Clinical Significance of Bilateral Failures on Wada Memory Testing

Objective: The goal of this study is to better understand the significance of bilateral memory failures on Wada testing Background: The intracarotid amobarbital procedure, or Wada Test, evaluates the risk of language or memory deficits following epilepsy surgery. Particularly in the people with temporal lobe epilepsy, bilateral failure of Wada memory testing indicates an increase risk of post surgical amnestic syndrome, and many centers reject those from Phase II evaluations or temporal lobe resections Design/Methods: It is a retrospective study of 32 consecutive patients who underwent Wada testing, as part of the pre surgical evaluation. We defined patients with bilateral failures, if they were able to recognize less than three out of eight objects after injection on both side. We compared this group of bilateral failures with patients that passed at least one side and compared localization of the seizure focus, etiology, ictal and interracial findings on scalp EEG and FSIQ Results: Patients failing memory testing bilaterally were slightly older (38 vs 32 years old), predominantly male (6/8 vs 8/24), with similar duration of epilepsy and general ability indices as the patients that passed at least one injection. The etiology of the epilepsy was mesial temporal sclerosis in half of the patients with bilateral failures, however in one case with neocortical temporal involvement, in the other with orbitofrontal encephalomalacia. Half of this group underwent extratemporal resections. Cortical dysplasia (3/8 vs 1/24) and encephalomalacia (2/8 vs 1/24) were also more common in the group with bilateral failures. Six of eight had left hemispheric seizure onset zone compared to 14 of 24 in the control group. Conclusions: Bilateral failure of Wada memory testing is associated with male sex and increased prevalence of extratemporal epileptogenic zones with cortical developmental pathology or injury. While there is a need to correlate these abnormalities with EEG findings, bilateral memory failure may reflect extratemporal pathology, and may require more extensive cortical sampling in the setting of Phase II investigations. Disclosure: Dr. Suchita has nothing to disclose. Dr. Gonzalez has nothing to disclose. Dr. Morgan has nothing to disclose. Dr. Karkar has nothing to disclose. Dr. Lie has nothing to disclose. Dr. Rashid has nothing to disclose. Dr. Sullivan has nothing to disclose. Dr. Papanastassiou has nothing to disclose. Dr. Szabo has nothing to disclose.