Discordant Wada and fMRI language lateralization: a case report

Area of Science:

• Neuroimaging and Neuroscience
• Clinical Neurology
• Epilepsy Research

Background:

• Functional MRI (fMRI) is increasingly used for preoperative language assessment.
• Discrepancies between fMRI and Wada testing can occur, especially in atypical cases.
• Understanding hemispheric language dominance is crucial for neurosurgical planning.

Purpose of the Study:

• To report a rare case of language function dissociation in an epileptic patient.
• To investigate the clinical implications of fMRI laterality indices in atypical language representation.
• To explore the theoretical relationship between motor speech, language comprehension, and Broca's area.

Main Methods:

• Case report of an epileptic patient undergoing presurgical evaluation.
• Utilized functional MRI (fMRI) to assess language lateralization.
• Employed the Wada test (intracarotid amobarbital procedure) to evaluate hemispheric language functions.

Main Results:

• fMRI showed bilateral inferior frontal gyrus distribution and right dominance in the superior temporal gyrus.
• Wada testing revealed left hemisphere motor speech and right hemisphere language comprehension.
• A dissociation between motor speech and language comprehension was observed.

Conclusions:

• fMRI laterality indices for Broca's area should be interpreted cautiously in atypical patients.
• Findings support the separation of motor speech and language comprehension functions.
• This case may provide evidence for Broca's original conclusions regarding motor speech impairment.