Background and Aim: Autism-Spectrum Disorders (ASD) are neural connectivity abnormalities at global and local of brain levels. A one-dimensional non-invasive technique that allows a highly accurate measurement of brain function and connectivity is Quantitative electroencephalography (QEEG). This is a systemic review that encompasses the key finding of QEEG application in subjects with ASD, in order to assess the relevance of this approach in characterizing brain function and clustering phenotypes.

Materials and Methods: QEEG studies evaluating both the spontaneous brain activity and brain signals under controlled experimental stimuli were examined. In despite of conflicting results, literature analysis suggests that QEEG features are sensitive to modification in neuronal regulation dysfunctions which characterizes autistic brain but features types are very important.

Results: Therefore QEEG may help in detecting regions of altered brain function and connectivity abnormalities, in linking behavior with brain activity, and subgrouping affected individuals within the wide heterogeneity of ASD. The use of advanced techniques for the increase of the specificity and of spatial localization could allow finding distinctive patterns of QEEG abnormalities in ASD subjects, paving the way for the development of tailored intervention strategies.

Conclusion: Autism is a disorder in which multiple aspects of behavior, emotion, language and cognition are disrupted, among which, autistic individuals appear to have a range of perceptual processing abnormalities, expressed especially entirely by a high level of sensitivity to auditory and tactile stimuli. It seems Autism Spectrum Disorder (ASD) is potentially caused by unbalanced portion of excitation/inhibition, in other words a disproportionate high level of excitation (or disproportionately weak inhibition) in neural circuits that mediate language and social behaviors. Holistic approaches could help us to have better detections

Keywords: Diagnosis autism-spectrum disorder, Quantitative electroencephalography, Coherence, asymmetry, Non-linear techniques