Evaluation of individuals with otisim spectrum disorder with ABR testing

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that has been unidentified for a long time. Autism can be diagnosed at a very early age. In the patient's verbal and non-verbal communication; there are problems in their interactions with peers and especially in peer to peer interactions. With their lack of imagination, they remain in the background in participating in social life. Their skills of understanding and using abstract notions are not developed. In addition to the etiology of autism is not exactly known, several factors that may lead to autism can be listed. We can roughly classify them as environmental factors, genetic factors and neurological factors. According to DSM-5, there are 3 levels. Individuals at first level need support; Individuals at second level need significant support; Individuals at third level need very significant support. Sound waves emitted from a source are collected by the auricle and then they are transmitted to the tympanic membrane via the external ear. These transmitted mechanical sound waves reach the receptors in the inner ear by vibration. Firstly, these vibrations turn into biochemical energy in the inner ear and then they turn into electrical energy with interaction. This energy is transmitted to different places through neural coding. The interpretation of sound through auditory pathways in the auditory cortex is called hearing. Hearing tests consist of two parts, objective and subjective. Auditory Brainstem Response (ABR) test is one of the most used tests among the objective tests. This test is used to determine the hearing threshold of patients for whom it is difficult to obtain real results from subjective tests; infants, young children who cannot adapt to play audiometry, mentally disabled patients, patients with Down syndrome, ASD patients and patients with functional hearing loss. In addition to finding the hearing threshold, it can also be used for some auditory nerve diseases and situations where nerve transmission velocity needs to be measured. The patients is in a sleeping position in a way to reset the muscle tonus during the test. Electrodes are attached to certain places on the head, an insert or supra-aural headphone is attached to the ear, and measurements are conducted. In the ABR test, wave I is produced in the acoustic nerve, wave II in the cochlear nucleus, wave III in the superior olivary nucleus in the pons, wave IV in the lateral lemniscus, and wave V in the inferior colliculus in the interbrain. The communication difficulties in patients with ASD make it difficult for people around them to understand whether they have hearing loss or not. The fact that most language acquisition begins at a late age also increases these doubts. However, determining a reliable hearing threshold with tests such as pure tone audiometry that require patient participation is not possible due to the patient's social and mental state. In this situation, the objective auditory brainstem test (ABR) is used. In ABR, each wave stems from different regions in the brainstem. This situation is a guide for the problems that may occur in these roots. Even in individuals with normal hearing, the latencies of wave formation or interpeak latency differences among waves, morphology and even amplitudes give us information about problems in the auditory pathways. It is aimed to evaluate abnormalities on these pathways of ASD patients in the study. Differences between ASD patients and the control group were obtained in accordance with the literature. Autism, a neurodevelopmental disorder, leads to differences in the brainstem test ABR. In the studies conducted, prolongation exists in the I, III, V waves of ASD patients. Beside this, prolongation is detected in I-V, I-III, III-V interpeak latencies. These findings indicate brainstem distortion. A control group with normal hearing and ASD patients without hearing loss were addressed in our study. The III and V wave latencies, III-V interpeak latencies and amplitudes of the waves obtained at 20 dB were tested in the patients. In this study conducted with waves occurring at 20 dB, prolongation was obtained in individuals with autism. At the same time, 20 dB amplitudes were also obtained high level in the control group. However, these values were not found statistically significant (p>0.05). Keywords: audiology , hearing, hearing loss, Auditory pathways, auditory brainstem test (ABR), autism spectrum disorder