Wada Memory Disparities Predict Seizure Laterality and Postoperative Seizure Control

Publisher Website
Google Scholar
Abstract
Summary: We examined the efficacy of a memory difference score (DS: right minus left hemisphere memory) during the Wada test (intracarotid amobarbital procedure, IAP) for predicting seizure laterality and postoperative seizure outcome in 70 left speech dominant patients from two epilepsy centers. DS ≥2, after addition of 1 point to the left hemisphere injection score to account for aphasia, were noted in 71. 4% of patients and correctly predicted surgery side for 98. 0% of these patients. The DS related significantly to seizure outcome at 1–year follow‐up (p < 0.002) and correctly predicted 80% of patients who were The Wada test, or intracarotid amobarbital procedure (IAP), is traditionally used to determine the laterality of language dominance and to assess the memory competence in the hemisphere contralateral to the proposed temporal lobectomy in an effort to avoid postoperative amnesia (1–6). Ipsilateral memory testing (adequacy of the hemisphere ipsilateral to anticipated resection) also is frequently examined. The validity of IAP memory testing as a measure of temporal lobe function is demonstrated by correlating IAP memory scores of the affected hemisphere with hippocampal cell counts (7,8) and with hippocampal volume assessed by magnetic resonance imaging (MRI) (9). The disparity between ipsilateral and contralateral memory scores is often predictive of seizure focus laterality (1 1–18). However, most studies have examined group means rather than the utility of the DS for predicting the seizure focus in specific patients. To date, only Loring et al. (9) have reported Presented in part at the Annual Meeting of the International Neuropsychological Society, Galveston, Texas, February 1993. seizure‐free. Patients whose DS did not correctly predict seizure laterality more frequently required invasive studies to establish seizure onset. The relationship of the DS to laterality did not differ significantly by class of IAP memory stimuli. When seizures originate from the temporal lobe, the IAP memory DS predicts seizure laterality by assessing the functional adequacy of the involved hemisphere and is predictive of seizure control.