MEG: A Method Comparable to the Wada Procedure for Language Laterality Assessment.
Abstract number :
1.235
Submission category :
Year :
2001
Submission ID :
143
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
A.C. Papanicolaou, Ph.D., Neurosurgery, University of Texas - Houston Medical School, Houston, TX; P.G. Simos, Ph.D., Neurosurgery, University of Texas - Houston Medical School, Houston, TX; J.I. Breier, Ph.D., Neurosurgery, University of Texas - Houston
RATIONALE: During the past three years, in a series of studies involving over 200 individuals, we have demonstrated the feasibility of mapping receptive language-specific cortex in individual normal subjects and patients (Papanicolaou et al., 1999) using a relatively new functional brain imaging method, Magnetoencephalography (MEG). The reliability of such maps has been tested through repeated measurements of the same individuals over time, and the validity of the maps has been verified through comparisons with the results of direct cortical stimulation mapping (Papanicolaou et al., 1999; Simos et al., 1999). Preliminary evidence has also suggested the comparability of MEG to the Wada procedure for the assessment of hemispheric dominance for language (Breier et al., 1999, 2001). Having established the efficacy, efficiency and fidelity of the MEG method for language mapping, we sought to answer the question of whether it is comparable to the Wada procedure in assessing hemispheric dominance for language in a larger sample of patients.
METHODS: Language laterality assessments from both the Wada test and MEG language mapping were compared for their degree of agreement.
RESULTS: We have now accumulated additional evidence to the same effect from 34 new patients, both adults and children, who have undergone two independent assessments of their hemispheric dominance for language, namely through MEG and through the Wada procedure.
In this new sample, laterality judgments based on MEG and Wada agreed 88% of the time (20/22 judgments agreed for LH dominance, 1/2 judgments agreed for RH dominance, and 9/10 judgments agreed for bilateral language representation). When all data collected over the past three years are analyzed (n = 73 patients), our findings indicate that the agreement between MEG and the Wada procedure is very high (93.15%).
CONCLUSIONS: The exceptionally high degree of concordance between the two methods indicates that it may be possible in the near future to substitute the invasive Wada procedure through the completely noninvasive method of MEG. Accordingly, the purpose of this presentation is to describe the method and discuss the implications of its use with clinical populations.
Support: This work was partly supported by NIH grant RO1 N537941-01 to Andrew C. Papanicolaou.