Original articleAuditory processing disorder in patients with language-learning impairment and correlation with malformation of cortical development
Introduction
Malformations of cortical development have been described in children and families with language-learning impairment. The general term language-learning impairment refers to the population with specific language impairment and/or dyslexia in which symptoms of auditory processing disorder are often present [1].
Specific language impairment refers to inadequate oral language acquisition in the absence of sensory or intellectual deficits, pervasive developmental disorders, evident cerebral damage or severe environmental deprivation. The patients usually present with an abnormal cognitive linguistic performance and normal non-linguistic abilities [2], [3]. Many of these children develop some type of learning impairment, such as dyslexia [4].
The term learning impairment refers to a wide range of difficulties in reading, writing and mathematic abilities, while dyslexia is a specific learning disability of neurobiological origin that occurs in the presence of good cognitive performance and academic opportunity. Dyslexia is not associated with a generalized development disorder or sensory impairment and it is the most prevalent type of learning disorder [5].
Appropriate cortical organization is the basis for higher cortical functions such as memory, attention and language. In the brain, there is a dynamic set of interconnected regions that contribute to the operation of the system as a whole [6]. As the Sylvian fissure includes auditory and language processing, lesion in this region may compromise these functions in children development.
In an attempt to find the etiology of the language and learning impairment, some studies found a positive correlation between malformations of cortical development and these impairments, as they showed ectopia and polymicrogyria surrounding the perisylvian region [2], [7]. The neuronal migration disorder and malformation of cortical organization, subtle in most cases, may be caused by intrauterine infection, X-ray exposure, vascular damage – usually of genetic origin, with insult occurring between 16 and 24 weeks of gestation [8]. Bilateral perisylvian polymicrogyria is a malformation of cortical development characterized by excessively small gyri seen around both Sylvian fissures on magnetic resonance imaging (MRI). Bilateral perisylvian polymicrogyria has been associated with specific language impairment, pseudobulbar signs and epilepsy [2].
Some studies showed the correlation of malformation of cortical development and language-learning impairment [3], [9], [10]. MRI findings identified that the periventricular nodular heterotopia is associated with reading impairment despite of normal intelligence [9]. Other authors described linguistic and neurobiological aspects in children with specific language impairment and correlated clinical manifestations with cortical abnormalities [3]. The relation of language-learning impairment with familial perisylvian polymicrogyria showing that the perisylvian polymicrogyria may be a neuroanatomical substrate of these disorders was shown as well [10].
It seems that many children with language and learning impairment may show changes in both nonverbal as well as in verbal auditory processing. These children may have limitations in discrimination and sequencing of rapid auditory verbal stimuli, leading to difficulties in higher levels of language information processing [11], [12].
The auditory pathways need to be integrated to allow perfect functioning of language, reading and writing. The cortical auditory areas consist mainly of Heschl’s gyrus, the temporal lobe and the Sylvian fissure with insula [13]. The Sylvian fissure is located between anterior frontal and temporal lobes and it continues posteriorly to the supramarginal gyrus containing the primary auditory area and parts of the language area. Along with Wernicke’s area and the angular gyrus, these structures appear to integrate auditory and visual information, such as aspects of language, reading and writing [14]. The proximity of the Sylvian fissure to the auditory region and its association with areas responsible for language and learning means that a change in the former area can affect functions in the latter area. If polymicrogyria is found around the Sylvian fissure, these structures may not be integrated, and it is believed that this results in an abnormality of the auditory processing information.
In a previous study, we showed abnormalities in the auditory processing of children with bilateral perisylvian polymicrogyria, suggesting that the perisylvian polymicrogyric cortex is functionally abnormal [15]. Thus, the aim of this study was to assess the auditory processing in children with language-learning impairment in the presence or absence of an alteration in the auditory processing information areas as seen in neuroimaging.
Section snippets
Patients and methods
This work was carried out at the Neurology Department at the Clinical Hospital of the University of Campinas (Unicamp), Campinas, SP, Brazil after being approved by the Ethics Committee of the same university (protocol 196/2003). Parents gave permission for their children to participate in this research, signed the informed consent form and answered questions about the overall development of the children including the family history of specific language impairment and learning impairment,
Results
Fig. 1 shows image from patient of Group I with bilateral perisylvian polymicrogyria.
The mean age of the children in the three groups was homogeneous. The mean age of Group I was 134.45 months (SD = 28.13), Group II was 127.20 (SD = 19.96) and Group III was 141.09 (SD = 27.54). There was no statistically significant difference in age among the groups (p = 0.486).
When language aspects were analyzed, our findings showed a statistically significant difference in reading and written tests when the three
Discussion
Malformations of cortical development have been described in children and families with language-learning impairment [2], [3]. Language-learning impairment is multifactorial in nature, where subtle structural variations associated with possible genetic abnormalities during the prenatal period of neuronal migration may change the organization of cortical structure, affecting the processing of language and learning [7], [26].
Our study correlated language-learning impairment with malformations of
Acknowledgements
Mirela Boscariol received a scholarship from CNPq (grant number # 132461/2007-2) and FAPESP (grant number # 07/00806-4). Catarina A. Guimarães received a scholarship from FAPESP (grant number # 06/56257-6).
References (29)
- et al.
Characterization of language and reading skills in familial polymicrogyria
Brain Dev
(2008) Auditory temporal perception, phonics, and reading disabilities in children
Brain Lang
(1980)- et al.
Auditory processing disorder in perisylvian syndrome
Brain Dev
(2010) - et al.
Neurobiology of (central) auditory processing disorder and language-based learning disability
- et al.
Developmental language disorder associated with polymicrogyria
Neurology
(2002) - et al.
Specific language impairment: linguistic and neurobiological aspects
Arq Neuropsiquiatr
(2006) - et al.
Specific language impairment in families: evidence for co-occurrence with reading impairments
J Speech Lang Hear Res
(2003) - et al.
Defining dyslexia, comorbidity, teacher´s knowledge of language and reading: a definition of dyslexia
Ann Dyslexia
(2003) The working brain: an introduction to neuropsychology
(1973)- et al.
Developmental dyslexia: four consecutive patients with cortical anomalies
Ann Neurol
(1985)
Dyslexia–a molecular disorder of neuronal migration: the 2004 Norman Geschwind Memorial Lecture
Ann Dyslexia
Reading impairment in the neuronal migration disorder of periventricular nodular heterotopia
Neurology
The underlying nature of specific language impairment
J Child Psychol Psychiatry
The auditory system: anatomy, physiology, and clinical correlates
Cited by (27)
Insular cortex activity during food-specific inhibitory control is associated with academic achievement in children
2022, Physiology and BehaviorCitation Excerpt :The academic achievement test (AAT) is a psychometric instrument widely applied to children's reading, writing, and arithmetic abilities. This test has been used for children of the same nationality in other brain and behavior-related studies [3,19]. A total academic achievement composite variable was calculated by adding the performance of the three abilities evaluated (reading + writing + arithmetic).
Central auditory processing disorders in children and adults
2015, Handbook of Clinical NeurologyCitation Excerpt :Children with “developmental CAPD” demonstrate patterns of performance across these tests that are identical to those of children and adults with known CANS lesions (Bellis and Ferre, 1999; Bellis, 2002, 2003). Similarly, Boscariol et al. (2009, 2010, 2011) demonstrated that children with previously undetected neuromorphologic abnormalities also present with these same patterns. A final point to be considered is that, due to the variability in neuromaturation (particularly of the corpus callosum) in younger children, most behavioral central auditory diagnostic tests cannot be reliably administered and interpreted until the age of approximately 7 or 8 years.
Effects of test experience and neocortical microgyria on spatial and non-spatial learning in rats
2012, Behavioural Brain ResearchCitation Excerpt :For example, Galaburda et al. [4] identified clusters of ectopic molecular layer neurons and abnormality folded microgyric cortices in the brains of dyslexics examined post mortem. More recently, imaging studies have associated microgyria and periventricular nodular heterotopia with specific learning impairments in humans [2,3,5,6]. In concert with these associations, rodent models have revealed a link between a diverse spectrum of injury, genetic and teratogenic mediated neocortical malformations and specific learning and processing impairments [7–13], which parallel clinical phenotypes.