Predictive Power of Interictal Epileptiform Discharges in Fitness-to-Drive Evaluation

Abstract

Background:This study aimed to evaluate and predict the effects of interictal epileptiform discharges (IEDs) on driving ability using simple reaction tests and a driving simulator.Methods:Patients with various epilepsies were evaluated with simultaneous EEGs during their response to visual stimuli in a single-flash test, a car-driving videogame, and a realistic driving simulator. Reaction times (RT) and missed reactions or crashes (miss/crash) during normal EEG and IEDs were measured. IEDs, as considered here, were a series of epileptiform potentials (>1 potential) and were classified as generalized typical, generalized atypical, or focal. RT and miss/crash in relation to IED type, duration, and test type were analyzed. RT-prolongation, miss/crash probability, and odds ratio of miss/crash due to IEDs were calculated.Results:Generalized typical IEDs prolonged RT by 164ms, compared to generalized atypical IEDs (77.0ms) and focal IEDs (48.0ms) (p<0.01). Generalized typical IEDs had a session miss/crash probability of 14.7% compared to a zero median for focal and generalized atypical IEDs (p<0.01). Long repetitive bursts of focal IEDs lasting >2s had a 2.6% miss/crash probabilityIED. Cumulated miss/crash probability could be predicted from RT-prolongation: 90.3ms yielded a 20% miss/crash probability. All tests were non-superior to each other in detecting miss/crash probabilitiesIED(zero median for all three tests) or RT-prolongations (flash test: 56.4ms, car-driving videogame: 75.5ms, simulator 86.6ms). IEDs increased the odds ratio (OR) of miss/crash in the simulator by 4.9-fold compared to normal EEG. A table of expected RT-prolongations and miss/crash probabilities for IEDs of a given type and duration was created.Conclusion:IED-associated miss/crash probability and RT-prolongation were comparably well detected by all tests. Long focal IED-bursts carry a low risk, while generalized typical IEDs are the primary cause of miss/crash. We propose a cumulative 20% miss/crash risk at a RT-prolongation of 90.3ms as a clinically relevant IED effect. The IED-associated odds ratio in the simulator approximates the effects of sleepiness or low blood-alcohol level while driving on real roads. A decision aid for fitness-to-drive evaluation was created by providing the expected RT-prolongations and misses/crashes when IEDs of a certain type and duration are detected in routine EEG.

Clearance for Driving in Genetic Generalized Epilepsy

“…Thus, it appears prudent to not provide clearance for driving when discharges are longer than 2 seconds. 8,9 Finally, myoclonic seizures, by definition, do not lead to loss of awareness, but they are known to coalesce and lead to generalized tonic-clonic seizures. 10 Thus, it may be prudent to conclude seizure freedom only when myoclonic seizures are under complete control.…”

Implications for driving based on the risk of seizures after ischaemic stroke

“…3 4 Interictal discharges have an impact on a person's cognition and fitness to drive and need focused investigation in the stroke population. 5 Bioinformatics offers opportunities to assess the biofluid biomarkers of epileptogenicity. 6 Analysis of these multidimensional data to build a COSY prediction model is now possible, thanks to advances in computational neurosciences.…”