Background: Autism spectrum disorder is defined by the Diagnostic Statistical Manual of Mental Disorders V (DSM V) as a neurobehavioral disorder manifested by persistent deficits in social and communication interaction, deficits in developing, understanding and maintaining relationships, as well as abnormal and fixed interests and repetitive behavior. Symptoms must be present at early childhood and interfere with daily function. The majority of individuals with ASD demonstrate some degree of auditory dysfunction. The level and expression of this dysfunction ranges from deafness and increased thresholds to hyperacusis and difficulty listening with background noise.
Objective: The purpose of this study was to characterize the findings of audiological and electrophysiological hearing assessment in individuals with autism and to compare these findings to those obtained in typically developing individuals. Subjects, Materials & Method: Forty one Autistic children are divided into two groups:- group (1) Mild to moderate autism were seventeen children & group (2) Severe autism were twenty four children) were enrolled in this study (Whose ages were 2-6.5 years old) compared with ten typically developing matching peers. All Autistic children in the study had a definite medical diagnosis of Autism according to DSM-5 and based on the severity of symptomatology, ASD children were assessed and divided using CARS score (Childhood autism rating scale). Audiologic evaluation consisted of a case history, otoscopic examinatioin, behavioral free field evaluation, acoustic immittance measures (Tympanogram and Acoustic reflexes), speech audiometry, measurement of distortion product otoacoustic emissions and auditory brain stem response.
Results: Our results support an association between ASD and higher DPOAEs S/N ratios at only 500 & 750 Hz. Moreover, ABR in ASD children showed a significant increase in waves III & V absolute latencies and I- III & I-V inert peak latencies (In both groups of ASD), with inter aural asymmetry as shortened right ear III-V & I-V inter peak latencies reflecting a more right ear advantage (mild to moderate group), in addition to a significant decrease in waves V/I amplitude ratio (Both ASD groups).
Conclusion: The OAE responses of children with ASD were highly significantly only at 500 Hz (Both groups) 750 Hz (Mild to moderate group). ASD children (either mild to moderate or severe) had a significant increase in ABR waves III & V peak absolute latencies and I-III & I-V inter peak latencies. Asymmetrical ABR findings also noted in children with ASD (mild to moderate group) as shortened right ear III-V & I-V inter peak latencies (more prominent right ear advantage). In ABR also the amplitude of peak I in response to 90 dB nHL click stimulation was greater than the amplitude of peak V significantly in both groups of ASD children than controls.