ABSTRACT
OBJECTIVE To observe the changes of synaptic ultrastructures in the rat auditory center after long-term salicylate administration and to elucidate the role of neuroplasticity in some areas of the CNS and its involvement in tinnitus. METHODS The rats were divided into 4 groups: the control group, the acute treatment group, the chronic treatment group, and the recovery group. We investigated ultrastructural alterations in the synapses of inferior colliculus (IC), auditory center (AC) and cerebellum (CRB) by transmission electron microscopy. RESULTS There were more synaptic vesicles (tIC=-4. 61, tAC=-7. 00, P＜0. 01), with greater postsynaptic densities(tIC=-4. 72,P＜0. 01; tAc=-3. 15, P＜0. 05), longer synaptic active zone (tIC=-4. 89, tAC=-3. 48, P＜ 0. 01), and increased synaptic interface curvature (tIC=-2. 32, tAC=-3. 17, P＜0. 05) in the chronic treatment group, as compared with the control group. There were more synaptic vesicles but no other changes in the acute salicylate-treatment group(tIC=-10. 57, tAC=-8. 34, tCRB=-9. 18,P ＜0. 01). CONCLUSION These findings showed that long-term salicylate administration have induced synaptic ultrastructural changes in the IC and AC because of neuroplasticity. These structural changes may result in increased speed and efficacy of chemical synaptic transmission. Alterations to neuroplasticity of the auditory center pathway may lead to tinnitus.
ABSTRACT
Objective@#To explore the effects of bimodal intervention on the development of auditory and speech ability in the infants with unilateral cochlear implantation(CI).@*Methods@#Total 35 bilateral profound sensorineural hearing loss infants with unilateral CI, aged 0.7 to 2.8 years old, were selected. The subjects were divided into two groups: the group with unilateral CI(cochlear implant alone, n= 15), and the bimodal group with CI and contralateral fitting hearing aid(n= 20). Their auditory and speech abilities were estimated at the different time points after switch-on(the 0th, 0.5th, 1st, 3rd, 6th, 12th, 18th, and 24th month, respectively) using Infant Toddler-Meaningful Auditory Integration Scale(IT-MAIS), Meaningful Use of Speech Scale(MUSS), Categories of Auditory Performance(CAP), and Speech Intelligibility Rating(SIR) scores.@*Results@#The IT-MAIS scores of bimodal group after switch-on were higher than unilateral CI group(the 0.5th, 1st, 3rd, 6th, 12th, and 18th month), the statistical significances were identified at the 0.5th, 1st, 3rd, 6th, and 12th month, respectively(P<0.05). The CAP scores of bimodal group before CI operation and after switch-on(the 0.5th, 1st, 3rd, 6th, 12th, 18th and 24th month)were higher than unilateral CI group, the statistical significances were seen at the 3rd, 6th, 12th, 18th and 24th month after switch-on(P<0.05). The MUSS scores of bimodal group after switch-on were higher than unilateral CI group(the 1st, 3rd, 6th, 12th, 18th and 24th month), the statistical significances were found at the 12th, 18th and 24th month, respectively(P<0.05). The SIR scores of bimodal group after switch-on were higher than unilateral CI group(the 3rd, 6th, 12th, 18th and 24th month), and significant differences appeared at the 12th, 18th and 24th month after switch-on(P<0.05).@*Conclusion@#Bimodal intervention could be helpful to the development of auditory and speech ability of infants.
ABSTRACT
Objective To investigate the correlation between incidence rate of tinnitus and noise exposure time,age,hearing condition in noise exposure workers.Methods A total of 1 985 noise exposure workers (age between 20～60 years old;working length between 1 ～30 years) in a large dockyard were randomly selected as the subject of this study with 1 831 male workers and 154 female workers in average 36.3±8.25 years old.The average noise exposure time was 9.1±6.50 years and pure tone threshold of final candidates in sound-proofed environment was evaluated (at 0.25～8 kHz).The subjects were divided into four groups according to the subjective tinnitus level:mild tinnitus,moderate tinnitus,severe tinnitus and no tinnitus to analysis the correlation among incidence rate of tinnitus and noise exposure time,age,hearing condition,etc.Results Among all 1 985 subjects enrolled the occurrence rate of tinnitus was 20.55％ (408/1 985),with 367 acquired mild tinnitus(89.95％),39 acquired moderate tinnitus (9.56％) and 2 for severe tinnitus (0.49％).Mild tinnitus and moderate tinnitus showed a multi-step raising according to noise exposure time.Mild tinnitus increased continually with age while moderate tinnitus showed an accumulation in age group over 55 years old.Female was less likely to be annoyed by tinnitus than male.Conclusion Tinnitus can be early warning of auditory damage by noise exposure;older male group with longer noise exposure time is more vulnerable to tinnitus.Tinnitus acquired in noise environment is more likely to be mild.
ABSTRACT
Objective To investigate the neural activity in the central auditory pathway by using a tinnitus an-imal model .Methods Twenty -four rats were randomly divided into the control ,acute salicylate treatment ,chronic salicylate treatment ,and recovery groups .The gap prepulse inhibition of acoustic startle test was used to confirm tinnitus -like behavior .After delivery of an intravenous bolus of fluorine -18 fluorodeoxyglucose (18F -FDG ) , small animal positron emission tomography scans were performed on rats .Results Only rats in chronic salicylate -treatment group showed evidence of experiencing tinnitus .The SUV ratios of the AC were significantly greater in the acute salicylate treatment group than in the control group (P<0 .01) ,suggesting relatively increased metabolism in the two brain regions of the rats in this group .The SUV ratios of the IC and AC (P<0 .01) ,but not of the CRB (P>0 .05) were greater in the chronic salicylate treatment group than in the control groups .There was a significant difference in whole brain SUVs between the control and acute salicylate treatment groups (P<0 .01) ,the whole brain SUVs in chronic salicylate treatment group were a little higher but showed no significant difference (P>0 .05) .There was no significant difference in the SUVs between the control and recovery groups (P>0 .05) .Conclu-sion These findings indicate that long -term salicylate administration induced tinnitus in rats and may have en-hanced neural activity corresponded to the up -regulated metabolic rate in our study .Alterations to neuroplasticity of the CNS may lead to tinnitus .
ABSTRACT
Objective To evaluate the speech recognition ability in noise enviroment in older adults with age-related hearing loss and to discuss the influences of age ,hearing loss and cognitive function on the ability of speech recognition in noise enviroment .Methods A total of 90 older adults aged over 60 years at the hearing clinic of Xinhua hospital were divided into three groups according to the age ,which were 60~69 y group (88 ears) ,70~79 y group (64 ears) ,> 79 y group (28 ears) .All the participants completed pure tone audiometry ,the Mandarin hearing in noise test (MHINT) and the mini-mental state examination (MMSE) .The pure tone average hearing threshold (PTA) ,signal-to -noise ratio (SNR) of MHINT and MMSE scores were obtained .We used the statis_tical software SPSS 17 .0 to analyze the correlations among age ,PTA ,adaptive SNR and MMSE scores .ResuIts ①PTA and SNR increased with the age .The difference of PTA and SNR for different age groups was statistically sig_nificant (P<0 .01) .②The difference SNR among different PTA groups were significant (P<0 .01) ,and when the influence of MMSE scores was controlled the difference was still significant .There was a significant linear correlation between PTA and SNR (r=0 .326 ,P<0 .01) .MMSE scores decreased with the increasing of PTA ,and there was also a linear correlation between PTA and MMSE scores (-0 .187 ,P<0 .05) .③Adaptive SNR and MMSE scores were correlated (r= -0 .201 ,P<0 .01) ,but there was no significant linear relationship .Besides ,SNR of the cog_nitive function impairment group (<27 points) was significantly greater than that of the normal cognitive function group (27~30 points) (P<0 .01) .However ,among the three PTA groups ,the differences were not statistically significant .ConcIusion The hearing in noise test reflects the ability of speech recognition in noise enviroment in ol_der adults ,and can be used to assess the hearing functions in elder .Speech recognition in noise ,peripheral hearing loss and cognitive functions are relevant .Cognitive functions have an influence on the evaluation of the hearing func_tion for older adults .
ABSTRACT
Objective To investigate the relationship between pure -tone audiometry (PTA ) ,speech dis‐crimination abilities in quiet or in noise and the international outcome inventory for hearing aids (IOI-HA) in pres‐bycusis patients .Methods Twenty presbycusis subjects were tested in this study .Pure-tone audiometry (PTA) and speech discrimination threshold were obtained before being fitted with hearing aids .They weared hearig aids more than six months ,and pure-tone audiometry ,speech discrimination scores in quite(the level = 65 dB SPL) and in noise(signal to noise ratio = 10 dB) were carried out in sound field .A stepwise forward multiple-regression analysis was performed to investigate the impact of PTA and speech discrimination scores to IOI-HA .Results The PTAs before or after hearing aid fittings showed a negative association with IOI-HA ,while speech discrimination scores in quiet or in noise before or after hearing aid fittings showed a positive association with IOI-HA .Speech discrimination threshold in noise was identified as a single predictor of IOI-HA(P<0 .001) .Conclusion The relation between speech discrimination scores in noise and IOI-HA suggests that a poor score might limit the hearing aids outcome .The speech discrimination scores in noise help the clinicians predict the outcomes of hearing aid in real‐ities .
ABSTRACT
Tinnitus is the most common disease in Otology, and extremely difficult for treatment in clinic, abnormal events in the cochlea (the abnormal events can result in abnormal neuronal activity in central auditory pathways that can then be finally perceived as tinnitus). Neuroplasticity events at the auditory cortex (AC) have been reported to include hyperactive of cortical neurons and an increase in neuronal synchronization. Our recent studies showed the changes markedly, in the expression of the excitatory glutamate receptor subtype NR2B in mRNA and protein levels, and also some changes in synaptic ultrastructure of neurons in auditory cortex of tinnitus animal. We propose that the mechanisms of tinnitus centralization may arise from abnormal events in the cochlea, and result in abnormal neuronal activity at multiple levels which promote abnormal propagation of neural activity in the central auditory pathway. The plastic change may be positive and adaptive as with learning or memory, or in the compensation after abnormal events in the cochlea that results in new neuronal networks that restore normal function. Alternatively, the neuroplasticity changes might be maladaptive leading perhaps to an imbalance in excitatory and inhibitory events in the brain. Indeed, tinnitus may be the consequence of such maladaptive neuroplasticity brain alterations (synaptic structure) has even gone a step further and described tinnitus as the perceptual manifestation of plastic brain changes that result in abnormal neuronal activity. The neuroplasticity changes may also make tinnitus persists, eventually leading to the existence of tinnitus cochlear-originated in the central pathway. They may also extend to non-sensory areas of the brain giving rise to the attentional and emotional aspects that often accompany the disorder. New pathophysiological insights maybe prompt the development of management approaches to directly target the neuroplasticity processes correlates of tinnitus.
Subject(s)
Humans , Auditory Cortex , Neuronal Plasticity , Tinnitus , Diagnosis , TherapeuticsABSTRACT
Objective To investigate the reliability and practicality of Chinese version the hearing handicap in-ventory for the elderly -screening version(HHIE -S) scale for elderly hearing screening in China .Methods We compared the HHIE -S scores with results of pure -tone audiometry test .A total of 840 Chinese individuals older than 60 years filled in the scale all by themselves first ,then refilled it according to explanations of each question translated by researchers .All participants finished pure -tone audiometry test with frequencies of 0 .25 ,0 .5 ,1 .0 , 2 .0 ,and 4 .0 kHz .Sensitivity ,specificity ,positive predictive value (PPV ) ,false-negative rate and false -positive rate were compared with HHIE -S cut -off points of >8 or >10 and pure-tone averages (PTAs) greater than 25 ,40 and 60 dB HL .Analysis the area under the curve (AUC) values of receiver operating characteristic (ROC) curves for each three PTA levels .Results Cronbach's α of the scale was 0 .85 .HHIE -S scale pre -explanatory score was 7 .6 ± 10 .6 ,and post-explanatory score was 10 .8 ± 16 .7(P 8 points higher than H HIE-S> 10 points in the sensitivity ,positive predictive value increase ,specificity ,false-positive rate ,false negative rate decreased ,paired samples t - test sensitivity and false -negative rate (P 8 when grouping with PTA> 25 dB HL ,PTA> 40 dB HL and PTA>60 dB HL ,conducted ROC curve analysis ,the AUC value was 0 .70 ± 0 .03 ,0 .84 ± 0 .01 and 0 .88 ± 0 .02 .Conclusion The score of HHIE-S scale>8 points can be used when PTA> 40 dB HL as goal for hearing loss of old people , it can be more accurate after explanations ,so HHIE-S scale can be used as a preliminary hearing screening method for Chinese elderly people .
ABSTRACT
Objective To assess hearing and efferent system functions of autistic children.Methods Tests were performed on 30 Autistic children and 15 normal children to evaluate hearing objectively by using otoacoustic emission (OAE) and auditory brainstem response (ABR).The efferent system functions were analyzed through contralateral suppression in OAE.Results The mean ABR Ⅰ-Ⅴ interpeak latencies (IPLs) in children with Autism were significantly reduced than that in the control group.The amplitudes of OAE at 1 kHz and 2 kHz in autistic children were significantly different in two groups.There were no significant differences in contralateral suppressions between the Autistic children and the control.Conclusion Hearing impairment may be more common in children with Autism than in normal children,while for a few Autistic children,their efferent system functions are affected.
ABSTRACT
Objective To investigate the different expression levels of Na+ - K+ - 2Cl- co- transporter NKCC1 mRNA in the cochlea of rats after sodium salicylate injection and to explore the mechanism underlying the change of outer hair cells, induced by different salicylate administration. Methods Twenty-four normal adult rats were randomly divided into four groups with six rats in each group. Rats in control group,did not recieve sodium sa-licylate injection. The other three groups were acute group,chronic group,and recovered group according to the dif-ferent doses of sodium salicylate. The fluorescence quantitative PCR method was used to detect the expression levels of NKCC1 mRNA in the rat cochleas of the four groups. Results NKCC1 mRNA was expressed in all of the four groups. After sodium salicylate injection, the expressions of NKCC1 mRNA in chronic and recovered group were higher than that in control group(P<0.05). While the expression of NKCC1 mRNA in acute group was lower than that in control group(P(0. 05). Conclusion The expression of NKCC1 mRNA in the normal cochlea indicates that NKCC1 may play an important role in the maintenance of Cl- in the endolymph of the cochlea. The alteration of NKCC1 mRNA expression caused by sodium salicylate injection may lead to the change of the outer hair cell electro-motility.
ABSTRACT
OBJECTIVE@#To find the characteristic of tympanogram results obtained from normative neonates 2 - 7 days about low frequency (226 Hz) probe tone, and to determine the normative values for tympanometric variables.@*METHOD@#Transient evoked otoacoustic emission (TEOAE) screening were performed by using AccuScreen Pro instrument for 135 neonates. Among them, 105 neonates passed the TEOAE screening in both ears. The 226 Hz probe tone tympanograms and their normative values were obtained from them using GSI-33 middle ear analyzer.@*RESULT@#The 226 Hz tympanometric data for the 105 neonates (210 ears) passed the TEOAE screening in both ears showed a double-peaked tympanogram in 202 ears (96.19%), a single-peaked tympanogram in 8 ears (3.81%). For double-peaked tympanogram in 202 ears, the tympanometric normative values was below: the first peak admittance is (0.91 +/- 0.18)mmho, Tpp is about (18.02 +/- 12.26)daPa; the second peak admittance is (1.05 +/- 0.23)mmho, Tpp is about (-35.05 +/- 16.80) daPa; the admittance of notch between the two peaks is (0.74 +/- 2.57)mmho, its pressure is about (0.37 +/- 7.61) daPa. Vec is about (0.50 +/- 0.08)ml.@*CONCLUSION@#The 226 Hz tympanograms obtained from this cohort may serve as a guide for evaluating middle ear function in neonates.
Subject(s)
Female , Humans , Infant, Newborn , Male , Acoustic Impedance Tests , Methods , Acoustic Stimulation , Evoked Potentials, Auditory, Brain Stem , Neonatal Screening , Otoacoustic Emissions, Spontaneous , Reference ValuesABSTRACT
Objective To investigate the influence of long-term sound conditioning on the physiology of outer hair cells.Methods Twenty healthy guinea pigs were exposed to a broadband noise for 14 days consecutively at the level 90 dB(A),8 h/day.The DP-gram and input/output(I/O)function(1~8 kHz)were measured at pre-conditioning,fourteen days conditioning,seven days post-conditioning and fourteen days post-conditioning,respectively.Results The results of DP-gram measurements demonstrated that long-term sound conditioning could enhance the DPOAE amplitudes within low frequencies(1~3 kHz,especially 5.0 dB at 2 kHz and 7.5 dB at 3 kHz,P
ABSTRACT
Objective To study the change and the characteristics of distortion product otoacoustic emissions (DPOAE) of awake guinea pigs with the acute injection of sodium salicylate, and to investigate the ototoxicity of sodium salicylate to OHC. Methods With CELESTA 503 otoacoustic emission analyzer, DPOAE including DP-gram and DP-I/O function of awake guinea pigs were recorded.DPOAE were measared before and 2,4,8 h after acute injection of sodium salicylate or saline respectively. The data were analysed with SPSS 10.0.Results Acute sodium salicylate injection mainly caused the DPOAE amplitude and the I/O slope to reversibly decrease and increase respectively. The changes were largest 2 h after injection, and almost returned to normal level 8 h after injection. The differences between certain outcomes of DPOAE after and before injection were significant (P
ABSTRACT
In order to observe the DPOAE of guinea pigs under awake and anesthetic conditions, we invesitigated the amplitude of distortion product emission and I/O function curves and made a comparative analysis of their changes under different conditions. It was found that the amplitude of DPOAE and I/O curves did not show difference in the guinea pigs under awake and anesthetics conditions. We deem it credible and simple to measure DPOAE in the guinea pigs under awake condition, which is similar to measuring DPOAE in the guinea pigs under physiological condition.
Subject(s)
Animals , Female , Male , Acoustic Stimulation , Anesthesia , Cochlea , Physiology , Guinea Pigs , Otoacoustic Emissions, Spontaneous , PhysiologyABSTRACT
Objective To investigate the different expression levels of Na+-K+-2Cl-co-transporter NKCC1 mRNA in the cochlea of rats after sodium salicylate injection and to explore the mechanism underlying the change of outer hair cells,induced by different salicylate administration.Methods Twenty-four normal adult rats were randomly divided into four groups with six rats in each group. Rats in control group,did not recieve sodium salicylate injection. The other three groups were acute group,chronic group,and recovered group according to the different doses of sodium salicylate.The fluorescence quantitative PCR method was used to detect the expression levels of NKCC1 mRNA in the rat cochleas of the four groups.Results NKCC1 mRNA was expressed in all of the four groups.After sodium salicylate injection,the expressions of NKCC1 mRNA in chronic and recovered group were higher than that in control group(P
ABSTRACT
Objective To get the thresholds of single and simultaneously multiple bone conduction auditory steady-state response(BC-ASSR) of young adults with normal hearing,and to compare the thresholds obtained with the two methods.Methods BC-ASSR to single and simultaneously multiple stimuli and PTA were examined in 28(56 ears ) young adults with normal hearing.Results At 0.5,1,2,4 kHz,the thresholds of BC-ASSR to single stimuli were 53,47,53,51 dB SPL respectively;the thresholds of BC-ASSR to simultaneously multiple stimuli were 59,54,63,61 dB SPL respectively.There were significant differences between the two at each frequency. Conclusion There are some difference between the thresholds of ASSR to single and simultaneously multiple bone conduction stimuli,especially at the higher frequencies.
ABSTRACT
Objective To observe effect of olivo-cochlear feedback produced by a contralateral noise on the inhibition of electrophysiological cochleaoneural activity under sedation and anesthesia with or without maintenance of temperature to investigate the effect of sedation and anesthesia on the cochlear efferent system function. Methods The recording of electrophysiological cochleoneural activity was to implant an electrode at the round window, the ASECA (average spectrum of electrophysiological cochleaoneural activity) was obtained to FFT transform for the signal recorded. Results The results indicated that the effects of contralateral noise on ASECA were notably diminished during sedation and were almost completely suppressed during anesthesia either with or without maintenance temperature. Conclusion The present study shows that sedation and anesthesia respectively diminish and suppresse the cochlear efferent system functions.
ABSTRACT
AIM: To find the evidence of electrophysi ol ogic mechanisms associated with average spectrum of electrophysiological cochleo neural activity (ASECA), a measure of spontaneous auditory nerve activity altera tions. METHODS: The long-term salicylate treatment was used to establis h the available animal model of tinnitus, the ASECA was monitored, and the effec ts of various presented ipsilateral acoustic were investigated. RESULTS: (1) In the first treatment, ASECA decreased acutely dur ing several hours after salicylate administration. After several days (1 week an d 2 weeks) this decrease was reduced. (2) Over weeks of salicylate administratio n, the level of ASECA increased progressively, but at the end of treatment, acou stic tuning of ASECA showed a partially decreased sensitivity. (3) In control an imals, delivery of an ipsilateral noise reproduced the increase in the level of ASECA that was similar to the result observed in long-term salicylate-treated an imals. The noise (the white noise was 55-60 dB SPL) was of moderate level and it slightly elevated CAP thresholds at higher frequencies. CONCLUSION: In the long-term salicylate-treated animals, the ASE CA-1 kHz increased reflects strongly increased synchronized activity in the audi tory nerve.
ABSTRACT
AIM: To study the origin of the 1kHz peak of average spectrum electrophysiological cochleoneural activity (ASECA-1kHz),which is related to the firing of auditory neurous-a possible synchronized firing. METHODS: By using the various sound presented either ipsilaterally or contralaterally,the alterations of ASECA-1kHz were detected under the state of awakness. RESULTS: (1) Contralateral stimulation with noise bands at frequencies above 8kHz and below acoustic interaural cross-talk decreased the amplitude of ASECA-1kHz. (2) For the presentations of ipsilaterally noises,when the acoustic bandwidth was above or below 1.5kHz,then produced respectively an increase or a decrease of ASECA-1kHz. (3) Pure tones when presented contralaterally had no detectable effect,but when presented ipsilaterally pure tones with frequencies higher than 4kHz decreased the ASECA-1kHz. Moreover,the detailed time course of sound-induced variations of the 1kHz peak was measured by time averaging,the resulting response patterns were resemblance to PST histogram of the auditory nerve. CONCLUSIONS: The results suggest that the ASECA-1kHz peak in the guinea pig originates from a restricted tonotopic area corresponding to the high frequencies of 12.5-25 kHz and that it should correspond to a synchronized spontaneous firing of fibers.