Abstracts

While considerable attention has been paid to baseline material specific memory functioning as an indicator of seizure lateralization in patients with medically intractable temporal lobe epilepsy (TLE), less is known about the lateralization value of baseline discrepancies in other cognitive domains. Given the interconnections between the temporal lobes and brain areas ipsilateral to the seizure focus, disruption in these networks could impact other cognitive skills. This study explored the lateralization value of the verbal intelligence quotient (VIQ) and performance intelligence quotient (PIQ) in a pre-surgical TLE sample. Specifically, it was hypothesized that patients with VIQ less than PIQ will have a left hemisphere seizure onset while the reverse (PIQ[lt]VIQ) will be associated with a right hemisphere seizure onset., The sample consisted of 188 patients with intractable TLE who underwent anterior temporal lobectomy at the University of Washington Regional Epilepsy Center between 1998 and 2004. Intellectual functioning was assessed with the Wechsler Adult Intelligence Scale (3rd Edition) prior to surgery. Average full scale IQ for the entire sample was 88.42 (SD = 13.10). Seizure onset was localized by correlating long-term video/EEG monitoring and, if necessary, subsequent invasive recording with other diagnostic information, including cranial MRI, in all patients. The sample consisted of 114 (61%) patients with left temporal lobe seizure onset and 74 with right temporal lobe onset., As predicted, VIQ was significantly lower in patients with left temporal lobe seizure onset compared to those with right seizure onset [[italic]t[/italic](186) = -2.18, [italic]p[/italic] [lt].05], although PIQ did not differ across groups [[italic]t[/italic](186) = -.06, [italic]ns[/italic]]. Thirty-nine percent (n = 73) of the sample had a VIQ-PIQ discrepancy of greater than 10 points in either direction and were included in the following analyses. The likelihood of left or right hemisphere seizure onset varied significantly depending on the direction of the VIQ-PIQ discrepancy [[chi][sup2]= 5.27, [italic]p[/italic] [lt].05]. As hypothesized, among those with a VIQ[lt]PIQ (n = 53), 74% had a left hemisphere seizure onset. However, among those with a PIQ[lt]VIQ (n = 20), only 55% had a right hemisphere seizure onset., Our study indicates that patients with a left temporal lobe seizure onset have a lower VIQ, while those with right temporal lobe seizure onset do not have a lower PIQ. Further, while 74% of patients with VIQ[lt]PIQ have a left temporal lobe seizure onset, a discrepancy in the opposite direction is not associated with right temporal lobe seizure onset. This pattern of findings (i.e., verbal performance related to left hemisphere functioning; nonverbal performance unrelated to right hemisphere functioning) is consistent with findings from the material specific memory literature.,