Auditory Neuropathy Spectrum Disorders (ANSD) are new classification which was proposed in 2008 by Colorado Children’s Hospital Group and defined as normal otoacoustic emissions and absent ABRs in newborn. In our long term follow up study, hearing of ANSD are changed into three types. Type I is normal OAE and normal ABR (normal hearing), Type II is absent OAE and absent ABR (profound sensoryneural hearing loss), Type III is normal OAE and absent ABR (true auditory neuropathy). However, still complications of Al-Meqbel1 vestibular problems in ANSD are not known so far.

Background and Aim: Auditory neuropathy is an hearing disorder in which peripheral hearing is normal, but the eighth nerve and brainstem are abnormal. By clinical definition, patient with this disorder have normal OAE, but exhibit an absent or severely abnormal ABR. Auditory neuropathy was first reported in the late 1970s as different methods could identify discrepancy between absent ABR and present hearing threshold. Speech understanding difficulties are worse than can be predicted from other tests of hearing function. Auditory neuropathy may also affect vestibular function.Case Report: This article presents electrophysiological and behavioral data from a case of auditory neuropathy in a child with normal hearing after bilirubinemia in a 5 years follow-up. Audio logical findings demonstrate remarkable changes after multidisciplinary rehabilitation.Conclusion: auditory neuropathy may involve damage to the inner hair cells-specialized sensory cells in the inner ear that transmit information about sound through the nervous system to the brain. Other causes may include faulty connections between the inner hair cells and the nerve leading from the inner ear to the brain or damage to the nerve itself. People with auditory neuropathy have OAEs response but absent ABR and hearing loss threshold that can be permanent, get worse or get better.

Objective: The disorder known as "Auditory neuropathy (AN)" is not new but has recently become more clearly defined and understood. Auditory neuropathy is a form of hearing impairment in which the cochlear function is normal but neural transmission in the auditory pathway is disordered. This condition accounts for approximately 7% of permanent childhood hearing loss and 0.2-4% of high risk neonates. Case Reports: Four children (three boys and one girl) younger than two years with auditory neuropathy symptoms are presented. Based on audiologic and clinical findings there were high risk factors in two cases. In each case, absent auditory brainstem response (ABR), absent acoustic reflexes, present cochlear microphonics (CM) and present transient evoked otoacoustic emissions (TEOAE) were shown. Conclusion: This section discusses the clinical profile of cases regarding etiology (neonatal insults, infectious processes, genetic and syndromic factors), age of symptom onset, prevalence of AN/AD, outer hair cells function, audiogram, and acoustic reflexes in relation to other studies.

Background & Aim: Auditory steady state response(ASSR) is an auditory evoked response that has received a lot of attention nowadays. At present, ASSR is mostly used to estimate pure-tone thresholds. Clinical evidence of ASSR in combination with findings for auditory middle latency response (AMLR) and 40 Hz response support the assumption that based on stimulus modulation rate, the ASSR anatomic generators are sub-cortical and/or cortical. The goal of the present study was to investigate ASSR findings in a group of young adults with auditory neuropathy/dys-synchrony (AN/AD).Patients and Method: This cross-sectional analytical study was performed on 16 adults with AN/AD (mean age: 20 ± 5.30 years) and 28 subjects with normal hearing (mean age: 22± 3.80 years). ASSR test with high rate modulated stimulus was done at four octave frequencies of 500, 1000, 2000 and 4000 Hz on each ear individually in both AN/AD and control groups. Independent t-test was used to compare hearing thresholds obtained by behavioral evaluation and ASSR recording in each studied group individually.Results: Average pure-tone thresholds revealed moderate hearing loss in AN/AD individuals with focus on low frequencies so that the low-tone loss seen in audiograms was observed in almost two-thirds of the subjects, a finding which is common in adults with AN/AD. However, ASSR revealed profound hearing loss at four studied frequencies in all AN/AD patients regardless of behavioral hearing thresholds, and a significant difference was shown between hearing thresholds gained by these two methods, namely PTA and ASSR.Conclusion: Although in clinical setting ASSR is usually used to estimate hearing thresholds in different populations and degrees of hearing loss, its findings are different in AN/AD patients and can be used for differential diagnosis of this disorder. Using high rate modulated stimulus, severe and profound hearing loss or no ASSR is expected in AN/AD. Considering the fact that ABR also leads to the same abnormal results in AN/AD, it seems that the brain generators of both ABR and ASSR are the same and the concordance between their findings can confirm a defect in auditory brainstem function in patients with suspected AN/AD.

Background: Loss of speech perception is a major effect of hearing impairment.In many cases with "auditory neuropathy", speech perception sustains severe impairment and is disproportionate with behavioral pure-tone average. In a primary audiologic evaluation, there is usually no auditory brainstem response (ABR) or acoustic reflex, while the cochlear function is within normal range. Patients with auditory neuropathy exhibit impairments in psychoacoustic evaluations, and their difficulties in sound temporal processing are due to the dys-synchrony of their auditory nerve fibers.Methods: This cross-sectional analytical study was performed on 16 young adults with auditory neuropathy and 28 normal hearing subjects. In both auditory neuropathy and control groups, auditory middle latency response (AMLR) and auditory late response (ALR) were recorded and psychoacoustic measurements including "intensity discrimination", "frequency discrimination", and "gap detection" as well as a word discrimination test in silent and in three different signal-to-noise ratios were carried out.Results: There was no agreement between the pure-tone average (PTA) and word discrimination score (WDS). Despite AMLR absence in 6 patients, auditory late response ALR was recorded in all the individuals and there was a significant correlation between some characteristics of these responses and the word discrimination score. The patients revealed remarkable impairment in the discrimination of intensity, frequency, and temporal characteristics of sound.In addition, there was a significant correlation between each of these characteristics and WDS. The WDS showed considerable variability in individuals with auditory neuropathy and decreased in the presence of noise considerably.Conclusion: It seems that neural synchrony had different representations in short (and middle) auditory evoked responses by comparison with late ones. Auditory neuropathy patients’ difficulties in discriminating the intensity, frequency, and temporal characteristics of sound and their relation with WDS showed eight nerve functions in processing these psychoacoustic perceptions and their effects on speech understanding.

Background and Aim: Auditory neuropathy (AN) can be diagnosed by abnormal auditory brainstem response (ABR), in the presence of normal cochlear microphonic (CM) and otoacoustic emissions (OAEs). The aim of this study was to investigate the ABR and other electrodiagnostic test results of six patients suspicious to AN with problems in speech recognition.Materials and Methods: this cross sectional study was conducted on 6 AN patients with different ages evaluated by pure tone audiometry, speech discrimition score (SDS), immittance audiometry, electrocochleography, ABR, middle latancy response (MLR), late latency response (LLR), and OAEs. Results: Behavioral pure tone audiometric tests showed moderate to profound hearing loss. SDS was so poor which is not in accordance with pure tone thresholds. All patients had normal tympanogram but absent acoustic reflexes. CMs and OAEs were within normal limits. There was no contralateral suppression of OAEs. None of cases had normal ABR or MLR although LLR was recorded in 4.Conclusion: All patients in this study are typical cases of auditory neuropathy. Despite having abnormal input, LLR remains normal that indicates differences in auditory evoked potentials related to required neural synchrony. These findings show that auditory cortex may play a role in regulating presentation of deficient signals along auditory pathways in primary steps.

Background: Auditory neuropathy spectrum disorder (ANSD) in the auditory neural pathway can affect the auditory and speech development of children. Since the symptoms and complica-tions of this disorder are similar in different children, hearing management and rehabilitation can help with better development of speech/ language and hearing perception in children with ANSD. The Case: In this study, the case was a one-year-old boy with ANSD and mild to moderate high-frequency sensorineural hearing loss. He first underwent various audiological examinations. Then, an aural rehabilitation program containing different auditory information and games was provided to him, his family, and caregiver at their home and in the rehabilitation center. Conclusion: Although auditory neuropathy/ dissynchrony in the auditory neural pathway has negative effect on the auditory and speech deve-lopment, but the children with ANSD can use different inputs for language comprehension and acquisition if they receive effective education, especially auditory training at an earlier age.

Background and Aim: The central auditory nervous system has the ability to perceptually group similar sounds and segregates different sounds called auditory stream segregation or auditory streaming or auditory scene analysis. Identification of a change in spectral profile when the amplitude of a component of complex tone is changed is referred to as Spectral profile analysis. It serves as an important cue in auditory stream segregation as the spectra of the sound source vary. The aim of the study was to assess auditory stream segregation in individuals with cochlear pathology (CP) and auditory neuropathy spectrum disorder. Methods: In the present study, three groups of participants were included. Experimental groups included 21 ears in each group with cochlear hearing loss or auditory neuropathy spectrum disorders (ANSD) and control group with 21 ears with normal hearing. Profile analysis was assessed using "mlp" toolbox, which implements a maximum likelihood procedure in MATLAB. It was assessed at four frequencies (250 Hz, 500 Hz, 750 Hz, and 1000 Hz) for all three groups. Results: The results of the study indicate that the profile analysis threshold (at all four frequencies) was significantly poorer for individuals with CP or ANSD compared to the control group. Although, cochlear pathology group performed better than ANSD group. Conclusion: This could be because of poor spectral and temporal processing due to loss of outer hair cells at the level of the basilar membrane in cochlear pathology patients and due to the demyelination of auditory neurons in individuals with ANSD.

Objectives: Premature birth causes some permanent or temporary abnormalities in the hearing system of the newborn. Inadequate development of the central auditory nervous system and balance, as well as the delay in the formation of the nerve myelin, can be the cause of many hearing disorders, including permanent or temporary auditory neuropathy spectrum disorder (ANSD). The present study aims to identify and understand developmental delay disorder in the hearing system of infants and investigate the possibility of temporary auditory neuropathy in infants. Materials & Methods: In this comparative analytical study, twenty premature infants were randomly selected for hearing tests using auditory brainstem response and transient otoacoustic emissions at the time of discharge and three months after the first evaluation. The different components of these tests were analyzed and compared before and after developing the auditory system. Results: The OAEs test showed a signal-to-noise ratio above six dB with appropriate amplitudes in all infants. The grand average waveform of the ABR showed a significant difference between the amplitudes of waves III and V before and after maturation in both ears (p<0. 05). In addition, the absolute latency of waves, specifically III and V, showed a significant difference between the two assessment times (0. 05). Conclusion: The present study confirmed the occurrence of temporary ANSD or delayed maturation in premature infants following the lack of complete growth and myelination of auditory nerve fibers. There is a need to determine the hearing status of premature infants by frequent examinations and prevent any unnecessary prescription of amplifications.

Introduction: The auditory neuropathy is a disorder characterized by no or severely impaired brainstem responses in presence of cochlear hair cells functions preservation. Speech perception ability of these patients is disproportionate with their hearing sensitivity that results from impairment of temporal processing of auditory stimulus and auditory nerve dys-synchrony. Case Report: The patients were two 19 and 20 years old young women with no history of hearing loss, speech and language difficulties and hereditary or chronic diseases in their family. The auditory neuropathy in these patients was confirmed based on behavioral, electroacoustic and auditory evoked potentials tests. The neurologic, visual and somatosensory evaluations show no sensory and/or motor accompanying problems despite of several years after beginning of disorder. The result of MRI was normal too. Conclusion: According to all evaluations that reveal remarkable loss of speech perception because of eight nerve impairment without other accompanying neurologic disorders, these patients may be considered as two rare cases of pure auditory neuropathy.