Is ictal cognitive dysfunction predictable?

Accurate prediction of electrographic seizure onset may reduce injuries and improve quality of life in pharmaco-resistant epileptics. However, because sub-clinical, far out-number clinical seizures, indiscriminate issuance of warnings may have a paralyzing effect on these patients. This study investigates the predictability of ictal cognitive dysfunction.

Latency and percentage of correct responses to a reaction time test triggered by automated seizure detections were compared to those obtained inter-ictally in 14 subjects undergoing surgery evaluation. Since accurate prediction of seizures is elusive, early detection was used, as it indirectly but reliably investigates for the existence of a cognitive pre-ictal state.

Significant differences between ictal and inter-ictal cognitive performance were not uncovered until late into the temporal evolution of "focal" seizures.

These observations suggest that cognitive dysfunction is unpredictable in seizures originating from discrete cortical regions, as the transition into unawareness seems abrupt.

Prediction of electrographic seizure onsets with worthwhile accuracy would likely result in large numbers of daily warnings, the great majority for sub-clinical seizures. This outcome would considerably increase, without safety justification, patients' psychological burden inherent to each forecast, thus further diminishing quality of life.