Abstracts

Rationale: Why do seizures cause a loss of consciousness? Prior studies of consciousness with inpatient video/EEG monitoring have been based on a retrospective review of patient behavior and responses to questions or commands in a non-standardized fashion. We have developed a virtual reality driving task to prospectively study patient behavior during seizures. In addition, by using a driving task, we hope to identify brain regions associated with impaired driving safety in epilepsy. Methods: Patients undergoing continuous video/EEG monitoring played the racing car simulator video game, rFactor, with a steering wheel, throttle, and brake pedals. The game outputs continuous data on subject input (steering wheel position and throttle/brake depression) as well as vehicle telemetry (position, orientation, velocity, acceleration, etc) and performance. Game and video/EEG data were placed on the same time scale using a synchronization pulse generated by the game system and recorded on the EEG. Two types of impaired driving were identified: crashing into moving or immovable objects, and spinning out of control. Results: Fourteen patients enrolled in the study and played the game for sustained periods of time (43 hours total; range 1.5 to 9 hours per patient). In this sample, we observed two clinical seizures and nine subclinical seizures during simulated driving. The method of EEG-game synchronization was accurate and consistent to within a tenth of a second. Driving was impaired during some seizures and unimpaired in others. During a supplementary motor seizure, ictal arm movements caused the car to “spin out.” However, during a complex partial seizure, the patient continued to drive initially, and then did not avoid obstacles and struck a wall. During subclinical seizures, including prolonged focal spike-wave discharges in one patient, driving performance was not impaired based on this analysis. Conclusions: Patients were motivated to play this driving game for long periods of time during video/EEG monitoring. Seizures were recorded while engaged in the task, which demonstrates the feasibility of this method for prospectively evaluating consciousness during video/EEG monitoring. Further investigations will include: 1) more sophisticated analysis of game performance; 2) use of performance on these behavioral tasks together with ictal SPECT and intracranial EEG to localize the brain regions important for impaired driving performance during seizures; 3) develop a predictive model for determining driving safety risk in patients with epilepsy; and 4) develop other virtual reality systems to prospectively assess behavioral changes and impaired consciousness during seizures. This work was supported by the Donaghue Foundation and by Betsy and Jonathan Blattmachr.