Researchers at Departments of Neurology and Speech, University of Campinas, Brazil assessed the auditory processing function in children with language-learning impairment in relation to malformation of cortical development. Thirty-two children (19 males), aged 8-15 years, were divided into three groups: Group I included 11 children with language-learning impairment and bilateral perisylvian polymicrogyria, a malformation shown to be associated with auditory processing disorders; Group II included 10 children with language-learning impairment and normal MRI; and Group III comprised 11 normal children. All patients had an IQ>80, only 1 had epilepsy, and 5 had pseudobulbar signs. Tests of auditory processing function, including the Random Gap Detection Test and Digits Dichotic Test, showed a statistically significant difference among the group. Groups I and II showed abnormalities in auditory processing when compared with the control group, and children in Group I were more affected than children in Group II. Perisylvian cortical malformation correlates with impairment of auditory processing function. This is expressed as difficulty in phonemic awareness, verbal comprehension, writing and reading, and processing of rapid auditory stimuli. 
COMMENT. Cortical polymicrogyria malformation in the perisylvian regions may be associated with auditory processing dysfunction and language and learning disabilities, including dyslexia.