Abstracts

RATIONALE: Cross-center variation exists in the manner in which Wada procedures are performed, and this variation may well have increased over the past decade with the increasing numbers of epilepsy surgery centers. However, few data are available that characterize such the extent and nature of such variation. This poster is meant to (a) provide the reader with a current understanding of the variations in this component of neurological practice, and (b) highlight areas of discrepancy that empirical efforts may need to address.
METHODS: A 10-question survey on current Wada procedures was distributed via neurology and neuropsychology listservs, and responses were clarified via email when they were unclear. To date, 21 North American (20 US, 1 Canadian) centers have responded.
RESULTS: Fourteen of the 21 respondents perform more than one Wada per month. Nearly every center uses amytal rather than brevital, and all but one center test only the anterior circulation. Every center injects both hemispheres on the same day, but the time between injections remains quite variable (mean = 34.5, sd = 15.12). Dosages have become relatively consistent between centers (dose1: mean = 111.87, sd = 12.89; dose 2: mean = 111.77, sd = 12.89), although some variability remains in whether centers use the same dosage in each hemisphere (69%), dose each differently (6%), titrate each individually (10%), or link second dosage to response to first dosage (15%). Likewise, the endpoints used to determine when to begin testing (hemiplegia, focal slowing on EEG, both, or some other criterion) remain variable (10%, 10%, 62%, and 18%, respectively). Finally, substantial variability remains between centers in terms of when they perform baseline neuropsychological testing (same day [ndash] 43%, different day [ndash] 48%, both [ndash] 4%, none [ndash] 4%).
CONCLUSIONS: There continues to be substantial heterogeneity in specific protocols used, although some changes are evident relative to earlier surveys. The range of dosing appears smaller, and the use of superselective procedures has decreased from approximately 20% in the early 1990[ssquote]s. The clinical impact of the remaining differences remains largely unknown. It is hoped that this survey can help to guide empirical examinations of the potential clinical implications of such variations by highlighting the practices that remain most discrepant between centers.