fMRI and Wada

Lubdha M. Shah, MD

Key Facts

Wada

Wada test and intraoperative cortical stimulation have been considered gold standards for language representation
- Catheter carotid angiography
- Intracarotid administration of sodium amobarbital
- Assess consequent cognitive deficit
- Disadvantages: Invasive, expensive, nonlocalizing; equivocal results if patient is oversedated and cannot respond
Speech lateralization
Motor hemispheric localization
Memory

fMRI vs. Wada

Hemispheric language dominance shown to be consistent between the 2 modalities
High correlation between lateralization on fMRI and Wada testing
Many epileptologists now think that fMRI is adequate for language lateralization
In cases where fMRI results are divergent or activation is atypical or absent, Wada may be a helpful presurgical planning tool
Tasks
- Word-generation task significantly more specific than semantic-decision task
Safe
Replicable
Provides more precise anatomic localization within a hemisphere
Memory
- Memory task activation does not clearly predict postoperative memory impairment
- Therefore, fMRI not a definite substitution for Wada test for overall hemispheric lateralization

(Left) Coronal PET demonstrates hypometabolism in bilateral mesial temporal lobes in this patient with intractable complex partial seizures. The left temporal lobe