Abstracts

Duration of drug effect is a critical factor when measuring language and memory function during the intracarotid sodium amytal procedure (Wada test). Positive correlations have previously been reported between patient age and duration of drug effect. Prior studies have also indicated longer recovery times following the second injection if administered on the same day and greater sedation following dominant hemisphere injection.
The purpose of this study was to identify potential correlations between age and recovery times following sodium amytal injection. Potential differences in order and side of injection, and gender were also explored. A retrospective database study was completed of 93 patients who had Wada testing between 2002 and 2005 as part of their pre-surgical evaluation for medically intractable epilepsy. The Regional Epilepsy Center employs the Wada test protocol developed by the Medical College of Georgia. Patients whose injection amounts differed between injections were excluded from this study (36/93).
A total of 57 patients were included in this analysis (114 hemispheric injections). The patient group included 36 female and 21 male patients ranging in age from 8 to 73 years (mean = 38.32; SD = 15.86). Recovery times for motor function and EEG were correlated with each other and with age using Spearman[apos]s rank correlation coefficient. Within subjects analysis of variance was conducted to explore effects of order and side of injection, and gender on recovery times. Recovery time to baseline motor strength, drift, asterixis, and EEG were significantly correlated with one another (p [lt] .0001). Age, however, did not correlate with any of the recovery variables (p [gt] .05). There was also no significant effect of injection order, side of injection, or gender on any of the recovery time variables, based upon multiple ANOVA comparisons. Contrary to results of prior studies, this study found no correlation between age and recovery time for motor variables or baseline EEG. Additional analysis of our data using 10-year age clusters similar to those utilized in the Segal et al (2002) study did not reveal similar results, in that our youngest age clusters did not reveal faster recovery times, and the reason for this descrepancy in results is unknown.
In addition, prior research has suggested a cumulative effect of injections, but this study found no difference in recovery between the first and second injections. Furthermore, there were no noted differences in recovery times following left versus right injections or male versus female patients.
The lack of significant correlations between age and recovery of function, between administration order, side of injection, and gender suggest that Wada testing may be more robust than previous studies have indicated. Further prospective research on these variables with larger samples is recommended to determine their relationship, if any, on recovery of function following injection.