Abstracts

Rationale: Stereotactic laser amygdalohippocampectomy (SLAH) is an alternative to standard temporal lobectomy (STLE) in patients with temporal lobe epilepsy (TLE).  SLAH may be preferable to STLE because it is less invasive and has the potential to minimize post-surgical cognitive deficits; however, limited data comparing the cognitive outcomes between these procedures is available. Methods: Pre- and post-operative neuropsychological data from 23 patients who underwent dominant hemisphere STLE (12 males; age M = 33 years) and 21 patients who underwent dominant hemisphere SLAH (12 males; age M = 41 years) between 2008 and 2017 were retrospectively analyzed.  The groups did not differ in terms of age, gender, or intelligence (SLAH M = 94.77, SD = 19.03; STLE M = 90.16, SD = 18.46).  The left hemisphere was presumed language dominant in right-handed patients where Wada results were not available.  Wada results confirmed language laterality in all left-handed patients.  Pre-surgical MRIs indicated 31.82% (n = 14) of patients had normal MRIs, 40.91% (n = 18) had findings isolated to the left temporal lobe, and 25% (n = 11) had findings outside the left temporal lobe.  Mean evaluation time post-surgery was 5.9 months and 8.2 months for SLAH and STLE patients, respectively.  Outcome measures were Z-scores on the Boston Naming Test, Second Edition (BNT) and the Long Delay Free Recall portion of the California Verbal Learning Test, Second Edition (CVLT-II).  A change in raw score across the surgery of plus or minus 5 points on the BNT was used as a reliable change index (RCI), one measure of statistically meaningful change (Epilepsy Behav. 2012; 24(2): 194-8.). Results: Data were analyzed using a general linear model approach with post-operative performance as the dependent variable, surgery type (STLE, SLAH) as the independent variable, and pre-operative performance as a covariate entered first in the equation (Work. 2003; 20(2): 159-65.).  There were no significant findings for the CVLT-II, p < .30; however, findings for the BNT were significant, F(1,41) = 5.93, p < .02.  As shown in Table 1, the STLE group experienced a greater decline in naming, but not memory, after surgery than the SLAH group.  Analyses of group effect on RCI data using Fisher’s exact test were marginally significant (p < .07).  As shown in Table 2, more patients in the SLAH group exhibited improvement, and fewer a decline. Conclusions: Findings suggest patients undergoing dominant hemisphere SLAH experienced less decline in naming, but a similar decline in memory, after surgery as compared to STLE patients.  They also experienced a greater rate of improvement and a reduced rate of decline compared to the STLE group in visual naming.  These preliminary results suggest SLAH’s minimally-invasive nature may minimize some post-surgical verbal deficits compared to STLE, but does not appear to preserve verbal memory more effectively than STLE. Funding: No funding was received in support of this abstract.