Optimum recording time of routine electroencephalogram for adults with epilepsy*

Abstract

Background/aim This study aimed to reveal the optimum recording time of routine electroencephalogram (EEG) for adults with epilepsy. Materials and methods In this clinical observational study we investigated features of paroxysms that emerged in EEGs recorded for 45 min in adults with epilepsy. Results Paroxysms were detected in 38.14% of 97 patients. The probability of occurrence of paroxysm during the first 10 min was found to be statistically significantly low in comparison to the first 30 and 45 min (respectively P = 0.004, P = 0.0001). This probability was found to increase insignificantly when comparing the first 20 min with the first 30 min (P = 0.125), but it increased significantly in comparison to 45 min (P = 0.008). On the other hand, this probability was found to increase insignificantly when comparing the first 30 min with the first 45 min (P = 0.125). The cutoff point to specify the existence of interictal epileptiform discharges in the ROC analysis was found to be ≤39 min (95% CI: 0.958–1.000), and 90% of interictal epileptiform discharges were revealed during the first 30 min of EEG recording. Conclusion The recording time of routine EEGs for adults with epilepsy should not be less 30 min.