral sensorineural hearing loss caused by changes in the inner ear, is related to multiple factors such as noise exposure and otologic disease. In institute-based studies, we tried to determine the incidence of presbycusis in Korean populations living in Seoul, Kyunggi and Kangwon provinces by gender and age groups. The subjects were people who had visited health promotion centers. Pure tone audiometry was done over 20 years on 6,028 subjects. In a community-based study, the subjects were elderly residents of Kanghwa-do area. There were no obvious factors that could cause hearing impairment in the subjects. For the pure tone audiometry, hearing threshold was obtained by using the six-dimension method. The incidence of presbycusis for subjects aged 65 years and older was 37.8% and 8.3% for > or = 27 dB HL criterion and > or = 41 dB HL criterion, respectively. The incidence increased with age. A statistically significant difference in the hearing threshold was found between men and women aged 65 years or older. No differences were found between the community-based study and the institute- based studies. There was a high incidence (about 40%) of presbycusis among Koreans aged 65 years or older (for > or = 27 dB HL criterion). With an aging population, we anticipate that this report could be used to provide a basic data for the study of presbycusis.  (+info)

Children's detection of pure-tone signals with random multitone maskers. (6/570)

Preschoolers and adults were asked to detect a 1000-Hz signal, which was masked by a multitone complex. The frequencies and amplitudes of the components in the complex varied randomly and independently on each presentation. A staircase, cued two-interval, forced-choice procedure disguised as a "listening game" was used to obtain signal thresholds in quiet and in the presence of the multitone maskers. The number of components in the masker was fixed within an experimental condition and varied from 2 to 906 across experimental conditions. Thresholds were also measured with a broadband noise masker. Eight preschool children and eight adults were tested. Although individual differences were large, among both adults and children, there was little difference between the groups in the mean amount of masking produced by the maskers with large numbers of components (400 and 906). There was also a small but significant difference between adults and children in the mean amount of masking produced by the broadband noise. The difference between the groups was much larger with smaller numbers of components. Data obtained from the adults were basically similar to that previously reported [cf. Neff and Green, Percept. Psychophys. 41, 409-415 (1987); Oh and Lutfi, J. Acoust. Soc. Am. 104, 3489-3499 (1998)]: maskers comprised of 10-40 components produced as much as 30 to 60 dB of masking in some, but not all listeners. Those same maskers produced larger amounts of masking (70-83 dB) in many of the preschool children, although, as in the adult group, individual differences were large. The component-relative-entropy (CoRE) model [Lutfi, J. Acoust. Soc. Am. 94, 748-758 (1993)] was used to describe the differences in performance between the children and adults. According to this model the average child appears to integrate information over a larger number of auditory filters than the average adult.  (+info)

Hearing restoration from deafness after resection of a large cerebellopontine angle meningioma--case report. (7/570)

A 61-year-old man presented with a large cerebellopontine angle meningioma manifesting as a 1-year history of deafness on the right side, in whom hearing was restored from the deaf state immediately after tumor resection. Neuroimaging demonstrated a large mass in the right cerebellopontine angle, originating at the region adjacent to the jugular foramen. Audiometry showed his hearing was off-scale (> 105 dB) on the right. The tumor was successfully removed through the retrosigmoid approach, and the integrity of the 7th and 8th cranial nerves was maintained. The patient regained hearing on the day after the operation, which continued to improve until near-normal. The 8th cranial nerve function may recover dramatically after removal of non-acoustic tumors, even if preoperative hearing loss is profound. To maximize the opportunity to regain hearing, approaches which devastate cochlear function should be avoided and more meticulous manipulation during tumor removal is needed.  (+info)

Occurrence and risk of cochleotoxicity in cystic fibrosis patients receiving repeated high-dose aminoglycoside therapy. (8/570)

Cystic fibrosis (CF) patients receive repeated courses of aminoglycoside therapy. These patients would consequently be expected to be more susceptible to cochleotoxicity, a recognized side effect with single courses of aminoglycoside therapy. The primary aim of this retrospective study was to establish the incidence and severity of auditory deficit in CF patients. Standard (0.25- to 8-kHz) and high-frequency (10- to 16-kHz) pure-tone audiometry was carried out in 70 CF patients, and the results were compared with the results from 91 control subjects. These subjects were further divided into pediatric and adult groups. Of 70 CF patients, 12 (1 pediatric) displayed hearing loss considered to be caused by repeated exposure to aminoglycosides. There was a nonlinear relationship between the courses of therapy received and the incidence of hearing loss. The severity of the loss did not appear to be related to the number of courses received. Assuming the risk of loss to be independent for each course, preliminary estimates of per course risk of hearing loss were less than 2%. Upon comparison with previous clinical studies and experimental work, these findings suggest that the incidence of cochleotoxicity in CF patients is considerably lower than would be expected, suggesting that the CF condition may confer protection against aminoglycoside cochleotoxicity.  (+info)

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