Abstracts

This is a case report of a 33- year-old right-handed male with medical refractory seizures who was found to have partial agenesis of the corpus callosum during routine presurgical work-up. We report here pre- and post-surgical neuropsychological and fMRI testing in this patient with partial agenesis of the corpus callosum and bilateral language representation.
The patient initially had routine presurgical work-up for seizures refractory to multiple antiepileptic medications. Video EEG, MRI, and PET scans were obtained using standard methods.Routine WADA testing involved intracarotid Amytal injection with EEG monitoring and neuropsychological evaluation of speech and memory. The fMRI studies analyzed responses to six different language tasks. Neuropsychological testing was performed. The surgical procedure was a right frontotemporal craniotomy and partial right temporal lobectomy with intraoperative electrocorticography.
Video EEG monitoring revealed ictal recordings of right temporal onset seizures. PET scan showed right temporal hypometabolism. Structural MRI revealed partial agenesis of the corpus callosum with missing body and splenium. WADA (intracarotid amytal) testing suggested that language was bilaterally represented, with some advantage for the left hemisphere. Memory testing revealed better recall after right injection versus left injection, a finding that is consistent with a suspected right temporal seizure focus. Functional MRI (fMRI) performed prior to surgery also showed bilateral language representation with more involvement of the left hemisphere. Preoperative neuropsychological assessment revealed borderline overall intellectual functioning with average to defective language measures. Confrontation naming was lower than expected. Verbal memory testing was more impaired than visual memory testing. The patient underwent a right anterior temporal lobectomy with intraoperative electrocorticography and mild gliosis on pathology. At three months post-op the patient is seizure free with occasional auras (Engel class II). Repeat fMRI analysis after surgery revealed persistent bilateral language representation, with some possible increased left lateralization. Three month follow-up neuropsychological testing showed mild improvements in attention and expressive language (naming and verbal fluency).
In summary, this is a novel case of a patient with partial agenesis of the corpus callosum and bilateral language representation determined by WADA and fMRI. Post-surgical testing suggests a removal of inhibitory influence from the right hemisphere after surgery, allowing for increased language expression in the left hemisphere. Despite bilateral language, the patient tolerated right temporal lobectomy without any affect on language testing. In fact, there was a modest impovement on language testing after surgery.