Language Lateralization in Children Aged 10 to 11 Years: A Combined fMRI and Dichotic Listening Study

Fritjof Norrelgen,Anders Lilja,Martin Ingvar,Peter Fransson,Jens Gisselgård,Karl Herholz

doi:10.1371/journal.pone.0051872

Fritjof Norrelgen, Anders Lilja + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0051872

Copy DOI

Abstract

ObjectiveThe aims of this study were to develop and assess a method to map language networks in children with two auditory fMRI protocols in combination with a dichotic listening task (DL). The method is intended for pediatric patients prior to epilepsy surgery. To evaluate the potential clinical usefulness of the method we first wanted to assess data from a group of healthy children.MethodsIn a first step language test materials were developed, intended for subsequent implementation in fMRI protocols. An evaluation of this material was done in 30 children with typical development, 10 from the 1st, 4th and the 7th grade, respectively. The language test material was then adapted and implemented in two fMRI protocols intended to target frontal and posterior language networks. In a second step language lateralization was assessed in 17 typical 10–11 year olds with fMRI and DL. To reach a conclusion about language lateralization, firstly, quantitative analyses of the index data from the two fMRI tasks and the index data from the DL task were done separately. In a second step a set of criteria were applied to these results to reach a conclusion about language lateralization. The steps of these analyses are described in detail.ResultsThe behavioral assessment of the language test material showed that it was well suited for typical children. The results of the language lateralization assessments, based on fMRI data and DL data, showed that for 15 of the 17 subjects (88%) a conclusion could be reached about hemispheric language dominance. In 2 cases (12%) DL provided critical data.ConclusionsThe employment of DL combined with language mapping using fMRI for assessing hemispheric language dominance is novel and it was deemed valuable since it provided additional information compared to the results gained from each method individually.

Highlights

For patients with medically intractable epilepsy the option of epilepsy surgery is considered if the origin of the seizures can be located
Language fMRI is being used in many centres as a clinical tool in the planning of neurosurgical treatment of epilepsy in adults and, increasingly, in pediatric populations [3,10]
In a recent review of fMRI vs. WADA the authors argue that there may still not be sufficient data to support language fMRI as a routine procedure prior to epilepsy surgery [20]. These findings suggest that for some of the patients with intractable epilepsy it is not at all certain, or perhaps even likely, that adding more language fMRI tasks in an assessment would increase the reliability of the results

Summary

Introduction

For patients with medically intractable epilepsy the option of epilepsy surgery is considered if the origin of the seizures can be located. In the presurgical planning of such cases it is important to determine hemispheric dominance for language to weigh possible benefits of the surgery against the risks of postoperative deficits. The intracarotid amobarbital test, IAT ( known as the Wada test) was the state of the art method for determining hemispheric language dominance [1] but it is invasive, known to carry risks for complications [2], and is more expensive than language mapping using fMRI [3]. Intra-subject reproducibility of global and regional language lateralization results with fMRI within and across sessions for epilepsy patients has been reported to have sufficient reproducibility for clinical use [7,8,9]. Language fMRI is being used in many centres as a clinical tool in the planning of neurosurgical treatment of epilepsy in adults and, increasingly, in pediatric populations [3,10]

Methods

Results

Conclusion