Auditory Brainstem Response Values Research Articles

Protective effect of ethosuximide on hearing in NOD/LtJ mice via blockage of endogenous apoptosis

Purpose: To determine the protective effect of ethosuximide on the hearing of NOD/LtJ mice, and the underlying mechanism of action.
 Methods: The mice were randomly assigned to control and treatment groups (20 mice per group). Mice in the treatment group were administered ethosuximide intraperitoneally at a dose of 200mg/kg body weight (bwt), while those in the control group received an equivalent dose of saline via the same route. Both groups were subjected to auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) tests, as well as determination of mRNA expressions of α1G, α1H, α1I, m-calpain, μ-calpain, and caspase-3.
 Results: At ages of 6 and 9 weeks, ABR values were significantly lower in the treatment group than those in the control group (p < 0.05). At age 3, 6 and 9 weeks, control group DPOAE values were much lower than those in the treatment group. However, at signal frequency of 35344 Hz, DPOAE value was significantly reduced in the treatment group (p < 0.05). There was significant down-regulation in mRNA expressions of α1G, α1H, α1I, m-calpain, μ-calpain and caspase-3, in the treatment group, when compared with the control group (p < 0.05).
 Conclusion: Ethosuximide delays mice hearing loss and protects their hearing via a mechanism involving blockage of endogenous apoptotic pathways. This mechanism may provide guidance in the search for suitable new drugs.
 Keywords: Ethosuximide, Endogenous apoptosis, Hearing, Protection

Influence of Ginkgo Biloba extract (EGb 761) on expression of IL-1 Beta, IL-6, TNF-alfa, HSP-70, HSF-1 and COX-2 after noise exposure in the rat cochlea

ObjectiveThe objective of this study was to investigate the influence of Ginkgo Biloba in early treatment of noise induced hearing loss on expression of IL-6, IL-1 Beta, TNF-alfa, HSP-70, HSF-1 and COX-2 in the rat cochlea. MethodsThirty two female rats were randomly divided into four groups (Acoustic Trauma, Ginkgo Biloba, Acoustic Trauma+Ginkgo Biloba, Non Treatment). Auditory brainstem response (ABR) was applied in all the groups. At the end of the study, IL-1Beta, IL-6, TNF-alpha, HSP-70, HSF-1 and COX-2 were studied in cochlear tissue with ELISA and Western blot analysis. ResultsThere were significant increases in ABR values measured at days 1 and 7 compared to baseline values in Group 3. IL-1 Beta, IL-6 and TNF-alpha values were significantly higher in Group 1 than in the other groups. Whereas HSP-70 and HSF-1 values were found to be significantly lower in Group 1 compared to those in Group 2 and Group 3. COX-2 of Group 1 was significantly higher than the other groups. ConclusionGinkgo Biloba is helpful in the treatment of noise induced hearing loss and exerts its effect by inhibiting expression of IL-1 Beta, IL-6, TNF-alpha and COX-2 and increasing HSP-70 and HSF-1 values in rat cochlea.

The protective role of tetramethylpyrazine against cisplatin-induced ototoxicity

ObjectivesThe aim of the present study was to investigate the protective effect of tetramethylpyrazine (TMP) on cisplatin-induced ototoxicity in rats. MethodsForty healthy, female, 24-week-old, Sprague-Dawley rats (n = 40) were randomly assigned to four groups as follows: group one (n = 10) received intraperitoneal (i.p.) physiological saline at daily doses of 3 mg/kg for seven days; group two (n = 10) received a single dose of i.p. 15 mg/kg cisplatin; group three (n = 10) received i.p. 140 mg/kg TMP daily for seven days plus a single dose of i.p. 15 mg/kg cisplatin on the fourth day; group four (n = 10) received i.p. 140 mg/kg TMP daily for seven days. Auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) measurements were obtained from the animals (40 rats, 80 ears) under general anesthesia before and after drug administration. The temporal bulla of animals were bilaterally removed for immunohistopathological examination. ResultsIn group two, DPOAE and ABR values were significantly deteriorated after drug administration, whereas there was no statistically significant difference between the pre- and posttreatment DPOAE and ABR values for all frequencies for groups one, three and four. The mean scores for external ciliated cells (ECCs), stria vascularis (SV) and spiral ganglion (SG) injuries in hematoxylin and eosin (H&E) staining, and also caspase-3 immunoreactivity were significantly higher in group two than in the other groups. ConclusionIn the present study, the protective effect of TMP on cisplatin ototoxicity was demonstrated through studies of electrophysiology and immunohistopathology. Co-administration of TMP may have potential protective effects against cisplatin-induced ototoxicity.

The relationship between auditory brainstem response, nerve conduction studies, and metabolic risk factors in type II diabetes mellitus

Few studies have reported a correlation between auditory brainstem response (ABR) findings and nerve conduction studies (NCSs). The correlation between ABR findings and the metabolic profile of these patients is not well documented in previous studies. The present study was designed to investigate the impact of the disturbed metabolic profile (hyperglyceridemia and hyperlipidemia) in diabetic patients on the peripheral nervous system as well as the auditory brainstem response. The present study aimed to detect the effect of diabetic control on the presence of abnormal ABR and/or peripheral nerve affection in Egyptian diabetic patients. The study was conducted on two groups: the diabetic group (n=68) and the control group, which was matched for age, sex, blood pressure, and BMI (n=60). All participants were subjected to clinical assessment, basic audiologic assessment, brainstem auditory evoked potential, NCS, and metabolic profile [serum level of glycated hemoglobin (HbA1c%) and lipid profile]. There was a significant increase in absolute wave latencies of ABR and interpeak latencies (IPLs) in the diabetic group compared with the control group. Twenty-six (38.2%) patients had abnormal ABR values. IPLs (I–III and III–V) were significantly negatively correlated with sensory conduction velocity of the sural, median, and ulnar nerves as well as F-wave latency of the posterior tibial, median, and ulnar nerves (P=0.01 and 0.001, respectively). Moreover, IPL III–V and sural sensory conduction velocity were significantly correlated with HbA1c% and total cholesterol, as well as triglyceride serum levels. Brainstem dysfunction and ABR changes are common in patients with type II diabetes mellitus. These changes are significantly correlatedto NCS parameters on one hand and serum HbA1c% and lipid profile (total cholesterol and triglycerides) on the other hand.

Audiological findings in Noonan syndrome

ObjectivesThe aim of this study was to evaluate audiologic properties of patients with Noonan syndrome and compare these findings with those of unaffected peers. MethodsThe study included 17 children with Noonan syndrome and 20 typically developing children without Noonan syndrome. Pure tone and speech audiometry, immitancemetric measurement, otoacoustic emissions measurement and auditory brainstem response tests were applied to all (n = 37) children. ResultsHearing thresholds of children with Noonan syndrome were higher (poorer) than those observed unaffected peers, while the hearing sensitivity of the both groups were normal limits (p = 0.013 for right, p = 0.031 for left ear). Transient evoked otoacoustic emissions amplitudes of the children with Noonan syndrome were lower than the children without Noonan syndrome (p = 0.005 for right, p = 0.002 for left ear). Middle ear pressures and auditory brainstem response values were within normal limits and there was no difference between the two groups (p > 0.05). ConclusionGeneral benefit of the present study is to characterize the audiologic findings of children with Noonan syndrome, which is beneficial in clinics evaluating children with Noonan syndrome.

Hearing Outcomes After Stereotactic Radiosurgery for Vestibular Schwannomas : Mechanism of Hearing Loss and How to Preserve Hearing.

The use of stereotactic radiosurgery (SRS) expanded to include the treatment of vestibular schwannomas (VSs) in 1969; since then, efforts to increase tumour control and to reduce cranial neuropathy have continued. Using the currently recommended marginal dose of 12-13 Gy, long-term reported outcomes after SRS include not only excellent tumour control rates of 92-100 % but also outstanding functional preservation of the trigeminal and facial nerves, with values of 92-100 % and 94-100 %, respectively. Nonetheless, hearing preservation remains in the range of 32-81 %. Previous studies have suggested possible prognostic factors of hearing preservation such as the Gardner-Robertson grade, radiation dose to the cochlea, transient volume expansion (TVE) after SRS, length of irradiated cochlear nerve, marginal dose to the tumour, and age. However, we still do not clearly understand why patients lose their hearing after SRS for VS.Relevant to these considerations, one study recently reported that the auditory brainstem response (ABR) wave V latency and waves I and V interval (IL_I-V) correlated well with intracanalicular pressure values and even with hearing level. The demonstration that ABR values, especially wave V latency and IL_I-V, correlate well with intracanalicular pressure suggests that patients with previously elevated intracanalicular pressure might have an increased chance of hearing loss on development of TVE, which has been recognised as a common phenomenon after SRS or stereotactic radiotherapy (SRT) for intracranial schwannomas.In our experience, the ABR IL_I-V increased during the first 12 months after SRS for VSs in patients who lost their serviceable hearing. The effect of increased ABR IL_I-V on hearing outcome also became significant over time, especially at 12 months after SRS, and was more prominent in patients with poor initial pure-tone average (PTA) and/or ABR values. We hypothesise that patients with considerable intracanalicular pressure at the time of SRS are prone to lose their serviceable hearing due to the added intracanalicular pressure induced by TVE, which usually occurs within the first 12 months after SRS for VSs. Using these findings, we suggested a classification system for the prediction of hearing outcomes after SRS for VSs. This classification system could be useful in the proper selection of management modalities for hearing preservation, especially in patients with only hearing ear schwannoma or neurofibromatosis type 2.Advances in diagnostic tools, treatment modalities, and optimisation of radiosurgical dose have improved clinical outcomes, including tumour control and cranial neuropathies, in patients with VSs. However, the preservation of hearing function still falls short of our expectation. A prediction model for hearing preservation after each treatment modality will guide the proper selection of treatment modalities and permit the appropriate timing of active treatment, which will lead to the preservation of hearing function in patients with VSs.

Quercetine attenuates the gentamicin-induced ototoxicity in a rat model

ObjectivesThe aim of this study is to evaluate the protective role of quercetin in gentamicin-induced ototoxicity through an auditory brainstem response (ABR) test and a histopathological evaluation of the cochlea. MethodsIn this study, 48 female adult Sprague–Dawley rats aged 20–22 weeks and weighing 200–250g were used. An ABR test was carried out on all rats prior to drug administration, after which, the rats were divided into four groups of 12 animals each. Drug administration was gentamicin 120mg/kg plus ethanol in group one; gentamicin 120mg/kg plus quercetin 15mg/kg in group two; quercetin 15mg/kg in group three; and ethanol in group four. The drugs were administered intraperitoneally once a day for two weeks, and the ABR test was repeated after drug administration. Subsequently, the rats were sacrificed and their cochleae were dissected and examined histopathologically. ResultsThere was no significant difference between the pre-treatment ABR measurement values of the groups. However, a significant increase was detected in the ABR values in the group of rats that were administered gentamicin plus ethanol, while no statistically significant increase was found in the ABR values in the groups administered with gentamicin plus quercetin; quercetin alone; and ethanol alone. The number of TUNEL positive cells in the inner and outer hair cells in the Corti organ was found to be fewer, and Caspase 3 and 9 expressions were found to be weaker in the group receiving gentamicin plus quercetin than in the group receiving gentamicin plus ethanol. ConclusionsAuditory function was detected to be significantly protected and apoptotic cells were found to be decreased when quercetin was administered together with gentamicin. From these results it was concluded that quercetin, a powerful antioxidant, attenuates ABR thresholds and histopathological lesions in the cochlea in gentamicin-induced ototoxicity in rats.

Auditory brainstem response in gerbils submitted to ischemia and sepsis.

An ischemic stroke is a clinical condition that affects thousands of people worldwide. As a result of this injury, neuronal death can be observed, and in the natural course of recovery, the individual may develop sepsis. Sepsis is a systemic inflammatory response that can lead the patient to death. To assess the clinical condition of a patient with this condition, the Auditory Brainstem Response (ABR) can be useful, since it is not an invasive procedure, it is a fast technique and it can be done at the bedside. To assess auditory brainstem response (ABR) latency values in gerbils subjected to ischemia and sepsis. ABR values were collected from 72 adult male gerbils, which were divided into six groups: control, sepsis, ischemia, sham, ischemia with sepsis, and sham with sepsis. For the induction of sepsis, lipopolysaccharide (LPS) was applied intraperitoneally in gerbils. The animals were anesthetized with a ketamine/xylazine combination before collection; their ABR were collected before any procedure (base collection), after ischemia, and 24 hours after the application of LPS. The absolute latency of wave IV was evaluated, and the values were compared between groups. There were significant differences in the groups submitted to sepsis in the latency value of wave IV in relation with the other groups. ABR was sensitive to sepsis with the increase in latency of wave IV during the development of the disease in the experimental model used.

Protective effects of resveratrol on cisplatin-dependent inner-ear damage in rats

Cisplatin is a common chemotherapeutic agent used in many solid and hematologic malignancies. The main unwanted effect of cisplatin is ototoxicity, for which no standard treatment has been reported. The present study examined the protective efficacy of resveratrol on cisplatin-dependent ototoxicity through an experimental model. Fifteen rats were randomized into three groups. Group 1 (control group) (n = 5) received intraperitoneal (i.p.) 15 mg/kg cisplatin; group 2 (resveratrol group) (n = 5) received i.p. 100 mg/kg resveratrol, followed by i.p. 15 mg/kg cisplatin; group 3 (n = 5) served as a vehicle group and received i.p. 1 ml dimethyl sulfoxide. All rats underwent the auditory brainstem response (ABR) test before and 72 h after the treatment. Pretreatment ABR values of the groups were not significantly different. The pretreatment hearing threshold values of the groups were 30 ± 6.60 and 28.5 ± 5.29 dB in groups 1 and 2, respectively (p > 0.05). The post-ABR-I and post-ABR-IV values were, respectively, 1.41 ± 0.18 and 5.83 ± 0.16 ms in the control subjects and 1.19 ± 0.22 and 4.58 ± 0.27 ms in the study group. The ABR-I and ABR-IV durations in rats treated with resveratrol were significantly shorter (p < 0.01). A comparison of threshold values shows that the resveratrol-treated rats had significantly lower values than the control rats. After cisplatin injection, ABR I-IV intervals were compared among the groups. The ABR I-IV interval duration was 4.42 ± 0.16 ms in the control group, while the resveratrol-treated rats showed a significantly shorter ABR I-IV interval duration of 3.49 ± 0.27 ms (p < 0.001). Resveratrol attenuated cisplatin-dependent inner-ear damage, as shown by the ABR-I, ABR-IV, ABR I-IV interval, and hearing threshold values. Our results suggest that this natural antioxidant may be effectively used in reducing the unwanted effects of cisplatin on the ear physiology of patients, particularly those undergoing chemotherapy.

Protection against cisplatin-induced ototoxicity by N-acetylcysteine in a rat model

Cisplatin (CDDP) is a widely used chemotherapeutic agent that is highly ototoxic. Animal studies and clinical trials have shown that thiosulfates can protect against platinum-induced ototoxicity. This study investigated a new model for CDDP ototoxicity in the rat, and tested the potential chemoprotective effect of administering N-acetylcysteine (NAC) before giving CDDP. Long Evans rats were treated with CDDP 6 mg/kg delivered to the aorta via a retrograde right external carotid artery infusion, 15 min after intravenous (IV) infusion of saline ( n=8) or NAC 400 mg/kg ( n=8), such that the vertebral arteries were perfused. Subsequent groups were similarly treated with NAC 30 min before ( n=7) and 4 h after ( n=7) CDDP. Auditory brainstem response (ABR) thresholds were tested at 4–20 kHz, 7 days after treatment and compared to baseline ABR values. The NAC-treated rats exhibited no significant change from baseline values at all time intervals, while the saline-treated rats showed marked ototoxicity, especially at higher frequencies. Furthermore, the rats treated with NAC 15 min before CDDP exhibited less overall toxicity to CDDP, as evidenced in weight loss 7 days post-treatment (mean for saline=−39.63 g; mean for NAC=−21.13 g; p=0.0084). These data show that treatment with NAC can prevent CDDP-induced ototoxicity in rats.

Effects of patch or gel estrogen therapies on auditory brainstem response in surgically postmenopausal women: a prospective, randomized study

Objective To study the effects of gonadal steroids on the nongenital audiological target in surgically postmenopausal women treated with patch or gel transdermal estrogen therapy (ET). Design Prospective randomized study. Setting Research Group for Sexology, University of Catania, Italy. Patient(s) One hundred twenty-two surgically postmenopausal women. Intervention(s) Transdermal E 2 by patch or gel, and evaluation of auditory brainstem response by auditory-evoked potentials for waves I, III, and V latencies, and for interpeak I–III, I–V, and III–V intervals. Main outcome measure(s) Changes in auditory wave latencies and in interpeak intervals during treatment with ET with respect to baseline levels. Result(s) One hundred two women completed the study. Forty-eight subjects used E 2 patches and 54 E 2 gel. No significant difference was observed in plasma E 2 improvement and in auditory brainstem response values with the two estrogen (E) formulations. The wave latencies and the interpeak intervals showed lower values during the E treatment than at baseline. Conclusion(s) Auditory brainstem response seems to depend on the type of E given. Our data suggest that fluctuating E levels act on waves, even if the exact mechanism of the gonadal steroids is not clear. However, we believe that E could influence neuronal plasticity, the metabolic levels of neurotransmitters, and thus, the neuronal conduction time into the audiological system.

Long-term course of Landau-Kleffner syndrome:

Introduction. Landau-Kleffner Syndrome is characterized by normal speech acquisition followed by epileptic seizures, receptive and expressive language deterioration coupled with agnosia for non-verbal sounds, having variable long-term evolution. Case Report. It is described neurophysiologic and acoustic findings in a patient with Landau-Kleffner Syndrome, and correlate these with the results of a language evaluation carriedout 7 years after the acute phase. It is performed Electroencephalography, Immitance Measurements, Basic Audiometry, Auditory Brainstem Response, Middle Latency Response, and P300. Language was evaluated by Boston Diagnostic Aphasia Examination. Electroencephalography was normal and audiologic evaluation revealed normal Immitance Measurements, Basic Audiometry and Auditory Brainstem Response values. Anelectrode effect was present in the left hemisphere in Middle Latency Response, and bilateral P300 latencies delayed on the right. Language evaluation showed severe receptive and expressive impairment, severe phonemic substitutions, which had an impact on social and academic levels. There were contextual and gestual non-verbal compensations, evidencing intellectual and cognitive domain preservation. Conclusion. This case illustrates the specific cerebral areas that can be damaged in patients with Landau-Kleffner Syndrome and which are demonstrable by clinical evaluation and proper neurophysiology studies, showing the importance of neurological, audiological, electrophysiological and language exams in a longitudinal follow up.

Permanent Electrodes of Cochlear Microphonics In Guinea Pigs

Until now, it has been more difficult to maintain satisfactorily permanent electrodes for cochlear microphonic (CM) measurements in guinea pigs than in cats or rabbits. We implanted Teflon-coated electrodes on the round window of the cochlea in 40 guinea pigs, and also implanted electrodes for the recording of brain stem responses in their skulls. Using these, we recorded the auditory brain stem response (ABR) and CM potentials daily for about three months. The recorded amplitudes of the ABR and CM potentials dropped suddenly about a day after the operation, but returned to their original levels in about two weeks, and remained stable thereafter.During this initial two-week period, CM potentials and ABR were also measured by bone conduction. These ABR values remained steady, and the CM amplitudes were reduced but were larger than those measured by air conduction. These results suggest that postoperative serous exudate caused a decrease in the CM amplitudes to be measured.We found permanent electrodes for CM measurements in guinea pigs to be reliable and useful for many auditory experiments.