Comparison of Language and Memory Lateralization by Functional MRI and Wada Test in Epilepsy

Area of Science:

• Neuroscience
• Neurosurgery
• Epileptology

Background:

• The intracarotid sodium amobarbital procedure (Wada test) is a standard method for preoperative lateralization of cerebral functions.
• Functional magnetic resonance imaging (fMRI) is emerging as an alternative for assessing language and memory lateralization.
• Concordance between fMRI and Wada testing in epilepsy patients requires further investigation.

Purpose of the Study:

• To evaluate the concordance between fMRI and the Wada test for language and memory lateralization in patients with intractable seizures.
• To analyze the relationship between the distance from the epileptogenic focus to functional areas and postoperative deficits.
• To explore factors influencing postoperative seizure improvement.

Main Methods:

• 27 epilepsy patients with preoperative fMRI and Wada data were analyzed.
• Established fMRI paradigms were used to assess language and memory activation (Broca's and Wernicke's areas).
• The Wada test was performed using standard neuropsychiatry procedures. The language area to adjacent focus distance (LAD) was measured.

Main Results:

• Concordance between fMRI and Wada was fair to good for language (Kappa=0.41) and poor for memory (Kappa=0.1).
• No significant correlation was found between LAD and postoperative language deficits (p=0.439).
• A significant correlation was found between LAD and postoperative memory deficits (p=0.049), with greater distance associated with less memory loss. Females and right-handed subjects showed improved seizure control postoperatively.

Conclusions:

• fMRI is a useful adjunct to the Wada test for preoperative language lateralization in epilepsy patients.
• fMRI shows limited concordance with the Wada test for memory lateralization.
• Patient factors like gender and handedness may influence postoperative seizure outcomes.