![]() Monaural clicks set initially at 100 dBNA were used at least twice in BAEP testing to confirm the presence of overlapping waves. Response was interpreted as present in the frequencies in which the signal to noise ratio was 6 dB, reproducibility was equal to or greater than 70%, and stability was equal to or greater than 75%.īAEPs and CM were assessed using device Chartr EP (Otometrics) with patients wearing in-ear earphones. Distortion product otoacoustic emissions were recorded at 700 Hz and 8000 Hz, and intensity of stimuli was kept fixed on L1 at 65 dBNPS and L2 at 55 dBNPS along with a ratio between frequencies of 1.22 (F2/F1 = 1.22). OAEs were recorded with a Madsen Capela (Otometrics) device. ![]() ![]() The following devices were used: impedance testing device AT-235 (Interacoustics), audiometer AC-33 (Interacoustics). They underwent thorough assessment, comprised by ENT examination to find the status of the ear canal and the tympanic membrane through conventional otoscopy basic audiological examination including impedance tests, pure-tone audiometry, and speech audiometry. Subjects with retrocochlear disease seen on MRI scans.Ī total of 2,292 individuals diagnosed with sensorineural hearing loss with ages ranging from zero to 95 years were assessed. This study aimed to identify the prevalence of ANSD in a group of individuals with sensorineural hearing loss seen at an auditory health care center. Investigated sites include the inner hair cells, the synapses between inner hair cells and the auditory nerve, dendrites or neural axons, afferent and efferent activity of the auditory nerve, spiral ganglion neurons, and neurotransmitter biochemical anomalies 9, 15, 16. The site of injury in ANSD patients has not been clearly defined. ANSD patients often require specific approaches to address their auditory, communication, and language impairments, which differ from the therapies proposed to patients with peripheral hearing loss 11. A study with neonates screened for BAEPs found ANSD in 2.96% 14 of the subjects. A study on sensorineural hearing loss found ANSD in 1.6% 13 of the enrolled patients. Another study with children with hearing loss revealed prevalence rates ranging from 5.1% to 15% 12. However, the estimated prevalence of ANSD in a study with patients at risk for hearing loss was 1.3% 10, while a study with children at risk of hearing loss found a prevalence rate of ANSD of 0.94% 11. The published estimated prevalence rates of ANSD 7 range from 0.23% 8 to 15% 9 in individuals with hearing loss. ![]() Subjects with ANSD can often hear, but fail to discriminate words due to the loss of neural synchrony between the fibers of the vestibulocochlear nerve, thus severely impairing temporal auditory processing and speech discrimination 6. BAEP testing also shows widely variable audiological results, from severely altered wave morphology to no wave formation, thus reflecting the multifaceted and heterogeneous nature of the pathophysiology of this auditory disorder 5. Individuals with auditory neuropathy spectrum disorder (ANSD) may present mild to severe, unilateral or bilateral hearing loss associated with disproportional impairment of speech discrimination in relation to hearing loss 4. ![]() It was then realized that the term auditory neuropathy describes an array of disorders that may range from auditory dyssynchrony to auditory nerve neuropathy 3. The change in nomenclature was due to a study carried out in 2002 in which it was revealed that approximately half the children with auditory neuropathy had the same speech detection skills as children with sensorineural hearing loss, in addition to auditory brainstem responses, while the other half had unsatisfactory results in speech detection tests and no auditory brainstem responses. The term auditory neuropathy spectrum was produced through international consensus during the Guidelines Development Conference on the Identification and Management of Infants with Auditory Neuropathy, held in June of 2008 2. The term auditory neuropathy was used for the first time in a study carried out in 1996 to categorize a group of subjects with hearing symptoms and normal cochlear function associated with cochlear nerve dysfunction 1. The term auditory neuropathy has been used to describe diseases affecting children and adults characterized by normal outer hair cell function and anomalous or absent auditory nerve function it has been described as a set of auditory disorders that combine otoacoustic emissions (OAEs) and/or cochlear microphonics (CM) with absent or desynchronous waves generated in brainstem auditory evoked potentials (BAEPs). ![]()
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