Abstracts

Rationale: Impaired consciousness in epilepsy is challenging to study using objective measures. We previously devised a prospective testing battery which provides objective data on patient responsiveness and cognition during seizures, the Responsiveness in Epilepsy Scale (RES). However, since the RES was cumbersome to administer, we recently developed a simpler, revised version (RES-II). This revised scale still evaluates a wide range of cognitive and sensorimotor functions, yet was designed to be faster and less error-prone. Methods: To validate the new scale, we compared RES and RES-II in an epilepsy monitoring unit. Patients undergoing continuous video/EEG monitoring (VEEG) for seizure evaluation at Yale New Haven Hospital were tested with RES or RES-II during the ictal and immediate postictal periods. We compared data from RES (75 seizures in 24 patients) with RES-II (34 seizures in 11 patients). Results: With the new scale, more questions were asked per ictal period on average (13.4 vs 7.1). There was a trend towards a decrease in the average time required to ask one question during the ictal period, decreasing from a mean of 16.4 to 10.9 seconds (p=0.08). In spite of this quicker pace, and an identical administrator training process, there was a nearly 10-fold reduction in the average number of errors during administration of the revised scale, decreasing from 2.01 to 0.24 errors per seizure (p<0.01). All errors consisted of the tester asking a question out of sequence or asking the wrong question. Performance on the initial cycle of questions asked upon onset of partial seizures showed a bimodal distribution, similar to the pattern of impairment observed using RES. On these initial questions, patients tended to be either entirely unimpaired or completely unresponsive in most seizures. This distribution of impairment was typically sustained until seizure termination. These distinct patterns of impairment correlate with those seen in the traditional categories of "simple partial" and "complex partial" seizures. Conclusions: Our results demonstrate that prospective testing of responsiveness during seizures can be reliably performed using the revised RES-II scale. RES-II is substantially less error-prone and simpler to administer, yet patterns of impairment observed using the revised scale were similar to those using the prior scale. Improved objective testing of impaired consciousness in epilepsy may lead to better physiological understanding of ictal cognitive deficits.