Lateralizing language with magnetic source imaging: Validation based on the Wada test

Abstract

SUMMARYPurpose: Magnetoencephalography (MEG)/magnetic source imaging (MSI) is a noninvasive functional neuroimaging procedure used to localize language-specific regions in the brain. The Wada test, or intracarotid amobarbital procedure (IAP), is the gold standard in determining speech/language lateralization for presurgical planning, although it is invasive and associated with morbidity. The purpose of this study is to provide further validation on the use of MSI for presurgical language lateralization by comparing results against the IAP. Methods: The sample consisted of 35 patients with epilepsy and/or brain tumor undergoing presurgical evaluation at the Minnesota Epilepsy Group. All patients received both an IAP and MSI to determine hemispheric language dominance. For MSI, a 148-channel MEG system was used to record activation of language-specific cortex by an auditory word-recognition task.Results: The MSI and IAP were concordant in determining language in the hemisphere to be treated in 86% of the cases with sensitivity and specificity values of 80% and 100%, respectively. Conclusions: The results from this study are consistent with prior research findings comparing functional neuroimaging procedures to the IAP in determining language lateralization in presurgical patients. The current study provides an important replication and support for Papanicolaou et al.'s findings in 2004 using a consecutive clinical sample from a different institution. An unusually high rate of atypical IAP language cases in this sample and differences between the two procedures are believed to explain the noted discrepancies. MSI is a viable noninvasive alternative to the IAP in the presurgical determination of language lateralization.

Assessment of hemispheric dominance for receptive language in pediatric patients under sedation using magnetoencephalography

“…In particular, the reliability with which this protocol has been used to establish hemispheric dominance for receptive language in children has been shown in several normative, as well as clinical, cohorts. Moreover, the suitability of MEG language mapping protocols as an alternative to the Wada procedure have been addressed over the course of several validation studies, with concordance rates ranging from 87% in the study with largest sample to date (Papanicolaou et al, 2004) to 100% agreement in the first sub-sample of patients of the same series (Breier et al, 1999), with the rest of the studies reporting uniformly, high agreement (Breier et al, 2001; Maestú et al, 2002; Hirata et al, 2004; Bowyer et al, 2005; Merrifield et al, 2007; Doss et al, 2009; McDonald et al, 2009; Hirata et al, 2010; Findlay et al, 2012; Tanaka et al, 2013). …”

Past, Current and Future Clinical Applications of MEG

“…The MEG and IAP lateralisations were concordant to a level of 87%. This study was replicated by Doss et al (2009) using a cohort of 35 surgery candidates. The MEG and IAP laterality results were concordant in 86% of cases, with high levels of sensitivity (80%) and specificity (100%).…”

Frameless Stereotactic Functional Neuronavigation Combined with Intraoperative Magnetic Resonance Imaging as a Strategy in Highly Eloquent Located Tumors Causing Epilepsy

“…Functional brain areas such as primary motor and somatosensory region, Broca's and Wernicke's language areas and their connecting fiber tracts within the CNS are amongst eloquent cortex that can be mapped by functional MRI and DTI [17]. Additionally, MEG is a valid and useful alternative technique for detection of functional brain regions and epileptogenic brain tissue [18,19,20]. …”